From 5914fb779ff22ca2e58f78bace7176c5fccbd788 Mon Sep 17 00:00:00 2001
From: Urgau <urgau@numericable.fr>
Date: Sun, 15 Dec 2024 16:17:05 +0100
Subject: Stabilize `num_midpoint_signed` feature

---
 library/core/src/num/mod.rs    | 8 ++++----
 library/coretests/tests/lib.rs | 1 -
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/library/core/src/num/mod.rs b/library/core/src/num/mod.rs
index 6c1b568e231..b479b8502a8 100644
--- a/library/core/src/num/mod.rs
+++ b/library/core/src/num/mod.rs
@@ -163,14 +163,14 @@ macro_rules! midpoint_impl {
         /// # Examples
         ///
         /// ```
-        /// #![feature(num_midpoint_signed)]
         #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".midpoint(4), 2);")]
         #[doc = concat!("assert_eq!((-1", stringify!($SelfT), ").midpoint(2), 0);")]
         #[doc = concat!("assert_eq!((-7", stringify!($SelfT), ").midpoint(0), -3);")]
         #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".midpoint(-7), -3);")]
         #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".midpoint(7), 3);")]
         /// ```
-        #[unstable(feature = "num_midpoint_signed", issue = "110840")]
+        #[stable(feature = "num_midpoint_signed", since = "CURRENT_RUSTC_VERSION")]
+        #[rustc_const_stable(feature = "num_midpoint_signed", since = "CURRENT_RUSTC_VERSION")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -215,14 +215,14 @@ macro_rules! midpoint_impl {
         /// # Examples
         ///
         /// ```
-        /// #![feature(num_midpoint_signed)]
         #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".midpoint(4), 2);")]
         #[doc = concat!("assert_eq!((-1", stringify!($SelfT), ").midpoint(2), 0);")]
         #[doc = concat!("assert_eq!((-7", stringify!($SelfT), ").midpoint(0), -3);")]
         #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".midpoint(-7), -3);")]
         #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".midpoint(7), 3);")]
         /// ```
-        #[unstable(feature = "num_midpoint_signed", issue = "110840")]
+        #[stable(feature = "num_midpoint_signed", since = "CURRENT_RUSTC_VERSION")]
+        #[rustc_const_stable(feature = "num_midpoint_signed", since = "CURRENT_RUSTC_VERSION")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
diff --git a/library/coretests/tests/lib.rs b/library/coretests/tests/lib.rs
index 0607d508a48..7353f12f457 100644
--- a/library/coretests/tests/lib.rs
+++ b/library/coretests/tests/lib.rs
@@ -63,7 +63,6 @@
 #![feature(maybe_uninit_write_slice)]
 #![feature(min_specialization)]
 #![feature(never_type)]
-#![feature(num_midpoint_signed)]
 #![feature(numfmt)]
 #![feature(pattern)]
 #![feature(pointer_is_aligned_to)]
-- 
cgit 1.4.1-3-g733a5


From 2445dd794e4e24d62ab8d79ba8924baba44865ae Mon Sep 17 00:00:00 2001
From: kulst <kulst@mailbox.org>
Date: Sun, 9 Feb 2025 11:50:06 +0100
Subject: Persist target features used for codegen beyond tcx

Bitcode linkers like llvm-bitcode-linker or bpf linker hand over the target features to llvm during link stage. During link stage the `TyCtxt` is already gone so it is not possible to create a query for the global backend features any longer. The features preserved in `Session.target_features` only incorporate target features known to rustc. This would contradict with the behaviour during codegen stage which also passes target features to llvm which are unknown to rustc.
This commit adds target features as a field to the `CrateInfo` struct and queries the target features in its new function. This way the target features are preserved beyond tcx and available at link stage.
To make sure the `global_backend_features` query is always registered even if the CodegenBackend does not register it, this registration is added to the `provide`function of the `rustc_codegen_ssa` crate.
---
 compiler/rustc_codegen_ssa/src/base.rs | 1 +
 compiler/rustc_codegen_ssa/src/lib.rs  | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs
index e800492dad0..0b420fcfaae 100644
--- a/compiler/rustc_codegen_ssa/src/base.rs
+++ b/compiler/rustc_codegen_ssa/src/base.rs
@@ -921,6 +921,7 @@ impl CrateInfo {
         let n_crates = crates.len();
         let mut info = CrateInfo {
             target_cpu,
+            target_features: tcx.global_backend_features(()).clone(),
             crate_types,
             exported_symbols,
             linked_symbols,
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index 428a45975f1..9d2ac219d59 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -190,6 +190,7 @@ impl From<&cstore::NativeLib> for NativeLib {
 #[derive(Debug, Encodable, Decodable)]
 pub struct CrateInfo {
     pub target_cpu: String,
+    pub target_features: Vec<String>,
     pub crate_types: Vec<CrateType>,
     pub exported_symbols: UnordMap<CrateType, Vec<String>>,
     pub linked_symbols: FxIndexMap<CrateType, Vec<(String, SymbolExportKind)>>,
@@ -230,6 +231,7 @@ pub fn provide(providers: &mut Providers) {
     crate::base::provide(providers);
     crate::target_features::provide(providers);
     crate::codegen_attrs::provide(providers);
+    providers.queries.global_backend_features = |_tcx: TyCtxt<'_>, ()| vec![];
 }
 
 /// Checks if the given filename ends with the `.rcgu.o` extension that `rustc`
-- 
cgit 1.4.1-3-g733a5


From 831d9f39e9c330934b7c4f35010477ba4a738d96 Mon Sep 17 00:00:00 2001
From: kulst <kulst@mailbox.org>
Date: Wed, 5 Feb 2025 21:33:58 +0100
Subject: Pass through of target features to llvm-bitcode-linker and handling
 them

The .ptx version produced by llc can be specified by passing it with --mattr. Currently it is not possible to specify the .ptx version with -Ctarget-feature because these are not passed through to llvm-bitcode-linker and handled by it. This commit adds both.
--target-feature and -mattr are passed with equals to mitigate issues when the value starts with a - (minus).
---
 compiler/rustc_codegen_ssa/src/back/link.rs                 |  6 ++++++
 .../llvm-bitcode-linker/src/bin/llvm-bitcode-linker.rs      |  6 +++++-
 src/tools/llvm-bitcode-linker/src/linker.rs                 | 13 ++++++++++++-
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 105a4cb81f0..dceef52e81a 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -2518,6 +2518,12 @@ fn add_order_independent_options(
             "--target-cpu",
             &codegen_results.crate_info.target_cpu,
         ]);
+        if codegen_results.crate_info.target_features.len() > 0 {
+            cmd.link_arg(&format!(
+                "--target-feature={}",
+                &codegen_results.crate_info.target_features.join(",")
+            ));
+        }
     } else if flavor == LinkerFlavor::Ptx {
         cmd.link_args(&["--fallback-arch", &codegen_results.crate_info.target_cpu]);
     } else if flavor == LinkerFlavor::Bpf {
diff --git a/src/tools/llvm-bitcode-linker/src/bin/llvm-bitcode-linker.rs b/src/tools/llvm-bitcode-linker/src/bin/llvm-bitcode-linker.rs
index fdbf6171c53..608c6605304 100644
--- a/src/tools/llvm-bitcode-linker/src/bin/llvm-bitcode-linker.rs
+++ b/src/tools/llvm-bitcode-linker/src/bin/llvm-bitcode-linker.rs
@@ -27,6 +27,10 @@ pub struct Args {
     #[arg(long)]
     target_cpu: Option<String>,
 
+    /// The target features
+    #[arg(long)]
+    target_feature: Option<String>,
+
     /// Write output to the filename
     #[arg(short, long)]
     output: PathBuf,
@@ -49,7 +53,7 @@ fn main() -> anyhow::Result<()> {
 
     let args = Args::parse();
 
-    let mut linker = Session::new(args.target, args.target_cpu, args.output);
+    let mut linker = Session::new(args.target, args.target_cpu, args.target_feature, args.output);
 
     linker.add_exported_symbols(args.export_symbol);
 
diff --git a/src/tools/llvm-bitcode-linker/src/linker.rs b/src/tools/llvm-bitcode-linker/src/linker.rs
index 9f579d10094..dafd847e768 100644
--- a/src/tools/llvm-bitcode-linker/src/linker.rs
+++ b/src/tools/llvm-bitcode-linker/src/linker.rs
@@ -8,6 +8,7 @@ use crate::{Optimization, Target};
 pub struct Session {
     target: Target,
     cpu: Option<String>,
+    feature: Option<String>,
     symbols: Vec<String>,
 
     /// A file that `llvm-link` supports, like a bitcode file or an archive.
@@ -21,7 +22,12 @@ pub struct Session {
 }
 
 impl Session {
-    pub fn new(target: crate::Target, cpu: Option<String>, out_path: PathBuf) -> Self {
+    pub fn new(
+        target: crate::Target,
+        cpu: Option<String>,
+        feature: Option<String>,
+        out_path: PathBuf,
+    ) -> Self {
         let link_path = out_path.with_extension("o");
         let opt_path = out_path.with_extension("optimized.o");
         let sym_path = out_path.with_extension("symbols.txt");
@@ -29,6 +35,7 @@ impl Session {
         Session {
             target,
             cpu,
+            feature,
             symbols: Vec::new(),
             files: Vec::new(),
             link_path,
@@ -134,6 +141,10 @@ impl Session {
             lcc_command.arg("--mcpu").arg(mcpu);
         }
 
+        if let Some(mattr) = &self.feature {
+            lcc_command.arg(&format!("--mattr={}", mattr));
+        }
+
         let lcc_output = lcc_command
             .arg(&self.opt_path)
             .arg("-o").arg(&self.out_path)
-- 
cgit 1.4.1-3-g733a5


From 35febd7a6d57179f41cb5b4a37f9545915e4d7a5 Mon Sep 17 00:00:00 2001
From: Li Keqing <auroracloud4096@gmail.com>
Date: Wed, 19 Feb 2025 18:05:37 +0800
Subject: Fix `*-win7-windows-msvc` target since
 26eeac1a1e9fe46ffd80dd0d3dafdd2c2a644306

---
 library/std/src/sys/pal/windows/c.rs                | 4 ++--
 library/std/src/sys/random/windows.rs               | 2 +-
 library/std/src/sys/sync/mutex/windows7.rs          | 2 +-
 library/std/src/sys/sync/thread_parking/windows7.rs | 8 ++++----
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/library/std/src/sys/pal/windows/c.rs b/library/std/src/sys/pal/windows/c.rs
index 8dc61edb603..4fbdc839939 100644
--- a/library/std/src/sys/pal/windows/c.rs
+++ b/library/std/src/sys/pal/windows/c.rs
@@ -204,7 +204,7 @@ compat_fn_with_fallback! {
     pub fn NtReleaseKeyedEvent(
         EventHandle: HANDLE,
         Key: *const c_void,
-        Alertable: BOOLEAN,
+        Alertable: bool,
         Timeout: *mut i64
     ) -> NTSTATUS {
         panic!("keyed events not available")
@@ -213,7 +213,7 @@ compat_fn_with_fallback! {
     pub fn NtWaitForKeyedEvent(
         EventHandle: HANDLE,
         Key: *const c_void,
-        Alertable: BOOLEAN,
+        Alertable: bool,
         Timeout: *mut i64
     ) -> NTSTATUS {
         panic!("keyed events not available")
diff --git a/library/std/src/sys/random/windows.rs b/library/std/src/sys/random/windows.rs
index 7566000f9e6..f5da637f56c 100644
--- a/library/std/src/sys/random/windows.rs
+++ b/library/std/src/sys/random/windows.rs
@@ -14,7 +14,7 @@ pub fn fill_bytes(mut bytes: &mut [u8]) {
     while !bytes.is_empty() {
         let len = bytes.len().try_into().unwrap_or(u32::MAX);
         let ret = unsafe { c::RtlGenRandom(bytes.as_mut_ptr().cast(), len) };
-        assert_ne!(ret, 0, "failed to generate random data");
+        assert!(ret, "failed to generate random data");
         bytes = &mut bytes[len as usize..];
     }
 }
diff --git a/library/std/src/sys/sync/mutex/windows7.rs b/library/std/src/sys/sync/mutex/windows7.rs
index 689dba10f01..0b57de78ba6 100644
--- a/library/std/src/sys/sync/mutex/windows7.rs
+++ b/library/std/src/sys/sync/mutex/windows7.rs
@@ -44,7 +44,7 @@ impl Mutex {
 
     #[inline]
     pub fn try_lock(&self) -> bool {
-        unsafe { c::TryAcquireSRWLockExclusive(raw(self)) != 0 }
+        unsafe { c::TryAcquireSRWLockExclusive(raw(self)) }
     }
 
     #[inline]
diff --git a/library/std/src/sys/sync/thread_parking/windows7.rs b/library/std/src/sys/sync/thread_parking/windows7.rs
index f7585e882f0..a1a0f8427cd 100644
--- a/library/std/src/sys/sync/thread_parking/windows7.rs
+++ b/library/std/src/sys/sync/thread_parking/windows7.rs
@@ -195,7 +195,7 @@ mod keyed_events {
 
     pub unsafe fn park(parker: Pin<&Parker>) {
         // Wait for unpark() to produce this event.
-        c::NtWaitForKeyedEvent(keyed_event_handle(), parker.ptr(), 0, ptr::null_mut());
+        c::NtWaitForKeyedEvent(keyed_event_handle(), parker.ptr(), false, ptr::null_mut());
         // Set the state back to EMPTY (from either PARKED or NOTIFIED).
         // Note that we don't just write EMPTY, but use swap() to also
         // include an acquire-ordered read to synchronize with unpark()'s
@@ -218,7 +218,7 @@ mod keyed_events {
 
         // Wait for unpark() to produce this event.
         let unparked =
-            c::NtWaitForKeyedEvent(handle, parker.ptr(), 0, &mut timeout) == c::STATUS_SUCCESS;
+            c::NtWaitForKeyedEvent(handle, parker.ptr(), false, &mut timeout) == c::STATUS_SUCCESS;
 
         // Set the state back to EMPTY (from either PARKED or NOTIFIED).
         let prev_state = parker.state.swap(EMPTY, Acquire);
@@ -228,7 +228,7 @@ mod keyed_events {
             // was set to NOTIFIED, which means we *just* missed an
             // unpark(), which is now blocked on us to wait for it.
             // Wait for it to consume the event and unblock that thread.
-            c::NtWaitForKeyedEvent(handle, parker.ptr(), 0, ptr::null_mut());
+            c::NtWaitForKeyedEvent(handle, parker.ptr(), false, ptr::null_mut());
         }
     }
     pub unsafe fn unpark(parker: Pin<&Parker>) {
@@ -239,7 +239,7 @@ mod keyed_events {
         // To prevent this thread from blocking indefinitely in that case,
         // park_impl() will, after seeing the state set to NOTIFIED after
         // waking up, call NtWaitForKeyedEvent again to unblock us.
-        c::NtReleaseKeyedEvent(keyed_event_handle(), parker.ptr(), 0, ptr::null_mut());
+        c::NtReleaseKeyedEvent(keyed_event_handle(), parker.ptr(), false, ptr::null_mut());
     }
 
     fn keyed_event_handle() -> c::HANDLE {
-- 
cgit 1.4.1-3-g733a5


From 78ddabf31d3147a19be77c3b38b49fe60915d75a Mon Sep 17 00:00:00 2001
From: Patryk Wychowaniec <pwychowaniec@pm.me>
Date: Sun, 13 Oct 2024 14:58:44 +0200
Subject: Create a generic AVR target: avr-none

This commit removes the `avr-unknown-gnu-atmega328` target and replaces
it with a more generic `avr-none` variant that must be specialized with
the `-C target-cpu` flag (e.g. `-C target-cpu=atmega328p`).
---
 compiler/rustc_codegen_ssa/src/back/link.rs        |   1 +
 compiler/rustc_codegen_ssa/src/back/linker.rs      |  12 +
 compiler/rustc_target/src/spec/base/avr.rs         | 337 ++++++++++++++++++
 compiler/rustc_target/src/spec/base/avr_gnu.rs     | 377 ---------------------
 compiler/rustc_target/src/spec/base/mod.rs         |   2 +-
 compiler/rustc_target/src/spec/mod.rs              |   9 +-
 compiler/rustc_target/src/spec/targets/avr_none.rs |  32 ++
 .../src/spec/targets/avr_unknown_gnu_atmega328.rs  |   5 -
 src/doc/rustc/src/platform-support.md              |   2 +-
 src/doc/rustc/src/platform-support/avr-none.md     |  81 +++++
 src/tools/compiletest/src/header/tests.rs          |   3 +
 .../run-make-support/src/external_deps/rustc.rs    |   7 +
 tests/assembly/asm/avr-modifiers.rs                |   2 +-
 tests/assembly/asm/avr-types.rs                    |   2 +-
 tests/assembly/targets/targets-pe.rs               |   6 +-
 tests/codegen/asm/avr-clobbers.rs                  |   2 +-
 tests/codegen/avr/avr-func-addrspace.rs            |   2 +-
 tests/run-make/avr-rjmp-offset/rmake.rs            |   4 +-
 .../feature-gate-abi-avr-interrupt.rs              |   2 +-
 tests/ui/repr/16-bit-repr-c-enum.rs                |   2 +-
 20 files changed, 493 insertions(+), 397 deletions(-)
 create mode 100644 compiler/rustc_target/src/spec/base/avr.rs
 delete mode 100644 compiler/rustc_target/src/spec/base/avr_gnu.rs
 create mode 100644 compiler/rustc_target/src/spec/targets/avr_none.rs
 delete mode 100644 compiler/rustc_target/src/spec/targets/avr_unknown_gnu_atmega328.rs
 create mode 100644 src/doc/rustc/src/platform-support/avr-none.md

diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 105a4cb81f0..0399ea77c72 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -1990,6 +1990,7 @@ fn add_pre_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor)
     if let Some(args) = sess.target.pre_link_args.get(&flavor) {
         cmd.verbatim_args(args.iter().map(Deref::deref));
     }
+
     cmd.verbatim_args(&sess.opts.unstable_opts.pre_link_args);
 }
 
diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs
index e3ace01c1eb..8900405c1b8 100644
--- a/compiler/rustc_codegen_ssa/src/back/linker.rs
+++ b/compiler/rustc_codegen_ssa/src/back/linker.rs
@@ -153,6 +153,7 @@ pub(crate) fn get_linker<'a>(
             hinted_static: None,
             is_ld: cc == Cc::No,
             is_gnu: flavor.is_gnu(),
+            uses_lld: flavor.uses_lld(),
         }) as Box<dyn Linker>,
         LinkerFlavor::Msvc(..) => Box::new(MsvcLinker { cmd, sess }) as Box<dyn Linker>,
         LinkerFlavor::EmCc => Box::new(EmLinker { cmd, sess }) as Box<dyn Linker>,
@@ -361,6 +362,7 @@ struct GccLinker<'a> {
     // Link as ld
     is_ld: bool,
     is_gnu: bool,
+    uses_lld: bool,
 }
 
 impl<'a> GccLinker<'a> {
@@ -552,6 +554,7 @@ impl<'a> Linker for GccLinker<'a> {
                 self.link_args(&["--entry", "_initialize"]);
             }
         }
+
         // VxWorks compiler driver introduced `--static-crt` flag specifically for rustc,
         // it switches linking for libc and similar system libraries to static without using
         // any `#[link]` attributes in the `libc` crate, see #72782 for details.
@@ -567,6 +570,15 @@ impl<'a> Linker for GccLinker<'a> {
         {
             self.cc_arg("--static-crt");
         }
+
+        // avr-none doesn't have default ISA, users must specify which specific
+        // CPU (well, microcontroller) they are targetting using `-Ctarget-cpu`.
+        //
+        // Currently this makes sense only when using avr-gcc as a linker, since
+        // it brings a couple of hand-written important intrinsics from libgcc.
+        if self.sess.target.arch == "avr" && !self.uses_lld {
+            self.verbatim_arg(format!("-mmcu={}", self.target_cpu));
+        }
     }
 
     fn link_dylib_by_name(&mut self, name: &str, verbatim: bool, as_needed: bool) {
diff --git a/compiler/rustc_target/src/spec/base/avr.rs b/compiler/rustc_target/src/spec/base/avr.rs
new file mode 100644
index 00000000000..85b73e61e52
--- /dev/null
+++ b/compiler/rustc_target/src/spec/base/avr.rs
@@ -0,0 +1,337 @@
+use object::elf;
+
+/// Resolve the value of the EF_AVR_ARCH field for AVR ELF files, given the
+/// name of the target CPU / MCU.
+///
+/// In ELF files using the AVR architecture, the lower 7 bits of the e_flags
+/// field is a code that identifies the "ISA revision" of the object code.
+///
+/// This flag is generally set by AVR compilers in their output ELF files,
+/// and linkers like avr-ld check this flag in all of their input files to
+/// make sure they are compiled with the same ISA revision.
+pub fn ef_avr_arch(target_cpu: &str) -> u32 {
+    // Adapted from llvm-project/llvm/lib/target/AVR/AVRDevices.td
+    match target_cpu {
+        // Generic MCUs
+        "avr1" => elf::EF_AVR_ARCH_AVR1,
+        "avr2" => elf::EF_AVR_ARCH_AVR2,
+        "avr25" => elf::EF_AVR_ARCH_AVR25,
+        "avr3" => elf::EF_AVR_ARCH_AVR3,
+        "avr31" => elf::EF_AVR_ARCH_AVR31,
+        "avr35" => elf::EF_AVR_ARCH_AVR35,
+        "avr4" => elf::EF_AVR_ARCH_AVR4,
+        "avr5" => elf::EF_AVR_ARCH_AVR5,
+        "avr51" => elf::EF_AVR_ARCH_AVR51,
+        "avr6" => elf::EF_AVR_ARCH_AVR6,
+        "avrxmega1" => elf::EF_AVR_ARCH_XMEGA1,
+        "avrxmega2" => elf::EF_AVR_ARCH_XMEGA2,
+        "avrxmega3" => elf::EF_AVR_ARCH_XMEGA3,
+        "avrxmega4" => elf::EF_AVR_ARCH_XMEGA4,
+        "avrxmega5" => elf::EF_AVR_ARCH_XMEGA5,
+        "avrxmega6" => elf::EF_AVR_ARCH_XMEGA6,
+        "avrxmega7" => elf::EF_AVR_ARCH_XMEGA7,
+        "avrtiny" => elf::EF_AVR_ARCH_AVRTINY,
+
+        // Specific MCUs
+        "at90s1200" => elf::EF_AVR_ARCH_AVR1,
+        "attiny11" => elf::EF_AVR_ARCH_AVR1,
+        "attiny12" => elf::EF_AVR_ARCH_AVR1,
+        "attiny15" => elf::EF_AVR_ARCH_AVR1,
+        "attiny28" => elf::EF_AVR_ARCH_AVR1,
+        "at90s2313" => elf::EF_AVR_ARCH_AVR2,
+        "at90s2323" => elf::EF_AVR_ARCH_AVR2,
+        "at90s2333" => elf::EF_AVR_ARCH_AVR2,
+        "at90s2343" => elf::EF_AVR_ARCH_AVR2,
+        "attiny22" => elf::EF_AVR_ARCH_AVR2,
+        "attiny26" => elf::EF_AVR_ARCH_AVR2,
+        "at86rf401" => elf::EF_AVR_ARCH_AVR25,
+        "at90s4414" => elf::EF_AVR_ARCH_AVR2,
+        "at90s4433" => elf::EF_AVR_ARCH_AVR2,
+        "at90s4434" => elf::EF_AVR_ARCH_AVR2,
+        "at90s8515" => elf::EF_AVR_ARCH_AVR2,
+        "at90c8534" => elf::EF_AVR_ARCH_AVR2,
+        "at90s8535" => elf::EF_AVR_ARCH_AVR2,
+        "ata5272" => elf::EF_AVR_ARCH_AVR25,
+        "ata6616c" => elf::EF_AVR_ARCH_AVR25,
+        "attiny13" => elf::EF_AVR_ARCH_AVR25,
+        "attiny13a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny2313" => elf::EF_AVR_ARCH_AVR25,
+        "attiny2313a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny24" => elf::EF_AVR_ARCH_AVR25,
+        "attiny24a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny4313" => elf::EF_AVR_ARCH_AVR25,
+        "attiny44" => elf::EF_AVR_ARCH_AVR25,
+        "attiny44a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny84" => elf::EF_AVR_ARCH_AVR25,
+        "attiny84a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny25" => elf::EF_AVR_ARCH_AVR25,
+        "attiny45" => elf::EF_AVR_ARCH_AVR25,
+        "attiny85" => elf::EF_AVR_ARCH_AVR25,
+        "attiny261" => elf::EF_AVR_ARCH_AVR25,
+        "attiny261a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny441" => elf::EF_AVR_ARCH_AVR25,
+        "attiny461" => elf::EF_AVR_ARCH_AVR25,
+        "attiny461a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny841" => elf::EF_AVR_ARCH_AVR25,
+        "attiny861" => elf::EF_AVR_ARCH_AVR25,
+        "attiny861a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny87" => elf::EF_AVR_ARCH_AVR25,
+        "attiny43u" => elf::EF_AVR_ARCH_AVR25,
+        "attiny48" => elf::EF_AVR_ARCH_AVR25,
+        "attiny88" => elf::EF_AVR_ARCH_AVR25,
+        "attiny828" => elf::EF_AVR_ARCH_AVR25,
+        "at43usb355" => elf::EF_AVR_ARCH_AVR3,
+        "at76c711" => elf::EF_AVR_ARCH_AVR3,
+        "atmega103" => elf::EF_AVR_ARCH_AVR31,
+        "at43usb320" => elf::EF_AVR_ARCH_AVR31,
+        "attiny167" => elf::EF_AVR_ARCH_AVR35,
+        "at90usb82" => elf::EF_AVR_ARCH_AVR35,
+        "at90usb162" => elf::EF_AVR_ARCH_AVR35,
+        "ata5505" => elf::EF_AVR_ARCH_AVR35,
+        "ata6617c" => elf::EF_AVR_ARCH_AVR35,
+        "ata664251" => elf::EF_AVR_ARCH_AVR35,
+        "atmega8u2" => elf::EF_AVR_ARCH_AVR35,
+        "atmega16u2" => elf::EF_AVR_ARCH_AVR35,
+        "atmega32u2" => elf::EF_AVR_ARCH_AVR35,
+        "attiny1634" => elf::EF_AVR_ARCH_AVR35,
+        "atmega8" => elf::EF_AVR_ARCH_AVR4,
+        "ata6289" => elf::EF_AVR_ARCH_AVR4,
+        "atmega8a" => elf::EF_AVR_ARCH_AVR4,
+        "ata6285" => elf::EF_AVR_ARCH_AVR4,
+        "ata6286" => elf::EF_AVR_ARCH_AVR4,
+        "ata6612c" => elf::EF_AVR_ARCH_AVR4,
+        "atmega48" => elf::EF_AVR_ARCH_AVR4,
+        "atmega48a" => elf::EF_AVR_ARCH_AVR4,
+        "atmega48pa" => elf::EF_AVR_ARCH_AVR4,
+        "atmega48pb" => elf::EF_AVR_ARCH_AVR4,
+        "atmega48p" => elf::EF_AVR_ARCH_AVR4,
+        "atmega88" => elf::EF_AVR_ARCH_AVR4,
+        "atmega88a" => elf::EF_AVR_ARCH_AVR4,
+        "atmega88p" => elf::EF_AVR_ARCH_AVR4,
+        "atmega88pa" => elf::EF_AVR_ARCH_AVR4,
+        "atmega88pb" => elf::EF_AVR_ARCH_AVR4,
+        "atmega8515" => elf::EF_AVR_ARCH_AVR4,
+        "atmega8535" => elf::EF_AVR_ARCH_AVR4,
+        "atmega8hva" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm1" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm2" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm2b" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm3" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm3b" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm81" => elf::EF_AVR_ARCH_AVR4,
+        "ata5702m322" => elf::EF_AVR_ARCH_AVR5,
+        "ata5782" => elf::EF_AVR_ARCH_AVR5,
+        "ata5790" => elf::EF_AVR_ARCH_AVR5,
+        "ata5790n" => elf::EF_AVR_ARCH_AVR5,
+        "ata5791" => elf::EF_AVR_ARCH_AVR5,
+        "ata5795" => elf::EF_AVR_ARCH_AVR5,
+        "ata5831" => elf::EF_AVR_ARCH_AVR5,
+        "ata6613c" => elf::EF_AVR_ARCH_AVR5,
+        "ata6614q" => elf::EF_AVR_ARCH_AVR5,
+        "ata8210" => elf::EF_AVR_ARCH_AVR5,
+        "ata8510" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega161" => elf::EF_AVR_ARCH_AVR5,
+        "atmega162" => elf::EF_AVR_ARCH_AVR5,
+        "atmega163" => elf::EF_AVR_ARCH_AVR5,
+        "atmega164a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega164p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega164pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega165" => elf::EF_AVR_ARCH_AVR5,
+        "atmega165a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega165p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega165pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega168" => elf::EF_AVR_ARCH_AVR5,
+        "atmega168a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega168p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega168pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega168pb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega169" => elf::EF_AVR_ARCH_AVR5,
+        "atmega169a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega169p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega169pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega323" => elf::EF_AVR_ARCH_AVR5,
+        "atmega324a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega324p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega324pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega324pb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega325" => elf::EF_AVR_ARCH_AVR5,
+        "atmega325a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega325p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega325pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3250" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3250a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3250p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3250pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega328" => elf::EF_AVR_ARCH_AVR5,
+        "atmega328p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega328pb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega329" => elf::EF_AVR_ARCH_AVR5,
+        "atmega329a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega329p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega329pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3290" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3290a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3290p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3290pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega406" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega640" => elf::EF_AVR_ARCH_AVR5,
+        "atmega644" => elf::EF_AVR_ARCH_AVR5,
+        "atmega644a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega644p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega644pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega645" => elf::EF_AVR_ARCH_AVR5,
+        "atmega645a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega645p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega649" => elf::EF_AVR_ARCH_AVR5,
+        "atmega649a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega649p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6450" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6450a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6450p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6490" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6490a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6490p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64rfr2" => elf::EF_AVR_ARCH_AVR5,
+        "atmega644rfr2" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16hva" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16hva2" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16hvb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16hvbrevb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32hvb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32hvbrevb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64hve" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64hve2" => elf::EF_AVR_ARCH_AVR5,
+        "at90can32" => elf::EF_AVR_ARCH_AVR5,
+        "at90can64" => elf::EF_AVR_ARCH_AVR5,
+        "at90pwm161" => elf::EF_AVR_ARCH_AVR5,
+        "at90pwm216" => elf::EF_AVR_ARCH_AVR5,
+        "at90pwm316" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32c1" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64c1" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16m1" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32m1" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64m1" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16u4" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32u4" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32u6" => elf::EF_AVR_ARCH_AVR5,
+        "at90usb646" => elf::EF_AVR_ARCH_AVR5,
+        "at90usb647" => elf::EF_AVR_ARCH_AVR5,
+        "at90scr100" => elf::EF_AVR_ARCH_AVR5,
+        "at94k" => elf::EF_AVR_ARCH_AVR5,
+        "m3000" => elf::EF_AVR_ARCH_AVR5,
+        "atmega128" => elf::EF_AVR_ARCH_AVR51,
+        "atmega128a" => elf::EF_AVR_ARCH_AVR51,
+        "atmega1280" => elf::EF_AVR_ARCH_AVR51,
+        "atmega1281" => elf::EF_AVR_ARCH_AVR51,
+        "atmega1284" => elf::EF_AVR_ARCH_AVR51,
+        "atmega1284p" => elf::EF_AVR_ARCH_AVR51,
+        "atmega128rfa1" => elf::EF_AVR_ARCH_AVR51,
+        "atmega128rfr2" => elf::EF_AVR_ARCH_AVR51,
+        "atmega1284rfr2" => elf::EF_AVR_ARCH_AVR51,
+        "at90can128" => elf::EF_AVR_ARCH_AVR51,
+        "at90usb1286" => elf::EF_AVR_ARCH_AVR51,
+        "at90usb1287" => elf::EF_AVR_ARCH_AVR51,
+        "atmega2560" => elf::EF_AVR_ARCH_AVR6,
+        "atmega2561" => elf::EF_AVR_ARCH_AVR6,
+        "atmega256rfr2" => elf::EF_AVR_ARCH_AVR6,
+        "atmega2564rfr2" => elf::EF_AVR_ARCH_AVR6,
+        "atxmega16a4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega16a4u" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega16c4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega16d4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32a4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32a4u" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32c3" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32c4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32d3" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32d4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32e5" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega16e5" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega8e5" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega64a3" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64a3u" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64a4u" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64b1" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64b3" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64c3" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64d3" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64d4" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64a1" => elf::EF_AVR_ARCH_XMEGA5,
+        "atxmega64a1u" => elf::EF_AVR_ARCH_XMEGA5,
+        "atxmega128a3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128a3u" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128b1" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128b3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128c3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128d3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128d4" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega192a3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega192a3u" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega192c3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega192d3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256a3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256a3u" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256a3b" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256a3bu" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256c3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256d3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega384c3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega384d3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128a1" => elf::EF_AVR_ARCH_XMEGA7,
+        "atxmega128a1u" => elf::EF_AVR_ARCH_XMEGA7,
+        "atxmega128a4u" => elf::EF_AVR_ARCH_XMEGA7,
+        "attiny4" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny5" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny9" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny10" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny20" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny40" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny102" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny104" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny202" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny402" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny204" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny404" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny804" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1604" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny406" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny806" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1606" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny807" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1607" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny212" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny412" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny214" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny414" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny814" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1614" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny416" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny816" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1616" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny3216" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny417" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny817" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1617" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny3217" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1624" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1626" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1627" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega808" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega809" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega1608" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega1609" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega3208" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega3209" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega4808" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega4809" => elf::EF_AVR_ARCH_XMEGA3,
+
+        // Unknown target CPU => Unspecified/generic code
+        _ => 0,
+    }
+}
diff --git a/compiler/rustc_target/src/spec/base/avr_gnu.rs b/compiler/rustc_target/src/spec/base/avr_gnu.rs
deleted file mode 100644
index 3554dcfcb4a..00000000000
--- a/compiler/rustc_target/src/spec/base/avr_gnu.rs
+++ /dev/null
@@ -1,377 +0,0 @@
-use object::elf;
-
-use crate::spec::{Cc, LinkerFlavor, Lld, RelocModel, Target, TargetOptions};
-
-/// A base target for AVR devices using the GNU toolchain.
-///
-/// Requires GNU avr-gcc and avr-binutils on the host system.
-/// FIXME: Remove the second parameter when const string concatenation is possible.
-pub(crate) fn target(target_cpu: &'static str, mmcu: &'static str) -> Target {
-    Target {
-        arch: "avr".into(),
-        metadata: crate::spec::TargetMetadata {
-            description: None,
-            tier: None,
-            host_tools: None,
-            std: None,
-        },
-        data_layout: "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8".into(),
-        llvm_target: "avr-unknown-unknown".into(),
-        pointer_width: 16,
-        options: TargetOptions {
-            env: "gnu".into(),
-
-            c_int_width: "16".into(),
-            cpu: target_cpu.into(),
-            exe_suffix: ".elf".into(),
-
-            linker: Some("avr-gcc".into()),
-            eh_frame_header: false,
-            pre_link_args: TargetOptions::link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &[mmcu]),
-            late_link_args: TargetOptions::link_args(
-                LinkerFlavor::Gnu(Cc::Yes, Lld::No),
-                &["-lgcc"],
-            ),
-            max_atomic_width: Some(16),
-            atomic_cas: false,
-            relocation_model: RelocModel::Static,
-            ..TargetOptions::default()
-        },
-    }
-}
-
-/// Resolve the value of the EF_AVR_ARCH field for AVR ELF files, given the
-/// name of the target CPU / MCU.
-///
-/// In ELF files using the AVR architecture, the lower 7 bits of the e_flags
-/// field is a code that identifies the "ISA revision" of the object code.
-///
-/// This flag is generally set by AVR compilers in their output ELF files,
-/// and linkers like avr-ld check this flag in all of their input files to
-/// make sure they are compiled with the same ISA revision.
-pub fn ef_avr_arch(target_cpu: &str) -> u32 {
-    // Adapted from llvm-project/llvm/lib/target/AVR/AVRDevices.td
-    match target_cpu {
-        // Generic MCUs
-        "avr1" => elf::EF_AVR_ARCH_AVR1,
-        "avr2" => elf::EF_AVR_ARCH_AVR2,
-        "avr25" => elf::EF_AVR_ARCH_AVR25,
-        "avr3" => elf::EF_AVR_ARCH_AVR3,
-        "avr31" => elf::EF_AVR_ARCH_AVR31,
-        "avr35" => elf::EF_AVR_ARCH_AVR35,
-        "avr4" => elf::EF_AVR_ARCH_AVR4,
-        "avr5" => elf::EF_AVR_ARCH_AVR5,
-        "avr51" => elf::EF_AVR_ARCH_AVR51,
-        "avr6" => elf::EF_AVR_ARCH_AVR6,
-        "avrxmega1" => elf::EF_AVR_ARCH_XMEGA1,
-        "avrxmega2" => elf::EF_AVR_ARCH_XMEGA2,
-        "avrxmega3" => elf::EF_AVR_ARCH_XMEGA3,
-        "avrxmega4" => elf::EF_AVR_ARCH_XMEGA4,
-        "avrxmega5" => elf::EF_AVR_ARCH_XMEGA5,
-        "avrxmega6" => elf::EF_AVR_ARCH_XMEGA6,
-        "avrxmega7" => elf::EF_AVR_ARCH_XMEGA7,
-        "avrtiny" => elf::EF_AVR_ARCH_AVRTINY,
-
-        // Specific MCUs
-        "at90s1200" => elf::EF_AVR_ARCH_AVR1,
-        "attiny11" => elf::EF_AVR_ARCH_AVR1,
-        "attiny12" => elf::EF_AVR_ARCH_AVR1,
-        "attiny15" => elf::EF_AVR_ARCH_AVR1,
-        "attiny28" => elf::EF_AVR_ARCH_AVR1,
-        "at90s2313" => elf::EF_AVR_ARCH_AVR2,
-        "at90s2323" => elf::EF_AVR_ARCH_AVR2,
-        "at90s2333" => elf::EF_AVR_ARCH_AVR2,
-        "at90s2343" => elf::EF_AVR_ARCH_AVR2,
-        "attiny22" => elf::EF_AVR_ARCH_AVR2,
-        "attiny26" => elf::EF_AVR_ARCH_AVR2,
-        "at86rf401" => elf::EF_AVR_ARCH_AVR25,
-        "at90s4414" => elf::EF_AVR_ARCH_AVR2,
-        "at90s4433" => elf::EF_AVR_ARCH_AVR2,
-        "at90s4434" => elf::EF_AVR_ARCH_AVR2,
-        "at90s8515" => elf::EF_AVR_ARCH_AVR2,
-        "at90c8534" => elf::EF_AVR_ARCH_AVR2,
-        "at90s8535" => elf::EF_AVR_ARCH_AVR2,
-        "ata5272" => elf::EF_AVR_ARCH_AVR25,
-        "ata6616c" => elf::EF_AVR_ARCH_AVR25,
-        "attiny13" => elf::EF_AVR_ARCH_AVR25,
-        "attiny13a" => elf::EF_AVR_ARCH_AVR25,
-        "attiny2313" => elf::EF_AVR_ARCH_AVR25,
-        "attiny2313a" => elf::EF_AVR_ARCH_AVR25,
-        "attiny24" => elf::EF_AVR_ARCH_AVR25,
-        "attiny24a" => elf::EF_AVR_ARCH_AVR25,
-        "attiny4313" => elf::EF_AVR_ARCH_AVR25,
-        "attiny44" => elf::EF_AVR_ARCH_AVR25,
-        "attiny44a" => elf::EF_AVR_ARCH_AVR25,
-        "attiny84" => elf::EF_AVR_ARCH_AVR25,
-        "attiny84a" => elf::EF_AVR_ARCH_AVR25,
-        "attiny25" => elf::EF_AVR_ARCH_AVR25,
-        "attiny45" => elf::EF_AVR_ARCH_AVR25,
-        "attiny85" => elf::EF_AVR_ARCH_AVR25,
-        "attiny261" => elf::EF_AVR_ARCH_AVR25,
-        "attiny261a" => elf::EF_AVR_ARCH_AVR25,
-        "attiny441" => elf::EF_AVR_ARCH_AVR25,
-        "attiny461" => elf::EF_AVR_ARCH_AVR25,
-        "attiny461a" => elf::EF_AVR_ARCH_AVR25,
-        "attiny841" => elf::EF_AVR_ARCH_AVR25,
-        "attiny861" => elf::EF_AVR_ARCH_AVR25,
-        "attiny861a" => elf::EF_AVR_ARCH_AVR25,
-        "attiny87" => elf::EF_AVR_ARCH_AVR25,
-        "attiny43u" => elf::EF_AVR_ARCH_AVR25,
-        "attiny48" => elf::EF_AVR_ARCH_AVR25,
-        "attiny88" => elf::EF_AVR_ARCH_AVR25,
-        "attiny828" => elf::EF_AVR_ARCH_AVR25,
-        "at43usb355" => elf::EF_AVR_ARCH_AVR3,
-        "at76c711" => elf::EF_AVR_ARCH_AVR3,
-        "atmega103" => elf::EF_AVR_ARCH_AVR31,
-        "at43usb320" => elf::EF_AVR_ARCH_AVR31,
-        "attiny167" => elf::EF_AVR_ARCH_AVR35,
-        "at90usb82" => elf::EF_AVR_ARCH_AVR35,
-        "at90usb162" => elf::EF_AVR_ARCH_AVR35,
-        "ata5505" => elf::EF_AVR_ARCH_AVR35,
-        "ata6617c" => elf::EF_AVR_ARCH_AVR35,
-        "ata664251" => elf::EF_AVR_ARCH_AVR35,
-        "atmega8u2" => elf::EF_AVR_ARCH_AVR35,
-        "atmega16u2" => elf::EF_AVR_ARCH_AVR35,
-        "atmega32u2" => elf::EF_AVR_ARCH_AVR35,
-        "attiny1634" => elf::EF_AVR_ARCH_AVR35,
-        "atmega8" => elf::EF_AVR_ARCH_AVR4,
-        "ata6289" => elf::EF_AVR_ARCH_AVR4,
-        "atmega8a" => elf::EF_AVR_ARCH_AVR4,
-        "ata6285" => elf::EF_AVR_ARCH_AVR4,
-        "ata6286" => elf::EF_AVR_ARCH_AVR4,
-        "ata6612c" => elf::EF_AVR_ARCH_AVR4,
-        "atmega48" => elf::EF_AVR_ARCH_AVR4,
-        "atmega48a" => elf::EF_AVR_ARCH_AVR4,
-        "atmega48pa" => elf::EF_AVR_ARCH_AVR4,
-        "atmega48pb" => elf::EF_AVR_ARCH_AVR4,
-        "atmega48p" => elf::EF_AVR_ARCH_AVR4,
-        "atmega88" => elf::EF_AVR_ARCH_AVR4,
-        "atmega88a" => elf::EF_AVR_ARCH_AVR4,
-        "atmega88p" => elf::EF_AVR_ARCH_AVR4,
-        "atmega88pa" => elf::EF_AVR_ARCH_AVR4,
-        "atmega88pb" => elf::EF_AVR_ARCH_AVR4,
-        "atmega8515" => elf::EF_AVR_ARCH_AVR4,
-        "atmega8535" => elf::EF_AVR_ARCH_AVR4,
-        "atmega8hva" => elf::EF_AVR_ARCH_AVR4,
-        "at90pwm1" => elf::EF_AVR_ARCH_AVR4,
-        "at90pwm2" => elf::EF_AVR_ARCH_AVR4,
-        "at90pwm2b" => elf::EF_AVR_ARCH_AVR4,
-        "at90pwm3" => elf::EF_AVR_ARCH_AVR4,
-        "at90pwm3b" => elf::EF_AVR_ARCH_AVR4,
-        "at90pwm81" => elf::EF_AVR_ARCH_AVR4,
-        "ata5702m322" => elf::EF_AVR_ARCH_AVR5,
-        "ata5782" => elf::EF_AVR_ARCH_AVR5,
-        "ata5790" => elf::EF_AVR_ARCH_AVR5,
-        "ata5790n" => elf::EF_AVR_ARCH_AVR5,
-        "ata5791" => elf::EF_AVR_ARCH_AVR5,
-        "ata5795" => elf::EF_AVR_ARCH_AVR5,
-        "ata5831" => elf::EF_AVR_ARCH_AVR5,
-        "ata6613c" => elf::EF_AVR_ARCH_AVR5,
-        "ata6614q" => elf::EF_AVR_ARCH_AVR5,
-        "ata8210" => elf::EF_AVR_ARCH_AVR5,
-        "ata8510" => elf::EF_AVR_ARCH_AVR5,
-        "atmega16" => elf::EF_AVR_ARCH_AVR5,
-        "atmega16a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega161" => elf::EF_AVR_ARCH_AVR5,
-        "atmega162" => elf::EF_AVR_ARCH_AVR5,
-        "atmega163" => elf::EF_AVR_ARCH_AVR5,
-        "atmega164a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega164p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega164pa" => elf::EF_AVR_ARCH_AVR5,
-        "atmega165" => elf::EF_AVR_ARCH_AVR5,
-        "atmega165a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega165p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega165pa" => elf::EF_AVR_ARCH_AVR5,
-        "atmega168" => elf::EF_AVR_ARCH_AVR5,
-        "atmega168a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega168p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega168pa" => elf::EF_AVR_ARCH_AVR5,
-        "atmega168pb" => elf::EF_AVR_ARCH_AVR5,
-        "atmega169" => elf::EF_AVR_ARCH_AVR5,
-        "atmega169a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega169p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega169pa" => elf::EF_AVR_ARCH_AVR5,
-        "atmega32" => elf::EF_AVR_ARCH_AVR5,
-        "atmega32a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega323" => elf::EF_AVR_ARCH_AVR5,
-        "atmega324a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega324p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega324pa" => elf::EF_AVR_ARCH_AVR5,
-        "atmega324pb" => elf::EF_AVR_ARCH_AVR5,
-        "atmega325" => elf::EF_AVR_ARCH_AVR5,
-        "atmega325a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega325p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega325pa" => elf::EF_AVR_ARCH_AVR5,
-        "atmega3250" => elf::EF_AVR_ARCH_AVR5,
-        "atmega3250a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega3250p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega3250pa" => elf::EF_AVR_ARCH_AVR5,
-        "atmega328" => elf::EF_AVR_ARCH_AVR5,
-        "atmega328p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega328pb" => elf::EF_AVR_ARCH_AVR5,
-        "atmega329" => elf::EF_AVR_ARCH_AVR5,
-        "atmega329a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega329p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega329pa" => elf::EF_AVR_ARCH_AVR5,
-        "atmega3290" => elf::EF_AVR_ARCH_AVR5,
-        "atmega3290a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega3290p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega3290pa" => elf::EF_AVR_ARCH_AVR5,
-        "atmega406" => elf::EF_AVR_ARCH_AVR5,
-        "atmega64" => elf::EF_AVR_ARCH_AVR5,
-        "atmega64a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega640" => elf::EF_AVR_ARCH_AVR5,
-        "atmega644" => elf::EF_AVR_ARCH_AVR5,
-        "atmega644a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega644p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega644pa" => elf::EF_AVR_ARCH_AVR5,
-        "atmega645" => elf::EF_AVR_ARCH_AVR5,
-        "atmega645a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega645p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega649" => elf::EF_AVR_ARCH_AVR5,
-        "atmega649a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega649p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega6450" => elf::EF_AVR_ARCH_AVR5,
-        "atmega6450a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega6450p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega6490" => elf::EF_AVR_ARCH_AVR5,
-        "atmega6490a" => elf::EF_AVR_ARCH_AVR5,
-        "atmega6490p" => elf::EF_AVR_ARCH_AVR5,
-        "atmega64rfr2" => elf::EF_AVR_ARCH_AVR5,
-        "atmega644rfr2" => elf::EF_AVR_ARCH_AVR5,
-        "atmega16hva" => elf::EF_AVR_ARCH_AVR5,
-        "atmega16hva2" => elf::EF_AVR_ARCH_AVR5,
-        "atmega16hvb" => elf::EF_AVR_ARCH_AVR5,
-        "atmega16hvbrevb" => elf::EF_AVR_ARCH_AVR5,
-        "atmega32hvb" => elf::EF_AVR_ARCH_AVR5,
-        "atmega32hvbrevb" => elf::EF_AVR_ARCH_AVR5,
-        "atmega64hve" => elf::EF_AVR_ARCH_AVR5,
-        "atmega64hve2" => elf::EF_AVR_ARCH_AVR5,
-        "at90can32" => elf::EF_AVR_ARCH_AVR5,
-        "at90can64" => elf::EF_AVR_ARCH_AVR5,
-        "at90pwm161" => elf::EF_AVR_ARCH_AVR5,
-        "at90pwm216" => elf::EF_AVR_ARCH_AVR5,
-        "at90pwm316" => elf::EF_AVR_ARCH_AVR5,
-        "atmega32c1" => elf::EF_AVR_ARCH_AVR5,
-        "atmega64c1" => elf::EF_AVR_ARCH_AVR5,
-        "atmega16m1" => elf::EF_AVR_ARCH_AVR5,
-        "atmega32m1" => elf::EF_AVR_ARCH_AVR5,
-        "atmega64m1" => elf::EF_AVR_ARCH_AVR5,
-        "atmega16u4" => elf::EF_AVR_ARCH_AVR5,
-        "atmega32u4" => elf::EF_AVR_ARCH_AVR5,
-        "atmega32u6" => elf::EF_AVR_ARCH_AVR5,
-        "at90usb646" => elf::EF_AVR_ARCH_AVR5,
-        "at90usb647" => elf::EF_AVR_ARCH_AVR5,
-        "at90scr100" => elf::EF_AVR_ARCH_AVR5,
-        "at94k" => elf::EF_AVR_ARCH_AVR5,
-        "m3000" => elf::EF_AVR_ARCH_AVR5,
-        "atmega128" => elf::EF_AVR_ARCH_AVR51,
-        "atmega128a" => elf::EF_AVR_ARCH_AVR51,
-        "atmega1280" => elf::EF_AVR_ARCH_AVR51,
-        "atmega1281" => elf::EF_AVR_ARCH_AVR51,
-        "atmega1284" => elf::EF_AVR_ARCH_AVR51,
-        "atmega1284p" => elf::EF_AVR_ARCH_AVR51,
-        "atmega128rfa1" => elf::EF_AVR_ARCH_AVR51,
-        "atmega128rfr2" => elf::EF_AVR_ARCH_AVR51,
-        "atmega1284rfr2" => elf::EF_AVR_ARCH_AVR51,
-        "at90can128" => elf::EF_AVR_ARCH_AVR51,
-        "at90usb1286" => elf::EF_AVR_ARCH_AVR51,
-        "at90usb1287" => elf::EF_AVR_ARCH_AVR51,
-        "atmega2560" => elf::EF_AVR_ARCH_AVR6,
-        "atmega2561" => elf::EF_AVR_ARCH_AVR6,
-        "atmega256rfr2" => elf::EF_AVR_ARCH_AVR6,
-        "atmega2564rfr2" => elf::EF_AVR_ARCH_AVR6,
-        "atxmega16a4" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega16a4u" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega16c4" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega16d4" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega32a4" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega32a4u" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega32c3" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega32c4" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega32d3" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega32d4" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega32e5" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega16e5" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega8e5" => elf::EF_AVR_ARCH_XMEGA2,
-        "atxmega64a3" => elf::EF_AVR_ARCH_XMEGA4,
-        "atxmega64a3u" => elf::EF_AVR_ARCH_XMEGA4,
-        "atxmega64a4u" => elf::EF_AVR_ARCH_XMEGA4,
-        "atxmega64b1" => elf::EF_AVR_ARCH_XMEGA4,
-        "atxmega64b3" => elf::EF_AVR_ARCH_XMEGA4,
-        "atxmega64c3" => elf::EF_AVR_ARCH_XMEGA4,
-        "atxmega64d3" => elf::EF_AVR_ARCH_XMEGA4,
-        "atxmega64d4" => elf::EF_AVR_ARCH_XMEGA4,
-        "atxmega64a1" => elf::EF_AVR_ARCH_XMEGA5,
-        "atxmega64a1u" => elf::EF_AVR_ARCH_XMEGA5,
-        "atxmega128a3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega128a3u" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega128b1" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega128b3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega128c3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega128d3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega128d4" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega192a3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega192a3u" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega192c3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega192d3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega256a3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega256a3u" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega256a3b" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega256a3bu" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega256c3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega256d3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega384c3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega384d3" => elf::EF_AVR_ARCH_XMEGA6,
-        "atxmega128a1" => elf::EF_AVR_ARCH_XMEGA7,
-        "atxmega128a1u" => elf::EF_AVR_ARCH_XMEGA7,
-        "atxmega128a4u" => elf::EF_AVR_ARCH_XMEGA7,
-        "attiny4" => elf::EF_AVR_ARCH_AVRTINY,
-        "attiny5" => elf::EF_AVR_ARCH_AVRTINY,
-        "attiny9" => elf::EF_AVR_ARCH_AVRTINY,
-        "attiny10" => elf::EF_AVR_ARCH_AVRTINY,
-        "attiny20" => elf::EF_AVR_ARCH_AVRTINY,
-        "attiny40" => elf::EF_AVR_ARCH_AVRTINY,
-        "attiny102" => elf::EF_AVR_ARCH_AVRTINY,
-        "attiny104" => elf::EF_AVR_ARCH_AVRTINY,
-        "attiny202" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny402" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny204" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny404" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny804" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny1604" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny406" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny806" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny1606" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny807" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny1607" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny212" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny412" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny214" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny414" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny814" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny1614" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny416" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny816" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny1616" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny3216" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny417" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny817" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny1617" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny3217" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny1624" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny1626" => elf::EF_AVR_ARCH_XMEGA3,
-        "attiny1627" => elf::EF_AVR_ARCH_XMEGA3,
-        "atmega808" => elf::EF_AVR_ARCH_XMEGA3,
-        "atmega809" => elf::EF_AVR_ARCH_XMEGA3,
-        "atmega1608" => elf::EF_AVR_ARCH_XMEGA3,
-        "atmega1609" => elf::EF_AVR_ARCH_XMEGA3,
-        "atmega3208" => elf::EF_AVR_ARCH_XMEGA3,
-        "atmega3209" => elf::EF_AVR_ARCH_XMEGA3,
-        "atmega4808" => elf::EF_AVR_ARCH_XMEGA3,
-        "atmega4809" => elf::EF_AVR_ARCH_XMEGA3,
-
-        // Unknown target CPU => Unspecified/generic code
-        _ => 0,
-    }
-}
diff --git a/compiler/rustc_target/src/spec/base/mod.rs b/compiler/rustc_target/src/spec/base/mod.rs
index b9139c8452c..6f88be5d37f 100644
--- a/compiler/rustc_target/src/spec/base/mod.rs
+++ b/compiler/rustc_target/src/spec/base/mod.rs
@@ -1,7 +1,7 @@
 pub(crate) mod aix;
 pub(crate) mod android;
 pub(crate) mod apple;
-pub(crate) mod avr_gnu;
+pub(crate) mod avr;
 pub(crate) mod bpf;
 pub(crate) mod cygwin;
 pub(crate) mod dragonfly;
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index f7e467b0c11..3b943fc178f 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -60,7 +60,7 @@ pub mod crt_objects;
 mod base;
 mod json;
 
-pub use base::avr_gnu::ef_avr_arch;
+pub use base::avr::ef_avr_arch;
 
 /// Linker is called through a C/C++ compiler.
 #[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
@@ -1797,7 +1797,7 @@ supported_targets! {
     ("riscv64gc-unknown-fuchsia", riscv64gc_unknown_fuchsia),
     ("x86_64-unknown-fuchsia", x86_64_unknown_fuchsia),
 
-    ("avr-unknown-gnu-atmega328", avr_unknown_gnu_atmega328),
+    ("avr-none", avr_none),
 
     ("x86_64-unknown-l4re-uclibc", x86_64_unknown_l4re_uclibc),
 
@@ -3062,7 +3062,10 @@ impl Target {
             &self.post_link_args,
         ] {
             for (&flavor, flavor_args) in args {
-                check!(!flavor_args.is_empty(), "linker flavor args must not be empty");
+                check!(
+                    !flavor_args.is_empty() || self.arch == "avr",
+                    "linker flavor args must not be empty"
+                );
                 // Check that flavors mentioned in link args are compatible with the default flavor.
                 match self.linker_flavor {
                     LinkerFlavor::Gnu(..) => {
diff --git a/compiler/rustc_target/src/spec/targets/avr_none.rs b/compiler/rustc_target/src/spec/targets/avr_none.rs
new file mode 100644
index 00000000000..91d3197d099
--- /dev/null
+++ b/compiler/rustc_target/src/spec/targets/avr_none.rs
@@ -0,0 +1,32 @@
+use crate::spec::{Cc, LinkerFlavor, Lld, RelocModel, Target, TargetOptions};
+
+pub(crate) fn target() -> Target {
+    Target {
+        arch: "avr".into(),
+        metadata: crate::spec::TargetMetadata {
+            description: None,
+            tier: None,
+            host_tools: None,
+            std: None,
+        },
+        data_layout: "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8".into(),
+        llvm_target: "avr-unknown-unknown".into(),
+        pointer_width: 16,
+        options: TargetOptions {
+            c_int_width: "16".into(),
+            exe_suffix: ".elf".into(),
+            linker: Some("avr-gcc".into()),
+            eh_frame_header: false,
+            pre_link_args: TargetOptions::link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &[]),
+            late_link_args: TargetOptions::link_args(
+                LinkerFlavor::Gnu(Cc::Yes, Lld::No),
+                &["-lgcc"],
+            ),
+            max_atomic_width: Some(16),
+            atomic_cas: false,
+            relocation_model: RelocModel::Static,
+            need_explicit_cpu: true,
+            ..TargetOptions::default()
+        },
+    }
+}
diff --git a/compiler/rustc_target/src/spec/targets/avr_unknown_gnu_atmega328.rs b/compiler/rustc_target/src/spec/targets/avr_unknown_gnu_atmega328.rs
deleted file mode 100644
index c3d6fb72273..00000000000
--- a/compiler/rustc_target/src/spec/targets/avr_unknown_gnu_atmega328.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-use crate::spec::{Target, base};
-
-pub(crate) fn target() -> Target {
-    base::avr_gnu::target("atmega328", "-mmcu=atmega328")
-}
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index b5cd3864620..c7f4ab48ab1 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -301,7 +301,7 @@ target | std | host | notes
 [`armv8r-none-eabihf`](platform-support/armv8r-none-eabihf.md) | * |  | Bare Armv8-R, hardfloat
 [`armv7a-nuttx-eabi`](platform-support/nuttx.md) | ✓ |  | ARMv7-A with NuttX
 [`armv7a-nuttx-eabihf`](platform-support/nuttx.md) | ✓ |  | ARMv7-A with NuttX, hardfloat
-`avr-unknown-gnu-atmega328` | * |  | AVR. Requires `-Z build-std=core`
+`avr-none` | * |  | AVR; requires `-Zbuild-std=core` and `-Ctarget-cpu=...`
 `bpfeb-unknown-none` | * |  | BPF (big endian)
 `bpfel-unknown-none` | * |  | BPF (little endian)
 `csky-unknown-linux-gnuabiv2` | ✓ |  | C-SKY abiv2 Linux (little endian)
diff --git a/src/doc/rustc/src/platform-support/avr-none.md b/src/doc/rustc/src/platform-support/avr-none.md
new file mode 100644
index 00000000000..9c1836222c1
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/avr-none.md
@@ -0,0 +1,81 @@
+# `avr-none`
+
+Series of microcontrollers from Atmel: ATmega8, ATmega328p etc.
+
+**Tier: 3**
+
+## Target maintainers
+
+- [Patryk Wychowaniec](https://github.com/Patryk27) <pwychowaniec@pm.me>
+
+## Requirements
+
+This target is only cross-compiled; x86-64 Linux, x86-64 macOS and aarch64 macOS
+hosts are confirmed to work, but in principle any machine able to run rustc and
+avr-gcc should be good.
+
+Compiling for this target requires `avr-gcc` installed, because a couple of
+intrinsics (like 32-bit multiplication) rely on [`libgcc`](https://github.com/gcc-mirror/gcc/blob/3269a722b7a03613e9c4e2862bc5088c4a17cc11/libgcc/config/avr/lib1funcs.S)
+and can't be provided through `compiler-builtins` yet. This is a limitation that
+[we hope to lift in the future](https://github.com/rust-lang/compiler-builtins/issues/711).
+
+You'll also need to setup the `.cargo/config` file - see below for details.
+
+## Building the target
+
+Rust comes with AVR support enabled, you don't have to rebuild the compiler.
+
+## Building Rust programs
+
+Install `avr-gcc`:
+
+```console
+# Ubuntu:
+$ sudo apt-get install gcc-avr
+
+# Mac:
+$ brew tap osx-cross/avr && brew install avr-gcc
+
+# NixOS (takes a couple of minutes, since it's not provided through Hydra):
+$ nix shell nixpkgs#pkgsCross.avr.buildPackages.gcc11
+```
+
+... setup `.cargo/config` for your project:
+
+```toml
+[build]
+target = "avr-none"
+rustflags = ["-C", "target-cpu=atmega328p"]
+
+[unstable]
+build-std = ["core"]
+```
+
+... and then simply run:
+
+```console
+$ cargo build --release
+```
+
+The final binary will be placed into
+`./target/avr-none/release/your-project.elf`.
+
+Note that since AVRs have rather small amounts of registers, ROM and RAM, it's
+recommended to always use `--release` to avoid running out of space.
+
+Also, please note that specifying `-C target-cpu` is required - here's a list of
+the possible variants:
+
+https://github.com/llvm/llvm-project/blob/093d4db2f3c874d4683fb01194b00dbb20e5c713/clang/lib/Basic/Targets/AVR.cpp#L32
+
+## Testing
+
+You can use [`simavr`](https://github.com/buserror/simavr) to emulate the
+resulting firmware on your machine:
+
+```console
+$ simavr -m atmega328p ./target/avr-none/release/your-project.elf
+```
+
+Alternatively, if you want to write a couple of actual `#[test]`s, you can use
+[`avr-tester`](https://github.com/Patryk27/avr-tester).
diff --git a/src/tools/compiletest/src/header/tests.rs b/src/tools/compiletest/src/header/tests.rs
index 55292c46bba..c65f10a52bd 100644
--- a/src/tools/compiletest/src/header/tests.rs
+++ b/src/tools/compiletest/src/header/tests.rs
@@ -465,7 +465,10 @@ fn profiler_runtime() {
 #[test]
 fn asm_support() {
     let asms = [
+        #[cfg(bootstrap)]
         ("avr-unknown-gnu-atmega328", false),
+        #[cfg(not(bootstrap))]
+        ("avr-none", false),
         ("i686-unknown-netbsd", true),
         ("riscv32gc-unknown-linux-gnu", true),
         ("riscv64imac-unknown-none-elf", true),
diff --git a/src/tools/run-make-support/src/external_deps/rustc.rs b/src/tools/run-make-support/src/external_deps/rustc.rs
index fd4a20278ad..710ba025830 100644
--- a/src/tools/run-make-support/src/external_deps/rustc.rs
+++ b/src/tools/run-make-support/src/external_deps/rustc.rs
@@ -253,6 +253,13 @@ impl Rustc {
         self
     }
 
+    /// Specify the target CPU.
+    pub fn target_cpu<S: AsRef<str>>(&mut self, target_cpu: S) -> &mut Self {
+        let target_cpu = target_cpu.as_ref();
+        self.cmd.arg(format!("-Ctarget-cpu={target_cpu}"));
+        self
+    }
+
     /// Specify the crate type.
     pub fn crate_type(&mut self, crate_type: &str) -> &mut Self {
         self.cmd.arg("--crate-type");
diff --git a/tests/assembly/asm/avr-modifiers.rs b/tests/assembly/asm/avr-modifiers.rs
index 585fdd7b725..124cad9bef6 100644
--- a/tests/assembly/asm/avr-modifiers.rs
+++ b/tests/assembly/asm/avr-modifiers.rs
@@ -1,6 +1,6 @@
 //@ add-core-stubs
 //@ assembly-output: emit-asm
-//@ compile-flags: --target avr-unknown-gnu-atmega328
+//@ compile-flags: --target avr-none -C target-cpu=atmega328p
 //@ needs-llvm-components: avr
 
 #![feature(no_core, asm_experimental_arch)]
diff --git a/tests/assembly/asm/avr-types.rs b/tests/assembly/asm/avr-types.rs
index 25cf3ec3b4b..309405f4d51 100644
--- a/tests/assembly/asm/avr-types.rs
+++ b/tests/assembly/asm/avr-types.rs
@@ -1,6 +1,6 @@
 //@ add-core-stubs
 //@ assembly-output: emit-asm
-//@ compile-flags: --target avr-unknown-gnu-atmega328
+//@ compile-flags: --target avr-none -C target-cpu=atmega328p
 //@ needs-llvm-components: avr
 
 #![feature(no_core, asm_experimental_arch)]
diff --git a/tests/assembly/targets/targets-pe.rs b/tests/assembly/targets/targets-pe.rs
index 1fa4dc821dd..b74d0181c4d 100644
--- a/tests/assembly/targets/targets-pe.rs
+++ b/tests/assembly/targets/targets-pe.rs
@@ -15,9 +15,9 @@
 //@ revisions: arm64ec_pc_windows_msvc
 //@ [arm64ec_pc_windows_msvc] compile-flags: --target arm64ec-pc-windows-msvc
 //@ [arm64ec_pc_windows_msvc] needs-llvm-components: aarch64
-//@ revisions: avr_unknown_gnu_atmega328
-//@ [avr_unknown_gnu_atmega328] compile-flags: --target avr-unknown-gnu-atmega328
-//@ [avr_unknown_gnu_atmega328] needs-llvm-components: avr
+//@ revisions: avr_none
+//@ [avr_none] compile-flags: --target avr-none -C target-cpu=atmega328p
+//@ [avr_none] needs-llvm-components: avr
 //@ revisions: bpfeb_unknown_none
 //@ [bpfeb_unknown_none] compile-flags: --target bpfeb-unknown-none
 //@ [bpfeb_unknown_none] needs-llvm-components: bpf
diff --git a/tests/codegen/asm/avr-clobbers.rs b/tests/codegen/asm/avr-clobbers.rs
index 56218cd7bcf..9451127bf04 100644
--- a/tests/codegen/asm/avr-clobbers.rs
+++ b/tests/codegen/asm/avr-clobbers.rs
@@ -1,6 +1,6 @@
 //@ add-core-stubs
 //@ assembly-output: emit-asm
-//@ compile-flags: --target avr-unknown-gnu-atmega328
+//@ compile-flags: --target avr-none -C target-cpu=atmega328p
 //@ needs-llvm-components: avr
 
 #![crate_type = "rlib"]
diff --git a/tests/codegen/avr/avr-func-addrspace.rs b/tests/codegen/avr/avr-func-addrspace.rs
index ed8acccb1ad..2ec7c86b5f4 100644
--- a/tests/codegen/avr/avr-func-addrspace.rs
+++ b/tests/codegen/avr/avr-func-addrspace.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Copt-level=3 --target=avr-unknown-gnu-atmega328 --crate-type=rlib -C panic=abort
+//@ compile-flags: -Copt-level=3 --target=avr-none -C target-cpu=atmega328p --crate-type=rlib -C panic=abort
 //@ needs-llvm-components: avr
 
 // This test validates that function pointers can be stored in global variables
diff --git a/tests/run-make/avr-rjmp-offset/rmake.rs b/tests/run-make/avr-rjmp-offset/rmake.rs
index de64b724eed..73b6ab3977e 100644
--- a/tests/run-make/avr-rjmp-offset/rmake.rs
+++ b/tests/run-make/avr-rjmp-offset/rmake.rs
@@ -22,7 +22,8 @@ fn main() {
         .input("avr-rjmp-offsets.rs")
         .opt_level("s")
         .panic("abort")
-        .target("avr-unknown-gnu-atmega328")
+        .target("avr-none")
+        .target_cpu("avr")
         // normally one links with `avr-gcc`, but this is not available in CI,
         // hence this test diverges from the default behavior to enable linking
         // at all, which is necessary for the test (to resolve the labels). To
@@ -49,6 +50,7 @@ fn main() {
     // of the Rust compiler did produce a label `rjmp .-4` (misses the first
     // instruction in the loop).
     assert!(disassembly.contains("<main>"), "no main function in output");
+
     disassembly
         .trim()
         .lines()
diff --git a/tests/ui/feature-gates/feature-gate-abi-avr-interrupt.rs b/tests/ui/feature-gates/feature-gate-abi-avr-interrupt.rs
index 5386628a8e0..ce3d3fc645d 100644
--- a/tests/ui/feature-gates/feature-gate-abi-avr-interrupt.rs
+++ b/tests/ui/feature-gates/feature-gate-abi-avr-interrupt.rs
@@ -1,5 +1,5 @@
 //@ needs-llvm-components: avr
-//@ compile-flags: --target=avr-unknown-gnu-atmega328 --crate-type=rlib
+//@ compile-flags: --target=avr-none -C target-cpu=atmega328p --crate-type=rlib
 #![no_core]
 #![feature(no_core, lang_items)]
 #[lang="sized"]
diff --git a/tests/ui/repr/16-bit-repr-c-enum.rs b/tests/ui/repr/16-bit-repr-c-enum.rs
index 2b6bbf12650..011076882d2 100644
--- a/tests/ui/repr/16-bit-repr-c-enum.rs
+++ b/tests/ui/repr/16-bit-repr-c-enum.rs
@@ -2,7 +2,7 @@
 //@ revisions: avr msp430
 //
 //@ [avr] needs-llvm-components: avr
-//@ [avr] compile-flags: --target=avr-unknown-gnu-atmega328 --crate-type=rlib
+//@ [avr] compile-flags: --target=avr-none -C target-cpu=atmega328p --crate-type=rlib
 //@ [msp430] needs-llvm-components: msp430
 //@ [msp430] compile-flags: --target=msp430-none-elf --crate-type=rlib
 #![feature(no_core, lang_items, intrinsics, staged_api, rustc_attrs)]
-- 
cgit 1.4.1-3-g733a5


From 81ab20f34e5447108c8103c10cd3f106f338e7e1 Mon Sep 17 00:00:00 2001
From: Jordan McQueen <j@jm.dev>
Date: Thu, 20 Feb 2025 10:37:28 +0000
Subject: Update references to cc_detect.rs

The locations of these files have since been changed. This is a simple
change to update the references to these files.
---
 config.example.toml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/config.example.toml b/config.example.toml
index fd27b24e461..a17d3ec9f88 100644
--- a/config.example.toml
+++ b/config.example.toml
@@ -793,12 +793,12 @@
 # C compiler to be used to compile C code. Note that the
 # default value is platform specific, and if not specified it may also depend on
 # what platform is crossing to what platform.
-# See `src/bootstrap/cc_detect.rs` for details.
+# See `src/bootstrap/src/utils/cc_detect.rs` for details.
 #cc = "cc" (path)
 
 # C++ compiler to be used to compile C++ code (e.g. LLVM and our LLVM shims).
 # This is only used for host targets.
-# See `src/bootstrap/cc_detect.rs` for details.
+# See `src/bootstrap/src/utils/cc_detect.rs` for details.
 #cxx = "c++" (path)
 
 # Archiver to be used to assemble static libraries compiled from C/C++ code.
-- 
cgit 1.4.1-3-g733a5


From c23bf48e4fedafee67ae1e52edeb8f3f94268a7d Mon Sep 17 00:00:00 2001
From: usamoi <usamoi@outlook.com>
Date: Mon, 3 Feb 2025 16:43:24 +0800
Subject: infer linker flavor by linker name if it's sufficiently specific

---
 compiler/rustc_target/src/spec/mod.rs | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index f7e467b0c11..60e1699b11d 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -303,15 +303,16 @@ impl LinkerFlavor {
         }
     }
 
-    fn infer_linker_hints(linker_stem: &str) -> (Option<Cc>, Option<Lld>) {
+    fn infer_linker_hints(linker_stem: &str) -> Result<Self, (Option<Cc>, Option<Lld>)> {
         // Remove any version postfix.
         let stem = linker_stem
             .rsplit_once('-')
             .and_then(|(lhs, rhs)| rhs.chars().all(char::is_numeric).then_some(lhs))
             .unwrap_or(linker_stem);
 
-        // GCC/Clang can have an optional target prefix.
-        if stem == "emcc"
+        if stem == "llvm-bitcode-linker" {
+            Ok(Self::Llbc)
+        } else if stem == "emcc" // GCC/Clang can have an optional target prefix.
             || stem == "gcc"
             || stem.ends_with("-gcc")
             || stem == "g++"
@@ -321,7 +322,7 @@ impl LinkerFlavor {
             || stem == "clang++"
             || stem.ends_with("-clang++")
         {
-            (Some(Cc::Yes), Some(Lld::No))
+            Err((Some(Cc::Yes), Some(Lld::No)))
         } else if stem == "wasm-ld"
             || stem.ends_with("-wasm-ld")
             || stem == "ld.lld"
@@ -329,11 +330,11 @@ impl LinkerFlavor {
             || stem == "rust-lld"
             || stem == "lld-link"
         {
-            (Some(Cc::No), Some(Lld::Yes))
+            Err((Some(Cc::No), Some(Lld::Yes)))
         } else if stem == "ld" || stem.ends_with("-ld") || stem == "link" {
-            (Some(Cc::No), Some(Lld::No))
+            Err((Some(Cc::No), Some(Lld::No)))
         } else {
-            (None, None)
+            Err((None, None))
         }
     }
 
@@ -357,7 +358,10 @@ impl LinkerFlavor {
     }
 
     pub fn with_linker_hints(self, linker_stem: &str) -> LinkerFlavor {
-        self.with_hints(LinkerFlavor::infer_linker_hints(linker_stem))
+        match LinkerFlavor::infer_linker_hints(linker_stem) {
+            Ok(linker_flavor) => linker_flavor,
+            Err(hints) => self.with_hints(hints),
+        }
     }
 
     pub fn check_compatibility(self, cli: LinkerFlavorCli) -> Option<String> {
-- 
cgit 1.4.1-3-g733a5


From d5128f92745774a93cd4384a71c7df727bc87377 Mon Sep 17 00:00:00 2001
From: Patryk Wychowaniec <pwychowaniec@pm.me>
Date: Thu, 20 Feb 2025 15:05:06 +0100
Subject: avr-rjmp-offset: Explain `.target_cpu()`

---
 tests/run-make/avr-rjmp-offset/rmake.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tests/run-make/avr-rjmp-offset/rmake.rs b/tests/run-make/avr-rjmp-offset/rmake.rs
index 73b6ab3977e..da314f26ca7 100644
--- a/tests/run-make/avr-rjmp-offset/rmake.rs
+++ b/tests/run-make/avr-rjmp-offset/rmake.rs
@@ -23,6 +23,10 @@ fn main() {
         .opt_level("s")
         .panic("abort")
         .target("avr-none")
+        // rust-lld has some troubles understanding the -mmcu flag, so for the
+        // time being let's tell rustc to emit binary that's compatible with the
+        // target CPU that lld defaults to, i.e. just `avr` (that's simply the
+        // minimal common instruction set across all AVRs)
         .target_cpu("avr")
         // normally one links with `avr-gcc`, but this is not available in CI,
         // hence this test diverges from the default behavior to enable linking
-- 
cgit 1.4.1-3-g733a5


From 18c210c7869b5786acde4d343a47df99113dba9b Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 20 Feb 2025 15:06:53 +0000
Subject: Workaround Cranelift not yet properly supporting vectors smaller than
 128bit

While it would technically be possible to workaround this in cg_clif, it
quickly becomes very messy and would likely cause correctness issues.
Working around it in rustc instead is much simper and won't have any
negative impact for code running on stable as vectors smaller than
128bit can only be made on nightly using core::simd or #[repr(simd)].
---
 compiler/rustc_target/src/callconv/mod.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_target/src/callconv/mod.rs b/compiler/rustc_target/src/callconv/mod.rs
index c2a176facdf..b90a006ac51 100644
--- a/compiler/rustc_target/src/callconv/mod.rs
+++ b/compiler/rustc_target/src/callconv/mod.rs
@@ -737,7 +737,9 @@ impl<'a, Ty> FnAbi<'a, Ty> {
             // to 128-bit-sized vectors.
             "x86" if spec.rustc_abi == Some(RustcAbi::X86Sse2) => arg.layout.size.bits() <= 128,
             "x86_64" if spec.rustc_abi != Some(RustcAbi::X86Softfloat) => {
-                arg.layout.size.bits() <= 128
+                // FIXME once https://github.com/bytecodealliance/wasmtime/issues/10254 is fixed
+                // accept vectors up to 128bit rather than vectors of exactly 128bit.
+                arg.layout.size.bits() == 128
             }
             // So far, we haven't implemented this logic for any other target.
             _ => false,
-- 
cgit 1.4.1-3-g733a5


From c2aed39ea7285d86d4a9c1b02e221bddc1d9a45f Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Thu, 20 Feb 2025 08:15:07 -0800
Subject: Update docs for default features of wasm targets

LLVM 20 enabled the `nontrapping-fptoint` and `bulk-memory` features by
default, so this updates the corresponding documentation for the
`wasm32-*` targets (which all point to `wasm32-unknown-unknown`).

cc #137315
---
 src/doc/rustc/src/platform-support/wasm32-unknown-unknown.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/doc/rustc/src/platform-support/wasm32-unknown-unknown.md b/src/doc/rustc/src/platform-support/wasm32-unknown-unknown.md
index 73264aba858..ba95ab7af6d 100644
--- a/src/doc/rustc/src/platform-support/wasm32-unknown-unknown.md
+++ b/src/doc/rustc/src/platform-support/wasm32-unknown-unknown.md
@@ -129,6 +129,8 @@ As of the time of this writing the proposals that are enabled by default (the
 * `mutable-globals`
 * `reference-types`
 * `sign-ext`
+* `nontrapping-fptoint` (Rust 1.87.0+, LLVM 20+)
+* `bulk-memory` (Rust 1.87.0+, LLVM 20+)
 
 If you're compiling WebAssembly code for an engine that does not support a
 feature in LLVM's default feature set then the feature must be disabled at
-- 
cgit 1.4.1-3-g733a5


From 32a1ff1aafba04670f557c7175d6962148a0260f Mon Sep 17 00:00:00 2001
From: Florian Bartels <Florian.Bartels@elektrobit.com>
Date: Thu, 20 Feb 2025 16:40:50 +0000
Subject: Make x86 QNX target name consistent with other Rust targets

---
 compiler/rustc_target/src/spec/mod.rs              |  2 +-
 .../src/spec/targets/i586_pc_nto_qnx700.rs         | 30 ----------------------
 .../src/spec/targets/i686_pc_nto_qnx700.rs         | 30 ++++++++++++++++++++++
 src/doc/rustc/src/platform-support.md              |  2 +-
 src/doc/rustc/src/platform-support/nto-qnx.md      |  2 +-
 src/tools/tidy/src/target_policy.rs                |  1 +
 tests/assembly/targets/targets-elf.rs              |  6 ++---
 7 files changed, 37 insertions(+), 36 deletions(-)
 delete mode 100644 compiler/rustc_target/src/spec/targets/i586_pc_nto_qnx700.rs
 create mode 100644 compiler/rustc_target/src/spec/targets/i686_pc_nto_qnx700.rs

diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index f7e467b0c11..e9733113acc 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -2001,7 +2001,7 @@ supported_targets! {
     ("x86_64-pc-nto-qnx710", x86_64_pc_nto_qnx710),
     ("x86_64-pc-nto-qnx710_iosock", x86_64_pc_nto_qnx710_iosock),
     ("x86_64-pc-nto-qnx800", x86_64_pc_nto_qnx800),
-    ("i586-pc-nto-qnx700", i586_pc_nto_qnx700),
+    ("i686-pc-nto-qnx700", i686_pc_nto_qnx700),
 
     ("aarch64-unknown-linux-ohos", aarch64_unknown_linux_ohos),
     ("armv7-unknown-linux-ohos", armv7_unknown_linux_ohos),
diff --git a/compiler/rustc_target/src/spec/targets/i586_pc_nto_qnx700.rs b/compiler/rustc_target/src/spec/targets/i586_pc_nto_qnx700.rs
deleted file mode 100644
index 6a98a763b36..00000000000
--- a/compiler/rustc_target/src/spec/targets/i586_pc_nto_qnx700.rs
+++ /dev/null
@@ -1,30 +0,0 @@
-use crate::spec::base::nto_qnx;
-use crate::spec::{RustcAbi, StackProbeType, Target, TargetOptions, base};
-
-pub(crate) fn target() -> Target {
-    let mut meta = nto_qnx::meta();
-    meta.description = Some("32-bit x86 QNX Neutrino 7.0 RTOS".into());
-    meta.std = Some(false);
-    Target {
-        llvm_target: "i586-pc-unknown".into(),
-        metadata: meta,
-        pointer_width: 32,
-        data_layout: "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-\
-            i128:128-f64:32:64-f80:32-n8:16:32-S128"
-            .into(),
-        arch: "x86".into(),
-        options: TargetOptions {
-            rustc_abi: Some(RustcAbi::X86Sse2),
-            cpu: "pentium4".into(),
-            max_atomic_width: Some(64),
-            pre_link_args: nto_qnx::pre_link_args(
-                nto_qnx::ApiVariant::Default,
-                nto_qnx::Arch::I586,
-            ),
-            env: "nto70".into(),
-            vendor: "pc".into(),
-            stack_probes: StackProbeType::Inline,
-            ..base::nto_qnx::opts()
-        },
-    }
-}
diff --git a/compiler/rustc_target/src/spec/targets/i686_pc_nto_qnx700.rs b/compiler/rustc_target/src/spec/targets/i686_pc_nto_qnx700.rs
new file mode 100644
index 00000000000..6a98a763b36
--- /dev/null
+++ b/compiler/rustc_target/src/spec/targets/i686_pc_nto_qnx700.rs
@@ -0,0 +1,30 @@
+use crate::spec::base::nto_qnx;
+use crate::spec::{RustcAbi, StackProbeType, Target, TargetOptions, base};
+
+pub(crate) fn target() -> Target {
+    let mut meta = nto_qnx::meta();
+    meta.description = Some("32-bit x86 QNX Neutrino 7.0 RTOS".into());
+    meta.std = Some(false);
+    Target {
+        llvm_target: "i586-pc-unknown".into(),
+        metadata: meta,
+        pointer_width: 32,
+        data_layout: "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-\
+            i128:128-f64:32:64-f80:32-n8:16:32-S128"
+            .into(),
+        arch: "x86".into(),
+        options: TargetOptions {
+            rustc_abi: Some(RustcAbi::X86Sse2),
+            cpu: "pentium4".into(),
+            max_atomic_width: Some(64),
+            pre_link_args: nto_qnx::pre_link_args(
+                nto_qnx::ApiVariant::Default,
+                nto_qnx::Arch::I586,
+            ),
+            env: "nto70".into(),
+            vendor: "pc".into(),
+            stack_probes: StackProbeType::Inline,
+            ..base::nto_qnx::opts()
+        },
+    }
+}
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index b5cd3864620..86a210a0d9c 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -309,10 +309,10 @@ target | std | host | notes
 [`hexagon-unknown-linux-musl`](platform-support/hexagon-unknown-linux-musl.md) | ✓ | | Hexagon Linux with musl 1.2.3
 [`hexagon-unknown-none-elf`](platform-support/hexagon-unknown-none-elf.md)| * | | Bare Hexagon (v60+, HVX)
 [`i386-apple-ios`](platform-support/apple-ios.md) | ✓ |  | 32-bit x86 iOS (Penryn) [^x86_32-floats-return-ABI]
-[`i586-pc-nto-qnx700`](platform-support/nto-qnx.md) | * |  | 32-bit x86 QNX Neutrino 7.0 RTOS (Pentium 4) [^x86_32-floats-return-ABI]
 [`i586-unknown-netbsd`](platform-support/netbsd.md) | ✓ |  | 32-bit x86 (original Pentium) [^x86_32-floats-x87]
 [`i586-unknown-redox`](platform-support/redox.md) | ✓ |  | 32-bit x86 Redox OS (PentiumPro) [^x86_32-floats-x87]
 [`i686-apple-darwin`](platform-support/apple-darwin.md) | ✓ | ✓ | 32-bit macOS (10.12+, Sierra+, Penryn) [^x86_32-floats-return-ABI]
+[`i686-pc-nto-qnx700`](platform-support/nto-qnx.md) | * |  | 32-bit x86 QNX Neutrino 7.0 RTOS (Pentium 4) [^x86_32-floats-return-ABI]
 `i686-unknown-haiku` | ✓ | ✓ | 32-bit Haiku (Pentium 4) [^x86_32-floats-return-ABI]
 [`i686-unknown-hurd-gnu`](platform-support/hurd.md) | ✓ | ✓ | 32-bit GNU/Hurd (Pentium 4) [^x86_32-floats-return-ABI]
 [`i686-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | NetBSD/i386 (Pentium 4) [^x86_32-floats-return-ABI]
diff --git a/src/doc/rustc/src/platform-support/nto-qnx.md b/src/doc/rustc/src/platform-support/nto-qnx.md
index 339741f1472..77e8caaee4c 100644
--- a/src/doc/rustc/src/platform-support/nto-qnx.md
+++ b/src/doc/rustc/src/platform-support/nto-qnx.md
@@ -31,7 +31,7 @@ Currently, the following QNX versions and compilation targets are supported:
 | `aarch64-unknown-nto-qnx710_iosock` | QNX Neutrino 7.1 with io-sock | AArch64             |      ?       |        ✓         |
 | `x86_64-pc-nto-qnx710_iosock`       | QNX Neutrino 7.1 with io-sock | x86_64              |      ?       |        ✓         |
 | `aarch64-unknown-nto-qnx700`        | QNX Neutrino 7.0              | AArch64             |      ?       |        ✓         |
-| `i586-pc-nto-qnx700`                | QNX Neutrino 7.0              | x86                 |              |        ✓         |
+| `i686-pc-nto-qnx700`                | QNX Neutrino 7.0              | x86                 |              |        ✓         |
 
 On QNX Neutrino 7.0 and 7.1, `io-pkt` is used as network stack by default.
 QNX Neutrino 7.1 includes the optional network stack `io-sock`.
diff --git a/src/tools/tidy/src/target_policy.rs b/src/tools/tidy/src/target_policy.rs
index 776221d3062..b2681934417 100644
--- a/src/tools/tidy/src/target_policy.rs
+++ b/src/tools/tidy/src/target_policy.rs
@@ -21,6 +21,7 @@ const EXCEPTIONS: &[&str] = &[
     "xtensa_esp32s2_espidf",
     "xtensa_esp32s3_none_elf",
     "xtensa_esp32s3_espidf",
+    "i586_pc_nto_qnx700", // Renamed to i686-pc-nto-qnx700, see https://github.com/rust-lang/rust/issues/136495
 ];
 
 pub fn check(root_path: &Path, bad: &mut bool) {
diff --git a/tests/assembly/targets/targets-elf.rs b/tests/assembly/targets/targets-elf.rs
index b5c0ee5a107..3e73d2c6eb7 100644
--- a/tests/assembly/targets/targets-elf.rs
+++ b/tests/assembly/targets/targets-elf.rs
@@ -216,9 +216,9 @@
 //@ revisions: hexagon_unknown_none_elf
 //@ [hexagon_unknown_none_elf] compile-flags: --target hexagon-unknown-none-elf
 //@ [hexagon_unknown_none_elf] needs-llvm-components: hexagon
-//@ revisions: i586_pc_nto_qnx700
-//@ [i586_pc_nto_qnx700] compile-flags: --target i586-pc-nto-qnx700
-//@ [i586_pc_nto_qnx700] needs-llvm-components: x86
+//@ revisions: i686_pc_nto_qnx700
+//@ [i686_pc_nto_qnx700] compile-flags: --target i686-pc-nto-qnx700
+//@ [i686_pc_nto_qnx700] needs-llvm-components: x86
 //@ revisions: i586_unknown_linux_gnu
 //@ [i586_unknown_linux_gnu] compile-flags: --target i586-unknown-linux-gnu
 //@ [i586_unknown_linux_gnu] needs-llvm-components: x86
-- 
cgit 1.4.1-3-g733a5


From 7ba3d7b54e7688f6f1a0fd22fe274ee7b06fea3e Mon Sep 17 00:00:00 2001
From: Zachary S <zasample18+github@gmail.com>
Date: Sat, 25 Jan 2025 20:15:24 -0600
Subject: Remove `BackendRepr::Uninhabited`, replaced with an `uninhabited:
 bool` field in `LayoutData`.

Also update comments that refered to BackendRepr::Uninhabited.
---
 compiler/rustc_abi/src/callconv.rs                 |  2 --
 compiler/rustc_abi/src/layout.rs                   | 23 +++++++-------
 compiler/rustc_abi/src/lib.rs                      | 35 ++++++++++------------
 .../rustc_codegen_cranelift/src/value_and_place.rs |  4 +--
 compiler/rustc_codegen_gcc/src/intrinsic/mod.rs    |  2 +-
 compiler/rustc_codegen_gcc/src/type_of.rs          | 13 ++++----
 compiler/rustc_codegen_llvm/src/intrinsic.rs       |  2 +-
 compiler/rustc_codegen_llvm/src/type_of.rs         | 13 ++++----
 compiler/rustc_codegen_ssa/src/mir/operand.rs      |  4 +--
 compiler/rustc_const_eval/src/interpret/operand.rs |  2 +-
 .../rustc_const_eval/src/interpret/validity.rs     |  8 ++---
 .../src/util/check_validity_requirement.rs         | 16 +++++-----
 compiler/rustc_middle/src/ty/layout.rs             |  3 +-
 compiler/rustc_mir_transform/src/gvn.rs            |  5 +++-
 compiler/rustc_smir/src/rustc_smir/convert/abi.rs  |  1 -
 compiler/rustc_target/src/callconv/loongarch.rs    |  2 +-
 compiler/rustc_target/src/callconv/mod.rs          |  3 +-
 compiler/rustc_target/src/callconv/riscv.rs        |  2 +-
 compiler/rustc_target/src/callconv/x86.rs          |  4 +--
 compiler/rustc_target/src/callconv/x86_64.rs       |  2 --
 compiler/rustc_target/src/callconv/x86_win64.rs    |  2 +-
 compiler/rustc_ty_utils/src/abi.rs                 |  4 +--
 compiler/rustc_ty_utils/src/layout.rs              | 21 ++++++-------
 compiler/rustc_ty_utils/src/layout/invariant.rs    | 15 ++++++----
 compiler/stable_mir/src/abi.rs                     |  6 +---
 .../rust-analyzer/crates/hir-ty/src/layout.rs      | 12 ++++----
 26 files changed, 93 insertions(+), 113 deletions(-)

diff --git a/compiler/rustc_abi/src/callconv.rs b/compiler/rustc_abi/src/callconv.rs
index 9fb70b80c9e..4529ab8058e 100644
--- a/compiler/rustc_abi/src/callconv.rs
+++ b/compiler/rustc_abi/src/callconv.rs
@@ -65,8 +65,6 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
         Ty: TyAbiInterface<'a, C> + Copy,
     {
         match self.backend_repr {
-            BackendRepr::Uninhabited => Err(Heterogeneous),
-
             // The primitive for this algorithm.
             BackendRepr::Scalar(scalar) => {
                 let kind = match scalar.primitive() {
diff --git a/compiler/rustc_abi/src/layout.rs b/compiler/rustc_abi/src/layout.rs
index 45cd0b517f6..53243266f99 100644
--- a/compiler/rustc_abi/src/layout.rs
+++ b/compiler/rustc_abi/src/layout.rs
@@ -130,6 +130,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             },
             backend_repr: BackendRepr::ScalarPair(a, b),
             largest_niche,
+            uninhabited: false,
             align,
             size,
             max_repr_align: None,
@@ -221,8 +222,9 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         LayoutData {
             variants: Variants::Empty,
             fields: FieldsShape::Primitive,
-            backend_repr: BackendRepr::Uninhabited,
+            backend_repr: BackendRepr::Memory { sized: true },
             largest_niche: None,
+            uninhabited: true,
             align: dl.i8_align,
             size: Size::ZERO,
             max_repr_align: None,
@@ -400,6 +402,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             fields: FieldsShape::Union(union_field_count),
             backend_repr: abi,
             largest_niche: None,
+            uninhabited: false,
             align,
             size: size.align_to(align.abi),
             max_repr_align,
@@ -447,7 +450,6 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                 Scalar::Union { .. } => {}
             };
             match &mut st.backend_repr {
-                BackendRepr::Uninhabited => {}
                 BackendRepr::Scalar(scalar) => hide_niches(scalar),
                 BackendRepr::ScalarPair(a, b) => {
                     hide_niches(a);
@@ -639,9 +641,8 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             let same_size = size == variant_layouts[largest_variant_index].size;
             let same_align = align == variant_layouts[largest_variant_index].align;
 
-            let abi = if variant_layouts.iter().all(|v| v.is_uninhabited()) {
-                BackendRepr::Uninhabited
-            } else if same_size && same_align && others_zst {
+            let uninhabited = variant_layouts.iter().all(|v| v.is_uninhabited());
+            let abi = if same_size && same_align && others_zst {
                 match variant_layouts[largest_variant_index].backend_repr {
                     // When the total alignment and size match, we can use the
                     // same ABI as the scalar variant with the reserved niche.
@@ -683,6 +684,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                 },
                 backend_repr: abi,
                 largest_niche,
+                uninhabited,
                 size,
                 align,
                 max_repr_align,
@@ -853,9 +855,8 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         };
         let mut abi = BackendRepr::Memory { sized: true };
 
-        if layout_variants.iter().all(|v| v.is_uninhabited()) {
-            abi = BackendRepr::Uninhabited;
-        } else if tag.size(dl) == size {
+        let uninhabited = layout_variants.iter().all(|v| v.is_uninhabited());
+        if tag.size(dl) == size {
             // Make sure we only use scalar layout when the enum is entirely its
             // own tag (i.e. it has no padding nor any non-ZST variant fields).
             abi = BackendRepr::Scalar(tag);
@@ -995,6 +996,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                 memory_index: [0].into(),
             },
             largest_niche,
+            uninhabited,
             backend_repr: abi,
             align,
             size,
@@ -1355,9 +1357,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                 _ => {}
             }
         }
-        if fields.iter().any(|f| f.is_uninhabited()) {
-            abi = BackendRepr::Uninhabited;
-        }
+        let uninhabited = fields.iter().any(|f| f.is_uninhabited());
 
         let unadjusted_abi_align = if repr.transparent() {
             match layout_of_single_non_zst_field {
@@ -1378,6 +1378,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             fields: FieldsShape::Arbitrary { offsets, memory_index },
             backend_repr: abi,
             largest_niche,
+            uninhabited,
             align,
             size,
             max_repr_align,
diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs
index dbb4bed5cdd..14a8a579200 100644
--- a/compiler/rustc_abi/src/lib.rs
+++ b/compiler/rustc_abi/src/lib.rs
@@ -1404,7 +1404,6 @@ impl AddressSpace {
 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
 #[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
 pub enum BackendRepr {
-    Uninhabited,
     Scalar(Scalar),
     ScalarPair(Scalar, Scalar),
     Vector {
@@ -1423,10 +1422,9 @@ impl BackendRepr {
     #[inline]
     pub fn is_unsized(&self) -> bool {
         match *self {
-            BackendRepr::Uninhabited
-            | BackendRepr::Scalar(_)
-            | BackendRepr::ScalarPair(..)
-            | BackendRepr::Vector { .. } => false,
+            BackendRepr::Scalar(_) | BackendRepr::ScalarPair(..) | BackendRepr::Vector { .. } => {
+                false
+            }
             BackendRepr::Memory { sized } => !sized,
         }
     }
@@ -1445,12 +1443,6 @@ impl BackendRepr {
         }
     }
 
-    /// Returns `true` if this is an uninhabited type
-    #[inline]
-    pub fn is_uninhabited(&self) -> bool {
-        matches!(*self, BackendRepr::Uninhabited)
-    }
-
     /// Returns `true` if this is a scalar type
     #[inline]
     pub fn is_scalar(&self) -> bool {
@@ -1471,7 +1463,7 @@ impl BackendRepr {
             BackendRepr::Vector { element, count } => {
                 cx.data_layout().vector_align(element.size(cx) * count)
             }
-            BackendRepr::Uninhabited | BackendRepr::Memory { .. } => return None,
+            BackendRepr::Memory { .. } => return None,
         })
     }
 
@@ -1492,7 +1484,7 @@ impl BackendRepr {
                 // to make the size a multiple of align (e.g. for vectors of size 3).
                 (element.size(cx) * count).align_to(self.inherent_align(cx)?.abi)
             }
-            BackendRepr::Uninhabited | BackendRepr::Memory { .. } => return None,
+            BackendRepr::Memory { .. } => return None,
         })
     }
 
@@ -1506,9 +1498,7 @@ impl BackendRepr {
             BackendRepr::Vector { element, count } => {
                 BackendRepr::Vector { element: element.to_union(), count }
             }
-            BackendRepr::Uninhabited | BackendRepr::Memory { .. } => {
-                BackendRepr::Memory { sized: true }
-            }
+            BackendRepr::Memory { .. } => BackendRepr::Memory { sized: true },
         }
     }
 
@@ -1704,6 +1694,11 @@ pub struct LayoutData<FieldIdx: Idx, VariantIdx: Idx> {
     /// The leaf scalar with the largest number of invalid values
     /// (i.e. outside of its `valid_range`), if it exists.
     pub largest_niche: Option<Niche>,
+    /// Is this type known to be uninhabted?
+    ///
+    /// This is separate from BackendRepr, because an uninhabited return type may require special
+    /// consideration based on its size or other attributes.
+    pub uninhabited: bool,
 
     pub align: AbiAndPrefAlign,
     pub size: Size,
@@ -1735,14 +1730,14 @@ impl<FieldIdx: Idx, VariantIdx: Idx> LayoutData<FieldIdx, VariantIdx> {
     /// Returns `true` if this is an aggregate type (including a ScalarPair!)
     pub fn is_aggregate(&self) -> bool {
         match self.backend_repr {
-            BackendRepr::Uninhabited | BackendRepr::Scalar(_) | BackendRepr::Vector { .. } => false,
+            BackendRepr::Scalar(_) | BackendRepr::Vector { .. } => false,
             BackendRepr::ScalarPair(..) | BackendRepr::Memory { .. } => true,
         }
     }
 
     /// Returns `true` if this is an uninhabited type
     pub fn is_uninhabited(&self) -> bool {
-        self.backend_repr.is_uninhabited()
+        self.uninhabited
     }
 
     pub fn scalar<C: HasDataLayout>(cx: &C, scalar: Scalar) -> Self {
@@ -1778,6 +1773,7 @@ impl<FieldIdx: Idx, VariantIdx: Idx> LayoutData<FieldIdx, VariantIdx> {
             fields: FieldsShape::Primitive,
             backend_repr: BackendRepr::Scalar(scalar),
             largest_niche,
+            uninhabited: false,
             size,
             align,
             max_repr_align: None,
@@ -1802,6 +1798,7 @@ where
             backend_repr,
             fields,
             largest_niche,
+            uninhabited,
             variants,
             max_repr_align,
             unadjusted_abi_align,
@@ -1813,6 +1810,7 @@ where
             .field("abi", backend_repr)
             .field("fields", fields)
             .field("largest_niche", largest_niche)
+            .field("uninhabited", uninhabited)
             .field("variants", variants)
             .field("max_repr_align", max_repr_align)
             .field("unadjusted_abi_align", unadjusted_abi_align)
@@ -1877,7 +1875,6 @@ impl<FieldIdx: Idx, VariantIdx: Idx> LayoutData<FieldIdx, VariantIdx> {
             BackendRepr::Scalar(_) | BackendRepr::ScalarPair(..) | BackendRepr::Vector { .. } => {
                 false
             }
-            BackendRepr::Uninhabited => self.size.bytes() == 0,
             BackendRepr::Memory { sized } => sized && self.size.bytes() == 0,
         }
     }
diff --git a/compiler/rustc_codegen_cranelift/src/value_and_place.rs b/compiler/rustc_codegen_cranelift/src/value_and_place.rs
index a9b8e1bd393..1b3f86c8405 100644
--- a/compiler/rustc_codegen_cranelift/src/value_and_place.rs
+++ b/compiler/rustc_codegen_cranelift/src/value_and_place.rs
@@ -638,9 +638,7 @@ impl<'tcx> CPlace<'tcx> {
             }
             CPlaceInner::Addr(_, Some(_)) => bug!("Can't write value to unsized place {:?}", self),
             CPlaceInner::Addr(to_ptr, None) => {
-                if dst_layout.size == Size::ZERO
-                    || dst_layout.backend_repr == BackendRepr::Uninhabited
-                {
+                if dst_layout.size == Size::ZERO {
                     return;
                 }
 
diff --git a/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs b/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
index 5322b731d8b..433868e238a 100644
--- a/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
+++ b/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
@@ -315,7 +315,7 @@ impl<'a, 'gcc, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tc
                 let layout = self.layout_of(tp_ty).layout;
                 let _use_integer_compare = match layout.backend_repr() {
                     Scalar(_) | ScalarPair(_, _) => true,
-                    Uninhabited | Vector { .. } => false,
+                    Vector { .. } => false,
                     Memory { .. } => {
                         // For rusty ABIs, small aggregates are actually passed
                         // as `RegKind::Integer` (see `FnAbi::adjust_for_abi`),
diff --git a/compiler/rustc_codegen_gcc/src/type_of.rs b/compiler/rustc_codegen_gcc/src/type_of.rs
index 8b8b54753e7..bac4fc51300 100644
--- a/compiler/rustc_codegen_gcc/src/type_of.rs
+++ b/compiler/rustc_codegen_gcc/src/type_of.rs
@@ -84,7 +84,7 @@ fn uncached_gcc_type<'gcc, 'tcx>(
                 false,
             );
         }
-        BackendRepr::Uninhabited | BackendRepr::Memory { .. } => {}
+        BackendRepr::Memory { .. } => {}
     }
 
     let name = match *layout.ty.kind() {
@@ -179,19 +179,16 @@ impl<'tcx> LayoutGccExt<'tcx> for TyAndLayout<'tcx> {
     fn is_gcc_immediate(&self) -> bool {
         match self.backend_repr {
             BackendRepr::Scalar(_) | BackendRepr::Vector { .. } => true,
-            BackendRepr::ScalarPair(..) | BackendRepr::Uninhabited | BackendRepr::Memory { .. } => {
-                false
-            }
+            BackendRepr::ScalarPair(..) | BackendRepr::Memory { .. } => false,
         }
     }
 
     fn is_gcc_scalar_pair(&self) -> bool {
         match self.backend_repr {
             BackendRepr::ScalarPair(..) => true,
-            BackendRepr::Uninhabited
-            | BackendRepr::Scalar(_)
-            | BackendRepr::Vector { .. }
-            | BackendRepr::Memory { .. } => false,
+            BackendRepr::Scalar(_) | BackendRepr::Vector { .. } | BackendRepr::Memory { .. } => {
+                false
+            }
         }
     }
 
diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index 7e1a9d361e6..f68365f6c69 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -476,7 +476,7 @@ impl<'ll, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
                 let layout = self.layout_of(tp_ty).layout;
                 let use_integer_compare = match layout.backend_repr() {
                     Scalar(_) | ScalarPair(_, _) => true,
-                    Uninhabited | Vector { .. } => false,
+                    Vector { .. } => false,
                     Memory { .. } => {
                         // For rusty ABIs, small aggregates are actually passed
                         // as `RegKind::Integer` (see `FnAbi::adjust_for_abi`),
diff --git a/compiler/rustc_codegen_llvm/src/type_of.rs b/compiler/rustc_codegen_llvm/src/type_of.rs
index b0b6da869da..ba01fbff385 100644
--- a/compiler/rustc_codegen_llvm/src/type_of.rs
+++ b/compiler/rustc_codegen_llvm/src/type_of.rs
@@ -23,7 +23,7 @@ fn uncached_llvm_type<'a, 'tcx>(
             let element = layout.scalar_llvm_type_at(cx, element);
             return cx.type_vector(element, count);
         }
-        BackendRepr::Uninhabited | BackendRepr::Memory { .. } | BackendRepr::ScalarPair(..) => {}
+        BackendRepr::Memory { .. } | BackendRepr::ScalarPair(..) => {}
     }
 
     let name = match layout.ty.kind() {
@@ -172,19 +172,16 @@ impl<'tcx> LayoutLlvmExt<'tcx> for TyAndLayout<'tcx> {
     fn is_llvm_immediate(&self) -> bool {
         match self.backend_repr {
             BackendRepr::Scalar(_) | BackendRepr::Vector { .. } => true,
-            BackendRepr::ScalarPair(..) | BackendRepr::Uninhabited | BackendRepr::Memory { .. } => {
-                false
-            }
+            BackendRepr::ScalarPair(..) | BackendRepr::Memory { .. } => false,
         }
     }
 
     fn is_llvm_scalar_pair(&self) -> bool {
         match self.backend_repr {
             BackendRepr::ScalarPair(..) => true,
-            BackendRepr::Uninhabited
-            | BackendRepr::Scalar(_)
-            | BackendRepr::Vector { .. }
-            | BackendRepr::Memory { .. } => false,
+            BackendRepr::Scalar(_) | BackendRepr::Vector { .. } | BackendRepr::Memory { .. } => {
+                false
+            }
         }
     }
 
diff --git a/compiler/rustc_codegen_ssa/src/mir/operand.rs b/compiler/rustc_codegen_ssa/src/mir/operand.rs
index 958a52a2cb1..faf1300e473 100644
--- a/compiler/rustc_codegen_ssa/src/mir/operand.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/operand.rs
@@ -422,9 +422,7 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
                          See <https://github.com/rust-lang/rust/issues/137108>",
                     );
                 }
-                BackendRepr::Uninhabited
-                | BackendRepr::ScalarPair(_, _)
-                | BackendRepr::Memory { sized: false } => bug!(),
+                BackendRepr::ScalarPair(_, _) | BackendRepr::Memory { sized: false } => bug!(),
             })
         };
 
diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs
index 5d905cff1f2..36da9037e43 100644
--- a/compiler/rustc_const_eval/src/interpret/operand.rs
+++ b/compiler/rustc_const_eval/src/interpret/operand.rs
@@ -385,7 +385,7 @@ impl<'tcx, Prov: Provenance> ImmTy<'tcx, Prov> {
             (Immediate::Uninit, _) => Immediate::Uninit,
             // If the field is uninhabited, we can forget the data (can happen in ConstProp).
             // `enum S { A(!), B, C }` is an example of an enum with Scalar layout that
-            // has an `Uninhabited` variant, which means this case is possible.
+            // has an uninhabited variant, which means this case is possible.
             _ if layout.is_uninhabited() => Immediate::Uninit,
             // the field contains no information, can be left uninit
             // (Scalar/ScalarPair can contain even aligned ZST, not just 1-ZST)
diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs
index 0ac34f4633b..3667cc84d70 100644
--- a/compiler/rustc_const_eval/src/interpret/validity.rs
+++ b/compiler/rustc_const_eval/src/interpret/validity.rs
@@ -1274,11 +1274,11 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValueVisitor<'tcx, M> for ValidityVisitor<'rt,
         // FIXME: We could avoid some redundant checks here. For newtypes wrapping
         // scalars, we do the same check on every "level" (e.g., first we check
         // MyNewtype and then the scalar in there).
+        if val.layout.is_uninhabited() {
+            let ty = val.layout.ty;
+            throw_validation_failure!(self.path, UninhabitedVal { ty });
+        }
         match val.layout.backend_repr {
-            BackendRepr::Uninhabited => {
-                let ty = val.layout.ty;
-                throw_validation_failure!(self.path, UninhabitedVal { ty });
-            }
             BackendRepr::Scalar(scalar_layout) => {
                 if !scalar_layout.is_uninit_valid() {
                     // There is something to check here.
diff --git a/compiler/rustc_const_eval/src/util/check_validity_requirement.rs b/compiler/rustc_const_eval/src/util/check_validity_requirement.rs
index 79baf91c3ce..6426bca2332 100644
--- a/compiler/rustc_const_eval/src/util/check_validity_requirement.rs
+++ b/compiler/rustc_const_eval/src/util/check_validity_requirement.rs
@@ -111,13 +111,15 @@ fn check_validity_requirement_lax<'tcx>(
     };
 
     // Check the ABI.
-    let valid = match this.backend_repr {
-        BackendRepr::Uninhabited => false, // definitely UB
-        BackendRepr::Scalar(s) => scalar_allows_raw_init(s),
-        BackendRepr::ScalarPair(s1, s2) => scalar_allows_raw_init(s1) && scalar_allows_raw_init(s2),
-        BackendRepr::Vector { element: s, count } => count == 0 || scalar_allows_raw_init(s),
-        BackendRepr::Memory { .. } => true, // Fields are checked below.
-    };
+    let valid = !this.is_uninhabited() // definitely UB if uninhabited
+        && match this.backend_repr {
+            BackendRepr::Scalar(s) => scalar_allows_raw_init(s),
+            BackendRepr::ScalarPair(s1, s2) => {
+                scalar_allows_raw_init(s1) && scalar_allows_raw_init(s2)
+            }
+            BackendRepr::Vector { element: s, count } => count == 0 || scalar_allows_raw_init(s),
+            BackendRepr::Memory { .. } => true, // Fields are checked below.
+        };
     if !valid {
         // This is definitely not okay.
         return Ok(false);
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 19fa8323574..eb14ed20fba 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -794,8 +794,9 @@ where
                         Some(fields) => FieldsShape::Union(fields),
                         None => FieldsShape::Arbitrary { offsets: IndexVec::new(), memory_index: IndexVec::new() },
                     },
-                    backend_repr: BackendRepr::Uninhabited,
+                    backend_repr: BackendRepr::Memory { sized: true },
                     largest_niche: None,
+                    uninhabited: true,
                     align: tcx.data_layout.i8_align,
                     size: Size::ZERO,
                     max_repr_align: None,
diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs
index 77a3854ebde..2f8a3050199 100644
--- a/compiler/rustc_mir_transform/src/gvn.rs
+++ b/compiler/rustc_mir_transform/src/gvn.rs
@@ -1558,8 +1558,11 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
             return true;
         };
 
+        if layout.uninhabited {
+            return true;
+        }
+
         match layout.backend_repr {
-            BackendRepr::Uninhabited => true,
             BackendRepr::Scalar(a) => !a.is_always_valid(&self.ecx),
             BackendRepr::ScalarPair(a, b) => {
                 !a.is_always_valid(&self.ecx) || !b.is_always_valid(&self.ecx)
diff --git a/compiler/rustc_smir/src/rustc_smir/convert/abi.rs b/compiler/rustc_smir/src/rustc_smir/convert/abi.rs
index fb2e838cdc9..a627e0e69b6 100644
--- a/compiler/rustc_smir/src/rustc_smir/convert/abi.rs
+++ b/compiler/rustc_smir/src/rustc_smir/convert/abi.rs
@@ -202,7 +202,6 @@ impl<'tcx> Stable<'tcx> for rustc_abi::BackendRepr {
 
     fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
         match *self {
-            rustc_abi::BackendRepr::Uninhabited => ValueAbi::Uninhabited,
             rustc_abi::BackendRepr::Scalar(scalar) => ValueAbi::Scalar(scalar.stable(tables)),
             rustc_abi::BackendRepr::ScalarPair(first, second) => {
                 ValueAbi::ScalarPair(first.stable(tables), second.stable(tables))
diff --git a/compiler/rustc_target/src/callconv/loongarch.rs b/compiler/rustc_target/src/callconv/loongarch.rs
index 47566bde6b4..3fa67c624a7 100644
--- a/compiler/rustc_target/src/callconv/loongarch.rs
+++ b/compiler/rustc_target/src/callconv/loongarch.rs
@@ -80,7 +80,7 @@ where
                 }
             }
         },
-        BackendRepr::Vector { .. } | BackendRepr::Uninhabited => return Err(CannotUseFpConv),
+        BackendRepr::Vector { .. } => return Err(CannotUseFpConv),
         BackendRepr::ScalarPair(..) | BackendRepr::Memory { .. } => match arg_layout.fields {
             FieldsShape::Primitive => {
                 unreachable!("aggregates can't have `FieldsShape::Primitive`")
diff --git a/compiler/rustc_target/src/callconv/mod.rs b/compiler/rustc_target/src/callconv/mod.rs
index c2a176facdf..e5f986269dd 100644
--- a/compiler/rustc_target/src/callconv/mod.rs
+++ b/compiler/rustc_target/src/callconv/mod.rs
@@ -38,7 +38,7 @@ mod xtensa;
 pub enum PassMode {
     /// Ignore the argument.
     ///
-    /// The argument is either uninhabited or a ZST.
+    /// The argument is a ZST.
     Ignore,
     /// Pass the argument directly.
     ///
@@ -350,7 +350,6 @@ impl<'a, Ty> ArgAbi<'a, Ty> {
         scalar_attrs: impl Fn(&TyAndLayout<'a, Ty>, Scalar, Size) -> ArgAttributes,
     ) -> Self {
         let mode = match layout.backend_repr {
-            BackendRepr::Uninhabited => PassMode::Ignore,
             BackendRepr::Scalar(scalar) => {
                 PassMode::Direct(scalar_attrs(&layout, scalar, Size::ZERO))
             }
diff --git a/compiler/rustc_target/src/callconv/riscv.rs b/compiler/rustc_target/src/callconv/riscv.rs
index 265ae20f991..785175229b0 100644
--- a/compiler/rustc_target/src/callconv/riscv.rs
+++ b/compiler/rustc_target/src/callconv/riscv.rs
@@ -86,7 +86,7 @@ where
                 }
             }
         },
-        BackendRepr::Vector { .. } | BackendRepr::Uninhabited => return Err(CannotUseFpConv),
+        BackendRepr::Vector { .. } => return Err(CannotUseFpConv),
         BackendRepr::ScalarPair(..) | BackendRepr::Memory { .. } => match arg_layout.fields {
             FieldsShape::Primitive => {
                 unreachable!("aggregates can't have `FieldsShape::Primitive`")
diff --git a/compiler/rustc_target/src/callconv/x86.rs b/compiler/rustc_target/src/callconv/x86.rs
index 5f4f4cd57f6..7e5aab0201b 100644
--- a/compiler/rustc_target/src/callconv/x86.rs
+++ b/compiler/rustc_target/src/callconv/x86.rs
@@ -108,9 +108,7 @@ where
                 Ty: TyAbiInterface<'a, C> + Copy,
             {
                 match layout.backend_repr {
-                    BackendRepr::Uninhabited
-                    | BackendRepr::Scalar(_)
-                    | BackendRepr::ScalarPair(..) => false,
+                    BackendRepr::Scalar(_) | BackendRepr::ScalarPair(..) => false,
                     BackendRepr::Vector { .. } => true,
                     BackendRepr::Memory { .. } => {
                         for i in 0..layout.fields.count() {
diff --git a/compiler/rustc_target/src/callconv/x86_64.rs b/compiler/rustc_target/src/callconv/x86_64.rs
index b15d82c26da..ab306e20239 100644
--- a/compiler/rustc_target/src/callconv/x86_64.rs
+++ b/compiler/rustc_target/src/callconv/x86_64.rs
@@ -51,8 +51,6 @@ where
         }
 
         let mut c = match layout.backend_repr {
-            BackendRepr::Uninhabited => return Ok(()),
-
             BackendRepr::Scalar(scalar) => match scalar.primitive() {
                 Primitive::Int(..) | Primitive::Pointer(_) => Class::Int,
                 Primitive::Float(_) => Class::Sse,
diff --git a/compiler/rustc_target/src/callconv/x86_win64.rs b/compiler/rustc_target/src/callconv/x86_win64.rs
index 2ef5127de04..4d99a9f9ba0 100644
--- a/compiler/rustc_target/src/callconv/x86_win64.rs
+++ b/compiler/rustc_target/src/callconv/x86_win64.rs
@@ -8,7 +8,7 @@ use crate::spec::{HasTargetSpec, RustcAbi};
 pub(crate) fn compute_abi_info<Ty>(cx: &impl HasTargetSpec, fn_abi: &mut FnAbi<'_, Ty>) {
     let fixup = |a: &mut ArgAbi<'_, Ty>, is_ret: bool| {
         match a.layout.backend_repr {
-            BackendRepr::Uninhabited | BackendRepr::Memory { sized: false } => {}
+            BackendRepr::Memory { sized: false } => {}
             BackendRepr::ScalarPair(..) | BackendRepr::Memory { sized: true } => {
                 match a.layout.size.bits() {
                     8 => a.cast_to(Reg::i8()),
diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs
index c5d2d0afbfa..2d20ef3d690 100644
--- a/compiler/rustc_ty_utils/src/abi.rs
+++ b/compiler/rustc_ty_utils/src/abi.rs
@@ -472,9 +472,7 @@ fn fn_abi_sanity_check<'tcx>(
                 // `layout.backend_repr` and ignore everything else. We should just reject
                 //`Aggregate` entirely here, but some targets need to be fixed first.
                 match arg.layout.backend_repr {
-                    BackendRepr::Uninhabited
-                    | BackendRepr::Scalar(_)
-                    | BackendRepr::Vector { .. } => {}
+                    BackendRepr::Scalar(_) | BackendRepr::Vector { .. } => {}
                     BackendRepr::ScalarPair(..) => {
                         panic!("`PassMode::Direct` used for ScalarPair type {}", arg.layout.ty)
                     }
diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs
index 556512e0236..b6a14d147ca 100644
--- a/compiler/rustc_ty_utils/src/layout.rs
+++ b/compiler/rustc_ty_utils/src/layout.rs
@@ -348,19 +348,17 @@ fn layout_of_uncached<'tcx>(
                 .checked_mul(count, dl)
                 .ok_or_else(|| error(cx, LayoutError::SizeOverflow(ty)))?;
 
-            let abi = if count != 0 && ty.is_privately_uninhabited(tcx, cx.typing_env) {
-                BackendRepr::Uninhabited
-            } else {
-                BackendRepr::Memory { sized: true }
-            };
+            let abi = BackendRepr::Memory { sized: true };
 
             let largest_niche = if count != 0 { element.largest_niche } else { None };
+            let uninhabited = if count != 0 { element.uninhabited } else { false };
 
             tcx.mk_layout(LayoutData {
                 variants: Variants::Single { index: FIRST_VARIANT },
                 fields: FieldsShape::Array { stride: element.size, count },
                 backend_repr: abi,
                 largest_niche,
+                uninhabited,
                 align: element.align,
                 size,
                 max_repr_align: None,
@@ -375,6 +373,7 @@ fn layout_of_uncached<'tcx>(
                 fields: FieldsShape::Array { stride: element.size, count: 0 },
                 backend_repr: BackendRepr::Memory { sized: false },
                 largest_niche: None,
+                uninhabited: false,
                 align: element.align,
                 size: Size::ZERO,
                 max_repr_align: None,
@@ -390,6 +389,7 @@ fn layout_of_uncached<'tcx>(
             fields: FieldsShape::Array { stride: Size::from_bytes(1), count: 0 },
             backend_repr: BackendRepr::Memory { sized: false },
             largest_niche: None,
+            uninhabited: false,
             align: dl.i8_align,
             size: Size::ZERO,
             max_repr_align: None,
@@ -555,6 +555,7 @@ fn layout_of_uncached<'tcx>(
                 fields,
                 backend_repr: abi,
                 largest_niche: e_ly.largest_niche,
+                uninhabited: false,
                 size,
                 align,
                 max_repr_align: None,
@@ -1014,13 +1015,8 @@ fn coroutine_layout<'tcx>(
 
     size = size.align_to(align.abi);
 
-    let abi = if prefix.backend_repr.is_uninhabited()
-        || variants.iter().all(|v| v.backend_repr.is_uninhabited())
-    {
-        BackendRepr::Uninhabited
-    } else {
-        BackendRepr::Memory { sized: true }
-    };
+    let uninhabited = prefix.uninhabited || variants.iter().all(|v| v.is_uninhabited());
+    let abi = BackendRepr::Memory { sized: true };
 
     // this is similar to how ReprOptions populates its field_shuffle_seed
     let def_hash = tcx.def_path_hash(def_id).0.to_smaller_hash();
@@ -1041,6 +1037,7 @@ fn coroutine_layout<'tcx>(
         // See <https://github.com/rust-lang/rust/issues/63818>, <https://github.com/rust-lang/miri/issues/3780>.
         // FIXME: Remove when <https://github.com/rust-lang/rust/issues/125735> is implemented and aliased coroutine fields are wrapped in `UnsafePinned`.
         largest_niche: None,
+        uninhabited,
         size,
         align,
         max_repr_align: None,
diff --git a/compiler/rustc_ty_utils/src/layout/invariant.rs b/compiler/rustc_ty_utils/src/layout/invariant.rs
index 8d5403ed324..5ea6716c5ca 100644
--- a/compiler/rustc_ty_utils/src/layout/invariant.rs
+++ b/compiler/rustc_ty_utils/src/layout/invariant.rs
@@ -10,7 +10,11 @@ pub(super) fn layout_sanity_check<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLayou
 
     // Type-level uninhabitedness should always imply ABI uninhabitedness.
     if layout.ty.is_privately_uninhabited(tcx, cx.typing_env) {
-        assert!(layout.is_uninhabited());
+        assert!(
+            layout.is_uninhabited(),
+            "{:?} is type-level uninhabited but not ABI-uninhabited?",
+            layout.ty
+        );
     }
 
     if layout.size.bytes() % layout.align.abi.bytes() != 0 {
@@ -71,7 +75,7 @@ pub(super) fn layout_sanity_check<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLayou
         let Some((align, size)) = align.zip(size) else {
             assert_matches!(
                 layout.layout.backend_repr(),
-                BackendRepr::Uninhabited | BackendRepr::Memory { .. },
+                BackendRepr::Memory { .. },
                 "ABI unexpectedly missing alignment and/or size in {layout:#?}"
             );
             return;
@@ -235,7 +239,7 @@ pub(super) fn layout_sanity_check<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLayou
                 assert!(align >= element.align(cx).abi); // just sanity-checking `vector_align`.
                 // FIXME: Do some kind of check of the inner type, like for Scalar and ScalarPair.
             }
-            BackendRepr::Uninhabited | BackendRepr::Memory { .. } => {} // Nothing to check.
+            BackendRepr::Memory { .. } => {} // Nothing to check.
         }
     }
 
@@ -291,8 +295,8 @@ pub(super) fn layout_sanity_check<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLayou
                     || variant.is_uninhabited()
                 {
                     // These are never actually accessed anyway, so we can skip the coherence check
-                    // for them. They also fail that check, since they have
-                    // `Aggregate`/`Uninhabited` ABI even when the main type is
+                    // for them. They also fail that check, since they may have
+                    // a different ABI even when the main type is
                     // `Scalar`/`ScalarPair`. (Note that sometimes, variants with fields have size
                     // 0, and sometimes, variants without fields have non-0 size.)
                     continue;
@@ -306,7 +310,6 @@ pub(super) fn layout_sanity_check<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLayou
                     (BackendRepr::ScalarPair(a1, b1), BackendRepr::ScalarPair(a2, b2)) => {
                         scalar_coherent(a1, a2) && scalar_coherent(b1, b2)
                     }
-                    (BackendRepr::Uninhabited, _) => true,
                     (BackendRepr::Memory { .. }, _) => true,
                     _ => false,
                 };
diff --git a/compiler/stable_mir/src/abi.rs b/compiler/stable_mir/src/abi.rs
index 861b6692b53..091f3e1a95e 100644
--- a/compiler/stable_mir/src/abi.rs
+++ b/compiler/stable_mir/src/abi.rs
@@ -227,7 +227,6 @@ pub enum TagEncoding {
 /// in terms of categories of C types there are ABI rules for.
 #[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
 pub enum ValueAbi {
-    Uninhabited,
     Scalar(Scalar),
     ScalarPair(Scalar, Scalar),
     Vector {
@@ -244,10 +243,7 @@ impl ValueAbi {
     /// Returns `true` if the layout corresponds to an unsized type.
     pub fn is_unsized(&self) -> bool {
         match *self {
-            ValueAbi::Uninhabited
-            | ValueAbi::Scalar(_)
-            | ValueAbi::ScalarPair(..)
-            | ValueAbi::Vector { .. } => false,
+            ValueAbi::Scalar(_) | ValueAbi::ScalarPair(..) | ValueAbi::Vector { .. } => false,
             ValueAbi::Aggregate { sized } => !sized,
         }
     }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/layout.rs b/src/tools/rust-analyzer/crates/hir-ty/src/layout.rs
index b6f7c44c2ae..f5a7b658123 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/layout.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/layout.rs
@@ -194,6 +194,7 @@ fn layout_of_simd_ty(
         fields,
         backend_repr: BackendRepr::Vector { element: e_abi, count: e_len },
         largest_niche: e_ly.largest_niche,
+        uninhabited: false,
         size,
         align,
         max_repr_align: None,
@@ -297,20 +298,17 @@ pub fn layout_of_ty_query(
                 .checked_mul(count, dl)
                 .ok_or(LayoutError::BadCalc(LayoutCalculatorError::SizeOverflow))?;
 
-            let backend_repr =
-                if count != 0 && matches!(element.backend_repr, BackendRepr::Uninhabited) {
-                    BackendRepr::Uninhabited
-                } else {
-                    BackendRepr::Memory { sized: true }
-                };
+            let backend_repr = BackendRepr::Memory { sized: true };
 
             let largest_niche = if count != 0 { element.largest_niche } else { None };
+            let uninhabited = if count != 0 { element.uninhabited } else { false };
 
             Layout {
                 variants: Variants::Single { index: struct_variant_idx() },
                 fields: FieldsShape::Array { stride: element.size, count },
                 backend_repr,
                 largest_niche,
+                uninhabited,
                 align: element.align,
                 size,
                 max_repr_align: None,
@@ -325,6 +323,7 @@ pub fn layout_of_ty_query(
                 fields: FieldsShape::Array { stride: element.size, count: 0 },
                 backend_repr: BackendRepr::Memory { sized: false },
                 largest_niche: None,
+                uninhabited: false,
                 align: element.align,
                 size: Size::ZERO,
                 max_repr_align: None,
@@ -337,6 +336,7 @@ pub fn layout_of_ty_query(
             fields: FieldsShape::Array { stride: Size::from_bytes(1), count: 0 },
             backend_repr: BackendRepr::Memory { sized: false },
             largest_niche: None,
+            uninhabited: false,
             align: dl.i8_align,
             size: Size::ZERO,
             max_repr_align: None,
-- 
cgit 1.4.1-3-g733a5


From c33fb5ae854e8ac26d75e72b7cb31519730f51d6 Mon Sep 17 00:00:00 2001
From: Zachary S <zasample18+github@gmail.com>
Date: Sat, 25 Jan 2025 21:28:54 -0600
Subject: Update ui tests with `LayoutData { uninhabited: ... }` etc

---
 tests/ui/abi/c-zst.aarch64-darwin.stderr           |  2 +
 tests/ui/abi/c-zst.powerpc-linux.stderr            |  2 +
 tests/ui/abi/c-zst.s390x-linux.stderr              |  2 +
 tests/ui/abi/c-zst.sparc64-linux.stderr            |  2 +
 tests/ui/abi/c-zst.x86_64-linux.stderr             |  2 +
 tests/ui/abi/c-zst.x86_64-pc-windows-gnu.stderr    |  2 +
 tests/ui/abi/debug.stderr                          | 24 +++++++++++
 tests/ui/abi/sysv64-zst.stderr                     |  2 +
 tests/ui/layout/debug.stderr                       | 22 +++++++++-
 tests/ui/layout/hexagon-enum.stderr                | 10 +++++
 ...96158-scalarpair-payload-might-be-uninit.stderr | 17 ++++++++
 .../ui/layout/issue-96185-overaligned-enum.stderr  |  6 +++
 tests/ui/layout/thumb-enum.stderr                  | 10 +++++
 tests/ui/layout/zero-sized-array-enum-niche.stderr | 13 ++++++
 ...-dead-variants.aarch64-unknown-linux-gnu.stderr | 50 +++++++++++++++++++---
 .../repr-c-dead-variants.armebv7r-none-eabi.stderr | 50 +++++++++++++++++++---
 ...epr-c-dead-variants.i686-pc-windows-msvc.stderr | 50 +++++++++++++++++++---
 ...c-dead-variants.x86_64-unknown-linux-gnu.stderr | 50 +++++++++++++++++++---
 tests/ui/repr/repr-c-int-dead-variants.stderr      | 50 +++++++++++++++++++---
 tests/ui/type/pattern_types/range_patterns.stderr  |  9 ++++
 20 files changed, 349 insertions(+), 26 deletions(-)

diff --git a/tests/ui/abi/c-zst.aarch64-darwin.stderr b/tests/ui/abi/c-zst.aarch64-darwin.stderr
index c8f7d0a517c..57cc48aa9cf 100644
--- a/tests/ui/abi/c-zst.aarch64-darwin.stderr
+++ b/tests/ui/abi/c-zst.aarch64-darwin.stderr
@@ -17,6 +17,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                                memory_index: [],
                            },
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -45,6 +46,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
diff --git a/tests/ui/abi/c-zst.powerpc-linux.stderr b/tests/ui/abi/c-zst.powerpc-linux.stderr
index 1015f7d8898..67380176730 100644
--- a/tests/ui/abi/c-zst.powerpc-linux.stderr
+++ b/tests/ui/abi/c-zst.powerpc-linux.stderr
@@ -17,6 +17,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                                memory_index: [],
                            },
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -56,6 +57,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
diff --git a/tests/ui/abi/c-zst.s390x-linux.stderr b/tests/ui/abi/c-zst.s390x-linux.stderr
index 1015f7d8898..67380176730 100644
--- a/tests/ui/abi/c-zst.s390x-linux.stderr
+++ b/tests/ui/abi/c-zst.s390x-linux.stderr
@@ -17,6 +17,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                                memory_index: [],
                            },
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -56,6 +57,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
diff --git a/tests/ui/abi/c-zst.sparc64-linux.stderr b/tests/ui/abi/c-zst.sparc64-linux.stderr
index 1015f7d8898..67380176730 100644
--- a/tests/ui/abi/c-zst.sparc64-linux.stderr
+++ b/tests/ui/abi/c-zst.sparc64-linux.stderr
@@ -17,6 +17,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                                memory_index: [],
                            },
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -56,6 +57,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
diff --git a/tests/ui/abi/c-zst.x86_64-linux.stderr b/tests/ui/abi/c-zst.x86_64-linux.stderr
index c8f7d0a517c..57cc48aa9cf 100644
--- a/tests/ui/abi/c-zst.x86_64-linux.stderr
+++ b/tests/ui/abi/c-zst.x86_64-linux.stderr
@@ -17,6 +17,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                                memory_index: [],
                            },
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -45,6 +46,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
diff --git a/tests/ui/abi/c-zst.x86_64-pc-windows-gnu.stderr b/tests/ui/abi/c-zst.x86_64-pc-windows-gnu.stderr
index 1015f7d8898..67380176730 100644
--- a/tests/ui/abi/c-zst.x86_64-pc-windows-gnu.stderr
+++ b/tests/ui/abi/c-zst.x86_64-pc-windows-gnu.stderr
@@ -17,6 +17,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                                memory_index: [],
                            },
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -56,6 +57,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
diff --git a/tests/ui/abi/debug.stderr b/tests/ui/abi/debug.stderr
index e550e5bfcf3..5f73ff7d6bd 100644
--- a/tests/ui/abi/debug.stderr
+++ b/tests/ui/abi/debug.stderr
@@ -20,6 +20,7 @@ error: fn_abi_of(test) = FnAbi {
                            ),
                            fields: Primitive,
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -67,6 +68,7 @@ error: fn_abi_of(test) = FnAbi {
                                valid_range: 0..=1,
                            },
                        ),
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -125,6 +127,7 @@ error: fn_abi_of(TestFnPtr) = FnAbi {
                                    valid_range: 0..=1,
                                },
                            ),
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -163,6 +166,7 @@ error: fn_abi_of(TestFnPtr) = FnAbi {
                        ),
                        fields: Primitive,
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -213,6 +217,7 @@ error: fn_abi_of(test_generic) = FnAbi {
                            ),
                            fields: Primitive,
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -248,6 +253,7 @@ error: fn_abi_of(test_generic) = FnAbi {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -297,6 +303,7 @@ error: ABIs are not compatible
                            ),
                            fields: Primitive,
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -332,6 +339,7 @@ error: ABIs are not compatible
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -369,6 +377,7 @@ error: ABIs are not compatible
                            ),
                            fields: Primitive,
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -404,6 +413,7 @@ error: ABIs are not compatible
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -444,6 +454,7 @@ error: ABIs are not compatible
                                count: 32,
                            },
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -483,6 +494,7 @@ error: ABIs are not compatible
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -517,6 +529,7 @@ error: ABIs are not compatible
                                count: 32,
                            },
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -556,6 +569,7 @@ error: ABIs are not compatible
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -598,6 +612,7 @@ error: ABIs are not compatible
                            ),
                            fields: Primitive,
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -633,6 +648,7 @@ error: ABIs are not compatible
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -670,6 +686,7 @@ error: ABIs are not compatible
                            ),
                            fields: Primitive,
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -705,6 +722,7 @@ error: ABIs are not compatible
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -748,6 +766,7 @@ error: ABIs are not compatible
                            ),
                            fields: Primitive,
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -783,6 +802,7 @@ error: ABIs are not compatible
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -820,6 +840,7 @@ error: ABIs are not compatible
                            ),
                            fields: Primitive,
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -855,6 +876,7 @@ error: ABIs are not compatible
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -923,6 +945,7 @@ error: fn_abi_of(assoc_test) = FnAbi {
                                    valid_range: $NON_NULL,
                                },
                            ),
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -960,6 +983,7 @@ error: fn_abi_of(assoc_test) = FnAbi {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
diff --git a/tests/ui/abi/sysv64-zst.stderr b/tests/ui/abi/sysv64-zst.stderr
index 781e9b2f4c9..ec85030c106 100644
--- a/tests/ui/abi/sysv64-zst.stderr
+++ b/tests/ui/abi/sysv64-zst.stderr
@@ -17,6 +17,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                                memory_index: [],
                            },
                            largest_niche: None,
+                           uninhabited: false,
                            variants: Single {
                                index: 0,
                            },
@@ -45,6 +46,7 @@ error: fn_abi_of(pass_zst) = FnAbi {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
diff --git a/tests/ui/layout/debug.stderr b/tests/ui/layout/debug.stderr
index 0daf2d3b9e7..07cad776692 100644
--- a/tests/ui/layout/debug.stderr
+++ b/tests/ui/layout/debug.stderr
@@ -31,6 +31,7 @@ error: layout_of(E) = Layout {
                    valid_range: 0..=0,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -56,6 +57,7 @@ error: layout_of(E) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -69,7 +71,9 @@ error: layout_of(E) = Layout {
                            abi: Align(4 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Memory {
+                           sized: true,
+                       },
                        fields: Arbitrary {
                            offsets: [
                                Size(4 bytes),
@@ -83,6 +87,7 @@ error: layout_of(E) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 1,
                        },
@@ -136,6 +141,7 @@ error: layout_of(S) = Layout {
                ],
            },
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -161,6 +167,7 @@ error: layout_of(U) = Layout {
                2,
            ),
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -213,6 +220,7 @@ error: layout_of(Result<i32, i32>) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -255,6 +263,7 @@ error: layout_of(Result<i32, i32>) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -293,6 +302,7 @@ error: layout_of(Result<i32, i32>) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -328,6 +338,7 @@ error: layout_of(i32) = Layout {
            ),
            fields: Primitive,
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -353,6 +364,7 @@ error: layout_of(V) = Layout {
                2,
            ),
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -378,6 +390,7 @@ error: layout_of(W) = Layout {
                2,
            ),
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -403,6 +416,7 @@ error: layout_of(Y) = Layout {
                2,
            ),
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -428,6 +442,7 @@ error: layout_of(P1) = Layout {
                1,
            ),
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -453,6 +468,7 @@ error: layout_of(P2) = Layout {
                1,
            ),
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -478,6 +494,7 @@ error: layout_of(P3) = Layout {
                1,
            ),
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -503,6 +520,7 @@ error: layout_of(P4) = Layout {
                1,
            ),
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -533,6 +551,7 @@ error: layout_of(P5) = Layout {
                2,
            ),
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -563,6 +582,7 @@ error: layout_of(MaybeUninit<u8>) = Layout {
                2,
            ),
            largest_niche: None,
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
diff --git a/tests/ui/layout/hexagon-enum.stderr b/tests/ui/layout/hexagon-enum.stderr
index 96f0a8c8740..90c06ba1f83 100644
--- a/tests/ui/layout/hexagon-enum.stderr
+++ b/tests/ui/layout/hexagon-enum.stderr
@@ -31,6 +31,7 @@ error: layout_of(A) = Layout {
                    valid_range: 0..=0,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -56,6 +57,7 @@ error: layout_of(A) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -107,6 +109,7 @@ error: layout_of(B) = Layout {
                    valid_range: 255..=255,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -132,6 +135,7 @@ error: layout_of(B) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -183,6 +187,7 @@ error: layout_of(C) = Layout {
                    valid_range: 256..=256,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -208,6 +213,7 @@ error: layout_of(C) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -259,6 +265,7 @@ error: layout_of(P) = Layout {
                    valid_range: 268435456..=268435456,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -284,6 +291,7 @@ error: layout_of(P) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -335,6 +343,7 @@ error: layout_of(T) = Layout {
                    valid_range: 2164260864..=2164260864,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -360,6 +369,7 @@ error: layout_of(T) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
diff --git a/tests/ui/layout/issue-96158-scalarpair-payload-might-be-uninit.stderr b/tests/ui/layout/issue-96158-scalarpair-payload-might-be-uninit.stderr
index cd9e4c02781..3bdb9c5c143 100644
--- a/tests/ui/layout/issue-96158-scalarpair-payload-might-be-uninit.stderr
+++ b/tests/ui/layout/issue-96158-scalarpair-payload-might-be-uninit.stderr
@@ -37,6 +37,7 @@ error: layout_of(MissingPayloadField) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -78,6 +79,7 @@ error: layout_of(MissingPayloadField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -99,6 +101,7 @@ error: layout_of(MissingPayloadField) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -157,6 +160,7 @@ error: layout_of(CommonPayloadField) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -199,6 +203,7 @@ error: layout_of(CommonPayloadField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -237,6 +242,7 @@ error: layout_of(CommonPayloadField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -294,6 +300,7 @@ error: layout_of(CommonPayloadFieldIsMaybeUninit) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -335,6 +342,7 @@ error: layout_of(CommonPayloadFieldIsMaybeUninit) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -372,6 +380,7 @@ error: layout_of(CommonPayloadFieldIsMaybeUninit) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -429,6 +438,7 @@ error: layout_of(NicheFirst) = Layout {
                    valid_range: 0..=4,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -486,6 +496,7 @@ error: layout_of(NicheFirst) = Layout {
                                valid_range: 0..=2,
                            },
                        ),
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -507,6 +518,7 @@ error: layout_of(NicheFirst) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -528,6 +540,7 @@ error: layout_of(NicheFirst) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 2,
                        },
@@ -585,6 +598,7 @@ error: layout_of(NicheSecond) = Layout {
                    valid_range: 0..=4,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -642,6 +656,7 @@ error: layout_of(NicheSecond) = Layout {
                                valid_range: 0..=2,
                            },
                        ),
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -663,6 +678,7 @@ error: layout_of(NicheSecond) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -684,6 +700,7 @@ error: layout_of(NicheSecond) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 2,
                        },
diff --git a/tests/ui/layout/issue-96185-overaligned-enum.stderr b/tests/ui/layout/issue-96185-overaligned-enum.stderr
index 15a3f6004f5..1d4e4436448 100644
--- a/tests/ui/layout/issue-96185-overaligned-enum.stderr
+++ b/tests/ui/layout/issue-96185-overaligned-enum.stderr
@@ -25,6 +25,7 @@ error: layout_of(Aligned1) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -50,6 +51,7 @@ error: layout_of(Aligned1) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -73,6 +75,7 @@ error: layout_of(Aligned1) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -128,6 +131,7 @@ error: layout_of(Aligned2) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -153,6 +157,7 @@ error: layout_of(Aligned2) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -176,6 +181,7 @@ error: layout_of(Aligned2) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
diff --git a/tests/ui/layout/thumb-enum.stderr b/tests/ui/layout/thumb-enum.stderr
index 120081d193c..0c343318564 100644
--- a/tests/ui/layout/thumb-enum.stderr
+++ b/tests/ui/layout/thumb-enum.stderr
@@ -31,6 +31,7 @@ error: layout_of(A) = Layout {
                    valid_range: 0..=0,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -56,6 +57,7 @@ error: layout_of(A) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -107,6 +109,7 @@ error: layout_of(B) = Layout {
                    valid_range: 255..=255,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -132,6 +135,7 @@ error: layout_of(B) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -183,6 +187,7 @@ error: layout_of(C) = Layout {
                    valid_range: 256..=256,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -208,6 +213,7 @@ error: layout_of(C) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -259,6 +265,7 @@ error: layout_of(P) = Layout {
                    valid_range: 268435456..=268435456,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -284,6 +291,7 @@ error: layout_of(P) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -335,6 +343,7 @@ error: layout_of(T) = Layout {
                    valid_range: 2164260864..=2164260864,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -360,6 +369,7 @@ error: layout_of(T) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
diff --git a/tests/ui/layout/zero-sized-array-enum-niche.stderr b/tests/ui/layout/zero-sized-array-enum-niche.stderr
index b6fcc14c063..33d2eede220 100644
--- a/tests/ui/layout/zero-sized-array-enum-niche.stderr
+++ b/tests/ui/layout/zero-sized-array-enum-niche.stderr
@@ -25,6 +25,7 @@ error: layout_of(Result<[u32; 0], bool>) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -54,6 +55,7 @@ error: layout_of(Result<[u32; 0], bool>) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -88,6 +90,7 @@ error: layout_of(Result<[u32; 0], bool>) = Layout {
                                valid_range: 0..=1,
                            },
                        ),
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -133,6 +136,7 @@ error: layout_of(MultipleAlignments) = Layout {
                    valid_range: 0..=2,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -162,6 +166,7 @@ error: layout_of(MultipleAlignments) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -187,6 +192,7 @@ error: layout_of(MultipleAlignments) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -221,6 +227,7 @@ error: layout_of(MultipleAlignments) = Layout {
                                valid_range: 0..=1,
                            },
                        ),
+                       uninhabited: false,
                        variants: Single {
                            index: 2,
                        },
@@ -266,6 +273,7 @@ error: layout_of(Result<[u32; 0], Packed<NonZero<u16>>>) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -295,6 +303,7 @@ error: layout_of(Result<[u32; 0], Packed<NonZero<u16>>>) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -329,6 +338,7 @@ error: layout_of(Result<[u32; 0], Packed<NonZero<u16>>>) = Layout {
                                valid_range: 1..=65535,
                            },
                        ),
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -374,6 +384,7 @@ error: layout_of(Result<[u32; 0], Packed<U16IsZero>>) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -407,6 +418,7 @@ error: layout_of(Result<[u32; 0], Packed<U16IsZero>>) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -441,6 +453,7 @@ error: layout_of(Result<[u32; 0], Packed<U16IsZero>>) = Layout {
                                valid_range: 0..=0,
                            },
                        ),
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
diff --git a/tests/ui/repr/repr-c-dead-variants.aarch64-unknown-linux-gnu.stderr b/tests/ui/repr/repr-c-dead-variants.aarch64-unknown-linux-gnu.stderr
index 8e8f1d159b7..204db30786e 100644
--- a/tests/ui/repr/repr-c-dead-variants.aarch64-unknown-linux-gnu.stderr
+++ b/tests/ui/repr/repr-c-dead-variants.aarch64-unknown-linux-gnu.stderr
@@ -4,7 +4,15 @@ error: layout_of(Univariant) = Layout {
                abi: Align(4 bytes),
                pref: $SOME_ALIGN,
            },
-           abi: Uninhabited,
+           abi: Scalar(
+               Initialized {
+                   value: Int(
+                       I32,
+                       false,
+                   ),
+                   valid_range: 0..=0,
+               },
+           ),
            fields: Arbitrary {
                offsets: [
                    Size(0 bytes),
@@ -23,6 +31,7 @@ error: layout_of(Univariant) = Layout {
                    valid_range: 0..=0,
                },
            ),
+           uninhabited: true,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -40,7 +49,15 @@ error: layout_of(Univariant) = Layout {
                            abi: Align(4 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Scalar(
+                           Initialized {
+                               value: Int(
+                                   I32,
+                                   false,
+                               ),
+                               valid_range: 0..=0,
+                           },
+                       ),
                        fields: Arbitrary {
                            offsets: [
                                Size(4 bytes),
@@ -50,6 +67,7 @@ error: layout_of(Univariant) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -107,6 +125,7 @@ error: layout_of(TwoVariants) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -119,12 +138,26 @@ error: layout_of(TwoVariants) = Layout {
                tag_field: 0,
                variants: [
                    Layout {
-                       size: Size(4 bytes),
+                       size: Size(8 bytes),
                        align: AbiAndPrefAlign {
                            abi: Align(4 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: ScalarPair(
+                           Initialized {
+                               value: Int(
+                                   I32,
+                                   false,
+                               ),
+                               valid_range: 0..=1,
+                           },
+                           Union {
+                               value: Int(
+                                   I8,
+                                   false,
+                               ),
+                           },
+                       ),
                        fields: Arbitrary {
                            offsets: [
                                Size(4 bytes),
@@ -134,6 +167,7 @@ error: layout_of(TwoVariants) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -171,6 +205,7 @@ error: layout_of(TwoVariants) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -216,6 +251,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -233,7 +269,9 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            abi: Align(8 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Memory {
+                           sized: true,
+                       },
                        fields: Arbitrary {
                            offsets: [
                                Size(8 bytes),
@@ -245,6 +283,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -272,6 +311,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
diff --git a/tests/ui/repr/repr-c-dead-variants.armebv7r-none-eabi.stderr b/tests/ui/repr/repr-c-dead-variants.armebv7r-none-eabi.stderr
index 2cd0960ce3e..1fab00bf50c 100644
--- a/tests/ui/repr/repr-c-dead-variants.armebv7r-none-eabi.stderr
+++ b/tests/ui/repr/repr-c-dead-variants.armebv7r-none-eabi.stderr
@@ -4,7 +4,15 @@ error: layout_of(Univariant) = Layout {
                abi: Align(1 bytes),
                pref: $SOME_ALIGN,
            },
-           abi: Uninhabited,
+           abi: Scalar(
+               Initialized {
+                   value: Int(
+                       I8,
+                       false,
+                   ),
+                   valid_range: 0..=0,
+               },
+           ),
            fields: Arbitrary {
                offsets: [
                    Size(0 bytes),
@@ -23,6 +31,7 @@ error: layout_of(Univariant) = Layout {
                    valid_range: 0..=0,
                },
            ),
+           uninhabited: true,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -40,7 +49,15 @@ error: layout_of(Univariant) = Layout {
                            abi: Align(1 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Scalar(
+                           Initialized {
+                               value: Int(
+                                   I8,
+                                   false,
+                               ),
+                               valid_range: 0..=0,
+                           },
+                       ),
                        fields: Arbitrary {
                            offsets: [
                                Size(1 bytes),
@@ -50,6 +67,7 @@ error: layout_of(Univariant) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -107,6 +125,7 @@ error: layout_of(TwoVariants) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -119,12 +138,26 @@ error: layout_of(TwoVariants) = Layout {
                tag_field: 0,
                variants: [
                    Layout {
-                       size: Size(1 bytes),
+                       size: Size(2 bytes),
                        align: AbiAndPrefAlign {
                            abi: Align(1 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: ScalarPair(
+                           Initialized {
+                               value: Int(
+                                   I8,
+                                   false,
+                               ),
+                               valid_range: 0..=1,
+                           },
+                           Union {
+                               value: Int(
+                                   I8,
+                                   false,
+                               ),
+                           },
+                       ),
                        fields: Arbitrary {
                            offsets: [
                                Size(1 bytes),
@@ -134,6 +167,7 @@ error: layout_of(TwoVariants) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -171,6 +205,7 @@ error: layout_of(TwoVariants) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -216,6 +251,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -233,7 +269,9 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            abi: Align(8 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Memory {
+                           sized: true,
+                       },
                        fields: Arbitrary {
                            offsets: [
                                Size(8 bytes),
@@ -245,6 +283,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -272,6 +311,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
diff --git a/tests/ui/repr/repr-c-dead-variants.i686-pc-windows-msvc.stderr b/tests/ui/repr/repr-c-dead-variants.i686-pc-windows-msvc.stderr
index 8e8f1d159b7..204db30786e 100644
--- a/tests/ui/repr/repr-c-dead-variants.i686-pc-windows-msvc.stderr
+++ b/tests/ui/repr/repr-c-dead-variants.i686-pc-windows-msvc.stderr
@@ -4,7 +4,15 @@ error: layout_of(Univariant) = Layout {
                abi: Align(4 bytes),
                pref: $SOME_ALIGN,
            },
-           abi: Uninhabited,
+           abi: Scalar(
+               Initialized {
+                   value: Int(
+                       I32,
+                       false,
+                   ),
+                   valid_range: 0..=0,
+               },
+           ),
            fields: Arbitrary {
                offsets: [
                    Size(0 bytes),
@@ -23,6 +31,7 @@ error: layout_of(Univariant) = Layout {
                    valid_range: 0..=0,
                },
            ),
+           uninhabited: true,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -40,7 +49,15 @@ error: layout_of(Univariant) = Layout {
                            abi: Align(4 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Scalar(
+                           Initialized {
+                               value: Int(
+                                   I32,
+                                   false,
+                               ),
+                               valid_range: 0..=0,
+                           },
+                       ),
                        fields: Arbitrary {
                            offsets: [
                                Size(4 bytes),
@@ -50,6 +67,7 @@ error: layout_of(Univariant) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -107,6 +125,7 @@ error: layout_of(TwoVariants) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -119,12 +138,26 @@ error: layout_of(TwoVariants) = Layout {
                tag_field: 0,
                variants: [
                    Layout {
-                       size: Size(4 bytes),
+                       size: Size(8 bytes),
                        align: AbiAndPrefAlign {
                            abi: Align(4 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: ScalarPair(
+                           Initialized {
+                               value: Int(
+                                   I32,
+                                   false,
+                               ),
+                               valid_range: 0..=1,
+                           },
+                           Union {
+                               value: Int(
+                                   I8,
+                                   false,
+                               ),
+                           },
+                       ),
                        fields: Arbitrary {
                            offsets: [
                                Size(4 bytes),
@@ -134,6 +167,7 @@ error: layout_of(TwoVariants) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -171,6 +205,7 @@ error: layout_of(TwoVariants) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -216,6 +251,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -233,7 +269,9 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            abi: Align(8 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Memory {
+                           sized: true,
+                       },
                        fields: Arbitrary {
                            offsets: [
                                Size(8 bytes),
@@ -245,6 +283,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -272,6 +311,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
diff --git a/tests/ui/repr/repr-c-dead-variants.x86_64-unknown-linux-gnu.stderr b/tests/ui/repr/repr-c-dead-variants.x86_64-unknown-linux-gnu.stderr
index 8e8f1d159b7..204db30786e 100644
--- a/tests/ui/repr/repr-c-dead-variants.x86_64-unknown-linux-gnu.stderr
+++ b/tests/ui/repr/repr-c-dead-variants.x86_64-unknown-linux-gnu.stderr
@@ -4,7 +4,15 @@ error: layout_of(Univariant) = Layout {
                abi: Align(4 bytes),
                pref: $SOME_ALIGN,
            },
-           abi: Uninhabited,
+           abi: Scalar(
+               Initialized {
+                   value: Int(
+                       I32,
+                       false,
+                   ),
+                   valid_range: 0..=0,
+               },
+           ),
            fields: Arbitrary {
                offsets: [
                    Size(0 bytes),
@@ -23,6 +31,7 @@ error: layout_of(Univariant) = Layout {
                    valid_range: 0..=0,
                },
            ),
+           uninhabited: true,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -40,7 +49,15 @@ error: layout_of(Univariant) = Layout {
                            abi: Align(4 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Scalar(
+                           Initialized {
+                               value: Int(
+                                   I32,
+                                   false,
+                               ),
+                               valid_range: 0..=0,
+                           },
+                       ),
                        fields: Arbitrary {
                            offsets: [
                                Size(4 bytes),
@@ -50,6 +67,7 @@ error: layout_of(Univariant) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -107,6 +125,7 @@ error: layout_of(TwoVariants) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -119,12 +138,26 @@ error: layout_of(TwoVariants) = Layout {
                tag_field: 0,
                variants: [
                    Layout {
-                       size: Size(4 bytes),
+                       size: Size(8 bytes),
                        align: AbiAndPrefAlign {
                            abi: Align(4 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: ScalarPair(
+                           Initialized {
+                               value: Int(
+                                   I32,
+                                   false,
+                               ),
+                               valid_range: 0..=1,
+                           },
+                           Union {
+                               value: Int(
+                                   I8,
+                                   false,
+                               ),
+                           },
+                       ),
                        fields: Arbitrary {
                            offsets: [
                                Size(4 bytes),
@@ -134,6 +167,7 @@ error: layout_of(TwoVariants) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -171,6 +205,7 @@ error: layout_of(TwoVariants) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -216,6 +251,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -233,7 +269,9 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            abi: Align(8 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Memory {
+                           sized: true,
+                       },
                        fields: Arbitrary {
                            offsets: [
                                Size(8 bytes),
@@ -245,6 +283,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -272,6 +311,7 @@ error: layout_of(DeadBranchHasOtherField) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
diff --git a/tests/ui/repr/repr-c-int-dead-variants.stderr b/tests/ui/repr/repr-c-int-dead-variants.stderr
index fa08b323dec..f852212deb9 100644
--- a/tests/ui/repr/repr-c-int-dead-variants.stderr
+++ b/tests/ui/repr/repr-c-int-dead-variants.stderr
@@ -4,7 +4,15 @@ error: layout_of(UnivariantU8) = Layout {
                abi: Align(1 bytes),
                pref: $SOME_ALIGN,
            },
-           abi: Uninhabited,
+           abi: Scalar(
+               Initialized {
+                   value: Int(
+                       I8,
+                       false,
+                   ),
+                   valid_range: 0..=0,
+               },
+           ),
            fields: Arbitrary {
                offsets: [
                    Size(0 bytes),
@@ -23,6 +31,7 @@ error: layout_of(UnivariantU8) = Layout {
                    valid_range: 0..=0,
                },
            ),
+           uninhabited: true,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -40,7 +49,15 @@ error: layout_of(UnivariantU8) = Layout {
                            abi: Align(1 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Scalar(
+                           Initialized {
+                               value: Int(
+                                   I8,
+                                   false,
+                               ),
+                               valid_range: 0..=0,
+                           },
+                       ),
                        fields: Arbitrary {
                            offsets: [
                                Size(1 bytes),
@@ -50,6 +67,7 @@ error: layout_of(UnivariantU8) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -107,6 +125,7 @@ error: layout_of(TwoVariantsU8) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -119,12 +138,26 @@ error: layout_of(TwoVariantsU8) = Layout {
                tag_field: 0,
                variants: [
                    Layout {
-                       size: Size(1 bytes),
+                       size: Size(2 bytes),
                        align: AbiAndPrefAlign {
                            abi: Align(1 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: ScalarPair(
+                           Initialized {
+                               value: Int(
+                                   I8,
+                                   false,
+                               ),
+                               valid_range: 0..=1,
+                           },
+                           Union {
+                               value: Int(
+                                   I8,
+                                   false,
+                               ),
+                           },
+                       ),
                        fields: Arbitrary {
                            offsets: [
                                Size(1 bytes),
@@ -134,6 +167,7 @@ error: layout_of(TwoVariantsU8) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -171,6 +205,7 @@ error: layout_of(TwoVariantsU8) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -216,6 +251,7 @@ error: layout_of(DeadBranchHasOtherFieldU8) = Layout {
                    valid_range: 0..=1,
                },
            ),
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -233,7 +269,9 @@ error: layout_of(DeadBranchHasOtherFieldU8) = Layout {
                            abi: Align(8 bytes),
                            pref: $SOME_ALIGN,
                        },
-                       abi: Uninhabited,
+                       abi: Memory {
+                           sized: true,
+                       },
                        fields: Arbitrary {
                            offsets: [
                                Size(8 bytes),
@@ -245,6 +283,7 @@ error: layout_of(DeadBranchHasOtherFieldU8) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: true,
                        variants: Single {
                            index: 0,
                        },
@@ -272,6 +311,7 @@ error: layout_of(DeadBranchHasOtherFieldU8) = Layout {
                            ],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
diff --git a/tests/ui/type/pattern_types/range_patterns.stderr b/tests/ui/type/pattern_types/range_patterns.stderr
index 7da8cfd4dbc..690592ba0b8 100644
--- a/tests/ui/type/pattern_types/range_patterns.stderr
+++ b/tests/ui/type/pattern_types/range_patterns.stderr
@@ -31,6 +31,7 @@ error: layout_of(NonZero<u32>) = Layout {
                    valid_range: 1..=4294967295,
                },
            ),
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -69,6 +70,7 @@ error: layout_of((u32) is 1..=) = Layout {
                    valid_range: 1..=4294967295,
                },
            ),
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
@@ -105,6 +107,7 @@ error: layout_of(Option<(u32) is 1..=>) = Layout {
                ],
            },
            largest_niche: None,
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -134,6 +137,7 @@ error: layout_of(Option<(u32) is 1..=>) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -174,6 +178,7 @@ error: layout_of(Option<(u32) is 1..=>) = Layout {
                                valid_range: 1..=4294967295,
                            },
                        ),
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -216,6 +221,7 @@ error: layout_of(Option<NonZero<u32>>) = Layout {
                ],
            },
            largest_niche: None,
+           uninhabited: false,
            variants: Multiple {
                tag: Initialized {
                    value: Int(
@@ -245,6 +251,7 @@ error: layout_of(Option<NonZero<u32>>) = Layout {
                            memory_index: [],
                        },
                        largest_niche: None,
+                       uninhabited: false,
                        variants: Single {
                            index: 0,
                        },
@@ -285,6 +292,7 @@ error: layout_of(Option<NonZero<u32>>) = Layout {
                                valid_range: 1..=4294967295,
                            },
                        ),
+                       uninhabited: false,
                        variants: Single {
                            index: 1,
                        },
@@ -336,6 +344,7 @@ error: layout_of(NonZeroU32New) = Layout {
                    valid_range: 1..=4294967295,
                },
            ),
+           uninhabited: false,
            variants: Single {
                index: 0,
            },
-- 
cgit 1.4.1-3-g733a5


From bcfde13d51229e5ba4cb324194561b18e9326680 Mon Sep 17 00:00:00 2001
From: Zachary S <zasample18+github@gmail.com>
Date: Tue, 28 Jan 2025 01:29:37 -0600
Subject: Update check to reflect that non-ZST uninhabited types should not be
 PassMode::Ignore.

---
 compiler/rustc_ty_utils/src/abi.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs
index 2d20ef3d690..0ff82f0c256 100644
--- a/compiler/rustc_ty_utils/src/abi.rs
+++ b/compiler/rustc_ty_utils/src/abi.rs
@@ -464,7 +464,7 @@ fn fn_abi_sanity_check<'tcx>(
 
         match &arg.mode {
             PassMode::Ignore => {
-                assert!(arg.layout.is_zst() || arg.layout.is_uninhabited());
+                assert!(arg.layout.is_zst());
             }
             PassMode::Direct(_) => {
                 // Here the Rust type is used to determine the actual ABI, so we have to be very
-- 
cgit 1.4.1-3-g733a5


From 58ebf6afdd01d32f9f6d22d2e788c0dc10bc65a5 Mon Sep 17 00:00:00 2001
From: Zachary S <zasample18+github@gmail.com>
Date: Thu, 13 Feb 2025 13:17:39 -0600
Subject: Add test that uninhabited repr(transparent) type has same function
 return ABI as wrapped type.

Fix codegen of uninhabited PassMode::Indirect return types.

Add codegen test for uninhabited PassMode::Indirect return types.

Enable optimizations for uninhabited return type codegen test
---
 compiler/rustc_codegen_ssa/src/mir/block.rs        | 28 ++++----------
 .../codegen/uninhabited-transparent-return-abi.rs  | 44 ++++++++++++++++++++++
 .../uninhabited-transparent-return-abi.rs          | 33 ++++++++++++++++
 3 files changed, 84 insertions(+), 21 deletions(-)
 create mode 100644 tests/codegen/uninhabited-transparent-return-abi.rs
 create mode 100644 tests/ui/uninhabited/uninhabited-transparent-return-abi.rs

diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index 0620f08fc73..49074996174 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -4,9 +4,7 @@ use rustc_abi::{BackendRepr, ExternAbi, HasDataLayout, Reg, WrappingRange};
 use rustc_ast as ast;
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_hir::lang_items::LangItem;
-use rustc_middle::mir::{
-    self, AssertKind, BasicBlock, InlineAsmMacro, SwitchTargets, UnwindTerminateReason,
-};
+use rustc_middle::mir::{self, AssertKind, InlineAsmMacro, SwitchTargets, UnwindTerminateReason};
 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, ValidityRequirement};
 use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
 use rustc_middle::ty::{self, Instance, Ty};
@@ -942,7 +940,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     &fn_abi.ret,
                     &mut llargs,
                     Some(intrinsic),
-                    target,
                 );
                 let dest = match ret_dest {
                     _ if fn_abi.ret.is_indirect() => llargs[0],
@@ -998,19 +995,12 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         };
 
         let mut llargs = Vec::with_capacity(arg_count);
-        let destination = target.as_ref().map(|&target| {
-            (
-                self.make_return_dest(
-                    bx,
-                    destination,
-                    &fn_abi.ret,
-                    &mut llargs,
-                    None,
-                    Some(target),
-                ),
-                target,
-            )
-        });
+
+        // We still need to call `make_return_dest` even if there's no `target`, since
+        // `fn_abi.ret` could be `PassMode::Indirect`, even if it is uninhabited,
+        // and `make_return_dest` adds the return-place indirect pointer to `llargs`.
+        let return_dest = self.make_return_dest(bx, destination, &fn_abi.ret, &mut llargs, None);
+        let destination = target.map(|target| (return_dest, target));
 
         // Split the rust-call tupled arguments off.
         let (first_args, untuple) = if abi == ExternAbi::RustCall && !args.is_empty() {
@@ -1813,11 +1803,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         fn_ret: &ArgAbi<'tcx, Ty<'tcx>>,
         llargs: &mut Vec<Bx::Value>,
         intrinsic: Option<ty::IntrinsicDef>,
-        target: Option<BasicBlock>,
     ) -> ReturnDest<'tcx, Bx::Value> {
-        if target.is_none() {
-            return ReturnDest::Nothing;
-        }
         // If the return is ignored, we can just return a do-nothing `ReturnDest`.
         if fn_ret.is_ignore() {
             return ReturnDest::Nothing;
diff --git a/tests/codegen/uninhabited-transparent-return-abi.rs b/tests/codegen/uninhabited-transparent-return-abi.rs
new file mode 100644
index 00000000000..6e8b1683163
--- /dev/null
+++ b/tests/codegen/uninhabited-transparent-return-abi.rs
@@ -0,0 +1,44 @@
+//@ compile-flags: -Copt-level=3
+
+// See https://github.com/rust-lang/rust/issues/135802
+
+#![crate_type = "lib"]
+
+enum Void {}
+
+// Should be ABI-compatible with T, but wasn't prior to the PR adding this test.
+#[repr(transparent)]
+struct NoReturn<T>(T, Void);
+
+// Returned by invisible reference (in most ABIs)
+#[allow(dead_code)]
+struct Large(u64, u64, u64);
+
+extern "Rust" {
+    fn opaque() -> NoReturn<Large>;
+    fn opaque_with_arg(rsi: u32) -> NoReturn<Large>;
+}
+
+// CHECK-LABEL: @test_uninhabited_ret_by_ref
+#[no_mangle]
+pub fn test_uninhabited_ret_by_ref() {
+    // CHECK: %_1 = alloca [24 x i8], align {{8|4}}
+    // CHECK-NEXT: call void @llvm.lifetime.start.p0(i64 24, ptr nonnull %_1)
+    // CHECK-NEXT: call void @opaque(ptr noalias nocapture noundef nonnull sret([24 x i8]) align {{8|4}} dereferenceable(24) %_1) #2
+    // CHECK-NEXT: unreachable
+    unsafe {
+        opaque();
+    }
+}
+
+// CHECK-LABEL: @test_uninhabited_ret_by_ref_with_arg
+#[no_mangle]
+pub fn test_uninhabited_ret_by_ref_with_arg(rsi: u32) {
+    // CHECK: %_2 = alloca [24 x i8], align {{8|4}}
+    // CHECK-NEXT: call void @llvm.lifetime.start.p0(i64 24, ptr nonnull %_2)
+    // CHECK-NEXT: call void @opaque_with_arg(ptr noalias nocapture noundef nonnull sret([24 x i8]) align {{8|4}} dereferenceable(24) %_2, i32 noundef %rsi) #2
+    // CHECK-NEXT: unreachable
+    unsafe {
+        opaque_with_arg(rsi);
+    }
+}
diff --git a/tests/ui/uninhabited/uninhabited-transparent-return-abi.rs b/tests/ui/uninhabited/uninhabited-transparent-return-abi.rs
new file mode 100644
index 00000000000..2c2788a3e56
--- /dev/null
+++ b/tests/ui/uninhabited/uninhabited-transparent-return-abi.rs
@@ -0,0 +1,33 @@
+//@ run-pass
+//@ needs-unwind
+// See https://github.com/rust-lang/rust/issues/135802
+
+enum Void {}
+
+// Should be ABI-compatible with T, but wasn't prior to the PR adding this test.
+#[repr(transparent)]
+struct NoReturn<T>(T, Void);
+
+// Returned by invisible reference (in most ABIs)
+#[allow(dead_code)]
+struct Large(u64, u64, u64);
+
+// Prior to the PR adding this test, this function had a different ABI than
+// `fn() -> Large` (on `x86_64-unknown-linux-gnu` at least), so calling it as `fn() -> Large`
+// would pass the return place pointer in rdi and `correct` in rsi, but the function
+// would expect `correct` in rdi.
+fn never(correct: &mut bool) -> NoReturn<Large> {
+    *correct = true;
+    panic!("catch this")
+}
+
+fn main() {
+    let mut correct = false;
+    let never: fn(&mut bool) -> NoReturn<Large> = never;
+    // Safety: `NoReturn<Large>` is a `repr(transparent)` wrapper around `Large`,
+    // so they should be ABI-compatible.
+    let never: fn(&mut bool) -> Large = unsafe { std::mem::transmute(never) };
+    let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| never(&mut correct)));
+    assert!(result.is_err(), "function should have panicked");
+    assert!(correct, "function should have stored `true` into `correct`");
+}
-- 
cgit 1.4.1-3-g733a5


From 6493cd8699cc6d55a38b5187ff4cc731f969c483 Mon Sep 17 00:00:00 2001
From: zachs18 <8355914+zachs18@users.noreply.github.com>
Date: Mon, 17 Feb 2025 18:49:18 -0600
Subject: Adjust LayoutData::uninhabited doc comment.

Co-authored-by: Jubilee <workingjubilee@gmail.com>
---
 compiler/rustc_abi/src/lib.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs
index 14a8a579200..098638b6bcf 100644
--- a/compiler/rustc_abi/src/lib.rs
+++ b/compiler/rustc_abi/src/lib.rs
@@ -1696,8 +1696,8 @@ pub struct LayoutData<FieldIdx: Idx, VariantIdx: Idx> {
     pub largest_niche: Option<Niche>,
     /// Is this type known to be uninhabted?
     ///
-    /// This is separate from BackendRepr, because an uninhabited return type may require special
-    /// consideration based on its size or other attributes.
+    /// This is separate from BackendRepr because uninhabited return types can affect ABI,
+    /// especially in the case of by-pointer struct returns, which allocate stack even when unused.
     pub uninhabited: bool,
 
     pub align: AbiAndPrefAlign,
-- 
cgit 1.4.1-3-g733a5


From e3f5db07e0daa833c51c335fa07d87affd8a8bf9 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Tue, 18 Feb 2025 11:31:38 +0100
Subject: fine-tune comment

---
 compiler/rustc_const_eval/src/interpret/validity.rs | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs
index 3667cc84d70..40dec0cb39e 100644
--- a/compiler/rustc_const_eval/src/interpret/validity.rs
+++ b/compiler/rustc_const_eval/src/interpret/validity.rs
@@ -1264,12 +1264,11 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValueVisitor<'tcx, M> for ValidityVisitor<'rt,
             }
         }
 
-        // *After* all of this, check the ABI. We need to check the ABI to handle
-        // types like `NonNull` where the `Scalar` info is more restrictive than what
-        // the fields say (`rustc_layout_scalar_valid_range_start`).
-        // But in most cases, this will just propagate what the fields say,
-        // and then we want the error to point at the field -- so, first recurse,
-        // then check ABI.
+        // *After* all of this, check further information stored in the layout. We need to check
+        // this to handle types like `NonNull` where the `Scalar` info is more restrictive than what
+        // the fields say (`rustc_layout_scalar_valid_range_start`). But in most cases, this will
+        // just propagate what the fields say, and then we want the error to point at the field --
+        // so, we first recurse, then we do this check.
         //
         // FIXME: We could avoid some redundant checks here. For newtypes wrapping
         // scalars, we do the same check on every "level" (e.g., first we check
-- 
cgit 1.4.1-3-g733a5


From 953515131b32deaf26410cb78b7eb6fe93d4d9b4 Mon Sep 17 00:00:00 2001
From: Jakub Beránek <berykubik@gmail.com>
Date: Thu, 20 Feb 2025 20:43:57 +0100
Subject: Improve error message when a submodule directory is missing
 completely

---
 src/bootstrap/src/lib.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/bootstrap/src/lib.rs b/src/bootstrap/src/lib.rs
index dfaf0418d9a..c41be41219e 100644
--- a/src/bootstrap/src/lib.rs
+++ b/src/bootstrap/src/lib.rs
@@ -488,7 +488,7 @@ impl Build {
         }
         self.config.update_submodule(submodule);
         let absolute_path = self.config.src.join(submodule);
-        if dir_is_empty(&absolute_path) {
+        if !absolute_path.exists() || dir_is_empty(&absolute_path) {
             let maybe_enable = if !self.config.submodules()
                 && self.config.rust_info.is_managed_git_subrepository()
             {
-- 
cgit 1.4.1-3-g733a5


From d2203ad59c67a6acb2968ea77e1e9dea5530e518 Mon Sep 17 00:00:00 2001
From: onur-ozkan <work@onurozkan.dev>
Date: Thu, 20 Feb 2025 22:48:39 +0300
Subject: skip submodule updating logics on tarballs

Signed-off-by: onur-ozkan <work@onurozkan.dev>
---
 src/bootstrap/src/core/config/config.rs | 2 +-
 src/bootstrap/src/lib.rs                | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index 64a510240f8..172b8d78764 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -2767,7 +2767,7 @@ impl Config {
         ),
     )]
     pub(crate) fn update_submodule(&self, relative_path: &str) {
-        if !self.submodules() {
+        if self.rust_info.is_from_tarball() || !self.submodules() {
             return;
         }
 
diff --git a/src/bootstrap/src/lib.rs b/src/bootstrap/src/lib.rs
index dfaf0418d9a..a0934a8d556 100644
--- a/src/bootstrap/src/lib.rs
+++ b/src/bootstrap/src/lib.rs
@@ -481,6 +481,10 @@ impl Build {
         ),
     )]
     pub fn require_submodule(&self, submodule: &str, err_hint: Option<&str>) {
+        if self.rust_info().is_from_tarball() {
+            return;
+        }
+
         // When testing bootstrap itself, it is much faster to ignore
         // submodules. Almost all Steps work fine without their submodules.
         if cfg!(test) && !self.config.submodules() {
-- 
cgit 1.4.1-3-g733a5


From c0bea5d92d69c93ec8b6d4374df6863ff312e20f Mon Sep 17 00:00:00 2001
From: Jakub Beránek <berykubik@gmail.com>
Date: Thu, 20 Feb 2025 21:06:25 +0100
Subject: Add a notice about missing GCC sources in source tarballs

---
 src/bootstrap/src/core/build_steps/dist.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/bootstrap/src/core/build_steps/dist.rs b/src/bootstrap/src/core/build_steps/dist.rs
index 85b224771bb..795f9506a25 100644
--- a/src/bootstrap/src/core/build_steps/dist.rs
+++ b/src/bootstrap/src/core/build_steps/dist.rs
@@ -1029,6 +1029,17 @@ impl Step for PlainSourceTarball {
             ],
             plain_dst_src,
         );
+        // We keep something in src/gcc because it is a registered submodule,
+        // and if it misses completely it can cause issues elsewhere
+        // (see https://github.com/rust-lang/rust/issues/137332).
+        // We can also let others know why is the source code missing.
+        if !builder.config.dry_run() {
+            builder.create_dir(&plain_dst_src.join("src/gcc"));
+            t!(std::fs::write(
+                plain_dst_src.join("src/gcc/notice.txt"),
+                "The GCC source code is not included due to unclear licensing implications\n"
+            ));
+        }
 
         // Copy the files normally
         for item in &src_files {
-- 
cgit 1.4.1-3-g733a5