Move versioned LLVM target creation to rustc_codegen_ssa

The OS version depends on the deployment target environment variables,
the access of which we want to move to later in the compilation pipeline
that has access to more information, for example `env_depinfo`.

3 files changed, 16 insertions, 128 deletions

diff --git a/compiler/rustc_target/src/spec/base/apple/mod.rs b/compiler/rustc_target/src/spec/base/apple/mod.rs
index 73763cf034c..837af954a07 100644
--- a/compiler/rustc_target/src/spec/base/apple/mod.rs
+++ b/compiler/rustc_target/src/spec/base/apple/mod.rs
@@ -1,6 +1,5 @@
 use std::borrow::Cow;
 use std::env;
-use std::num::ParseIntError;
 
 use crate::spec::{
     Cc, DebuginfoKind, FramePointer, LinkerFlavor, Lld, SplitDebuginfo, StackProbeType, StaticCow,
@@ -97,9 +96,8 @@ impl TargetAbi {
     }
 }
 
-/// Get the base target options, LLVM target and `target_arch` from the three
-/// things that uniquely identify Rust's Apple targets: The OS, the
-/// architecture, and the ABI.
+/// Get the base target options, unversioned LLVM target and `target_arch` from the three
+/// things that uniquely identify Rust's Apple targets: The OS, the architecture, and the ABI.
 pub(crate) fn base(
     os: &'static str,
     arch: Arch,
@@ -155,7 +153,7 @@ pub(crate) fn base(
 
         ..Default::default()
     };
-    (opts, llvm_target(os, arch, abi), arch.target_arch())
+    (opts, unversioned_llvm_target(os, arch, abi), arch.target_arch())
 }
 
 pub fn platform(target: &Target) -> Option<u32> {
@@ -175,97 +173,11 @@ pub fn platform(target: &Target) -> Option<u32> {
     })
 }
 
-/// Hack for calling `deployment_target` outside of this module.
-pub fn deployment_target_for_target(target: &Target) -> (u16, u8, u8) {
-    let arch = if target.llvm_target.starts_with("arm64e") {
-        Arch::Arm64e
-    } else if target.arch == "aarch64" {
-        Arch::Arm64
-    } else {
-        // Dummy architecture, only used by `deployment_target` anyhow
-        Arch::X86_64
-    };
-    let abi = match &*target.abi {
-        "macabi" => TargetAbi::MacCatalyst,
-        "sim" => TargetAbi::Simulator,
-        "" => TargetAbi::Normal,
-        abi => unreachable!("invalid abi '{abi}' for Apple target"),
-    };
-    deployment_target(&target.os, arch, abi)
-}
-
-/// Get the deployment target based on the standard environment variables, or
-/// fall back to a sane default.
-fn deployment_target(os: &str, arch: Arch, abi: TargetAbi) -> (u16, u8, u8) {
-    // When bumping a version in here, remember to update the platform-support
-    // docs too.
-    //
-    // NOTE: If you are looking for the default deployment target, prefer
-    // `rustc --print deployment-target`, as the default here may change in
-    // future `rustc` versions.
-
-    // Minimum operating system versions currently supported by `rustc`.
-    let os_min = match os {
-        "macos" => (10, 12, 0),
-        "ios" => (10, 0, 0),
-        "tvos" => (10, 0, 0),
-        "watchos" => (5, 0, 0),
-        "visionos" => (1, 0, 0),
-        _ => unreachable!("tried to get deployment target for non-Apple platform"),
-    };
-
-    // On certain targets it makes sense to raise the minimum OS version.
-    //
-    // This matches what LLVM does, see:
-    // <https://github.com/llvm/llvm-project/blob/llvmorg-18.1.8/llvm/lib/TargetParser/Triple.cpp#L1900-L1932>
-    let min = match (os, arch, abi) {
-        ("macos", Arch::Arm64 | Arch::Arm64e, _) => (11, 0, 0),
-        ("ios", Arch::Arm64 | Arch::Arm64e, TargetAbi::MacCatalyst) => (14, 0, 0),
-        ("ios", Arch::Arm64 | Arch::Arm64e, TargetAbi::Simulator) => (14, 0, 0),
-        ("ios", Arch::Arm64e, TargetAbi::Normal) => (14, 0, 0),
-        // Mac Catalyst defaults to 13.1 in Clang.
-        ("ios", _, TargetAbi::MacCatalyst) => (13, 1, 0),
-        ("tvos", Arch::Arm64 | Arch::Arm64e, TargetAbi::Simulator) => (14, 0, 0),
-        ("watchos", Arch::Arm64 | Arch::Arm64e, TargetAbi::Simulator) => (7, 0, 0),
-        _ => os_min,
-    };
-
-    // The environment variable used to fetch the deployment target.
-    let env_var = match os {
-        "macos" => "MACOSX_DEPLOYMENT_TARGET",
-        "ios" => "IPHONEOS_DEPLOYMENT_TARGET",
-        "watchos" => "WATCHOS_DEPLOYMENT_TARGET",
-        "tvos" => "TVOS_DEPLOYMENT_TARGET",
-        "visionos" => "XROS_DEPLOYMENT_TARGET",
-        _ => unreachable!("tried to get deployment target env var for non-Apple platform"),
-    };
-
-    if let Ok(deployment_target) = env::var(env_var) {
-        match parse_version(&deployment_target) {
-            // It is common that the deployment target is set too low, e.g. on
-            // macOS Aarch64 to also target older x86_64, the user may set a
-            // lower deployment target than supported.
-            //
-            // To avoid such issues, we silently raise the deployment target
-            // here.
-            // FIXME: We want to show a warning when `version < os_min`.
-            Ok(version) => version.max(min),
-            // FIXME: Report erroneous environment variable to user.
-            Err(_) => min,
-        }
-    } else {
-        min
-    }
-}
-
-/// Generate the target triple that we need to pass to LLVM and/or Clang.
-fn llvm_target(os: &str, arch: Arch, abi: TargetAbi) -> StaticCow<str> {
-    // The target triple depends on the deployment target, and is required to
-    // enable features such as cross-language LTO, and for picking the right
-    // Mach-O commands.
-    //
-    // Certain optimizations also depend on the deployment target.
-    let (major, minor, patch) = deployment_target(os, arch, abi);
+/// Generate part of the LLVM target triple.
+///
+/// See `rustc_codegen_ssa::back::versioned_llvm_target` for the full triple passed to LLVM and
+/// Clang.
+fn unversioned_llvm_target(os: &str, arch: Arch, abi: TargetAbi) -> StaticCow<str> {
     let arch = arch.target_name();
     // Convert to the "canonical" OS name used by LLVM:
     // https://github.com/llvm/llvm-project/blob/llvmorg-18.1.8/llvm/lib/TargetParser/Triple.cpp#L236-L282
@@ -282,7 +194,7 @@ fn llvm_target(os: &str, arch: Arch, abi: TargetAbi) -> StaticCow<str> {
         TargetAbi::MacCatalyst => "-macabi",
         TargetAbi::Simulator => "-simulator",
     };
-    format!("{arch}-apple-{os}{major}.{minor}.{patch}{environment}").into()
+    format!("{arch}-apple-{os}{environment}").into()
 }
 
 fn link_env_remove(os: &'static str) -> StaticCow<[StaticCow<str>]> {
@@ -321,20 +233,3 @@ fn link_env_remove(os: &'static str) -> StaticCow<[StaticCow<str>]> {
         cvs!["MACOSX_DEPLOYMENT_TARGET"]
     }
 }
-
-/// Parse an OS version triple (SDK version or deployment target).
-///
-/// The size of the returned numbers here are limited by Mach-O's
-/// `LC_BUILD_VERSION`.
-fn parse_version(version: &str) -> Result<(u16, u8, u8), ParseIntError> {
-    if let Some((major, minor)) = version.split_once('.') {
-        let major = major.parse()?;
-        if let Some((minor, patch)) = minor.split_once('.') {
-            Ok((major, minor.parse()?, patch.parse()?))
-        } else {
-            Ok((major, minor.parse()?, 0))
-        }
-    } else {
-        Ok((version.parse()?, 0, 0))
-    }
-}
diff --git a/compiler/rustc_target/src/spec/base/apple/tests.rs b/compiler/rustc_target/src/spec/base/apple/tests.rs
index 9435b9a5bad..a7335c9bcae 100644
--- a/compiler/rustc_target/src/spec/base/apple/tests.rs
+++ b/compiler/rustc_target/src/spec/base/apple/tests.rs
@@ -1,4 +1,3 @@
-use super::parse_version;
 use crate::spec::targets::{
     aarch64_apple_darwin, aarch64_apple_ios_sim, aarch64_apple_visionos_sim,
     aarch64_apple_watchos_sim, i686_apple_darwin, x86_64_apple_darwin, x86_64_apple_ios,
@@ -40,11 +39,3 @@ fn macos_link_environment_unmodified() {
         ],);
     }
 }
-
-#[test]
-fn test_parse_version() {
-    assert_eq!(parse_version("10"), Ok((10, 0, 0)));
-    assert_eq!(parse_version("10.12"), Ok((10, 12, 0)));
-    assert_eq!(parse_version("10.12.6"), Ok((10, 12, 6)));
-    assert_eq!(parse_version("9999.99.99"), Ok((9999, 99, 99)));
-}
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index f4cbe47e0f3..1265cc34549 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -59,10 +59,7 @@ pub mod abi;
 pub mod crt_objects;
 
 mod base;
-pub use base::apple::{
-    deployment_target_for_target as current_apple_deployment_target,
-    platform as current_apple_platform,
-};
+pub use base::apple::platform as current_apple_platform;
 pub use base::avr_gnu::ef_avr_arch;
 
 /// Linker is called through a C/C++ compiler.
@@ -2003,7 +2000,12 @@ impl TargetWarnings {
 /// Every field here must be specified, and has no default value.
 #[derive(PartialEq, Clone, Debug)]
 pub struct Target {
-    /// Target triple to pass to LLVM.
+    /// Unversioned target triple to pass to LLVM.
+    ///
+    /// Target triples can optionally contain an OS version (notably Apple targets), which rustc
+    /// cannot know without querying the environment.
+    ///
+    /// Use `rustc_codegen_ssa::back::versioned_llvm_target` if you need the full LLVM target.
     pub llvm_target: StaticCow<str>,
     /// Metadata about a target, for example the description or tier.
     /// Used for generating target documentation.