Merge from rustc

70 files changed, 1011 insertions, 763 deletions

diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs
index ec758785173..7b6abdf1ea9 100644
--- a/compiler/rustc_abi/src/lib.rs
+++ b/compiler/rustc_abi/src/lib.rs
@@ -1743,15 +1743,23 @@ pub enum PointerKind {
     Box { unpin: bool, global: bool },
 }
 
-/// Note that this information is advisory only, and backends are free to ignore it.
-/// It can only be used to encode potential optimizations, but no critical information.
+/// Encodes extra information we have about a pointer.
+/// Note that this information is advisory only, and backends are free to ignore it:
+/// if the information is wrong, that can cause UB, but if the information is absent,
+/// that must always be okay.
 #[derive(Copy, Clone, Debug)]
 pub struct PointeeInfo {
-    pub size: Size,
-    pub align: Align,
     /// If this is `None`, then this is a raw pointer, so size and alignment are not guaranteed to
     /// be reliable.
     pub safe: Option<PointerKind>,
+    /// If `safe` is `Some`, then the pointer is either null or dereferenceable for this many bytes.
+    /// On a function argument, "dereferenceable" here means "dereferenceable for the entire duration
+    /// of this function call", i.e. it is UB for the memory that this pointer points to to be freed
+    /// while this function is still running.
+    /// The size can be zero if the pointer is not dereferenceable.
+    pub size: Size,
+    /// If `safe` is `Some`, then the pointer is aligned as indicated.
+    pub align: Align,
 }
 
 impl<FieldIdx: Idx, VariantIdx: Idx> LayoutData<FieldIdx, VariantIdx> {
diff --git a/compiler/rustc_ast_lowering/src/asm.rs b/compiler/rustc_ast_lowering/src/asm.rs
index 6585a7de245..3acca94a54b 100644
--- a/compiler/rustc_ast_lowering/src/asm.rs
+++ b/compiler/rustc_ast_lowering/src/asm.rs
@@ -48,6 +48,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     | asm::InlineAsmArch::RiscV32
                     | asm::InlineAsmArch::RiscV64
                     | asm::InlineAsmArch::LoongArch64
+                    | asm::InlineAsmArch::S390x
             );
             if !is_stable && !self.tcx.features().asm_experimental_arch() {
                 feature_err(
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
index f9dd649ab9f..d676ce59cfe 100644
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
@@ -1,10 +1,7 @@
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::ErrorGuaranteed;
-use rustc_hir::OpaqueTyOrigin;
-use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalDefId;
 use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin, TyCtxtInferExt as _};
-use rustc_infer::traits::{Obligation, ObligationCause};
 use rustc_macros::extension;
 use rustc_middle::ty::visit::TypeVisitableExt;
 use rustc_middle::ty::{
@@ -12,7 +9,6 @@ use rustc_middle::ty::{
     TypingMode,
 };
 use rustc_span::Span;
-use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
 use rustc_trait_selection::traits::ObligationCtxt;
 use tracing::{debug, instrument};
 
@@ -303,91 +299,7 @@ impl<'tcx> InferCtxt<'tcx> {
             return Ty::new_error(self.tcx, e);
         }
 
-        // `definition_ty` does not live in of the current inference context,
-        // so lets make sure that we don't accidentally misuse our current `infcx`.
-        match check_opaque_type_well_formed(
-            self.tcx,
-            self.next_trait_solver(),
-            opaque_type_key.def_id,
-            instantiated_ty.span,
-            definition_ty,
-        ) {
-            Ok(hidden_ty) => hidden_ty,
-            Err(guar) => Ty::new_error(self.tcx, guar),
-        }
-    }
-}
-
-/// This logic duplicates most of `check_opaque_meets_bounds`.
-/// FIXME(oli-obk): Also do region checks here and then consider removing
-/// `check_opaque_meets_bounds` entirely.
-fn check_opaque_type_well_formed<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    next_trait_solver: bool,
-    def_id: LocalDefId,
-    definition_span: Span,
-    definition_ty: Ty<'tcx>,
-) -> Result<Ty<'tcx>, ErrorGuaranteed> {
-    // Only check this for TAIT. RPIT already supports `tests/ui/impl-trait/nested-return-type2.rs`
-    // on stable and we'd break that.
-    let opaque_ty_hir = tcx.hir().expect_opaque_ty(def_id);
-    let OpaqueTyOrigin::TyAlias { .. } = opaque_ty_hir.origin else {
-        return Ok(definition_ty);
-    };
-    let param_env = tcx.param_env(def_id);
-
-    let mut parent_def_id = def_id;
-    while tcx.def_kind(parent_def_id) == DefKind::OpaqueTy {
-        parent_def_id = tcx.local_parent(parent_def_id);
-    }
-
-    // FIXME(#132279): This should eventually use the already defined hidden types
-    // instead. Alternatively we'll entirely remove this function given we also check
-    // the opaque in `check_opaque_meets_bounds` later.
-    let infcx = tcx
-        .infer_ctxt()
-        .with_next_trait_solver(next_trait_solver)
-        .build(TypingMode::analysis_in_body(tcx, parent_def_id));
-    let ocx = ObligationCtxt::new_with_diagnostics(&infcx);
-    let identity_args = GenericArgs::identity_for_item(tcx, def_id);
-
-    // Require that the hidden type actually fulfills all the bounds of the opaque type, even without
-    // the bounds that the function supplies.
-    let opaque_ty = Ty::new_opaque(tcx, def_id.to_def_id(), identity_args);
-    ocx.eq(&ObligationCause::misc(definition_span, def_id), param_env, opaque_ty, definition_ty)
-        .map_err(|err| {
-            infcx
-                .err_ctxt()
-                .report_mismatched_types(
-                    &ObligationCause::misc(definition_span, def_id),
-                    param_env,
-                    opaque_ty,
-                    definition_ty,
-                    err,
-                )
-                .emit()
-        })?;
-
-    // Require the hidden type to be well-formed with only the generics of the opaque type.
-    // Defining use functions may have more bounds than the opaque type, which is ok, as long as the
-    // hidden type is well formed even without those bounds.
-    let predicate = ty::Binder::dummy(ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(
-        definition_ty.into(),
-    )));
-    ocx.register_obligation(Obligation::misc(tcx, definition_span, def_id, param_env, predicate));
-
-    // Check that all obligations are satisfied by the implementation's
-    // version.
-    let errors = ocx.select_all_or_error();
-
-    // This is fishy, but we check it again in `check_opaque_meets_bounds`.
-    // Remove once we can prepopulate with known hidden types.
-    let _ = infcx.take_opaque_types();
-
-    if errors.is_empty() {
-        Ok(definition_ty)
-    } else {
-        Err(infcx.err_ctxt().report_fulfillment_errors(errors))
+        definition_ty
     }
 }
 
diff --git a/compiler/rustc_codegen_cranelift/patches/0022-coretests-Disable-not-compiling-tests.patch b/compiler/rustc_codegen_cranelift/patches/0022-coretests-Disable-not-compiling-tests.patch
index 6ed22c5a18e..1860810e7f3 100644
--- a/compiler/rustc_codegen_cranelift/patches/0022-coretests-Disable-not-compiling-tests.patch
+++ b/compiler/rustc_codegen_cranelift/patches/0022-coretests-Disable-not-compiling-tests.patch
@@ -38,7 +38,7 @@ index 42a26ae..5ac1042 100644
 @@ -1,3 +1,4 @@
 +#![cfg(test)]
  // tidy-alphabetical-start
+ #![cfg_attr(bootstrap, feature(const_three_way_compare))]
  #![cfg_attr(bootstrap, feature(strict_provenance))]
- #![cfg_attr(not(bootstrap), feature(strict_provenance_lints))]
 --
 2.21.0 (Apple Git-122)
diff --git a/compiler/rustc_codegen_cranelift/patches/0027-coretests-128bit-atomic-operations.patch b/compiler/rustc_codegen_cranelift/patches/0027-coretests-128bit-atomic-operations.patch
index 50a42aea322..59653c6e875 100644
--- a/compiler/rustc_codegen_cranelift/patches/0027-coretests-128bit-atomic-operations.patch
+++ b/compiler/rustc_codegen_cranelift/patches/0027-coretests-128bit-atomic-operations.patch
@@ -15,7 +15,7 @@ index 1e336bf..35e6f54 100644
 --- a/lib.rs
 +++ b/lib.rs
 @@ -2,7 +2,6 @@
- // tidy-alphabetical-start
+ #![cfg_attr(bootstrap, feature(const_three_way_compare))]
  #![cfg_attr(bootstrap, feature(strict_provenance))]
  #![cfg_attr(not(bootstrap), feature(strict_provenance_lints))]
 -#![cfg_attr(target_has_atomic = "128", feature(integer_atomics))]
diff --git a/compiler/rustc_codegen_cranelift/rust-toolchain b/compiler/rustc_codegen_cranelift/rust-toolchain
index 2558b2b9f5d..a223cd7dbb8 100644
--- a/compiler/rustc_codegen_cranelift/rust-toolchain
+++ b/compiler/rustc_codegen_cranelift/rust-toolchain
@@ -1,4 +1,4 @@
 [toolchain]
-channel = "nightly-2024-11-02"
+channel = "nightly-2024-11-09"
 components = ["rust-src", "rustc-dev", "llvm-tools"]
 profile = "minimal"
diff --git a/compiler/rustc_codegen_cranelift/scripts/test_bootstrap.sh b/compiler/rustc_codegen_cranelift/scripts/test_bootstrap.sh
index 791d457993d..770f2b6df6c 100755
--- a/compiler/rustc_codegen_cranelift/scripts/test_bootstrap.sh
+++ b/compiler/rustc_codegen_cranelift/scripts/test_bootstrap.sh
@@ -11,5 +11,22 @@ rm -r compiler/rustc_codegen_cranelift/{Cargo.*,src}
 cp ../Cargo.* compiler/rustc_codegen_cranelift/
 cp -r ../src compiler/rustc_codegen_cranelift/src
 
+# FIXME(rust-lang/rust#132719) remove once it doesn't break without this patch
+cat <<EOF | git apply -
+diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
+index 3394f2a84a0..cb980dd4d7c 100644
+--- a/src/bootstrap/src/core/build_steps/compile.rs
++++ b/src/bootstrap/src/core/build_steps/compile.rs
+@@ -1976,7 +1976,7 @@ fn run(self, builder: &Builder<'_>) -> Compiler {
+             }
+         }
+
+-        {
++        if builder.config.llvm_enabled(target_compiler.host) && builder.config.llvm_tools_enabled {
+             // \`llvm-strip\` is used by rustc, which is actually just a symlink to \`llvm-objcopy\`,
+             // so copy and rename \`llvm-objcopy\`.
+             let src_exe = exe("llvm-objcopy", target_compiler.host);
+EOF
+
 ./x.py build --stage 1 library/std
 popd
diff --git a/compiler/rustc_codegen_cranelift/src/abi/comments.rs b/compiler/rustc_codegen_cranelift/src/abi/comments.rs
index daea789ee3e..521a250ab82 100644
--- a/compiler/rustc_codegen_cranelift/src/abi/comments.rs
+++ b/compiler/rustc_codegen_cranelift/src/abi/comments.rs
@@ -3,7 +3,7 @@
 
 use std::borrow::Cow;
 
-use rustc_target::abi::call::PassMode;
+use rustc_target::callconv::PassMode;
 
 use crate::prelude::*;
 
diff --git a/compiler/rustc_codegen_cranelift/src/abi/mod.rs b/compiler/rustc_codegen_cranelift/src/abi/mod.rs
index dfca5dcbec8..f647ee36c48 100644
--- a/compiler/rustc_codegen_cranelift/src/abi/mod.rs
+++ b/compiler/rustc_codegen_cranelift/src/abi/mod.rs
@@ -10,6 +10,7 @@ use std::mem;
 use cranelift_codegen::ir::{ArgumentPurpose, SigRef};
 use cranelift_codegen::isa::CallConv;
 use cranelift_module::ModuleError;
+use rustc_abi::ExternAbi;
 use rustc_codegen_ssa::base::is_call_from_compiler_builtins_to_upstream_monomorphization;
 use rustc_codegen_ssa::errors::CompilerBuiltinsCannotCall;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
@@ -18,8 +19,7 @@ use rustc_middle::ty::layout::FnAbiOf;
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_session::Session;
 use rustc_span::source_map::Spanned;
-use rustc_target::abi::call::{Conv, FnAbi, PassMode};
-use rustc_target::spec::abi::Abi;
+use rustc_target::callconv::{Conv, FnAbi, PassMode};
 
 use self::pass_mode::*;
 pub(crate) use self::returning::codegen_return;
@@ -443,7 +443,7 @@ pub(crate) fn codegen_terminator_call<'tcx>(
         RevealAllLayoutCx(fx.tcx).fn_abi_of_fn_ptr(fn_sig, extra_args)
     };
 
-    let is_cold = if fn_sig.abi() == Abi::RustCold {
+    let is_cold = if fn_sig.abi() == ExternAbi::RustCold {
         true
     } else {
         instance.is_some_and(|inst| {
@@ -458,7 +458,7 @@ pub(crate) fn codegen_terminator_call<'tcx>(
     }
 
     // Unpack arguments tuple for closures
-    let mut args = if fn_sig.abi() == Abi::RustCall {
+    let mut args = if fn_sig.abi() == ExternAbi::RustCall {
         let (self_arg, pack_arg) = match args {
             [pack_arg] => (None, codegen_call_argument_operand(fx, &pack_arg.node)),
             [self_arg, pack_arg] => (
diff --git a/compiler/rustc_codegen_cranelift/src/abi/pass_mode.rs b/compiler/rustc_codegen_cranelift/src/abi/pass_mode.rs
index ad0a13dc7e5..7594a53fc75 100644
--- a/compiler/rustc_codegen_cranelift/src/abi/pass_mode.rs
+++ b/compiler/rustc_codegen_cranelift/src/abi/pass_mode.rs
@@ -1,8 +1,9 @@
 //! Argument passing
 
 use cranelift_codegen::ir::{ArgumentExtension, ArgumentPurpose};
-use rustc_target::abi::call::{
-    ArgAbi, ArgAttributes, ArgExtension as RustcArgExtension, CastTarget, PassMode, Reg, RegKind,
+use rustc_abi::{Reg, RegKind};
+use rustc_target::callconv::{
+    ArgAbi, ArgAttributes, ArgExtension as RustcArgExtension, CastTarget, PassMode,
 };
 use smallvec::{SmallVec, smallvec};
 
diff --git a/compiler/rustc_codegen_cranelift/src/abi/returning.rs b/compiler/rustc_codegen_cranelift/src/abi/returning.rs
index a294c789b22..9e048c7badb 100644
--- a/compiler/rustc_codegen_cranelift/src/abi/returning.rs
+++ b/compiler/rustc_codegen_cranelift/src/abi/returning.rs
@@ -1,6 +1,6 @@
 //! Return value handling
 
-use rustc_target::abi::call::{ArgAbi, PassMode};
+use rustc_target::callconv::{ArgAbi, PassMode};
 use smallvec::{SmallVec, smallvec};
 
 use crate::prelude::*;
diff --git a/compiler/rustc_codegen_cranelift/src/base.rs b/compiler/rustc_codegen_cranelift/src/base.rs
index 10d5dce9b36..da3818ca25e 100644
--- a/compiler/rustc_codegen_cranelift/src/base.rs
+++ b/compiler/rustc_codegen_cranelift/src/base.rs
@@ -934,7 +934,7 @@ fn codegen_stmt<'tcx>(
                 let dst = codegen_operand(fx, dst);
                 let pointee = dst
                     .layout()
-                    .pointee_info_at(fx, rustc_target::abi::Size::ZERO)
+                    .pointee_info_at(fx, rustc_abi::Size::ZERO)
                     .expect("Expected pointer");
                 let dst = dst.load_scalar(fx);
                 let src = codegen_operand(fx, src).load_scalar(fx);
diff --git a/compiler/rustc_codegen_cranelift/src/common.rs b/compiler/rustc_codegen_cranelift/src/common.rs
index 69a32cc3d43..27e71b92561 100644
--- a/compiler/rustc_codegen_cranelift/src/common.rs
+++ b/compiler/rustc_codegen_cranelift/src/common.rs
@@ -1,13 +1,13 @@
 use cranelift_codegen::isa::TargetFrontendConfig;
 use cranelift_frontend::{FunctionBuilder, FunctionBuilderContext};
+use rustc_abi::{Float, Integer, Primitive};
 use rustc_index::IndexVec;
 use rustc_middle::ty::TypeFoldable;
 use rustc_middle::ty::layout::{
     self, FnAbiError, FnAbiOfHelpers, FnAbiRequest, LayoutError, LayoutOfHelpers,
 };
 use rustc_span::source_map::Spanned;
-use rustc_target::abi::call::FnAbi;
-use rustc_target::abi::{Float, Integer, Primitive};
+use rustc_target::callconv::FnAbi;
 use rustc_target::spec::{HasTargetSpec, Target};
 
 use crate::constant::ConstantCx;
@@ -162,8 +162,8 @@ pub(crate) fn codegen_icmp_imm(
 pub(crate) fn codegen_bitcast(fx: &mut FunctionCx<'_, '_, '_>, dst_ty: Type, val: Value) -> Value {
     let mut flags = MemFlags::new();
     flags.set_endianness(match fx.tcx.data_layout.endian {
-        rustc_target::abi::Endian::Big => cranelift_codegen::ir::Endianness::Big,
-        rustc_target::abi::Endian::Little => cranelift_codegen::ir::Endianness::Little,
+        rustc_abi::Endian::Big => cranelift_codegen::ir::Endianness::Big,
+        rustc_abi::Endian::Little => cranelift_codegen::ir::Endianness::Little,
     });
     fx.bcx.ins().bitcast(dst_ty, flags, val)
 }
@@ -333,8 +333,8 @@ impl<'tcx> layout::HasTyCtxt<'tcx> for FunctionCx<'_, '_, 'tcx> {
     }
 }
 
-impl<'tcx> rustc_target::abi::HasDataLayout for FunctionCx<'_, '_, 'tcx> {
-    fn data_layout(&self) -> &rustc_target::abi::TargetDataLayout {
+impl<'tcx> rustc_abi::HasDataLayout for FunctionCx<'_, '_, 'tcx> {
+    fn data_layout(&self) -> &rustc_abi::TargetDataLayout {
         &self.tcx.data_layout
     }
 }
@@ -491,8 +491,8 @@ impl<'tcx> layout::HasTyCtxt<'tcx> for RevealAllLayoutCx<'tcx> {
     }
 }
 
-impl<'tcx> rustc_target::abi::HasDataLayout for RevealAllLayoutCx<'tcx> {
-    fn data_layout(&self) -> &rustc_target::abi::TargetDataLayout {
+impl<'tcx> rustc_abi::HasDataLayout for RevealAllLayoutCx<'tcx> {
+    fn data_layout(&self) -> &rustc_abi::TargetDataLayout {
         &self.0.data_layout
     }
 }
diff --git a/compiler/rustc_codegen_cranelift/src/debuginfo/mod.rs b/compiler/rustc_codegen_cranelift/src/debuginfo/mod.rs
index 78ae43b1c4d..9025ea97b81 100644
--- a/compiler/rustc_codegen_cranelift/src/debuginfo/mod.rs
+++ b/compiler/rustc_codegen_cranelift/src/debuginfo/mod.rs
@@ -20,7 +20,7 @@ use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefIdMap;
 use rustc_session::Session;
 use rustc_span::{FileNameDisplayPreference, SourceFileHash, StableSourceFileId};
-use rustc_target::abi::call::FnAbi;
+use rustc_target::callconv::FnAbi;
 
 pub(crate) use self::emit::{DebugReloc, DebugRelocName};
 pub(crate) use self::types::TypeDebugContext;
diff --git a/compiler/rustc_codegen_cranelift/src/driver/aot.rs b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
index 419efa90600..8eab73ad5f9 100644
--- a/compiler/rustc_codegen_cranelift/src/driver/aot.rs
+++ b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
@@ -2,6 +2,7 @@
 //! standalone executable.
 
 use std::fs::{self, File};
+use std::io::BufWriter;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use std::thread::JoinHandle;
@@ -397,14 +398,19 @@ fn emit_module(
     }
 
     let tmp_file = output_filenames.temp_path(OutputType::Object, Some(&name));
-    let mut file = match File::create(&tmp_file) {
+    let file = match File::create(&tmp_file) {
         Ok(file) => file,
         Err(err) => return Err(format!("error creating object file: {}", err)),
     };
 
+    let mut file = BufWriter::new(file);
     if let Err(err) = object.write_stream(&mut file) {
         return Err(format!("error writing object file: {}", err));
     }
+    let file = match file.into_inner() {
+        Ok(file) => file,
+        Err(err) => return Err(format!("error writing object file: {}", err)),
+    };
 
     prof.artifact_size("object_file", &*name, file.metadata().unwrap().len());
 
diff --git a/compiler/rustc_codegen_cranelift/src/inline_asm.rs b/compiler/rustc_codegen_cranelift/src/inline_asm.rs
index 0fbd5a16830..a3f816f70a9 100644
--- a/compiler/rustc_codegen_cranelift/src/inline_asm.rs
+++ b/compiler/rustc_codegen_cranelift/src/inline_asm.rs
@@ -464,7 +464,7 @@ impl<'tcx> InlineAssemblyGenerator<'_, 'tcx> {
         let new_slot_fn = |slot_size: &mut Size, reg_class: InlineAsmRegClass| {
             let reg_size =
                 reg_class.supported_types(self.arch).iter().map(|(ty, _)| ty.size()).max().unwrap();
-            let align = rustc_target::abi::Align::from_bytes(reg_size.bytes()).unwrap();
+            let align = rustc_abi::Align::from_bytes(reg_size.bytes()).unwrap();
             let offset = slot_size.align_to(align);
             *slot_size = offset + reg_size;
             offset
diff --git a/compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs b/compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs
index 36a35d42c3e..f787b8a6fd9 100644
--- a/compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs
+++ b/compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs
@@ -1,7 +1,7 @@
 //! Codegen SIMD intrinsics.
 
 use cranelift_codegen::ir::immediates::Offset32;
-use rustc_target::abi::Endian;
+use rustc_abi::Endian;
 
 use super::*;
 use crate::prelude::*;
diff --git a/compiler/rustc_codegen_cranelift/src/lib.rs b/compiler/rustc_codegen_cranelift/src/lib.rs
index aba0c28f6b8..19a1de53d1d 100644
--- a/compiler/rustc_codegen_cranelift/src/lib.rs
+++ b/compiler/rustc_codegen_cranelift/src/lib.rs
@@ -241,6 +241,8 @@ impl CodegenBackend for CraneliftCodegenBackend {
         sess: &Session,
         outputs: &OutputFilenames,
     ) -> (CodegenResults, FxIndexMap<WorkProductId, WorkProduct>) {
+        let _timer = sess.timer("finish_ongoing_codegen");
+
         ongoing_codegen.downcast::<driver::aot::OngoingCodegen>().unwrap().join(
             sess,
             outputs,
diff --git a/compiler/rustc_codegen_cranelift/src/pointer.rs b/compiler/rustc_codegen_cranelift/src/pointer.rs
index 11ac6b94678..2750caa216e 100644
--- a/compiler/rustc_codegen_cranelift/src/pointer.rs
+++ b/compiler/rustc_codegen_cranelift/src/pointer.rs
@@ -2,7 +2,7 @@
 //! operations.
 
 use cranelift_codegen::ir::immediates::Offset32;
-use rustc_target::abi::Align;
+use rustc_abi::Align;
 
 use crate::prelude::*;
 
diff --git a/compiler/rustc_codegen_cranelift/src/pretty_clif.rs b/compiler/rustc_codegen_cranelift/src/pretty_clif.rs
index 282763279dd..cd254b04ed9 100644
--- a/compiler/rustc_codegen_cranelift/src/pretty_clif.rs
+++ b/compiler/rustc_codegen_cranelift/src/pretty_clif.rs
@@ -64,7 +64,7 @@ use cranelift_codegen::ir::entities::AnyEntity;
 use cranelift_codegen::write::{FuncWriter, PlainWriter};
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_session::config::{OutputFilenames, OutputType};
-use rustc_target::abi::call::FnAbi;
+use rustc_target::callconv::FnAbi;
 
 use crate::prelude::*;
 
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs b/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
index ac6c2fb1b83..0f1909486ec 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
@@ -1,11 +1,15 @@
+use std::collections::hash_map::Entry;
+
 use rustc_codegen_ssa::mir::debuginfo::{DebugScope, FunctionDebugContext};
 use rustc_codegen_ssa::traits::*;
+use rustc_data_structures::fx::FxHashMap;
 use rustc_index::Idx;
 use rustc_index::bit_set::BitSet;
 use rustc_middle::mir::{Body, SourceScope};
 use rustc_middle::ty::layout::FnAbiOf;
 use rustc_middle::ty::{self, Instance};
 use rustc_session::config::DebugInfo;
+use rustc_span::BytePos;
 
 use super::metadata::file_metadata;
 use super::utils::DIB;
@@ -37,10 +41,20 @@ pub(crate) fn compute_mir_scopes<'ll, 'tcx>(
         None
     };
     let mut instantiated = BitSet::new_empty(mir.source_scopes.len());
+    let mut discriminators = FxHashMap::default();
     // Instantiate all scopes.
     for idx in 0..mir.source_scopes.len() {
         let scope = SourceScope::new(idx);
-        make_mir_scope(cx, instance, mir, &variables, debug_context, &mut instantiated, scope);
+        make_mir_scope(
+            cx,
+            instance,
+            mir,
+            &variables,
+            debug_context,
+            &mut instantiated,
+            &mut discriminators,
+            scope,
+        );
     }
     assert!(instantiated.count() == mir.source_scopes.len());
 }
@@ -52,6 +66,7 @@ fn make_mir_scope<'ll, 'tcx>(
     variables: &Option<BitSet<SourceScope>>,
     debug_context: &mut FunctionDebugContext<'tcx, &'ll DIScope, &'ll DILocation>,
     instantiated: &mut BitSet<SourceScope>,
+    discriminators: &mut FxHashMap<BytePos, u32>,
     scope: SourceScope,
 ) {
     if instantiated.contains(scope) {
@@ -60,7 +75,16 @@ fn make_mir_scope<'ll, 'tcx>(
 
     let scope_data = &mir.source_scopes[scope];
     let parent_scope = if let Some(parent) = scope_data.parent_scope {
-        make_mir_scope(cx, instance, mir, variables, debug_context, instantiated, parent);
+        make_mir_scope(
+            cx,
+            instance,
+            mir,
+            variables,
+            debug_context,
+            instantiated,
+            discriminators,
+            parent,
+        );
         debug_context.scopes[parent]
     } else {
         // The root is the function itself.
@@ -117,7 +141,37 @@ fn make_mir_scope<'ll, 'tcx>(
         // FIXME(eddyb) this doesn't account for the macro-related
         // `Span` fixups that `rustc_codegen_ssa::mir::debuginfo` does.
         let callsite_scope = parent_scope.adjust_dbg_scope_for_span(cx, callsite_span);
-        cx.dbg_loc(callsite_scope, parent_scope.inlined_at, callsite_span)
+        let loc = cx.dbg_loc(callsite_scope, parent_scope.inlined_at, callsite_span);
+
+        // NB: In order to produce proper debug info for variables (particularly
+        // arguments) in multiply-inline functions, LLVM expects to see a single
+        // DILocalVariable with multiple different DILocations in the IR. While
+        // the source information for each DILocation would be identical, their
+        // inlinedAt attributes will be unique to the particular callsite.
+        //
+        // We generate DILocations here based on the callsite's location in the
+        // source code. A single location in the source code usually can't
+        // produce multiple distinct calls so this mostly works, until
+        // proc-macros get involved. A proc-macro can generate multiple calls
+        // at the same span, which breaks the assumption that we're going to
+        // produce a unique DILocation for every scope we process here. We
+        // have to explicitly add discriminators if we see inlines into the
+        // same source code location.
+        //
+        // Note further that we can't key this hashtable on the span itself,
+        // because these spans could have distinct SyntaxContexts. We have
+        // to key on exactly what we're giving to LLVM.
+        match discriminators.entry(callsite_span.lo()) {
+            Entry::Occupied(mut o) => {
+                *o.get_mut() += 1;
+                unsafe { llvm::LLVMRustDILocationCloneWithBaseDiscriminator(loc, *o.get()) }
+                    .expect("Failed to encode discriminator in DILocation")
+            }
+            Entry::Vacant(v) => {
+                v.insert(0);
+                loc
+            }
+        }
     });
 
     debug_context.scopes[scope] = DebugScope {
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 8508f87c8d3..75a5ec44c22 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -204,7 +204,7 @@ pub enum DLLStorageClass {
     DllExport = 2, // Function to be accessible from DLL.
 }
 
-/// Matches LLVMRustAttribute in LLVMWrapper.h
+/// Must match the layout of `LLVMRustAttributeKind`.
 /// Semantically a subset of the C++ enum llvm::Attribute::AttrKind,
 /// though it is not ABI compatible (since it's a C++ enum)
 #[repr(C)]
@@ -1766,11 +1766,9 @@ unsafe extern "C" {
     pub fn LLVMRustGetLastError() -> *const c_char;
 
     /// Prints the timing information collected by `-Ztime-llvm-passes`.
-    #[expect(improper_ctypes)]
     pub(crate) fn LLVMRustPrintPassTimings(OutStr: &RustString);
 
     /// Prints the statistics collected by `-Zprint-codegen-stats`.
-    #[expect(improper_ctypes)]
     pub(crate) fn LLVMRustPrintStatistics(OutStr: &RustString);
 
     /// Prepares inline assembly.
@@ -1791,7 +1789,6 @@ unsafe extern "C" {
         ConstraintsLen: size_t,
     ) -> bool;
 
-    #[allow(improper_ctypes)]
     pub(crate) fn LLVMRustCoverageWriteFilenamesToBuffer(
         Filenames: *const *const c_char,
         FilenamesLen: size_t,
@@ -1800,7 +1797,6 @@ unsafe extern "C" {
         BufferOut: &RustString,
     );
 
-    #[allow(improper_ctypes)]
     pub(crate) fn LLVMRustCoverageWriteFunctionMappingsToBuffer(
         VirtualFileMappingIDs: *const c_uint,
         NumVirtualFileMappingIDs: size_t,
@@ -1824,13 +1820,10 @@ unsafe extern "C" {
     ) -> &Value;
     pub(crate) fn LLVMRustCoverageHashBytes(Bytes: *const c_char, NumBytes: size_t) -> u64;
 
-    #[allow(improper_ctypes)]
     pub(crate) fn LLVMRustCoverageWriteCovmapSectionNameToString(M: &Module, OutStr: &RustString);
 
-    #[allow(improper_ctypes)]
     pub(crate) fn LLVMRustCoverageWriteCovfunSectionNameToString(M: &Module, OutStr: &RustString);
 
-    #[allow(improper_ctypes)]
     pub(crate) fn LLVMRustCoverageWriteCovmapVarNameToString(OutStr: &RustString);
 
     pub(crate) fn LLVMRustCoverageMappingVersion() -> u32;
@@ -2181,18 +2174,19 @@ unsafe extern "C" {
         Scope: &'a DIScope,
         InlinedAt: Option<&'a DILocation>,
     ) -> &'a DILocation;
+    pub fn LLVMRustDILocationCloneWithBaseDiscriminator<'a>(
+        Location: &'a DILocation,
+        BD: c_uint,
+    ) -> Option<&'a DILocation>;
     pub fn LLVMRustDIBuilderCreateOpDeref() -> u64;
     pub fn LLVMRustDIBuilderCreateOpPlusUconst() -> u64;
     pub fn LLVMRustDIBuilderCreateOpLLVMFragment() -> u64;
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustWriteTypeToString(Type: &Type, s: &RustString);
-    #[allow(improper_ctypes)]
     pub fn LLVMRustWriteValueToString(value_ref: &Value, s: &RustString);
 
     pub fn LLVMRustHasFeature(T: &TargetMachine, s: *const c_char) -> bool;
 
-    #[allow(improper_ctypes)]
     pub(crate) fn LLVMRustPrintTargetCPUs(TM: &TargetMachine, OutStr: &RustString);
     pub fn LLVMRustGetTargetFeaturesCount(T: &TargetMachine) -> size_t;
     pub fn LLVMRustGetTargetFeature(
@@ -2297,10 +2291,8 @@ unsafe extern "C" {
     pub fn LLVMRustArchiveIteratorFree<'a>(AIR: &'a mut ArchiveIterator<'a>);
     pub fn LLVMRustDestroyArchive(AR: &'static mut Archive);
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustWriteTwineToString(T: &Twine, s: &RustString);
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustUnpackOptimizationDiagnostic<'a>(
         DI: &'a DiagnosticInfo,
         pass_name_out: &RustString,
@@ -2318,7 +2310,6 @@ unsafe extern "C" {
         message_out: &mut Option<&'a Twine>,
     );
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustWriteDiagnosticInfoToString(DI: &DiagnosticInfo, s: &RustString);
     pub fn LLVMRustGetDiagInfoKind(DI: &DiagnosticInfo) -> DiagnosticKind;
 
@@ -2327,7 +2318,6 @@ unsafe extern "C" {
         cookie_out: &mut c_uint,
     ) -> &'a SMDiagnostic;
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustUnpackSMDiagnostic(
         d: &SMDiagnostic,
         message_out: &RustString,
@@ -2374,7 +2364,6 @@ unsafe extern "C" {
     pub fn LLVMRustModuleBufferLen(p: &ModuleBuffer) -> usize;
     pub fn LLVMRustModuleBufferFree(p: &'static mut ModuleBuffer);
     pub fn LLVMRustModuleCost(M: &Module) -> u64;
-    #[allow(improper_ctypes)]
     pub fn LLVMRustModuleInstructionStats(M: &Module, Str: &RustString);
 
     pub fn LLVMRustThinLTOBufferCreate(
@@ -2427,7 +2416,6 @@ unsafe extern "C" {
         bytecode_len: usize,
     ) -> bool;
     pub fn LLVMRustLinkerFree<'a>(linker: &'a mut Linker<'a>);
-    #[allow(improper_ctypes)]
     pub fn LLVMRustComputeLTOCacheKey(
         key_out: &RustString,
         mod_id: *const c_char,
@@ -2450,7 +2438,6 @@ unsafe extern "C" {
         pgo_available: bool,
     );
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustGetMangledName(V: &Value, out: &RustString);
 
     pub fn LLVMRustGetElementTypeArgIndex(CallSite: &Value) -> i32;
diff --git a/compiler/rustc_codegen_llvm/src/llvm/mod.rs b/compiler/rustc_codegen_llvm/src/llvm/mod.rs
index 3b0bf47366e..909afe35a17 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/mod.rs
@@ -1,6 +1,5 @@
 #![allow(non_snake_case)]
 
-use std::cell::RefCell;
 use std::ffi::{CStr, CString};
 use std::ops::Deref;
 use std::ptr;
@@ -301,15 +300,11 @@ pub fn set_value_name(value: &Value, name: &[u8]) {
 }
 
 pub fn build_string(f: impl FnOnce(&RustString)) -> Result<String, FromUtf8Error> {
-    let sr = RustString { bytes: RefCell::new(Vec::new()) };
-    f(&sr);
-    String::from_utf8(sr.bytes.into_inner())
+    String::from_utf8(RustString::build_byte_buffer(f))
 }
 
 pub fn build_byte_buffer(f: impl FnOnce(&RustString)) -> Vec<u8> {
-    let sr = RustString { bytes: RefCell::new(Vec::new()) };
-    f(&sr);
-    sr.bytes.into_inner()
+    RustString::build_byte_buffer(f)
 }
 
 pub fn twine_to_string(tr: &Twine) -> String {
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 6f2d86cc601..c382242d8d0 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -228,6 +228,8 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         "x86"
     } else if sess.target.arch == "arm64ec" {
         "aarch64"
+    } else if sess.target.arch == "sparc64" {
+        "sparc"
     } else {
         &*sess.target.arch
     };
@@ -280,6 +282,13 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         // Support for `wide-arithmetic` will first land in LLVM 20 as part of
         // llvm/llvm-project#111598
         ("wasm32" | "wasm64", "wide-arithmetic") if get_version() < (20, 0, 0) => None,
+        ("sparc", "leoncasa") => Some(LLVMFeature::new("hasleoncasa")),
+        // In LLVM 19, there is no `v8plus` feature and `v9` means "SPARC-V9 instruction available and SPARC-V8+ ABI used".
+        // https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp#L27-L28
+        // Before LLVM 19, there is no `v8plus` feature and `v9` means "SPARC-V9 instruction available".
+        // https://github.com/llvm/llvm-project/blob/llvmorg-18.1.0/llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp#L26
+        ("sparc", "v8plus") if get_version().0 == 19 => Some(LLVMFeature::new("v9")),
+        ("sparc", "v8plus") if get_version().0 < 19 => None,
         (_, s) => Some(LLVMFeature::new(s)),
     }
 }
@@ -619,6 +628,8 @@ pub(crate) fn global_llvm_features(
             .features
             .split(',')
             .filter(|v| !v.is_empty() && backend_feature_name(sess, v).is_some())
+            // Drop +v8plus feature introduced in LLVM 20.
+            .filter(|v| *v != "+v8plus" || get_version() >= (20, 0, 0))
             .map(String::from),
     );
 
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 8f754debaf0..3120b5bf0af 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -3305,23 +3305,6 @@ fn add_lld_args(
     let self_contained_cli = sess.opts.cg.link_self_contained.is_linker_enabled();
     let self_contained_target = self_contained_components.is_linker_enabled();
 
-    // FIXME: in the future, codegen backends may need to have more control over this process: they
-    // don't always support all the features the linker expects here, and vice versa. For example,
-    // at the time of writing this, lld expects a newer style of aarch64 TLS relocations that
-    // cranelift doesn't implement yet. That in turn can impact whether linking would succeed on
-    // such a target when using the `cg_clif` backend and lld.
-    //
-    // Until interactions between backends and linker features are expressible, we limit target
-    // specs to opt-in to lld only when we're on the llvm backend, where it's expected to work and
-    // tested on CI. As usual, the CLI still has precedence over this, so that users and developers
-    // can still override this default when needed (e.g. for tests).
-    let uses_llvm_backend =
-        matches!(sess.opts.unstable_opts.codegen_backend.as_deref(), None | Some("llvm"));
-    if !uses_llvm_backend && !self_contained_cli && sess.opts.cg.linker_flavor.is_none() {
-        // We bail if we're not using llvm and lld was not explicitly requested on the CLI.
-        return;
-    }
-
     let self_contained_linker = self_contained_cli || self_contained_target;
     if self_contained_linker && !sess.opts.cg.link_self_contained.is_linker_disabled() {
         let mut linker_path_exists = false;
diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs
index 3f3cb8b4073..bdf7030f946 100644
--- a/compiler/rustc_codegen_ssa/src/back/metadata.rs
+++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs
@@ -212,7 +212,7 @@ pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static
         "riscv32" => (Architecture::Riscv32, None),
         "riscv64" => (Architecture::Riscv64, None),
         "sparc" => {
-            if sess.target.options.cpu == "v9" {
+            if sess.unstable_target_features.contains(&sym::v8plus) {
                 // Target uses V8+, aka EM_SPARC32PLUS, aka 64-bit V9 but in 32-bit mode
                 (Architecture::Sparc32Plus, None)
             } else {
diff --git a/compiler/rustc_const_eval/messages.ftl b/compiler/rustc_const_eval/messages.ftl
index 826e34930ea..15027ae0c18 100644
--- a/compiler/rustc_const_eval/messages.ftl
+++ b/compiler/rustc_const_eval/messages.ftl
@@ -25,6 +25,10 @@ const_eval_closure_fndef_not_const =
     function defined here, but it is not `const`
 const_eval_closure_non_const =
     cannot call non-const closure in {const_eval_const_context}s
+
+const_eval_conditionally_const_call =
+    cannot call conditionally-const {$def_descr} `{$def_path_str}` in {const_eval_const_context}s
+
 const_eval_consider_dereferencing =
     consider dereferencing here
 
diff --git a/compiler/rustc_const_eval/src/check_consts/check.rs b/compiler/rustc_const_eval/src/check_consts/check.rs
index aea3d5bd3e7..8cd0ecb3e4e 100644
--- a/compiler/rustc_const_eval/src/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/check_consts/check.rs
@@ -15,7 +15,7 @@ use rustc_middle::mir::visit::Visitor;
 use rustc_middle::mir::*;
 use rustc_middle::span_bug;
 use rustc_middle::ty::adjustment::PointerCoercion;
-use rustc_middle::ty::{self, Instance, InstanceKind, Ty, TypeVisitableExt};
+use rustc_middle::ty::{self, Ty, TypeVisitableExt};
 use rustc_mir_dataflow::Analysis;
 use rustc_mir_dataflow::impls::MaybeStorageLive;
 use rustc_mir_dataflow::storage::always_storage_live_locals;
@@ -361,31 +361,21 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
         !is_transient
     }
 
+    /// Returns whether there are const-conditions.
     fn revalidate_conditional_constness(
         &mut self,
         callee: DefId,
         callee_args: ty::GenericArgsRef<'tcx>,
-        call_source: CallSource,
         call_span: Span,
-    ) {
+    ) -> bool {
         let tcx = self.tcx;
         if !tcx.is_conditionally_const(callee) {
-            return;
+            return false;
         }
 
         let const_conditions = tcx.const_conditions(callee).instantiate(tcx, callee_args);
-        // If there are any const conditions on this fn and `const_trait_impl`
-        // is not enabled, simply bail. We shouldn't be able to call conditionally
-        // const functions on stable.
-        if !const_conditions.is_empty() && !tcx.features().const_trait_impl() {
-            self.check_op(ops::FnCallNonConst {
-                callee,
-                args: callee_args,
-                span: call_span,
-                call_source,
-                feature: Some(sym::const_trait_impl),
-            });
-            return;
+        if const_conditions.is_empty() {
+            return false;
         }
 
         let infcx = tcx.infer_ctxt().build(self.body.typing_mode(tcx));
@@ -421,6 +411,8 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
             tcx.dcx()
                 .span_delayed_bug(call_span, "this should have reported a ~const error in HIR");
         }
+
+        true
     }
 }
 
@@ -627,11 +619,11 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                     _ => unreachable!(),
                 };
 
-                let ConstCx { tcx, body, param_env, .. } = *self.ccx;
+                let ConstCx { tcx, body, .. } = *self.ccx;
 
                 let fn_ty = func.ty(body, tcx);
 
-                let (mut callee, mut fn_args) = match *fn_ty.kind() {
+                let (callee, fn_args) = match *fn_ty.kind() {
                     ty::FnDef(def_id, fn_args) => (def_id, fn_args),
 
                     ty::FnPtr(..) => {
@@ -645,57 +637,38 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                     }
                 };
 
-                self.revalidate_conditional_constness(callee, fn_args, call_source, *fn_span);
+                let has_const_conditions =
+                    self.revalidate_conditional_constness(callee, fn_args, *fn_span);
 
-                let mut is_trait = false;
                 // Attempting to call a trait method?
                 if let Some(trait_did) = tcx.trait_of_item(callee) {
-                    trace!("attempting to call a trait method");
+                    // We can't determine the actual callee here, so we have to do different checks
+                    // than usual.
 
+                    trace!("attempting to call a trait method");
                     let trait_is_const = tcx.is_const_trait(trait_did);
-                    // trait method calls are only permitted when `effects` is enabled.
-                    // typeck ensures the conditions for calling a const trait method are met,
-                    // so we only error if the trait isn't const. We try to resolve the trait
-                    // into the concrete method, and uses that for const stability checks.
-                    // FIXME(const_trait_impl) we might consider moving const stability checks
-                    // to typeck as well.
-                    if tcx.features().const_trait_impl() && trait_is_const {
-                        // This skips the check below that ensures we only call `const fn`.
-                        is_trait = true;
-
-                        if let Ok(Some(instance)) =
-                            Instance::try_resolve(tcx, param_env, callee, fn_args)
-                            && let InstanceKind::Item(def) = instance.def
-                        {
-                            // Resolve a trait method call to its concrete implementation, which may be in a
-                            // `const` trait impl. This is only used for the const stability check below, since
-                            // we want to look at the concrete impl's stability.
-                            fn_args = instance.args;
-                            callee = def;
-                        }
+
+                    if trait_is_const {
+                        // Trait calls are always conditionally-const.
+                        self.check_op(ops::ConditionallyConstCall { callee, args: fn_args });
+                        // FIXME(const_trait_impl): do a more fine-grained check whether this
+                        // particular trait can be const-stably called.
                     } else {
-                        // if the trait is const but the user has not enabled the feature(s),
-                        // suggest them.
-                        let feature = if trait_is_const {
-                            Some(if tcx.features().const_trait_impl() {
-                                sym::effects
-                            } else {
-                                sym::const_trait_impl
-                            })
-                        } else {
-                            None
-                        };
+                        // Not even a const trait.
                         self.check_op(ops::FnCallNonConst {
                             callee,
                             args: fn_args,
                             span: *fn_span,
                             call_source,
-                            feature,
                         });
-                        // If we allowed this, we're in miri-unleashed mode, so we might
-                        // as well skip the remaining checks.
-                        return;
                     }
+                    // That's all we can check here.
+                    return;
+                }
+
+                // Even if we know the callee, ensure we can use conditionally-const calls.
+                if has_const_conditions {
+                    self.check_op(ops::ConditionallyConstCall { callee, args: fn_args });
                 }
 
                 // At this point, we are calling a function, `callee`, whose `DefId` is known...
@@ -783,14 +756,12 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                     return;
                 }
 
-                // Trait functions are not `const fn` so we have to skip them here.
-                if !tcx.is_const_fn(callee) && !is_trait {
+                if !tcx.is_const_fn(callee) {
                     self.check_op(ops::FnCallNonConst {
                         callee,
                         args: fn_args,
                         span: *fn_span,
                         call_source,
-                        feature: None,
                     });
                     // If we allowed this, we're in miri-unleashed mode, so we might
                     // as well skip the remaining checks.
diff --git a/compiler/rustc_const_eval/src/check_consts/ops.rs b/compiler/rustc_const_eval/src/check_consts/ops.rs
index 2931159842f..036ca763280 100644
--- a/compiler/rustc_const_eval/src/check_consts/ops.rs
+++ b/compiler/rustc_const_eval/src/check_consts/ops.rs
@@ -70,6 +70,37 @@ impl<'tcx> NonConstOp<'tcx> for FnCallIndirect {
     }
 }
 
+/// A call to a function that is in a trait, or has trait bounds that make it conditionally-const.
+#[derive(Debug)]
+pub(crate) struct ConditionallyConstCall<'tcx> {
+    pub callee: DefId,
+    pub args: GenericArgsRef<'tcx>,
+}
+
+impl<'tcx> NonConstOp<'tcx> for ConditionallyConstCall<'tcx> {
+    fn status_in_item(&self, _ccx: &ConstCx<'_, 'tcx>) -> Status {
+        // We use the `const_trait_impl` gate for all conditionally-const calls.
+        Status::Unstable {
+            gate: sym::const_trait_impl,
+            safe_to_expose_on_stable: false,
+            // We don't want the "mark the callee as `#[rustc_const_stable_indirect]`" hint
+            is_function_call: false,
+        }
+    }
+
+    fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
+        ccx.tcx.sess.create_feature_err(
+            errors::ConditionallyConstCall {
+                span,
+                def_path_str: ccx.tcx.def_path_str_with_args(self.callee, self.args),
+                def_descr: ccx.tcx.def_descr(self.callee),
+                kind: ccx.const_kind(),
+            },
+            sym::const_trait_impl,
+        )
+    }
+}
+
 /// A function call where the callee is not marked as `const`.
 #[derive(Debug, Clone, Copy)]
 pub(crate) struct FnCallNonConst<'tcx> {
@@ -77,7 +108,6 @@ pub(crate) struct FnCallNonConst<'tcx> {
     pub args: GenericArgsRef<'tcx>,
     pub span: Span,
     pub call_source: CallSource,
-    pub feature: Option<Symbol>,
 }
 
 impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
@@ -85,7 +115,7 @@ impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
     #[allow(rustc::diagnostic_outside_of_impl)]
     #[allow(rustc::untranslatable_diagnostic)]
     fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, _: Span) -> Diag<'tcx> {
-        let FnCallNonConst { callee, args, span, call_source, feature } = *self;
+        let FnCallNonConst { callee, args, span, call_source } = *self;
         let ConstCx { tcx, param_env, .. } = *ccx;
         let caller = ccx.def_id();
 
@@ -285,14 +315,6 @@ impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
             ccx.const_kind(),
         ));
 
-        if let Some(feature) = feature {
-            ccx.tcx.disabled_nightly_features(
-                &mut err,
-                Some(ccx.tcx.local_def_id_to_hir_id(caller)),
-                [(String::new(), feature)],
-            );
-        }
-
         if let ConstContext::Static(_) = ccx.const_kind() {
             err.note(fluent_generated::const_eval_lazy_lock);
         }
@@ -398,15 +420,8 @@ impl<'tcx> NonConstOp<'tcx> for Coroutine {
 
     fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
         let msg = format!("{:#}s are not allowed in {}s", self.0, ccx.const_kind());
-        if let hir::CoroutineKind::Desugared(
-            hir::CoroutineDesugaring::Async,
-            hir::CoroutineSource::Block,
-        ) = self.0
-        {
-            ccx.tcx.sess.create_feature_err(
-                errors::UnallowedOpInConstContext { span, msg },
-                sym::const_async_blocks,
-            )
+        if let Status::Unstable { gate, .. } = self.status_in_item(ccx) {
+            ccx.tcx.sess.create_feature_err(errors::UnallowedOpInConstContext { span, msg }, gate)
         } else {
             ccx.dcx().create_err(errors::UnallowedOpInConstContext { span, msg })
         }
diff --git a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
index 81b9d73b952..a430d9dc797 100644
--- a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
+++ b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
@@ -472,8 +472,9 @@ fn report_validation_error<'tcx>(
     backtrace.print_backtrace();
 
     let bytes = ecx.print_alloc_bytes_for_diagnostics(alloc_id);
-    let (size, align, _) = ecx.get_alloc_info(alloc_id);
-    let raw_bytes = errors::RawBytesNote { size: size.bytes(), align: align.bytes(), bytes };
+    let info = ecx.get_alloc_info(alloc_id);
+    let raw_bytes =
+        errors::RawBytesNote { size: info.size.bytes(), align: info.align.bytes(), bytes };
 
     crate::const_eval::report(
         *ecx.tcx,
diff --git a/compiler/rustc_const_eval/src/errors.rs b/compiler/rustc_const_eval/src/errors.rs
index 14e8bebbb18..604e5ed61a3 100644
--- a/compiler/rustc_const_eval/src/errors.rs
+++ b/compiler/rustc_const_eval/src/errors.rs
@@ -177,6 +177,16 @@ pub(crate) struct NonConstFmtMacroCall {
 }
 
 #[derive(Diagnostic)]
+#[diag(const_eval_conditionally_const_call)]
+pub(crate) struct ConditionallyConstCall {
+    #[primary_span]
+    pub span: Span,
+    pub def_path_str: String,
+    pub def_descr: &'static str,
+    pub kind: ConstContext,
+}
+
+#[derive(Diagnostic)]
 #[diag(const_eval_non_const_fn_call, code = E0015)]
 pub(crate) struct NonConstFnCall {
     #[primary_span]
diff --git a/compiler/rustc_const_eval/src/interpret/memory.rs b/compiler/rustc_const_eval/src/interpret/memory.rs
index 1ad8ffa4b53..09635c96e57 100644
--- a/compiler/rustc_const_eval/src/interpret/memory.rs
+++ b/compiler/rustc_const_eval/src/interpret/memory.rs
@@ -14,10 +14,9 @@ use std::{fmt, mem, ptr};
 use rustc_abi::{Align, HasDataLayout, Size};
 use rustc_ast::Mutability;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
-use rustc_hir::def::DefKind;
 use rustc_middle::bug;
 use rustc_middle::mir::display_allocation;
-use rustc_middle::ty::{self, Instance, ParamEnv, Ty, TyCtxt};
+use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
 use tracing::{debug, instrument, trace};
 
 use super::{
@@ -72,6 +71,21 @@ pub enum AllocKind {
     Dead,
 }
 
+/// Metadata about an `AllocId`.
+#[derive(Copy, Clone, PartialEq, Debug)]
+pub struct AllocInfo {
+    pub size: Size,
+    pub align: Align,
+    pub kind: AllocKind,
+    pub mutbl: Mutability,
+}
+
+impl AllocInfo {
+    fn new(size: Size, align: Align, kind: AllocKind, mutbl: Mutability) -> Self {
+        Self { size, align, kind, mutbl }
+    }
+}
+
 /// The value of a function pointer.
 #[derive(Debug, Copy, Clone)]
 pub enum FnVal<'tcx, Other> {
@@ -524,17 +538,22 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         match self.ptr_try_get_alloc_id(ptr, 0) {
             Err(addr) => is_offset_misaligned(addr, align),
             Ok((alloc_id, offset, _prov)) => {
-                let (_size, alloc_align, kind) = self.get_alloc_info(alloc_id);
-                if let Some(misalign) =
-                    M::alignment_check(self, alloc_id, alloc_align, kind, offset, align)
-                {
+                let alloc_info = self.get_alloc_info(alloc_id);
+                if let Some(misalign) = M::alignment_check(
+                    self,
+                    alloc_id,
+                    alloc_info.align,
+                    alloc_info.kind,
+                    offset,
+                    align,
+                ) {
                     Some(misalign)
                 } else if M::Provenance::OFFSET_IS_ADDR {
                     is_offset_misaligned(ptr.addr().bytes(), align)
                 } else {
                     // Check allocation alignment and offset alignment.
-                    if alloc_align.bytes() < align.bytes() {
-                        Some(Misalignment { has: alloc_align, required: align })
+                    if alloc_info.align.bytes() < align.bytes() {
+                        Some(Misalignment { has: alloc_info.align, required: align })
                     } else {
                         is_offset_misaligned(offset.bytes(), align)
                     }
@@ -818,82 +837,45 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
 
     /// Obtain the size and alignment of an allocation, even if that allocation has
     /// been deallocated.
-    pub fn get_alloc_info(&self, id: AllocId) -> (Size, Align, AllocKind) {
+    pub fn get_alloc_info(&self, id: AllocId) -> AllocInfo {
         // # Regular allocations
         // Don't use `self.get_raw` here as that will
         // a) cause cycles in case `id` refers to a static
         // b) duplicate a global's allocation in miri
         if let Some((_, alloc)) = self.memory.alloc_map.get(id) {
-            return (alloc.size(), alloc.align, AllocKind::LiveData);
+            return AllocInfo::new(
+                alloc.size(),
+                alloc.align,
+                AllocKind::LiveData,
+                alloc.mutability,
+            );
         }
 
         // # Function pointers
         // (both global from `alloc_map` and local from `extra_fn_ptr_map`)
         if self.get_fn_alloc(id).is_some() {
-            return (Size::ZERO, Align::ONE, AllocKind::Function);
+            return AllocInfo::new(Size::ZERO, Align::ONE, AllocKind::Function, Mutability::Not);
         }
 
-        // # Statics
-        // Can't do this in the match argument, we may get cycle errors since the lock would
-        // be held throughout the match.
-        match self.tcx.try_get_global_alloc(id) {
-            Some(GlobalAlloc::Static(def_id)) => {
-                // Thread-local statics do not have a constant address. They *must* be accessed via
-                // `ThreadLocalRef`; we can never have a pointer to them as a regular constant value.
-                assert!(!self.tcx.is_thread_local_static(def_id));
-
-                let DefKind::Static { nested, .. } = self.tcx.def_kind(def_id) else {
-                    bug!("GlobalAlloc::Static is not a static")
-                };
-
-                let (size, align) = if nested {
-                    // Nested anonymous statics are untyped, so let's get their
-                    // size and alignment from the allocation itself. This always
-                    // succeeds, as the query is fed at DefId creation time, so no
-                    // evaluation actually occurs.
-                    let alloc = self.tcx.eval_static_initializer(def_id).unwrap();
-                    (alloc.0.size(), alloc.0.align)
-                } else {
-                    // Use size and align of the type for everything else. We need
-                    // to do that to
-                    // * avoid cycle errors in case of self-referential statics,
-                    // * be able to get information on extern statics.
-                    let ty = self
-                        .tcx
-                        .type_of(def_id)
-                        .no_bound_vars()
-                        .expect("statics should not have generic parameters");
-                    let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap();
-                    assert!(layout.is_sized());
-                    (layout.size, layout.align.abi)
-                };
-                (size, align, AllocKind::LiveData)
-            }
-            Some(GlobalAlloc::Memory(alloc)) => {
-                // Need to duplicate the logic here, because the global allocations have
-                // different associated types than the interpreter-local ones.
-                let alloc = alloc.inner();
-                (alloc.size(), alloc.align, AllocKind::LiveData)
-            }
-            Some(GlobalAlloc::Function { .. }) => {
-                bug!("We already checked function pointers above")
-            }
-            Some(GlobalAlloc::VTable(..)) => {
-                // No data to be accessed here. But vtables are pointer-aligned.
-                return (Size::ZERO, self.tcx.data_layout.pointer_align.abi, AllocKind::VTable);
-            }
-            // The rest must be dead.
-            None => {
-                // Deallocated pointers are allowed, we should be able to find
-                // them in the map.
-                let (size, align) = *self
-                    .memory
-                    .dead_alloc_map
-                    .get(&id)
-                    .expect("deallocated pointers should all be recorded in `dead_alloc_map`");
-                (size, align, AllocKind::Dead)
-            }
+        // # Global allocations
+        if let Some(global_alloc) = self.tcx.try_get_global_alloc(id) {
+            let (size, align) = global_alloc.size_and_align(*self.tcx, self.param_env);
+            let mutbl = global_alloc.mutability(*self.tcx, self.param_env);
+            let kind = match global_alloc {
+                GlobalAlloc::Static { .. } | GlobalAlloc::Memory { .. } => AllocKind::LiveData,
+                GlobalAlloc::Function { .. } => bug!("We already checked function pointers above"),
+                GlobalAlloc::VTable { .. } => AllocKind::VTable,
+            };
+            return AllocInfo::new(size, align, kind, mutbl);
         }
+
+        // # Dead pointers
+        let (size, align) = *self
+            .memory
+            .dead_alloc_map
+            .get(&id)
+            .expect("deallocated pointers should all be recorded in `dead_alloc_map`");
+        AllocInfo::new(size, align, AllocKind::Dead, Mutability::Not)
     }
 
     /// Obtain the size and alignment of a *live* allocation.
@@ -902,11 +884,11 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         id: AllocId,
         msg: CheckInAllocMsg,
     ) -> InterpResult<'tcx, (Size, Align)> {
-        let (size, align, kind) = self.get_alloc_info(id);
-        if matches!(kind, AllocKind::Dead) {
+        let info = self.get_alloc_info(id);
+        if matches!(info.kind, AllocKind::Dead) {
             throw_ub!(PointerUseAfterFree(id, msg))
         }
-        interp_ok((size, align))
+        interp_ok((info.size, info.align))
     }
 
     fn get_fn_alloc(&self, id: AllocId) -> Option<FnVal<'tcx, M::ExtraFnVal>> {
@@ -1458,7 +1440,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 let ptr = scalar.to_pointer(self)?;
                 match self.ptr_try_get_alloc_id(ptr, 0) {
                     Ok((alloc_id, offset, _)) => {
-                        let (size, _align, _kind) = self.get_alloc_info(alloc_id);
+                        let size = self.get_alloc_info(alloc_id).size;
                         // If the pointer is out-of-bounds, it may be null.
                         // Note that one-past-the-end (offset == size) is still inbounds, and never null.
                         offset > size
diff --git a/compiler/rustc_const_eval/src/interpret/mod.rs b/compiler/rustc_const_eval/src/interpret/mod.rs
index 5e84626f77e..f5792aba207 100644
--- a/compiler/rustc_const_eval/src/interpret/mod.rs
+++ b/compiler/rustc_const_eval/src/interpret/mod.rs
@@ -31,7 +31,7 @@ pub use self::intern::{
 };
 pub(crate) use self::intrinsics::eval_nullary_intrinsic;
 pub use self::machine::{AllocMap, Machine, MayLeak, ReturnAction, compile_time_machine};
-pub use self::memory::{AllocKind, AllocRef, AllocRefMut, FnVal, Memory, MemoryKind};
+pub use self::memory::{AllocInfo, AllocKind, AllocRef, AllocRefMut, FnVal, Memory, MemoryKind};
 use self::operand::Operand;
 pub use self::operand::{ImmTy, Immediate, OpTy};
 pub use self::place::{MPlaceTy, MemPlaceMeta, PlaceTy, Writeable};
diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs
index cd2c1ef3613..3a68db9f7f7 100644
--- a/compiler/rustc_const_eval/src/interpret/validity.rs
+++ b/compiler/rustc_const_eval/src/interpret/validity.rs
@@ -31,8 +31,8 @@ use tracing::trace;
 
 use super::machine::AllocMap;
 use super::{
-    AllocId, AllocKind, CheckInAllocMsg, GlobalAlloc, ImmTy, Immediate, InterpCx, InterpResult,
-    MPlaceTy, Machine, MemPlaceMeta, PlaceTy, Pointer, Projectable, Scalar, ValueVisitor, err_ub,
+    AllocId, CheckInAllocMsg, GlobalAlloc, ImmTy, Immediate, InterpCx, InterpResult, MPlaceTy,
+    Machine, MemPlaceMeta, PlaceTy, Pointer, Projectable, Scalar, ValueVisitor, err_ub,
     format_interp_error,
 };
 
@@ -557,9 +557,20 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
                 if let Ok((alloc_id, _offset, _prov)) =
                     self.ecx.ptr_try_get_alloc_id(place.ptr(), 0)
                 {
-                    if let Some(GlobalAlloc::Static(did)) =
-                        self.ecx.tcx.try_get_global_alloc(alloc_id)
-                    {
+                    // Everything should be already interned.
+                    let Some(global_alloc) = self.ecx.tcx.try_get_global_alloc(alloc_id) else {
+                        assert!(self.ecx.memory.alloc_map.get(alloc_id).is_none());
+                        // We can't have *any* references to non-existing allocations in const-eval
+                        // as the rest of rustc isn't happy with them... so we throw an error, even
+                        // though for zero-sized references this isn't really UB.
+                        // A potential future alternative would be to resurrect this as a zero-sized allocation
+                        // (which codegen will then compile to an aligned dummy pointer anyway).
+                        throw_validation_failure!(self.path, DanglingPtrUseAfterFree { ptr_kind });
+                    };
+                    let (size, _align) =
+                        global_alloc.size_and_align(*self.ecx.tcx, self.ecx.param_env);
+
+                    if let GlobalAlloc::Static(did) = global_alloc {
                         let DefKind::Static { nested, .. } = self.ecx.tcx.def_kind(did) else {
                             bug!()
                         };
@@ -593,17 +604,6 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
                         }
                     }
 
-                    // Dangling and Mutability check.
-                    let (size, _align, alloc_kind) = self.ecx.get_alloc_info(alloc_id);
-                    if alloc_kind == AllocKind::Dead {
-                        // This can happen for zero-sized references. We can't have *any* references to
-                        // non-existing allocations in const-eval though, interning rejects them all as
-                        // the rest of rustc isn't happy with them... so we throw an error, even though
-                        // this isn't really UB.
-                        // A potential future alternative would be to resurrect this as a zero-sized allocation
-                        // (which codegen will then compile to an aligned dummy pointer anyway).
-                        throw_validation_failure!(self.path, DanglingPtrUseAfterFree { ptr_kind });
-                    }
                     // If this allocation has size zero, there is no actual mutability here.
                     if size != Size::ZERO {
                         // Determine whether this pointer expects to be pointing to something mutable.
@@ -618,7 +618,8 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
                             }
                         };
                         // Determine what it actually points to.
-                        let alloc_actual_mutbl = mutability(self.ecx, alloc_id);
+                        let alloc_actual_mutbl =
+                            global_alloc.mutability(*self.ecx.tcx, self.ecx.param_env);
                         // Mutable pointer to immutable memory is no good.
                         if ptr_expected_mutbl == Mutability::Mut
                             && alloc_actual_mutbl == Mutability::Not
@@ -842,9 +843,16 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
     }
 
     fn in_mutable_memory(&self, val: &PlaceTy<'tcx, M::Provenance>) -> bool {
+        debug_assert!(self.ctfe_mode.is_some());
         if let Some(mplace) = val.as_mplace_or_local().left() {
             if let Some(alloc_id) = mplace.ptr().provenance.and_then(|p| p.get_alloc_id()) {
-                mutability(self.ecx, alloc_id).is_mut()
+                let tcx = *self.ecx.tcx;
+                // Everything must be already interned.
+                let mutbl = tcx.global_alloc(alloc_id).mutability(tcx, self.ecx.param_env);
+                if let Some((_, alloc)) = self.ecx.memory.alloc_map.get(alloc_id) {
+                    assert_eq!(alloc.mutability, mutbl);
+                }
+                mutbl.is_mut()
             } else {
                 // No memory at all.
                 false
@@ -1016,53 +1024,6 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
     }
 }
 
-/// Returns whether the allocation is mutable, and whether it's actually a static.
-/// For "root" statics we look at the type to account for interior
-/// mutability; for nested statics we have no type and directly use the annotated mutability.
-fn mutability<'tcx>(ecx: &InterpCx<'tcx, impl Machine<'tcx>>, alloc_id: AllocId) -> Mutability {
-    // Let's see what kind of memory this points to.
-    // We're not using `try_global_alloc` since dangling pointers have already been handled.
-    match ecx.tcx.global_alloc(alloc_id) {
-        GlobalAlloc::Static(did) => {
-            let DefKind::Static { safety: _, mutability, nested } = ecx.tcx.def_kind(did) else {
-                bug!()
-            };
-            if nested {
-                assert!(
-                    ecx.memory.alloc_map.get(alloc_id).is_none(),
-                    "allocations of nested statics are already interned: {alloc_id:?}, {did:?}"
-                );
-                // Nested statics in a `static` are never interior mutable,
-                // so just use the declared mutability.
-                mutability
-            } else {
-                let mutability = match mutability {
-                    Mutability::Not
-                        if !ecx
-                            .tcx
-                            .type_of(did)
-                            .no_bound_vars()
-                            .expect("statics should not have generic parameters")
-                            .is_freeze(*ecx.tcx, ty::ParamEnv::reveal_all()) =>
-                    {
-                        Mutability::Mut
-                    }
-                    _ => mutability,
-                };
-                if let Some((_, alloc)) = ecx.memory.alloc_map.get(alloc_id) {
-                    assert_eq!(alloc.mutability, mutability);
-                }
-                mutability
-            }
-        }
-        GlobalAlloc::Memory(alloc) => alloc.inner().mutability,
-        GlobalAlloc::Function { .. } | GlobalAlloc::VTable(..) => {
-            // These are immutable, we better don't allow mutable pointers here.
-            Mutability::Not
-        }
-    }
-}
-
 impl<'rt, 'tcx, M: Machine<'tcx>> ValueVisitor<'tcx, M> for ValidityVisitor<'rt, 'tcx, M> {
     type V = PlaceTy<'tcx, M::Provenance>;
 
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index d2c4335cf2b..78ba841d89f 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -937,7 +937,7 @@ fn usage(verbose: bool, include_unstable_options: bool, nightly_build: bool) {
     let groups = if verbose { config::rustc_optgroups() } else { config::rustc_short_optgroups() };
     let mut options = getopts::Options::new();
     for option in groups.iter().filter(|x| include_unstable_options || x.is_stable()) {
-        (option.apply)(&mut options);
+        option.apply(&mut options);
     }
     let message = "Usage: rustc [OPTIONS] INPUT";
     let nightly_help = if nightly_build {
@@ -1219,7 +1219,7 @@ pub fn handle_options(early_dcx: &EarlyDiagCtxt, args: &[String]) -> Option<geto
     let mut options = getopts::Options::new();
     let optgroups = config::rustc_optgroups();
     for option in &optgroups {
-        (option.apply)(&mut options);
+        option.apply(&mut options);
     }
     let matches = options.parse(args).unwrap_or_else(|e| {
         let msg: Option<String> = match e {
@@ -1233,7 +1233,7 @@ pub fn handle_options(early_dcx: &EarlyDiagCtxt, args: &[String]) -> Option<geto
                 optgroups.iter().find(|option| option.name == opt).map(|option| {
                     // Print the help just for the option in question.
                     let mut options = getopts::Options::new();
-                    (option.apply)(&mut options);
+                    option.apply(&mut options);
                     // getopt requires us to pass a function for joining an iterator of
                     // strings, even though in this case we expect exactly one string.
                     options.usage_with_format(|it| {
diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
index 5f83c211b38..8326d0031ea 100644
--- a/compiler/rustc_feature/src/unstable.rs
+++ b/compiler/rustc_feature/src/unstable.rs
@@ -336,6 +336,7 @@ declare_features! (
     (unstable, riscv_target_feature, "1.45.0", Some(44839)),
     (unstable, rtm_target_feature, "1.35.0", Some(44839)),
     (unstable, s390x_target_feature, "1.82.0", Some(44839)),
+    (unstable, sparc_target_feature, "CURRENT_RUSTC_VERSION", Some(132783)),
     (unstable, sse4a_target_feature, "1.27.0", Some(44839)),
     (unstable, tbm_target_feature, "1.27.0", Some(44839)),
     (unstable, wasm_target_feature, "1.30.0", Some(44839)),
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 50ea8018e76..3080d8b3510 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -5,13 +5,14 @@ use rustc_abi::FieldIdx;
 use rustc_data_structures::unord::{UnordMap, UnordSet};
 use rustc_errors::MultiSpan;
 use rustc_errors::codes::*;
-use rustc_hir::Node;
 use rustc_hir::def::{CtorKind, DefKind};
+use rustc_hir::{Node, intravisit};
 use rustc_infer::infer::{RegionVariableOrigin, TyCtxtInferExt};
-use rustc_infer::traits::Obligation;
+use rustc_infer::traits::{Obligation, ObligationCauseCode};
 use rustc_lint_defs::builtin::{
     REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS, UNSUPPORTED_FN_PTR_CALLING_CONVENTIONS,
 };
+use rustc_middle::hir::nested_filter;
 use rustc_middle::middle::resolve_bound_vars::ResolvedArg;
 use rustc_middle::middle::stability::EvalResult;
 use rustc_middle::span_bug;
@@ -190,7 +191,7 @@ fn check_static_inhabited(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 /// Checks that an opaque type does not contain cycles and does not use `Self` or `T::Foo`
 /// projections that would result in "inheriting lifetimes".
 fn check_opaque(tcx: TyCtxt<'_>, def_id: LocalDefId) {
-    let hir::OpaqueTy { origin, .. } = tcx.hir().expect_opaque_ty(def_id);
+    let hir::OpaqueTy { origin, .. } = *tcx.hir().expect_opaque_ty(def_id);
 
     // HACK(jynelson): trying to infer the type of `impl trait` breaks documenting
     // `async-std` (and `pub async fn` in general).
@@ -200,23 +201,20 @@ fn check_opaque(tcx: TyCtxt<'_>, def_id: LocalDefId) {
         return;
     }
 
-    let span = tcx.def_span(def_id);
-
     if tcx.type_of(def_id).instantiate_identity().references_error() {
         return;
     }
-    if check_opaque_for_cycles(tcx, def_id, span).is_err() {
+    if check_opaque_for_cycles(tcx, def_id).is_err() {
         return;
     }
 
-    let _ = check_opaque_meets_bounds(tcx, def_id, span, origin);
+    let _ = check_opaque_meets_bounds(tcx, def_id, origin);
 }
 
 /// Checks that an opaque type does not contain cycles.
 pub(super) fn check_opaque_for_cycles<'tcx>(
     tcx: TyCtxt<'tcx>,
     def_id: LocalDefId,
-    span: Span,
 ) -> Result<(), ErrorGuaranteed> {
     let args = GenericArgs::identity_for_item(tcx, def_id);
 
@@ -233,7 +231,7 @@ pub(super) fn check_opaque_for_cycles<'tcx>(
             .try_expand_impl_trait_type(def_id.to_def_id(), args, InspectCoroutineFields::No)
             .is_err()
         {
-            let reported = opaque_type_cycle_error(tcx, def_id, span);
+            let reported = opaque_type_cycle_error(tcx, def_id);
             return Err(reported);
         }
 
@@ -267,10 +265,16 @@ pub(super) fn check_opaque_for_cycles<'tcx>(
 fn check_opaque_meets_bounds<'tcx>(
     tcx: TyCtxt<'tcx>,
     def_id: LocalDefId,
-    span: Span,
-    origin: &hir::OpaqueTyOrigin<LocalDefId>,
+    origin: hir::OpaqueTyOrigin<LocalDefId>,
 ) -> Result<(), ErrorGuaranteed> {
-    let defining_use_anchor = match *origin {
+    let (span, definition_def_id) =
+        if let Some((span, def_id)) = best_definition_site_of_opaque(tcx, def_id, origin) {
+            (span, Some(def_id))
+        } else {
+            (tcx.def_span(def_id), None)
+        };
+
+    let defining_use_anchor = match origin {
         hir::OpaqueTyOrigin::FnReturn { parent, .. }
         | hir::OpaqueTyOrigin::AsyncFn { parent, .. }
         | hir::OpaqueTyOrigin::TyAlias { parent, .. } => parent,
@@ -281,7 +285,7 @@ fn check_opaque_meets_bounds<'tcx>(
     let infcx = tcx.infer_ctxt().build(TypingMode::analysis_in_body(tcx, defining_use_anchor));
     let ocx = ObligationCtxt::new_with_diagnostics(&infcx);
 
-    let args = match *origin {
+    let args = match origin {
         hir::OpaqueTyOrigin::FnReturn { parent, .. }
         | hir::OpaqueTyOrigin::AsyncFn { parent, .. }
         | hir::OpaqueTyOrigin::TyAlias { parent, .. } => GenericArgs::identity_for_item(
@@ -306,8 +310,33 @@ fn check_opaque_meets_bounds<'tcx>(
         _ => re,
     });
 
-    let misc_cause = traits::ObligationCause::misc(span, def_id);
+    // HACK: We eagerly instantiate some bounds to report better errors for them...
+    // This isn't necessary for correctness, since we register these bounds when
+    // equating the opaque below, but we should clean this up in the new solver.
+    for (predicate, pred_span) in
+        tcx.explicit_item_bounds(def_id).iter_instantiated_copied(tcx, args)
+    {
+        let predicate = predicate.fold_with(&mut BottomUpFolder {
+            tcx,
+            ty_op: |ty| if ty == opaque_ty { hidden_ty } else { ty },
+            lt_op: |lt| lt,
+            ct_op: |ct| ct,
+        });
+
+        ocx.register_obligation(Obligation::new(
+            tcx,
+            ObligationCause::new(
+                span,
+                def_id,
+                ObligationCauseCode::OpaqueTypeBound(pred_span, definition_def_id),
+            ),
+            param_env,
+            predicate,
+        ));
+    }
 
+    let misc_cause = ObligationCause::misc(span, def_id);
+    // FIXME: We should just register the item bounds here, rather than equating.
     match ocx.eq(&misc_cause, param_env, opaque_ty, hidden_ty) {
         Ok(()) => {}
         Err(ty_err) => {
@@ -364,6 +393,97 @@ fn check_opaque_meets_bounds<'tcx>(
     }
 }
 
+fn best_definition_site_of_opaque<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    opaque_def_id: LocalDefId,
+    origin: hir::OpaqueTyOrigin<LocalDefId>,
+) -> Option<(Span, LocalDefId)> {
+    struct TaitConstraintLocator<'tcx> {
+        opaque_def_id: LocalDefId,
+        tcx: TyCtxt<'tcx>,
+    }
+    impl<'tcx> TaitConstraintLocator<'tcx> {
+        fn check(&self, item_def_id: LocalDefId) -> ControlFlow<(Span, LocalDefId)> {
+            if !self.tcx.has_typeck_results(item_def_id) {
+                return ControlFlow::Continue(());
+            }
+
+            if let Some(hidden_ty) =
+                self.tcx.mir_borrowck(item_def_id).concrete_opaque_types.get(&self.opaque_def_id)
+            {
+                ControlFlow::Break((hidden_ty.span, item_def_id))
+            } else {
+                ControlFlow::Continue(())
+            }
+        }
+    }
+    impl<'tcx> intravisit::Visitor<'tcx> for TaitConstraintLocator<'tcx> {
+        type NestedFilter = nested_filter::All;
+        type Result = ControlFlow<(Span, LocalDefId)>;
+        fn nested_visit_map(&mut self) -> Self::Map {
+            self.tcx.hir()
+        }
+        fn visit_expr(&mut self, ex: &'tcx hir::Expr<'tcx>) -> Self::Result {
+            if let hir::ExprKind::Closure(closure) = ex.kind {
+                self.check(closure.def_id)?;
+            }
+            intravisit::walk_expr(self, ex)
+        }
+        fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) -> Self::Result {
+            self.check(it.owner_id.def_id)?;
+            intravisit::walk_item(self, it)
+        }
+        fn visit_impl_item(&mut self, it: &'tcx hir::ImplItem<'tcx>) -> Self::Result {
+            self.check(it.owner_id.def_id)?;
+            intravisit::walk_impl_item(self, it)
+        }
+        fn visit_trait_item(&mut self, it: &'tcx hir::TraitItem<'tcx>) -> Self::Result {
+            self.check(it.owner_id.def_id)?;
+            intravisit::walk_trait_item(self, it)
+        }
+        fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) -> Self::Result {
+            intravisit::walk_foreign_item(self, it)
+        }
+    }
+
+    let mut locator = TaitConstraintLocator { tcx, opaque_def_id };
+    match origin {
+        hir::OpaqueTyOrigin::FnReturn { parent, .. }
+        | hir::OpaqueTyOrigin::AsyncFn { parent, .. } => locator.check(parent).break_value(),
+        hir::OpaqueTyOrigin::TyAlias { parent, in_assoc_ty: true } => {
+            let impl_def_id = tcx.local_parent(parent);
+            for assoc in tcx.associated_items(impl_def_id).in_definition_order() {
+                match assoc.kind {
+                    ty::AssocKind::Const | ty::AssocKind::Fn => {
+                        if let ControlFlow::Break(span) = locator.check(assoc.def_id.expect_local())
+                        {
+                            return Some(span);
+                        }
+                    }
+                    ty::AssocKind::Type => {}
+                }
+            }
+
+            None
+        }
+        hir::OpaqueTyOrigin::TyAlias { in_assoc_ty: false, .. } => {
+            let scope = tcx.hir().get_defining_scope(tcx.local_def_id_to_hir_id(opaque_def_id));
+            let found = if scope == hir::CRATE_HIR_ID {
+                tcx.hir().walk_toplevel_module(&mut locator)
+            } else {
+                match tcx.hir_node(scope) {
+                    Node::Item(it) => locator.visit_item(it),
+                    Node::ImplItem(it) => locator.visit_impl_item(it),
+                    Node::TraitItem(it) => locator.visit_trait_item(it),
+                    Node::ForeignItem(it) => locator.visit_foreign_item(it),
+                    other => bug!("{:?} is not a valid scope for an opaque type item", other),
+                }
+            };
+            found.break_value()
+        }
+    }
+}
+
 fn sanity_check_found_hidden_type<'tcx>(
     tcx: TyCtxt<'tcx>,
     key: ty::OpaqueTypeKey<'tcx>,
@@ -1535,11 +1655,8 @@ fn check_type_alias_type_params_are_used<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalD
 ///
 /// If all the return expressions evaluate to `!`, then we explain that the error will go away
 /// after changing it. This can happen when a user uses `panic!()` or similar as a placeholder.
-fn opaque_type_cycle_error(
-    tcx: TyCtxt<'_>,
-    opaque_def_id: LocalDefId,
-    span: Span,
-) -> ErrorGuaranteed {
+fn opaque_type_cycle_error(tcx: TyCtxt<'_>, opaque_def_id: LocalDefId) -> ErrorGuaranteed {
+    let span = tcx.def_span(opaque_def_id);
     let mut err = struct_span_code_err!(tcx.dcx(), span, E0720, "cannot resolve opaque type");
 
     let mut label = false;
diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs
index eaf40a193a6..cb20a1d7c7b 100644
--- a/compiler/rustc_hir_typeck/src/method/suggest.rs
+++ b/compiler/rustc_hir_typeck/src/method/suggest.rs
@@ -100,9 +100,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         ty: Ty<'tcx>,
         span: Span,
         unsatisfied_predicates: &Vec<(
-            ty::Predicate<'_>,
-            Option<ty::Predicate<'_>>,
-            Option<ObligationCause<'_>>,
+            ty::Predicate<'tcx>,
+            Option<ty::Predicate<'tcx>>,
+            Option<ObligationCause<'tcx>>,
         )>,
     ) -> bool {
         fn predicate_bounds_generic_param<'tcx>(
@@ -131,15 +131,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
         }
 
-        fn is_iterator_predicate(predicate: ty::Predicate<'_>, tcx: TyCtxt<'_>) -> bool {
+        let is_iterator_predicate = |predicate: ty::Predicate<'tcx>| -> bool {
             if let ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_pred)) =
                 predicate.kind().as_ref().skip_binder()
             {
-                tcx.is_diagnostic_item(sym::Iterator, trait_pred.trait_ref.def_id)
+                self.tcx.is_diagnostic_item(sym::Iterator, trait_pred.trait_ref.def_id)
+                    // ignore unsatisfied predicates generated from trying to auto-ref ty (#127511)
+                    && trait_pred.trait_ref.self_ty() == ty
             } else {
                 false
             }
-        }
+        };
 
         // Does the `ty` implement `IntoIterator`?
         let Some(into_iterator_trait) = self.tcx.get_diagnostic_item(sym::IntoIterator) else {
@@ -164,7 +166,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         generics,
                         generic_param,
                         self.tcx,
-                    ) && is_iterator_predicate(unsatisfied.0, self.tcx)
+                    ) && is_iterator_predicate(unsatisfied.0)
                     {
                         return true;
                     }
@@ -172,7 +174,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
             ty::Slice(..) | ty::Adt(..) | ty::Alias(ty::Opaque, _) => {
                 for unsatisfied in unsatisfied_predicates.iter() {
-                    if is_iterator_predicate(unsatisfied.0, self.tcx) {
+                    if is_iterator_predicate(unsatisfied.0) {
                         return true;
                     }
                 }
diff --git a/compiler/rustc_infer/src/infer/outlives/obligations.rs b/compiler/rustc_infer/src/infer/outlives/obligations.rs
index e0e03a29220..b1d5d688295 100644
--- a/compiler/rustc_infer/src/infer/outlives/obligations.rs
+++ b/compiler/rustc_infer/src/infer/outlives/obligations.rs
@@ -104,6 +104,7 @@ impl<'tcx> InferCtxt<'tcx> {
             infer::RelateParamBound(cause.span, sup_type, match cause.code().peel_derives() {
                 ObligationCauseCode::WhereClause(_, span)
                 | ObligationCauseCode::WhereClauseInExpr(_, span, ..)
+                | ObligationCauseCode::OpaqueTypeBound(span, _)
                     if !span.is_dummy() =>
                 {
                     Some(*span)
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index ce90ceeda56..2361231b3fb 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -102,7 +102,7 @@ where
 fn optgroups() -> getopts::Options {
     let mut opts = getopts::Options::new();
     for group in rustc_optgroups() {
-        (group.apply)(&mut opts);
+        group.apply(&mut opts);
     }
     return opts;
 }
diff --git a/compiler/rustc_lexer/src/lib.rs b/compiler/rustc_lexer/src/lib.rs
index b0ab50dd773..f9f2a14dbd2 100644
--- a/compiler/rustc_lexer/src/lib.rs
+++ b/compiler/rustc_lexer/src/lib.rs
@@ -715,7 +715,17 @@ impl Cursor<'_> {
             self.bump();
             self.bump();
             self.eat_while(is_id_continue);
-            return RawLifetime;
+            match self.first() {
+                '\'' => {
+                    // Check if after skipping literal contents we've met a closing
+                    // single quote (which means that user attempted to create a
+                    // string with single quotes).
+                    self.bump();
+                    let kind = Char { terminated: true };
+                    return Literal { kind, suffix_start: self.pos_within_token() };
+                }
+                _ => return RawLifetime,
+            }
         }
 
         // Either a lifetime or a character literal with
diff --git a/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp
index 2ee7454b652..0471baa1f9c 100644
--- a/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp
@@ -1,5 +1,9 @@
 #include "LLVMWrapper.h"
+
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/IR/Module.h"
 #include "llvm/ProfileData/Coverage/CoverageMapping.h"
 #include "llvm/ProfileData/Coverage/CoverageMappingWriter.h"
 #include "llvm/ProfileData/InstrProf.h"
diff --git a/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h b/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h
index 73bbc9de855..f6598f9faf5 100644
--- a/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h
+++ b/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h
@@ -1,31 +1,12 @@
+#ifndef INCLUDED_RUSTC_LLVM_LLVMWRAPPER_H
+#define INCLUDED_RUSTC_LLVM_LLVMWRAPPER_H
+
 #include "SuppressLLVMWarnings.h"
 
-#include "llvm-c/BitReader.h"
-#include "llvm-c/Core.h"
-#include "llvm-c/Object.h"
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/DenseSet.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/Analysis/Lint.h"
-#include "llvm/Analysis/Passes.h"
-#include "llvm/IR/IRBuilder.h"
-#include "llvm/IR/InlineAsm.h"
-#include "llvm/IR/LLVMContext.h"
-#include "llvm/IR/Module.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/DynamicLibrary.h"
-#include "llvm/Support/FormattedStream.h"
-#include "llvm/Support/JSON.h"
-#include "llvm/Support/Memory.h"
-#include "llvm/Support/SourceMgr.h"
-#include "llvm/Support/TargetSelect.h"
-#include "llvm/Support/Timer.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetOptions.h"
-#include "llvm/Transforms/IPO.h"
-#include "llvm/Transforms/Scalar.h"
+#include "llvm/Config/llvm-config.h"  // LLVM_VERSION_MAJOR, LLVM_VERSION_MINOR
+#include "llvm/Support/raw_ostream.h" // llvm::raw_ostream
+#include <cstddef>                    // size_t etc
+#include <cstdint>                    // uint64_t etc
 
 #define LLVM_VERSION_GE(major, minor)                                          \
   (LLVM_VERSION_MAJOR > (major) ||                                             \
@@ -33,79 +14,17 @@
 
 #define LLVM_VERSION_LT(major, minor) (!LLVM_VERSION_GE((major), (minor)))
 
-#if LLVM_VERSION_GE(20, 0)
-#include "llvm/Transforms/Utils/Instrumentation.h"
-#else
-#include "llvm/Transforms/Instrumentation.h"
-#endif
-
-#include "llvm/IR/LegacyPassManager.h"
-
-#include "llvm/Bitcode/BitcodeReader.h"
-#include "llvm/Bitcode/BitcodeWriter.h"
-
-#include "llvm/IR/DIBuilder.h"
-#include "llvm/IR/DebugInfo.h"
-#include "llvm/IR/IRPrintingPasses.h"
-#include "llvm/Linker/Linker.h"
-
-#include "llvm/TargetParser/Triple.h"
-
 extern "C" void LLVMRustSetLastError(const char *);
 
 enum class LLVMRustResult { Success, Failure };
 
-enum LLVMRustAttribute {
-  AlwaysInline = 0,
-  ByVal = 1,
-  Cold = 2,
-  InlineHint = 3,
-  MinSize = 4,
-  Naked = 5,
-  NoAlias = 6,
-  NoCapture = 7,
-  NoInline = 8,
-  NonNull = 9,
-  NoRedZone = 10,
-  NoReturn = 11,
-  NoUnwind = 12,
-  OptimizeForSize = 13,
-  ReadOnly = 14,
-  SExt = 15,
-  StructRet = 16,
-  UWTable = 17,
-  ZExt = 18,
-  InReg = 19,
-  SanitizeThread = 20,
-  SanitizeAddress = 21,
-  SanitizeMemory = 22,
-  NonLazyBind = 23,
-  OptimizeNone = 24,
-  ReadNone = 26,
-  SanitizeHWAddress = 28,
-  WillReturn = 29,
-  StackProtectReq = 30,
-  StackProtectStrong = 31,
-  StackProtect = 32,
-  NoUndef = 33,
-  SanitizeMemTag = 34,
-  NoCfCheck = 35,
-  ShadowCallStack = 36,
-  AllocSize = 37,
-  AllocatedPointer = 38,
-  AllocAlign = 39,
-  SanitizeSafeStack = 40,
-  FnRetThunkExtern = 41,
-  Writable = 42,
-  DeadOnUnwind = 43,
-};
-
 typedef struct OpaqueRustString *RustStringRef;
 typedef struct LLVMOpaqueTwine *LLVMTwineRef;
 typedef struct LLVMOpaqueSMDiagnostic *LLVMSMDiagnosticRef;
 
-extern "C" void LLVMRustStringWriteImpl(RustStringRef Str, const char *Ptr,
-                                        size_t Size);
+extern "C" void LLVMRustStringWriteImpl(RustStringRef buf,
+                                        const char *slice_ptr,
+                                        size_t slice_len);
 
 class RawRustStringOstream : public llvm::raw_ostream {
   RustStringRef Str;
@@ -126,3 +45,5 @@ public:
     flush();
   }
 };
+
+#endif // INCLUDED_RUSTC_LLVM_LLVMWRAPPER_H
diff --git a/compiler/rustc_llvm/llvm-wrapper/Linker.cpp b/compiler/rustc_llvm/llvm-wrapper/Linker.cpp
index f43128ed550..fdf54e2d9b4 100644
--- a/compiler/rustc_llvm/llvm-wrapper/Linker.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/Linker.cpp
@@ -1,8 +1,10 @@
-#include "llvm/Linker/Linker.h"
-#include "SuppressLLVMWarnings.h"
-
 #include "LLVMWrapper.h"
 
+#include "llvm/Bitcode/BitcodeReader.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Linker/Linker.h"
+#include "llvm/Support/MemoryBuffer.h"
+
 using namespace llvm;
 
 struct RustLinker {
diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
index eb99d560e57..1ed702ab4cb 100644
--- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
@@ -1,25 +1,21 @@
-#include <stdio.h>
-
-#include <cstddef>
-#include <iomanip>
-#include <set>
-#include <vector>
-
 #include "LLVMWrapper.h"
 
-#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm-c/Core.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Analysis/Lint.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
-#include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
 #include "llvm/CodeGen/CommandFlags.h"
-#include "llvm/CodeGen/TargetSubtargetInfo.h"
 #include "llvm/IR/AssemblyAnnotationWriter.h"
 #include "llvm/IR/AutoUpgrade.h"
-#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/PassManager.h"
 #include "llvm/IR/Verifier.h"
 #include "llvm/LTO/LTO.h"
+#include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MC/TargetRegistry.h"
-#include "llvm/Object/IRObjectFile.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Passes/PassBuilder.h"
 #include "llvm/Passes/PassPlugin.h"
@@ -30,25 +26,28 @@
 #include "llvm/Support/VirtualFileSystem.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/TargetParser/Host.h"
-#include "llvm/Transforms/IPO/AlwaysInliner.h"
 #include "llvm/Transforms/IPO/FunctionImport.h"
 #include "llvm/Transforms/IPO/Internalize.h"
 #include "llvm/Transforms/IPO/LowerTypeTests.h"
 #include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
 #include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
 #include "llvm/Transforms/Instrumentation/DataFlowSanitizer.h"
-#include "llvm/Transforms/Utils/AddDiscriminators.h"
-#include "llvm/Transforms/Utils/FunctionImportUtils.h"
-#if LLVM_VERSION_GE(19, 0)
-#include "llvm/Support/PGOOptions.h"
-#endif
 #include "llvm/Transforms/Instrumentation/HWAddressSanitizer.h"
 #include "llvm/Transforms/Instrumentation/InstrProfiling.h"
 #include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
 #include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
-#include "llvm/Transforms/Utils.h"
 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
+#include "llvm/Transforms/Utils/FunctionImportUtils.h"
 #include "llvm/Transforms/Utils/NameAnonGlobals.h"
+#include <set>
+#include <string>
+#include <vector>
+
+// Conditional includes prevent clang-format from fully sorting the list,
+// so keep them separate.
+#if LLVM_VERSION_GE(19, 0)
+#include "llvm/Support/PGOOptions.h"
+#endif
 
 using namespace llvm;
 
@@ -1624,5 +1623,6 @@ extern "C" void LLVMRustComputeLTOCacheKey(RustStringRef KeyOut,
                            CfiFunctionDefs, CfiFunctionDecls);
 #endif
 
-  LLVMRustStringWriteImpl(KeyOut, Key.c_str(), Key.size());
+  auto OS = RawRustStringOstream(KeyOut);
+  OS << Key.str();
 }
diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index a68eed03e61..cd70c3f2669 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -1,28 +1,38 @@
 #include "LLVMWrapper.h"
+
+#include "llvm-c/Core.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/BinaryFormat/Magic.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
+#include "llvm/IR/DIBuilder.h"
 #include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/DiagnosticHandler.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/Instructions.h"
-#include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/IntrinsicsARM.h"
+#include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/LLVMRemarkStreamer.h"
 #include "llvm/IR/Mangler.h"
+#include "llvm/IR/Module.h"
 #include "llvm/IR/Value.h"
-#include "llvm/Object/Archive.h"
 #include "llvm/Object/COFFImportFile.h"
-#include "llvm/Object/ObjectFile.h"
-#include "llvm/Pass.h"
 #include "llvm/Remarks/RemarkFormat.h"
 #include "llvm/Remarks/RemarkSerializer.h"
 #include "llvm/Remarks/RemarkStreamer.h"
+#include "llvm/Support/Compression.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/JSON.h"
 #include "llvm/Support/ModRef.h"
 #include "llvm/Support/Signals.h"
+#include "llvm/Support/Timer.h"
 #include "llvm/Support/ToolOutputFile.h"
-
 #include <iostream>
 
 // for raw `write` in the bad-alloc handler
@@ -216,94 +226,140 @@ extern "C" LLVMValueRef LLVMRustInsertPrivateGlobal(LLVMModuleRef M,
                                  GlobalValue::PrivateLinkage, nullptr));
 }
 
-static Attribute::AttrKind fromRust(LLVMRustAttribute Kind) {
+// Must match the layout of `rustc_codegen_llvm::llvm::ffi::AttributeKind`.
+enum class LLVMRustAttributeKind {
+  AlwaysInline = 0,
+  ByVal = 1,
+  Cold = 2,
+  InlineHint = 3,
+  MinSize = 4,
+  Naked = 5,
+  NoAlias = 6,
+  NoCapture = 7,
+  NoInline = 8,
+  NonNull = 9,
+  NoRedZone = 10,
+  NoReturn = 11,
+  NoUnwind = 12,
+  OptimizeForSize = 13,
+  ReadOnly = 14,
+  SExt = 15,
+  StructRet = 16,
+  UWTable = 17,
+  ZExt = 18,
+  InReg = 19,
+  SanitizeThread = 20,
+  SanitizeAddress = 21,
+  SanitizeMemory = 22,
+  NonLazyBind = 23,
+  OptimizeNone = 24,
+  ReadNone = 26,
+  SanitizeHWAddress = 28,
+  WillReturn = 29,
+  StackProtectReq = 30,
+  StackProtectStrong = 31,
+  StackProtect = 32,
+  NoUndef = 33,
+  SanitizeMemTag = 34,
+  NoCfCheck = 35,
+  ShadowCallStack = 36,
+  AllocSize = 37,
+  AllocatedPointer = 38,
+  AllocAlign = 39,
+  SanitizeSafeStack = 40,
+  FnRetThunkExtern = 41,
+  Writable = 42,
+  DeadOnUnwind = 43,
+};
+
+static Attribute::AttrKind fromRust(LLVMRustAttributeKind Kind) {
   switch (Kind) {
-  case AlwaysInline:
+  case LLVMRustAttributeKind::AlwaysInline:
     return Attribute::AlwaysInline;
-  case ByVal:
+  case LLVMRustAttributeKind::ByVal:
     return Attribute::ByVal;
-  case Cold:
+  case LLVMRustAttributeKind::Cold:
     return Attribute::Cold;
-  case InlineHint:
+  case LLVMRustAttributeKind::InlineHint:
     return Attribute::InlineHint;
-  case MinSize:
+  case LLVMRustAttributeKind::MinSize:
     return Attribute::MinSize;
-  case Naked:
+  case LLVMRustAttributeKind::Naked:
     return Attribute::Naked;
-  case NoAlias:
+  case LLVMRustAttributeKind::NoAlias:
     return Attribute::NoAlias;
-  case NoCapture:
+  case LLVMRustAttributeKind::NoCapture:
     return Attribute::NoCapture;
-  case NoCfCheck:
+  case LLVMRustAttributeKind::NoCfCheck:
     return Attribute::NoCfCheck;
-  case NoInline:
+  case LLVMRustAttributeKind::NoInline:
     return Attribute::NoInline;
-  case NonNull:
+  case LLVMRustAttributeKind::NonNull:
     return Attribute::NonNull;
-  case NoRedZone:
+  case LLVMRustAttributeKind::NoRedZone:
     return Attribute::NoRedZone;
-  case NoReturn:
+  case LLVMRustAttributeKind::NoReturn:
     return Attribute::NoReturn;
-  case NoUnwind:
+  case LLVMRustAttributeKind::NoUnwind:
     return Attribute::NoUnwind;
-  case OptimizeForSize:
+  case LLVMRustAttributeKind::OptimizeForSize:
     return Attribute::OptimizeForSize;
-  case ReadOnly:
+  case LLVMRustAttributeKind::ReadOnly:
     return Attribute::ReadOnly;
-  case SExt:
+  case LLVMRustAttributeKind::SExt:
     return Attribute::SExt;
-  case StructRet:
+  case LLVMRustAttributeKind::StructRet:
     return Attribute::StructRet;
-  case UWTable:
+  case LLVMRustAttributeKind::UWTable:
     return Attribute::UWTable;
-  case ZExt:
+  case LLVMRustAttributeKind::ZExt:
     return Attribute::ZExt;
-  case InReg:
+  case LLVMRustAttributeKind::InReg:
     return Attribute::InReg;
-  case SanitizeThread:
+  case LLVMRustAttributeKind::SanitizeThread:
     return Attribute::SanitizeThread;
-  case SanitizeAddress:
+  case LLVMRustAttributeKind::SanitizeAddress:
     return Attribute::SanitizeAddress;
-  case SanitizeMemory:
+  case LLVMRustAttributeKind::SanitizeMemory:
     return Attribute::SanitizeMemory;
-  case NonLazyBind:
+  case LLVMRustAttributeKind::NonLazyBind:
     return Attribute::NonLazyBind;
-  case OptimizeNone:
+  case LLVMRustAttributeKind::OptimizeNone:
     return Attribute::OptimizeNone;
-  case ReadNone:
+  case LLVMRustAttributeKind::ReadNone:
     return Attribute::ReadNone;
-  case SanitizeHWAddress:
+  case LLVMRustAttributeKind::SanitizeHWAddress:
     return Attribute::SanitizeHWAddress;
-  case WillReturn:
+  case LLVMRustAttributeKind::WillReturn:
     return Attribute::WillReturn;
-  case StackProtectReq:
+  case LLVMRustAttributeKind::StackProtectReq:
     return Attribute::StackProtectReq;
-  case StackProtectStrong:
+  case LLVMRustAttributeKind::StackProtectStrong:
     return Attribute::StackProtectStrong;
-  case StackProtect:
+  case LLVMRustAttributeKind::StackProtect:
     return Attribute::StackProtect;
-  case NoUndef:
+  case LLVMRustAttributeKind::NoUndef:
     return Attribute::NoUndef;
-  case SanitizeMemTag:
+  case LLVMRustAttributeKind::SanitizeMemTag:
     return Attribute::SanitizeMemTag;
-  case ShadowCallStack:
+  case LLVMRustAttributeKind::ShadowCallStack:
     return Attribute::ShadowCallStack;
-  case AllocSize:
+  case LLVMRustAttributeKind::AllocSize:
     return Attribute::AllocSize;
-  case AllocatedPointer:
+  case LLVMRustAttributeKind::AllocatedPointer:
     return Attribute::AllocatedPointer;
-  case AllocAlign:
+  case LLVMRustAttributeKind::AllocAlign:
     return Attribute::AllocAlign;
-  case SanitizeSafeStack:
+  case LLVMRustAttributeKind::SanitizeSafeStack:
     return Attribute::SafeStack;
-  case FnRetThunkExtern:
+  case LLVMRustAttributeKind::FnRetThunkExtern:
     return Attribute::FnRetThunkExtern;
-  case Writable:
+  case LLVMRustAttributeKind::Writable:
     return Attribute::Writable;
-  case DeadOnUnwind:
+  case LLVMRustAttributeKind::DeadOnUnwind:
     return Attribute::DeadOnUnwind;
   }
-  report_fatal_error("bad AttributeKind");
+  report_fatal_error("bad LLVMRustAttributeKind");
 }
 
 template <typename T>
@@ -333,7 +389,7 @@ extern "C" void LLVMRustAddCallSiteAttributes(LLVMValueRef Instr,
 }
 
 extern "C" LLVMAttributeRef
-LLVMRustCreateAttrNoValue(LLVMContextRef C, LLVMRustAttribute RustAttr) {
+LLVMRustCreateAttrNoValue(LLVMContextRef C, LLVMRustAttributeKind RustAttr) {
   return wrap(Attribute::get(*unwrap(C), fromRust(RustAttr)));
 }
 
@@ -1249,6 +1305,14 @@ LLVMRustDIBuilderCreateDebugLocation(unsigned Line, unsigned Column,
   return wrap(Loc);
 }
 
+extern "C" LLVMMetadataRef
+LLVMRustDILocationCloneWithBaseDiscriminator(LLVMMetadataRef Location,
+                                             unsigned BD) {
+  DILocation *Loc = unwrapDIPtr<DILocation>(Location);
+  auto NewLoc = Loc->cloneWithBaseDiscriminator(BD);
+  return wrap(NewLoc.has_value() ? NewLoc.value() : nullptr);
+}
+
 extern "C" uint64_t LLVMRustDIBuilderCreateOpDeref() {
   return dwarf::DW_OP_deref;
 }
@@ -1510,8 +1574,8 @@ LLVMRustUnpackSMDiagnostic(LLVMSMDiagnosticRef DRef, RustStringRef MessageOut,
   const SourceMgr &LSM = *D.getSourceMgr();
   const MemoryBuffer *LBuf =
       LSM.getMemoryBuffer(LSM.FindBufferContainingLoc(D.getLoc()));
-  LLVMRustStringWriteImpl(BufferOut, LBuf->getBufferStart(),
-                          LBuf->getBufferSize());
+  auto BufferOS = RawRustStringOstream(BufferOut);
+  BufferOS << LBuf->getBuffer();
 
   *LocOut = D.getLoc().getPointer() - LBuf->getBufferStart();
 
diff --git a/compiler/rustc_llvm/llvm-wrapper/SymbolWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/SymbolWrapper.cpp
index 54ee79dc290..a910e78d489 100644
--- a/compiler/rustc_llvm/llvm-wrapper/SymbolWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/SymbolWrapper.cpp
@@ -8,14 +8,14 @@
 // * https://github.com/llvm/llvm-project/blob/ef6d1ec07c693352c4a60dd58db08d2d8558f6ea/llvm/lib/Object/ArchiveWriter.cpp
 
 #include "LLVMWrapper.h"
-#include "SuppressLLVMWarnings.h"
+
 #include "llvm/ADT/SmallString.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/Object/COFF.h"
 #include "llvm/Object/COFFImportFile.h"
 #include "llvm/Object/IRObjectFile.h"
 #include "llvm/Object/ObjectFile.h"
-#include <llvm/Support/raw_ostream.h>
+#include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
 using namespace llvm::sys;
diff --git a/compiler/rustc_llvm/src/lib.rs b/compiler/rustc_llvm/src/lib.rs
index 055d2bd5bc9..eda9b2b1fc0 100644
--- a/compiler/rustc_llvm/src/lib.rs
+++ b/compiler/rustc_llvm/src/lib.rs
@@ -2,42 +2,75 @@
 #![allow(internal_features)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
+#![feature(extern_types)]
 #![feature(rustdoc_internals)]
 #![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
-// NOTE: This crate only exists to allow linking on mingw targets.
-
 use std::cell::RefCell;
-use std::slice;
+use std::{ptr, slice};
 
-use libc::{c_char, size_t};
+use libc::size_t;
 
-#[repr(C)]
-pub struct RustString {
-    pub bytes: RefCell<Vec<u8>>,
+unsafe extern "C" {
+    /// Opaque type that allows C++ code to write bytes to a Rust-side buffer,
+    /// in conjunction with `RawRustStringOstream`. Use this as `&RustString`
+    /// (Rust) and `RustStringRef` (C++) in FFI signatures.
+    pub type RustString;
 }
 
 impl RustString {
-    pub fn len(&self) -> usize {
-        self.bytes.borrow().len()
+    pub fn build_byte_buffer(closure: impl FnOnce(&Self)) -> Vec<u8> {
+        let buf = RustStringInner::default();
+        closure(buf.as_opaque());
+        buf.into_inner()
     }
+}
 
-    pub fn is_empty(&self) -> bool {
-        self.bytes.borrow().is_empty()
+/// Underlying implementation of [`RustString`].
+///
+/// Having two separate types makes it possible to use the opaque [`RustString`]
+/// in FFI signatures without `improper_ctypes` warnings. This is a workaround
+/// for the fact that there is no way to opt out of `improper_ctypes` when
+/// _declaring_ a type (as opposed to using that type).
+#[derive(Default)]
+struct RustStringInner {
+    bytes: RefCell<Vec<u8>>,
+}
+
+impl RustStringInner {
+    fn as_opaque(&self) -> &RustString {
+        let ptr: *const RustStringInner = ptr::from_ref(self);
+        // We can't use `ptr::cast` here because extern types are `!Sized`.
+        let ptr = ptr as *const RustString;
+        unsafe { &*ptr }
+    }
+
+    fn from_opaque(opaque: &RustString) -> &Self {
+        // SAFETY: A valid `&RustString` must have been created via `as_opaque`.
+        let ptr: *const RustString = ptr::from_ref(opaque);
+        let ptr: *const RustStringInner = ptr.cast();
+        unsafe { &*ptr }
+    }
+
+    fn into_inner(self) -> Vec<u8> {
+        self.bytes.into_inner()
     }
 }
 
-/// Appending to a Rust string -- used by RawRustStringOstream.
+/// Appends the contents of a byte slice to a [`RustString`].
+///
+/// This function is implemented in `rustc_llvm` so that the C++ code in this
+/// crate can link to it directly, without an implied link-time dependency on
+/// `rustc_codegen_llvm`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn LLVMRustStringWriteImpl(
-    sr: &RustString,
-    ptr: *const c_char,
-    size: size_t,
+    buf: &RustString,
+    slice_ptr: *const u8, // Same ABI as `*const c_char`
+    slice_len: size_t,
 ) {
-    let slice = unsafe { slice::from_raw_parts(ptr as *const u8, size) };
-
-    sr.bytes.borrow_mut().extend_from_slice(slice);
+    let slice = unsafe { slice::from_raw_parts(slice_ptr, slice_len) };
+    RustStringInner::from_opaque(buf).bytes.borrow_mut().extend_from_slice(slice);
 }
 
 /// Initialize targets enabled by the build script via `cfg(llvm_component = "...")`.
diff --git a/compiler/rustc_middle/src/mir/interpret/mod.rs b/compiler/rustc_middle/src/mir/interpret/mod.rs
index b0c0e1be500..f225ad94aa7 100644
--- a/compiler/rustc_middle/src/mir/interpret/mod.rs
+++ b/compiler/rustc_middle/src/mir/interpret/mod.rs
@@ -12,11 +12,12 @@ use std::io::{Read, Write};
 use std::num::NonZero;
 use std::{fmt, io};
 
-use rustc_abi::{AddressSpace, Endian, HasDataLayout};
-use rustc_ast::LitKind;
+use rustc_abi::{AddressSpace, Align, Endian, HasDataLayout, Size};
+use rustc_ast::{LitKind, Mutability};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lock;
 use rustc_errors::ErrorGuaranteed;
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_macros::{HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
 use rustc_middle::ty::print::with_no_trimmed_paths;
@@ -45,7 +46,7 @@ pub use self::pointer::{CtfeProvenance, Pointer, PointerArithmetic, Provenance};
 pub use self::value::Scalar;
 use crate::mir;
 use crate::ty::codec::{TyDecoder, TyEncoder};
-use crate::ty::{self, Instance, Ty, TyCtxt};
+use crate::ty::{self, Instance, ParamEnv, Ty, TyCtxt};
 
 /// Uniquely identifies one of the following:
 /// - A constant
@@ -310,6 +311,85 @@ impl<'tcx> GlobalAlloc<'tcx> {
             }
         }
     }
+
+    pub fn mutability(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Mutability {
+        // Let's see what kind of memory we are.
+        match self {
+            GlobalAlloc::Static(did) => {
+                let DefKind::Static { safety: _, mutability, nested } = tcx.def_kind(did) else {
+                    bug!()
+                };
+                if nested {
+                    // Nested statics in a `static` are never interior mutable,
+                    // so just use the declared mutability.
+                    if cfg!(debug_assertions) {
+                        let alloc = tcx.eval_static_initializer(did).unwrap();
+                        assert_eq!(alloc.0.mutability, mutability);
+                    }
+                    mutability
+                } else {
+                    let mutability = match mutability {
+                        Mutability::Not
+                            if !tcx
+                                .type_of(did)
+                                .no_bound_vars()
+                                .expect("statics should not have generic parameters")
+                                .is_freeze(tcx, param_env) =>
+                        {
+                            Mutability::Mut
+                        }
+                        _ => mutability,
+                    };
+                    mutability
+                }
+            }
+            GlobalAlloc::Memory(alloc) => alloc.inner().mutability,
+            GlobalAlloc::Function { .. } | GlobalAlloc::VTable(..) => {
+                // These are immutable.
+                Mutability::Not
+            }
+        }
+    }
+
+    pub fn size_and_align(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> (Size, Align) {
+        match self {
+            GlobalAlloc::Static(def_id) => {
+                let DefKind::Static { nested, .. } = tcx.def_kind(def_id) else {
+                    bug!("GlobalAlloc::Static is not a static")
+                };
+
+                if nested {
+                    // Nested anonymous statics are untyped, so let's get their
+                    // size and alignment from the allocation itself. This always
+                    // succeeds, as the query is fed at DefId creation time, so no
+                    // evaluation actually occurs.
+                    let alloc = tcx.eval_static_initializer(def_id).unwrap();
+                    (alloc.0.size(), alloc.0.align)
+                } else {
+                    // Use size and align of the type for everything else. We need
+                    // to do that to
+                    // * avoid cycle errors in case of self-referential statics,
+                    // * be able to get information on extern statics.
+                    let ty = tcx
+                        .type_of(def_id)
+                        .no_bound_vars()
+                        .expect("statics should not have generic parameters");
+                    let layout = tcx.layout_of(param_env.and(ty)).unwrap();
+                    assert!(layout.is_sized());
+                    (layout.size, layout.align.abi)
+                }
+            }
+            GlobalAlloc::Memory(alloc) => {
+                let alloc = alloc.inner();
+                (alloc.size(), alloc.align)
+            }
+            GlobalAlloc::Function { .. } => (Size::ZERO, Align::ONE),
+            GlobalAlloc::VTable(..) => {
+                // No data to be accessed here. But vtables are pointer-aligned.
+                return (Size::ZERO, tcx.data_layout.pointer_align.abi);
+            }
+        }
+    }
 }
 
 pub const CTFE_ALLOC_SALT: usize = 0;
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index 40e5ec45959..09731d565b6 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -193,6 +193,11 @@ pub enum ObligationCauseCode<'tcx> {
     /// The span corresponds to the clause.
     WhereClause(DefId, Span),
 
+    /// Represents a bound for an opaque we are checking the well-formedness of.
+    /// The def-id corresponds to a specific definition site that we found the
+    /// hidden type from, if any.
+    OpaqueTypeBound(Span, Option<LocalDefId>),
+
     /// Like `WhereClause`, but also identifies the expression
     /// which requires the `where` clause to be proven, and also
     /// identifies the index of the predicate in the `predicates_of`
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 76e3183fcbb..a0eb9029319 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -1011,25 +1011,41 @@ where
             }
 
             _ => {
-                let mut data_variant = match this.variants {
+                let mut data_variant = match &this.variants {
                     // Within the discriminant field, only the niche itself is
                     // always initialized, so we only check for a pointer at its
                     // offset.
                     //
-                    // If the niche is a pointer, it's either valid (according
-                    // to its type), or null (which the niche field's scalar
-                    // validity range encodes). This allows using
-                    // `dereferenceable_or_null` for e.g., `Option<&T>`, and
-                    // this will continue to work as long as we don't start
-                    // using more niches than just null (e.g., the first page of
-                    // the address space, or unaligned pointers).
+                    // Our goal here is to check whether this represents a
+                    // "dereferenceable or null" pointer, so we need to ensure
+                    // that there is only one other variant, and it must be null.
+                    // Below, we will then check whether the pointer is indeed
+                    // dereferenceable.
                     Variants::Multiple {
-                        tag_encoding: TagEncoding::Niche { untagged_variant, .. },
+                        tag_encoding:
+                            TagEncoding::Niche { untagged_variant, niche_variants, niche_start },
                         tag_field,
+                        variants,
                         ..
-                    } if this.fields.offset(tag_field) == offset => {
-                        Some(this.for_variant(cx, untagged_variant))
+                    } if variants.len() == 2 && this.fields.offset(*tag_field) == offset => {
+                        let tagged_variant = if untagged_variant.as_u32() == 0 {
+                            VariantIdx::from_u32(1)
+                        } else {
+                            VariantIdx::from_u32(0)
+                        };
+                        assert_eq!(tagged_variant, *niche_variants.start());
+                        if *niche_start == 0 {
+                            // The other variant is encoded as "null", so we can recurse searching for
+                            // a pointer here. This relies on the fact that the codegen backend
+                            // only adds "dereferenceable" if there's also a "nonnull" proof,
+                            // and that null is aligned for all alignments so it's okay to forward
+                            // the pointer's alignment.
+                            Some(this.for_variant(cx, *untagged_variant))
+                        } else {
+                            None
+                        }
                     }
+                    Variants::Multiple { .. } => None,
                     _ => Some(this),
                 };
 
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 6d9ba3d60e3..1a3128ed936 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1076,11 +1076,6 @@ impl<'tcx> ParamEnv<'tcx> {
         ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal }) }
     }
 
-    pub fn with_user_facing(mut self) -> Self {
-        self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
-        self
-    }
-
     /// Returns a new parameter environment with the same clauses, but
     /// which "reveals" the true results of projections in all cases
     /// (even for associated types that are specializable). This is
@@ -1095,6 +1090,12 @@ impl<'tcx> ParamEnv<'tcx> {
             return self;
         }
 
+        // No need to reveal opaques with the new solver enabled,
+        // since we have lazy norm.
+        if tcx.next_trait_solver_globally() {
+            return ParamEnv::new(self.caller_bounds(), Reveal::All);
+        }
+
         ParamEnv::new(tcx.reveal_opaque_types_in_bounds(self.caller_bounds()), Reveal::All)
     }
 
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index e27bb2fd135..142db8a17f0 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -1933,6 +1933,7 @@ impl<'tcx> Ty<'tcx> {
                 ty::UintTy::U64 => Some(sym::u64),
                 ty::UintTy::U128 => Some(sym::u128),
             },
+            ty::Str => Some(sym::str),
             _ => None,
         }
     }
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index fc5a3b762e5..3c6e34160f4 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -1751,6 +1751,7 @@ pub fn reveal_opaque_types_in_bounds<'tcx>(
     tcx: TyCtxt<'tcx>,
     val: ty::Clauses<'tcx>,
 ) -> ty::Clauses<'tcx> {
+    assert!(!tcx.next_trait_solver_globally());
     let mut visitor = OpaqueTypeExpander {
         seen_opaque_tys: FxHashSet::default(),
         expanded_cache: FxHashMap::default(),
diff --git a/compiler/rustc_parse/messages.ftl b/compiler/rustc_parse/messages.ftl
index 1af7fb9b86a..ef259703f0c 100644
--- a/compiler/rustc_parse/messages.ftl
+++ b/compiler/rustc_parse/messages.ftl
@@ -77,6 +77,8 @@ parse_box_syntax_removed_suggestion = use `Box::new()` instead
 
 parse_cannot_be_raw_ident = `{$ident}` cannot be a raw identifier
 
+parse_cannot_be_raw_lifetime = `{$ident}` cannot be a raw lifetime
+
 parse_catch_after_try = keyword `catch` cannot follow a `try` block
     .help = try using `match` on the result of the `try` block instead
 
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
index fdd500e90f8..7ec4ad6dc35 100644
--- a/compiler/rustc_parse/src/errors.rs
+++ b/compiler/rustc_parse/src/errors.rs
@@ -2019,6 +2019,14 @@ pub(crate) struct CannotBeRawIdent {
 }
 
 #[derive(Diagnostic)]
+#[diag(parse_cannot_be_raw_lifetime)]
+pub(crate) struct CannotBeRawLifetime {
+    #[primary_span]
+    pub span: Span,
+    pub ident: Symbol,
+}
+
+#[derive(Diagnostic)]
 #[diag(parse_keyword_lifetime)]
 pub(crate) struct KeywordLifetime {
     #[primary_span]
diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
index d627ef3d2cb..226de65445c 100644
--- a/compiler/rustc_parse/src/lexer/mod.rs
+++ b/compiler/rustc_parse/src/lexer/mod.rs
@@ -294,15 +294,21 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
                     let prefix_span = self.mk_sp(start, ident_start);
 
                     if prefix_span.at_least_rust_2021() {
-                        let lifetime_name_without_tick = self.str_from(ident_start);
+                        let span = self.mk_sp(start, self.pos);
+
+                        let lifetime_name_without_tick = Symbol::intern(&self.str_from(ident_start));
+                        if !lifetime_name_without_tick.can_be_raw() {
+                            self.dcx().emit_err(errors::CannotBeRawLifetime { span, ident: lifetime_name_without_tick });
+                        }
+
                         // Put the `'` back onto the lifetime name.
-                        let mut lifetime_name = String::with_capacity(lifetime_name_without_tick.len() + 1);
+                        let mut lifetime_name = String::with_capacity(lifetime_name_without_tick.as_str().len() + 1);
                         lifetime_name.push('\'');
-                        lifetime_name += lifetime_name_without_tick;
+                        lifetime_name += lifetime_name_without_tick.as_str();
                         let sym = Symbol::intern(&lifetime_name);
 
                         // Make sure we mark this as a raw identifier.
-                        self.psess.raw_identifier_spans.push(self.mk_sp(start, self.pos));
+                        self.psess.raw_identifier_spans.push(span);
 
                         token::Lifetime(sym, IdentIsRaw::Yes)
                     } else {
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index 42455983575..09f5a8e96d3 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -1472,7 +1472,7 @@ impl<'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
             };
 
             if lhs_span.eq_ctxt(rhs_span) {
-                err.span_suggestion(
+                err.span_suggestion_verbose(
                     lhs_span.between(rhs_span),
                     MESSAGE,
                     "::",
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index fe05605c1b9..fa2403db925 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -12,7 +12,7 @@ use std::hash::Hash;
 use std::path::{Path, PathBuf};
 use std::str::{self, FromStr};
 use std::sync::LazyLock;
-use std::{fmt, fs, iter};
+use std::{cmp, fmt, fs, iter};
 
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_data_structures::stable_hasher::{StableOrd, ToStableHashKey};
@@ -1367,13 +1367,38 @@ pub fn build_target_config(early_dcx: &EarlyDiagCtxt, opts: &Options, sysroot: &
 }
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
-enum OptionStability {
+pub enum OptionStability {
     Stable,
     Unstable,
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub enum OptionKind {
+    /// An option that takes a value, and cannot appear more than once (e.g. `--out-dir`).
+    ///
+    /// Corresponds to [`getopts::Options::optopt`].
+    Opt,
+
+    /// An option that takes a value, and can appear multiple times (e.g. `--emit`).
+    ///
+    /// Corresponds to [`getopts::Options::optmulti`].
+    Multi,
+
+    /// An option that does not take a value, and cannot appear more than once (e.g. `--help`).
+    ///
+    /// Corresponds to [`getopts::Options::optflag`].
+    /// The `hint` string must be empty.
+    Flag,
+
+    /// An option that does not take a value, and can appear multiple times (e.g. `-O`).
+    ///
+    /// Corresponds to [`getopts::Options::optflagmulti`].
+    /// The `hint` string must be empty.
+    FlagMulti,
+}
+
 pub struct RustcOptGroup {
-    pub apply: Box<dyn Fn(&mut getopts::Options) -> &mut getopts::Options>,
+    apply: Box<dyn Fn(&mut getopts::Options) -> &mut getopts::Options>,
     pub name: &'static str,
     stability: OptionStability,
 }
@@ -1383,73 +1408,42 @@ impl RustcOptGroup {
         self.stability == OptionStability::Stable
     }
 
-    pub fn stable<F>(name: &'static str, f: F) -> RustcOptGroup
-    where
-        F: Fn(&mut getopts::Options) -> &mut getopts::Options + 'static,
-    {
-        RustcOptGroup { name, apply: Box::new(f), stability: OptionStability::Stable }
-    }
-
-    pub fn unstable<F>(name: &'static str, f: F) -> RustcOptGroup
-    where
-        F: Fn(&mut getopts::Options) -> &mut getopts::Options + 'static,
-    {
-        RustcOptGroup { name, apply: Box::new(f), stability: OptionStability::Unstable }
+    pub fn apply(&self, options: &mut getopts::Options) {
+        (self.apply)(options);
     }
 }
 
-// The `opt` local module holds wrappers around the `getopts` API that
-// adds extra rustc-specific metadata to each option; such metadata
-// is exposed by . The public
-// functions below ending with `_u` are the functions that return
-// *unstable* options, i.e., options that are only enabled when the
-// user also passes the `-Z unstable-options` debugging flag.
-mod opt {
-    // The `fn flag*` etc below are written so that we can use them
-    // in the future; do not warn about them not being used right now.
-    #![allow(dead_code)]
-
-    use super::RustcOptGroup;
-
-    type R = RustcOptGroup;
-    type S = &'static str;
-
-    fn stable<F>(name: S, f: F) -> R
-    where
-        F: Fn(&mut getopts::Options) -> &mut getopts::Options + 'static,
-    {
-        RustcOptGroup::stable(name, f)
-    }
-
-    fn unstable<F>(name: S, f: F) -> R
-    where
-        F: Fn(&mut getopts::Options) -> &mut getopts::Options + 'static,
-    {
-        RustcOptGroup::unstable(name, f)
-    }
-
-    fn longer(a: S, b: S) -> S {
-        if a.len() > b.len() { a } else { b }
-    }
-
-    pub(crate) fn opt_s(a: S, b: S, c: S, d: S) -> R {
-        stable(longer(a, b), move |opts| opts.optopt(a, b, c, d))
-    }
-    pub(crate) fn multi_s(a: S, b: S, c: S, d: S) -> R {
-        stable(longer(a, b), move |opts| opts.optmulti(a, b, c, d))
-    }
-    pub(crate) fn flag_s(a: S, b: S, c: S) -> R {
-        stable(longer(a, b), move |opts| opts.optflag(a, b, c))
-    }
-    pub(crate) fn flagmulti_s(a: S, b: S, c: S) -> R {
-        stable(longer(a, b), move |opts| opts.optflagmulti(a, b, c))
-    }
-
-    fn opt(a: S, b: S, c: S, d: S) -> R {
-        unstable(longer(a, b), move |opts| opts.optopt(a, b, c, d))
-    }
-    pub(crate) fn multi(a: S, b: S, c: S, d: S) -> R {
-        unstable(longer(a, b), move |opts| opts.optmulti(a, b, c, d))
+pub fn make_opt(
+    stability: OptionStability,
+    kind: OptionKind,
+    short_name: &'static str,
+    long_name: &'static str,
+    desc: &'static str,
+    hint: &'static str,
+) -> RustcOptGroup {
+    RustcOptGroup {
+        name: cmp::max_by_key(short_name, long_name, |s| s.len()),
+        stability,
+        apply: match kind {
+            OptionKind::Opt => Box::new(move |opts: &mut getopts::Options| {
+                opts.optopt(short_name, long_name, desc, hint)
+            }),
+            OptionKind::Multi => Box::new(move |opts: &mut getopts::Options| {
+                opts.optmulti(short_name, long_name, desc, hint)
+            }),
+            OptionKind::Flag => {
+                assert_eq!(hint, "");
+                Box::new(move |opts: &mut getopts::Options| {
+                    opts.optflag(short_name, long_name, desc)
+                })
+            }
+            OptionKind::FlagMulti => {
+                assert_eq!(hint, "");
+                Box::new(move |opts: &mut getopts::Options| {
+                    opts.optflagmulti(short_name, long_name, desc)
+                })
+            }
+        },
     }
 }
 
@@ -1464,46 +1458,60 @@ The default is {DEFAULT_EDITION} and the latest stable edition is {LATEST_STABLE
 /// including metadata for each option, such as whether the option is
 /// part of the stable long-term interface for rustc.
 pub fn rustc_short_optgroups() -> Vec<RustcOptGroup> {
+    use OptionKind::{Flag, FlagMulti, Multi, Opt};
+    use OptionStability::Stable;
+
+    use self::make_opt as opt;
+
     vec![
-        opt::flag_s("h", "help", "Display this message"),
-        opt::multi_s("", "cfg", "Configure the compilation environment.
-                             SPEC supports the syntax `NAME[=\"VALUE\"]`.", "SPEC"),
-        opt::multi_s("", "check-cfg", "Provide list of expected cfgs for checking", "SPEC"),
-        opt::multi_s(
+        opt(Stable, Flag, "h", "help", "Display this message", ""),
+        opt(
+            Stable,
+            Multi,
+            "",
+            "cfg",
+            "Configure the compilation environment.\n\
+                SPEC supports the syntax `NAME[=\"VALUE\"]`.",
+            "SPEC",
+        ),
+        opt(Stable, Multi, "", "check-cfg", "Provide list of expected cfgs for checking", "SPEC"),
+        opt(
+            Stable,
+            Multi,
             "L",
             "",
-            "Add a directory to the library search path. The
-                             optional KIND can be one of dependency, crate, native,
-                             framework, or all (the default).",
+            "Add a directory to the library search path. \
+                The optional KIND can be one of dependency, crate, native, framework, or all (the default).",
             "[KIND=]PATH",
         ),
-        opt::multi_s(
+        opt(
+            Stable,
+            Multi,
             "l",
             "",
-            "Link the generated crate(s) to the specified native
-                             library NAME. The optional KIND can be one of
-                             static, framework, or dylib (the default).
-                             Optional comma separated MODIFIERS (bundle|verbatim|whole-archive|as-needed)
-                             may be specified each with a prefix of either '+' to
-                             enable or '-' to disable.",
+            "Link the generated crate(s) to the specified native\n\
+                library NAME. The optional KIND can be one of\n\
+                static, framework, or dylib (the default).\n\
+                Optional comma separated MODIFIERS\n\
+                (bundle|verbatim|whole-archive|as-needed)\n\
+                may be specified each with a prefix of either '+' to\n\
+                enable or '-' to disable.",
             "[KIND[:MODIFIERS]=]NAME[:RENAME]",
         ),
         make_crate_type_option(),
-        opt::opt_s("", "crate-name", "Specify the name of the crate being built", "NAME"),
-        opt::opt_s(
-            "",
-            "edition",
-            &EDITION_STRING,
-            EDITION_NAME_LIST,
-        ),
-        opt::multi_s(
+        opt(Stable, Opt, "", "crate-name", "Specify the name of the crate being built", "NAME"),
+        opt(Stable, Opt, "", "edition", &EDITION_STRING, EDITION_NAME_LIST),
+        opt(
+            Stable,
+            Multi,
             "",
             "emit",
-            "Comma separated list of types of output for \
-             the compiler to emit",
+            "Comma separated list of types of output for the compiler to emit",
             "[asm|llvm-bc|llvm-ir|obj|metadata|link|dep-info|mir]",
         ),
-        opt::multi_s(
+        opt(
+            Stable,
+            Multi,
             "",
             "print",
             "Compiler information to print on stdout",
@@ -1512,41 +1520,36 @@ pub fn rustc_short_optgroups() -> Vec<RustcOptGroup> {
              tls-models|target-spec-json|all-target-specs-json|native-static-libs|\
              stack-protector-strategies|link-args|deployment-target]",
         ),
-        opt::flagmulti_s("g", "", "Equivalent to -C debuginfo=2"),
-        opt::flagmulti_s("O", "", "Equivalent to -C opt-level=2"),
-        opt::opt_s("o", "", "Write output to <filename>", "FILENAME"),
-        opt::opt_s(
-            "",
-            "out-dir",
-            "Write output to compiler-chosen filename \
-             in <dir>",
-            "DIR",
-        ),
-        opt::opt_s(
+        opt(Stable, FlagMulti, "g", "", "Equivalent to -C debuginfo=2", ""),
+        opt(Stable, FlagMulti, "O", "", "Equivalent to -C opt-level=2", ""),
+        opt(Stable, Opt, "o", "", "Write output to <filename>", "FILENAME"),
+        opt(Stable, Opt, "", "out-dir", "Write output to compiler-chosen filename in <dir>", "DIR"),
+        opt(
+            Stable,
+            Opt,
             "",
             "explain",
-            "Provide a detailed explanation of an error \
-             message",
+            "Provide a detailed explanation of an error message",
             "OPT",
         ),
-        opt::flag_s("", "test", "Build a test harness"),
-        opt::opt_s("", "target", "Target triple for which the code is compiled", "TARGET"),
-        opt::multi_s("A", "allow", "Set lint allowed", "LINT"),
-        opt::multi_s("W", "warn", "Set lint warnings", "LINT"),
-        opt::multi_s("", "force-warn", "Set lint force-warn", "LINT"),
-        opt::multi_s("D", "deny", "Set lint denied", "LINT"),
-        opt::multi_s("F", "forbid", "Set lint forbidden", "LINT"),
-        opt::multi_s(
+        opt(Stable, Flag, "", "test", "Build a test harness", ""),
+        opt(Stable, Opt, "", "target", "Target triple for which the code is compiled", "TARGET"),
+        opt(Stable, Multi, "A", "allow", "Set lint allowed", "LINT"),
+        opt(Stable, Multi, "W", "warn", "Set lint warnings", "LINT"),
+        opt(Stable, Multi, "", "force-warn", "Set lint force-warn", "LINT"),
+        opt(Stable, Multi, "D", "deny", "Set lint denied", "LINT"),
+        opt(Stable, Multi, "F", "forbid", "Set lint forbidden", "LINT"),
+        opt(
+            Stable,
+            Multi,
             "",
             "cap-lints",
-            "Set the most restrictive lint level. \
-             More restrictive lints are capped at this \
-             level",
+            "Set the most restrictive lint level. More restrictive lints are capped at this level",
             "LEVEL",
         ),
-        opt::multi_s("C", "codegen", "Set a codegen option", "OPT[=VALUE]"),
-        opt::flag_s("V", "version", "Print version info and exit"),
-        opt::flag_s("v", "verbose", "Use verbose output"),
+        opt(Stable, Multi, "C", "codegen", "Set a codegen option", "OPT[=VALUE]"),
+        opt(Stable, Flag, "V", "version", "Print version info and exit", ""),
+        opt(Stable, Flag, "v", "verbose", "Use verbose output", ""),
     ]
 }
 
@@ -1554,25 +1557,36 @@ pub fn rustc_short_optgroups() -> Vec<RustcOptGroup> {
 /// each option, such as whether the option is part of the stable
 /// long-term interface for rustc.
 pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
+    use OptionKind::{Multi, Opt};
+    use OptionStability::{Stable, Unstable};
+
+    use self::make_opt as opt;
+
     let mut opts = rustc_short_optgroups();
     // FIXME: none of these descriptions are actually used
     opts.extend(vec![
-        opt::multi_s(
+        opt(
+            Stable,
+            Multi,
             "",
             "extern",
             "Specify where an external rust library is located",
             "NAME[=PATH]",
         ),
-        opt::opt_s("", "sysroot", "Override the system root", "PATH"),
-        opt::multi("Z", "", "Set unstable / perma-unstable options", "FLAG"),
-        opt::opt_s(
+        opt(Stable, Opt, "", "sysroot", "Override the system root", "PATH"),
+        opt(Unstable, Multi, "Z", "", "Set unstable / perma-unstable options", "FLAG"),
+        opt(
+            Stable,
+            Opt,
             "",
             "error-format",
             "How errors and other messages are produced",
             "human|json|short",
         ),
-        opt::multi_s("", "json", "Configure the JSON output of the compiler", "CONFIG"),
-        opt::opt_s(
+        opt(Stable, Multi, "", "json", "Configure the JSON output of the compiler", "CONFIG"),
+        opt(
+            Stable,
+            Opt,
             "",
             "color",
             "Configure coloring of output:
@@ -1581,19 +1595,23 @@ pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
                                  never  = never colorize output",
             "auto|always|never",
         ),
-        opt::opt_s(
+        opt(
+            Stable,
+            Opt,
             "",
             "diagnostic-width",
             "Inform rustc of the width of the output so that diagnostics can be truncated to fit",
             "WIDTH",
         ),
-        opt::multi_s(
+        opt(
+            Stable,
+            Multi,
             "",
             "remap-path-prefix",
             "Remap source names in all output (compiler messages and output files)",
             "FROM=TO",
         ),
-        opt::multi("", "env-set", "Inject an environment variable", "VAR=VALUE"),
+        opt(Unstable, Multi, "", "env-set", "Inject an environment variable", "VAR=VALUE"),
     ]);
     opts
 }
@@ -2756,7 +2774,9 @@ fn parse_pretty(early_dcx: &EarlyDiagCtxt, unstable_opts: &UnstableOptions) -> O
 }
 
 pub fn make_crate_type_option() -> RustcOptGroup {
-    opt::multi_s(
+    make_opt(
+        OptionStability::Stable,
+        OptionKind::Multi,
         "",
         "crate-type",
         "Comma separated list of types of crates
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index f20ae85b8e8..21c11655110 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -155,6 +155,7 @@ pub fn feature_warn_issue(
 }
 
 /// Adds the diagnostics for a feature to an existing error.
+/// Must be a language feature!
 pub fn add_feature_diagnostics<G: EmissionGuarantee>(
     err: &mut Diag<'_, G>,
     sess: &Session,
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 470e372ee48..9d9434a7776 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -300,6 +300,7 @@ impl Session {
         self.opts.test
     }
 
+    /// `feature` must be a language feature.
     #[track_caller]
     pub fn create_feature_err<'a>(&'a self, err: impl Diagnostic<'a>, feature: Symbol) -> Diag<'a> {
         let mut err = self.dcx().create_err(err);
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 82cfbd28fff..c04c793ba46 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1867,6 +1867,7 @@ symbols! {
         slice_patterns,
         slicing_syntax,
         soft,
+        sparc_target_feature,
         specialization,
         speed,
         spotlight,
@@ -2109,6 +2110,7 @@ symbols! {
         usize_legacy_fn_max_value,
         usize_legacy_fn_min_value,
         usize_legacy_mod,
+        v8plus,
         va_arg,
         va_copy,
         va_end,
diff --git a/compiler/rustc_target/src/callconv/mod.rs b/compiler/rustc_target/src/callconv/mod.rs
index 8c3df9c426b..aa639f1624f 100644
--- a/compiler/rustc_target/src/callconv/mod.rs
+++ b/compiler/rustc_target/src/callconv/mod.rs
@@ -143,7 +143,8 @@ pub struct ArgAttributes {
     pub regular: ArgAttribute,
     pub arg_ext: ArgExtension,
     /// The minimum size of the pointee, guaranteed to be valid for the duration of the whole call
-    /// (corresponding to LLVM's dereferenceable and dereferenceable_or_null attributes).
+    /// (corresponding to LLVM's dereferenceable_or_null attributes, i.e., it is okay for this to be
+    /// set on a null pointer, but all non-null pointers must be dereferenceable).
     pub pointee_size: Size,
     pub pointee_align: Option<Align>,
 }
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu.rs
index f1854353abd..1511c0ccaad 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu.rs
@@ -11,7 +11,7 @@ pub(crate) fn target() -> Target {
             std: Some(true),
         },
         pointer_width: 64,
-        data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
+        data_layout: "E-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
         arch: "aarch64".into(),
         options: TargetOptions {
             features: "+v8a,+outline-atomics".into(),
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu_ilp32.rs b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu_ilp32.rs
index 0dc51aaa73d..e7070778794 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu_ilp32.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu_ilp32.rs
@@ -14,7 +14,7 @@ pub(crate) fn target() -> Target {
             std: Some(true),
         },
         pointer_width: 32,
-        data_layout: "E-m:e-p:32:32-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
+        data_layout: "E-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
         arch: "aarch64".into(),
         options: TargetOptions {
             abi: "ilp32".into(),
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_netbsd.rs b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_netbsd.rs
index f99e7fe84f5..f0f6e49eedd 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_netbsd.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_netbsd.rs
@@ -11,7 +11,7 @@ pub(crate) fn target() -> Target {
             std: Some(true),
         },
         pointer_width: 64,
-        data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
+        data_layout: "E-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
         arch: "aarch64".into(),
         options: TargetOptions {
             mcount: "__mcount".into(),
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu_ilp32.rs b/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu_ilp32.rs
index f33a5873c09..7b0df7d1130 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu_ilp32.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu_ilp32.rs
@@ -10,7 +10,7 @@ pub(crate) fn target() -> Target {
             std: Some(true),
         },
         pointer_width: 32,
-        data_layout: "e-m:e-p:32:32-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
+        data_layout: "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
         arch: "aarch64".into(),
         options: TargetOptions {
             abi: "ilp32".into(),
diff --git a/compiler/rustc_target/src/spec/targets/sparc_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/targets/sparc_unknown_linux_gnu.rs
index 2777395757f..45941cd7c01 100644
--- a/compiler/rustc_target/src/spec/targets/sparc_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/targets/sparc_unknown_linux_gnu.rs
@@ -14,6 +14,7 @@ pub(crate) fn target() -> Target {
         data_layout: "E-m:e-p:32:32-i64:64-i128:128-f128:64-n32-S64".into(),
         arch: "sparc".into(),
         options: TargetOptions {
+            features: "+v8plus".into(),
             cpu: "v9".into(),
             endian: Endian::Big,
             late_link_args: TargetOptions::link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &[
diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
index 4dbaf1f7c95..c4f9c742650 100644
--- a/compiler/rustc_target/src/target_features.rs
+++ b/compiler/rustc_target/src/target_features.rs
@@ -545,6 +545,14 @@ const IBMZ_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     // tidy-alphabetical-end
 ];
 
+const SPARC_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
+    // tidy-alphabetical-start
+    ("leoncasa", Unstable(sym::sparc_target_feature), &[]),
+    ("v8plus", Unstable(sym::sparc_target_feature), &[]),
+    ("v9", Unstable(sym::sparc_target_feature), &[]),
+    // tidy-alphabetical-end
+];
+
 /// When rustdoc is running, provide a list of all known features so that all their respective
 /// primitives may be documented.
 ///
@@ -563,6 +571,7 @@ pub fn all_rust_features() -> impl Iterator<Item = (&'static str, Stability)> {
         .chain(CSKY_FEATURES)
         .chain(LOONGARCH_FEATURES)
         .chain(IBMZ_FEATURES)
+        .chain(SPARC_FEATURES)
         .cloned()
         .map(|(f, s, _)| (f, s))
 }
@@ -589,6 +598,7 @@ impl super::spec::Target {
             "csky" => CSKY_FEATURES,
             "loongarch64" => LOONGARCH_FEATURES,
             "s390x" => IBMZ_FEATURES,
+            "sparc" | "sparc64" => SPARC_FEATURES,
             _ => &[],
         }
     }
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
index 86fd4c230f6..a5e364d49f7 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
@@ -2953,6 +2953,22 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 // We hold the `DefId` of the item introducing the obligation, but displaying it
                 // doesn't add user usable information. It always point at an associated item.
             }
+            ObligationCauseCode::OpaqueTypeBound(span, definition_def_id) => {
+                err.span_note(span, "required by a bound in an opaque type");
+                if let Some(definition_def_id) = definition_def_id
+                    // If there are any stalled coroutine obligations, then this
+                    // error may be due to that, and not because the body has more
+                    // where-clauses.
+                    && self.tcx.typeck(definition_def_id).coroutine_stalled_predicates.is_empty()
+                {
+                    // FIXME(compiler-errors): We could probably point to something
+                    // specific here if we tried hard enough...
+                    err.span_note(
+                        tcx.def_span(definition_def_id),
+                        "this definition site has more where clauses than the opaque type",
+                    );
+                }
+            }
             ObligationCauseCode::Coercion { source, target } => {
                 let source =
                     tcx.short_ty_string(self.resolve_vars_if_possible(source), long_ty_file);