refactor: Move Apple OSVersion (back) to rustc_target

Also convert OSVersion into a proper struct for better type-safety.

compiler/rustc_codegen_ssa/src/back/apple.rs

@@ -1,7 +1,6 @@
 use std::env;
 use std::ffi::OsString;
-use std::fmt::{Display, from_fn};
+use std::str::FromStr;
-use std::num::ParseIntError;
 use std::path::PathBuf;
 use std::process::Command;
 
@@ -9,6 +8,7 @@ use itertools::Itertools;
 use rustc_middle::middle::exported_symbols::SymbolExportKind;
 use rustc_session::Session;
 use rustc_target::spec::Target;
+pub(super) use rustc_target::spec::apple::OSVersion;
 use tracing::debug;
 
 use crate::errors::{AppleDeploymentTarget, XcrunError, XcrunSdkPathWarning};
@@ -134,76 +134,6 @@ pub(super) fn add_data_and_relocation(
     Ok(())
 }
 
-/// Deployment target or SDK version.
-///
-/// The size of the numbers in here are limited by Mach-O's `LC_BUILD_VERSION`.
-type OSVersion = (u16, u8, u8);
-
-/// Parse an OS version triple (SDK version or deployment target).
-fn parse_version(version: &str) -> Result<OSVersion, 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))
-    }
-}
-
-pub fn pretty_version(version: OSVersion) -> impl Display {
-    let (major, minor, patch) = version;
-    from_fn(move |f| {
-        write!(f, "{major}.{minor}")?;
-        if patch != 0 {
-            write!(f, ".{patch}")?;
-        }
-        Ok(())
-    })
-}
-
-/// Minimum operating system versions currently supported by `rustc`.
-fn os_minimum_deployment_target(os: &str) -> OSVersion {
-    // When bumping a version in here, remember to update the platform-support docs too.
-    //
-    // NOTE: The defaults may change in future `rustc` versions, so if you are looking for the
-    // default deployment target, prefer:
-    // ```
-    // $ rustc --print deployment-target
-    // ```
-    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"),
-    }
-}
-
-/// The deployment target for the given target.
-///
-/// This is similar to `os_minimum_deployment_target`, except that on certain targets it makes sense
-/// to raise the minimum OS version.
-///
-/// This matches what LLVM does, see in part:
-/// <https://github.com/llvm/llvm-project/blob/llvmorg-18.1.8/llvm/lib/TargetParser/Triple.cpp#L1900-L1932>
-fn minimum_deployment_target(target: &Target) -> OSVersion {
-    match (&*target.os, &*target.arch, &*target.abi) {
-        ("macos", "aarch64", _) => (11, 0, 0),
-        ("ios", "aarch64", "macabi") => (14, 0, 0),
-        ("ios", "aarch64", "sim") => (14, 0, 0),
-        ("ios", _, _) if target.llvm_target.starts_with("arm64e") => (14, 0, 0),
-        // Mac Catalyst defaults to 13.1 in Clang.
-        ("ios", _, "macabi") => (13, 1, 0),
-        ("tvos", "aarch64", "sim") => (14, 0, 0),
-        ("watchos", "aarch64", "sim") => (7, 0, 0),
-        (os, _, _) => os_minimum_deployment_target(os),
-    }
-}
-
 /// Name of the environment variable used to fetch the deployment target on the given OS.
 pub fn deployment_target_env_var(os: &str) -> &'static str {
     match os {
@@ -219,13 +149,13 @@ pub fn deployment_target_env_var(os: &str) -> &'static str {
 /// Get the deployment target based on the standard environment variables, or fall back to the
 /// minimum version supported by `rustc`.
 pub fn deployment_target(sess: &Session) -> OSVersion {
-    let min = minimum_deployment_target(&sess.target);
+    let min = OSVersion::minimum_deployment_target(&sess.target);
     let env_var = deployment_target_env_var(&sess.target.os);
 
     if let Ok(deployment_target) = env::var(env_var) {
-        match parse_version(&deployment_target) {
+        match OSVersion::from_str(&deployment_target) {
             Ok(version) => {
-                let os_min = os_minimum_deployment_target(&sess.target.os);
+                let os_min = OSVersion::os_minimum_deployment_target(&sess.target.os);
                 // It is common that the deployment target is set a bit too low, for example on
                 // macOS Aarch64 to also target older x86_64. So we only want to warn when variable
                 // is lower than the minimum OS supported by rustc, not when the variable is lower
@@ -233,8 +163,8 @@ pub fn deployment_target(sess: &Session) -> OSVersion {
                 if version < os_min {
                     sess.dcx().emit_warn(AppleDeploymentTarget::TooLow {
                         env_var,
-                        version: pretty_version(version).to_string(),
+                        version: version.fmt_pretty().to_string(),
-                        os_min: pretty_version(os_min).to_string(),
+                        os_min: os_min.fmt_pretty().to_string(),
                     });
                 }
 
@@ -263,18 +193,17 @@ pub(super) fn add_version_to_llvm_target(
     let environment = components.next();
     assert_eq!(components.next(), None, "too many LLVM triple components");
 
-    let (major, minor, patch) = deployment_target;
-
     assert!(
         !os.contains(|c: char| c.is_ascii_digit()),
         "LLVM target must not already be versioned"
     );
 
+    let version = deployment_target.fmt_full();
     if let Some(env) = environment {
         // Insert version into OS, before environment
-        format!("{arch}-{vendor}-{os}{major}.{minor}.{patch}-{env}")
+        format!("{arch}-{vendor}-{os}{version}-{env}")
     } else {
-        format!("{arch}-{vendor}-{os}{major}.{minor}.{patch}")
+        format!("{arch}-{vendor}-{os}{version}")
     }
 }
 

compiler/rustc_codegen_ssa/src/back/apple/tests.rs

@@ -3,23 +3,15 @@ use super::*;
 #[test]
 fn test_add_version_to_llvm_target() {
     assert_eq!(
-        add_version_to_llvm_target("aarch64-apple-macosx", (10, 14, 1)),
+        add_version_to_llvm_target("aarch64-apple-macosx", OSVersion::new(10, 14, 1)),
         "aarch64-apple-macosx10.14.1"
     );
     assert_eq!(
-        add_version_to_llvm_target("aarch64-apple-ios-simulator", (16, 1, 0)),
+        add_version_to_llvm_target("aarch64-apple-ios-simulator", OSVersion::new(16, 1, 0)),
         "aarch64-apple-ios16.1.0-simulator"
     );
 }
 
-#[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)));
-}
-
 #[test]
 #[cfg_attr(not(target_os = "macos"), ignore = "xcode-select is only available on macOS")]
 fn lookup_developer_dir() {

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -3115,8 +3115,7 @@ fn add_apple_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavo
             _ => bug!("invalid OS/ABI combination for Apple target: {target_os}, {target_abi}"),
         };
 
-        let (major, minor, patch) = apple::deployment_target(sess);
+        let min_version = apple::deployment_target(sess).fmt_full().to_string();
-        let min_version = format!("{major}.{minor}.{patch}");
 
         // The SDK version is used at runtime when compiling with a newer SDK / version of Xcode:
         // - By dyld to give extra warnings and errors, see e.g.:
@@ -3185,10 +3184,10 @@ fn add_apple_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavo
 
             // The presence of `-mmacosx-version-min` makes CC default to
             // macOS, and it sets the deployment target.
-            let (major, minor, patch) = apple::deployment_target(sess);
+            let version = apple::deployment_target(sess).fmt_full();
             // Intentionally pass this as a single argument, Clang doesn't
             // seem to like it otherwise.
-            cmd.cc_arg(&format!("-mmacosx-version-min={major}.{minor}.{patch}"));
+            cmd.cc_arg(&format!("-mmacosx-version-min={version}"));
 
             // macOS has no environment, so with these two, we've told CC the
             // four desired parameters.

compiler/rustc_codegen_ssa/src/back/metadata.rs

@@ -388,7 +388,7 @@ pub(super) fn elf_e_flags(architecture: Architecture, sess: &Session) -> u32 {
 fn macho_object_build_version_for_target(sess: &Session) -> object::write::MachOBuildVersion {
     /// The `object` crate demands "X.Y.Z encoded in nibbles as xxxx.yy.zz"
     /// e.g. minOS 14.0 = 0x000E0000, or SDK 16.2 = 0x00100200
-    fn pack_version((major, minor, patch): (u16, u8, u8)) -> u32 {
+    fn pack_version(apple::OSVersion { major, minor, patch }: apple::OSVersion) -> u32 {
         let (major, minor, patch) = (major as u32, minor as u32, patch as u32);
         (major << 16) | (minor << 8) | patch
     }

compiler/rustc_codegen_ssa/src/lib.rs

@@ -7,7 +7,6 @@
 #![doc(rust_logo)]
 #![feature(assert_matches)]
 #![feature(box_patterns)]
-#![feature(debug_closure_helpers)]
 #![feature(file_buffered)]
 #![feature(if_let_guard)]
 #![feature(let_chains)]

compiler/rustc_driver_impl/src/lib.rs

@@ -811,7 +811,7 @@ fn print_crate_info(
                     println_info!(
                         "{}={}",
                         apple::deployment_target_env_var(&sess.target.os),
-                        apple::pretty_version(apple::deployment_target(sess)),
+                        apple::deployment_target(sess).fmt_pretty(),
                     )
                 } else {
                     #[allow(rustc::diagnostic_outside_of_impl)]

compiler/rustc_target/src/lib.rs

@@ -12,6 +12,7 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(assert_matches)]
+#![feature(debug_closure_helpers)]
 #![feature(iter_intersperse)]
 #![feature(let_chains)]
 #![feature(rustc_attrs)]

compiler/rustc_target/src/spec/base/apple/mod.rs

@@ -1,9 +1,12 @@
 use std::borrow::Cow;
 use std::env;
+use std::fmt::{Display, from_fn};
+use std::num::ParseIntError;
+use std::str::FromStr;
 
 use crate::spec::{
     BinaryFormat, Cc, DebuginfoKind, FloatAbi, FramePointer, LinkerFlavor, Lld, RustcAbi,
-    SplitDebuginfo, StackProbeType, StaticCow, TargetOptions, cvs,
+    SplitDebuginfo, StackProbeType, StaticCow, Target, TargetOptions, cvs,
 };
 
 #[cfg(test)]
@@ -222,3 +225,95 @@ fn link_env_remove(os: &'static str) -> StaticCow<[StaticCow<str>]> {
         cvs!["MACOSX_DEPLOYMENT_TARGET"]
     }
 }
+
+/// Deployment target or SDK version.
+///
+/// The size of the numbers in here are limited by Mach-O's `LC_BUILD_VERSION`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct OSVersion {
+    pub major: u16,
+    pub minor: u8,
+    pub patch: u8,
+}
+
+impl FromStr for OSVersion {
+    type Err = ParseIntError;
+
+    /// Parse an OS version triple (SDK version or deployment target).
+    fn from_str(version: &str) -> Result<Self, ParseIntError> {
+        if let Some((major, minor)) = version.split_once('.') {
+            let major = major.parse()?;
+            if let Some((minor, patch)) = minor.split_once('.') {
+                Ok(Self { major, minor: minor.parse()?, patch: patch.parse()? })
+            } else {
+                Ok(Self { major, minor: minor.parse()?, patch: 0 })
+            }
+        } else {
+            Ok(Self { major: version.parse()?, minor: 0, patch: 0 })
+        }
+    }
+}
+
+impl OSVersion {
+    pub fn new(major: u16, minor: u8, patch: u8) -> Self {
+        Self { major, minor, patch }
+    }
+
+    pub fn fmt_pretty(self) -> impl Display {
+        let Self { major, minor, patch } = self;
+        from_fn(move |f| {
+            write!(f, "{major}.{minor}")?;
+            if patch != 0 {
+                write!(f, ".{patch}")?;
+            }
+            Ok(())
+        })
+    }
+
+    pub fn fmt_full(self) -> impl Display {
+        let Self { major, minor, patch } = self;
+        from_fn(move |f| write!(f, "{major}.{minor}.{patch}"))
+    }
+
+    /// Minimum operating system versions currently supported by `rustc`.
+    pub fn os_minimum_deployment_target(os: &str) -> Self {
+        // When bumping a version in here, remember to update the platform-support docs too.
+        //
+        // NOTE: The defaults may change in future `rustc` versions, so if you are looking for the
+        // default deployment target, prefer:
+        // ```
+        // $ rustc --print deployment-target
+        // ```
+        let (major, minor, patch) = 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"),
+        };
+        Self { major, minor, patch }
+    }
+
+    /// The deployment target for the given target.
+    ///
+    /// This is similar to `os_minimum_deployment_target`, except that on certain targets it makes sense
+    /// to raise the minimum OS version.
+    ///
+    /// This matches what LLVM does, see in part:
+    /// <https://github.com/llvm/llvm-project/blob/llvmorg-18.1.8/llvm/lib/TargetParser/Triple.cpp#L1900-L1932>
+    pub fn minimum_deployment_target(target: &Target) -> Self {
+        let (major, minor, patch) = match (&*target.os, &*target.arch, &*target.abi) {
+            ("macos", "aarch64", _) => (11, 0, 0),
+            ("ios", "aarch64", "macabi") => (14, 0, 0),
+            ("ios", "aarch64", "sim") => (14, 0, 0),
+            ("ios", _, _) if target.llvm_target.starts_with("arm64e") => (14, 0, 0),
+            // Mac Catalyst defaults to 13.1 in Clang.
+            ("ios", _, "macabi") => (13, 1, 0),
+            ("tvos", "aarch64", "sim") => (14, 0, 0),
+            ("watchos", "aarch64", "sim") => (7, 0, 0),
+            (os, _, _) => return Self::os_minimum_deployment_target(os),
+        };
+        Self { major, minor, patch }
+    }
+}

compiler/rustc_target/src/spec/base/apple/tests.rs

@@ -1,3 +1,4 @@
+use super::OSVersion;
 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,
@@ -42,3 +43,11 @@ fn macos_link_environment_unmodified() {
         );
     }
 }
+
+#[test]
+fn test_parse_version() {
+    assert_eq!("10".parse(), Ok(OSVersion::new(10, 0, 0)));
+    assert_eq!("10.12".parse(), Ok(OSVersion::new(10, 12, 0)));
+    assert_eq!("10.12.6".parse(), Ok(OSVersion::new(10, 12, 6)));
+    assert_eq!("9999.99.99".parse(), Ok(OSVersion::new(9999, 99, 99)));
+}

compiler/rustc_target/src/spec/base/mod.rs

@@ -1,6 +1,6 @@
 pub(crate) mod aix;
 pub(crate) mod android;
-pub(crate) mod apple;
+pub mod apple;
 pub(crate) mod avr;
 pub(crate) mod bpf;
 pub(crate) mod cygwin;

compiler/rustc_target/src/spec/mod.rs

@@ -60,6 +60,7 @@ pub mod crt_objects;
 mod base;
 mod json;
 
+pub use base::apple;
 pub use base::avr::ef_avr_arch;
 
 /// Linker is called through a C/C++ compiler.