Auto merge of #138947 - madsmtm:refactor-apple-versions, r=Noratrieb

Refactor Apple version handling in the compiler

Move various Apple version handling code in the compiler out `rustc_codegen_ssa` and into a place where it can be accessed by `rustc_attr_parsing`, which I found to be necessary when doing https://github.com/rust-lang/rust/pull/136867. Thought I'd split it out to make it easier to land, and to make further changes like https://github.com/rust-lang/rust/pull/131477 have fewer conflicts / PR dependencies.

There should be no functional changes in this PR.

`@rustbot` label O-apple
r? rust-lang/compiler

7 files changed, 13 insertions, 153 deletions

diff --git a/compiler/rustc_codegen_ssa/src/back/apple.rs b/compiler/rustc_codegen_ssa/src/back/apple.rs
index 2c8b0ec418d..d242efaf4fd 100644
--- a/compiler/rustc_codegen_ssa/src/back/apple.rs
+++ b/compiler/rustc_codegen_ssa/src/back/apple.rs
@@ -1,7 +1,4 @@
-use std::env;
 use std::ffi::OsString;
-use std::fmt::{Display, from_fn};
-use std::num::ParseIntError;
 use std::path::PathBuf;
 use std::process::Command;
 
@@ -9,9 +6,10 @@ 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};
+use crate::errors::{XcrunError, XcrunSdkPathWarning};
 use crate::fluent_generated as fluent;
 
 #[cfg(test)]
@@ -134,124 +132,6 @@ 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 {
-        "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"),
-    }
-}
-
-/// 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 env_var = deployment_target_env_var(&sess.target.os);
-
-    if let Ok(deployment_target) = env::var(env_var) {
-        match parse_version(&deployment_target) {
-            Ok(version) => {
-                let os_min = 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
-                // than the minimum for a specific target.
-                if version < os_min {
-                    sess.dcx().emit_warn(AppleDeploymentTarget::TooLow {
-                        env_var,
-                        version: pretty_version(version).to_string(),
-                        os_min: pretty_version(os_min).to_string(),
-                    });
-                }
-
-                // Raise the deployment target to the minimum supported.
-                version.max(min)
-            }
-            Err(error) => {
-                sess.dcx().emit_err(AppleDeploymentTarget::Invalid { env_var, error });
-                min
-            }
-        }
-    } else {
-        // If no deployment target variable is set, default to the minimum found above.
-        min
-    }
-}
-
 pub(super) fn add_version_to_llvm_target(
     llvm_target: &str,
     deployment_target: OSVersion,
@@ -263,18 +143,17 @@ 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}")
     }
 }
 
diff --git a/compiler/rustc_codegen_ssa/src/back/apple/tests.rs b/compiler/rustc_codegen_ssa/src/back/apple/tests.rs
index 8df740a4bcf..5afe79b7195 100644
--- a/compiler/rustc_codegen_ssa/src/back/apple/tests.rs
+++ b/compiler/rustc_codegen_ssa/src/back/apple/tests.rs
@@ -3,24 +3,16 @@ 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() {
     let _developer_dir = xcode_select_developer_dir().unwrap();
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 1c885a2fd5f..1d05c4eee4d 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/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 = format!("{major}.{minor}.{patch}");
+        let min_version = sess.apple_deployment_target().fmt_full().to_string();
 
         // 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 = sess.apple_deployment_target().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.
diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs
index e2c009712d1..ebcccf1b97d 100644
--- a/compiler/rustc_codegen_ssa/src/back/metadata.rs
+++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs
@@ -388,13 +388,13 @@ 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
     }
 
     let platform = apple::macho_platform(&sess.target);
-    let min_os = apple::deployment_target(sess);
+    let min_os = sess.apple_deployment_target();
 
     let mut build_version = object::write::MachOBuildVersion::default();
     build_version.platform = platform;
diff --git a/compiler/rustc_codegen_ssa/src/back/mod.rs b/compiler/rustc_codegen_ssa/src/back/mod.rs
index 875fa6cfa57..8d1adb99930 100644
--- a/compiler/rustc_codegen_ssa/src/back/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/back/mod.rs
@@ -20,7 +20,7 @@ pub mod write;
 /// Certain optimizations also depend on the deployment target.
 pub fn versioned_llvm_target(sess: &Session) -> Cow<'_, str> {
     if sess.target.is_like_darwin {
-        apple::add_version_to_llvm_target(&sess.target.llvm_target, apple::deployment_target(sess))
+        apple::add_version_to_llvm_target(&sess.target.llvm_target, sess.apple_deployment_target())
             .into()
     } else {
         // FIXME(madsmtm): Certain other targets also include a version,
diff --git a/compiler/rustc_codegen_ssa/src/errors.rs b/compiler/rustc_codegen_ssa/src/errors.rs
index f52d29baf9d..b33de8802d8 100644
--- a/compiler/rustc_codegen_ssa/src/errors.rs
+++ b/compiler/rustc_codegen_ssa/src/errors.rs
@@ -3,7 +3,6 @@
 use std::borrow::Cow;
 use std::ffi::OsString;
 use std::io::Error;
-use std::num::ParseIntError;
 use std::path::{Path, PathBuf};
 use std::process::ExitStatus;
 
@@ -739,14 +738,6 @@ pub enum ExtractBundledLibsError<'a> {
 }
 
 #[derive(Diagnostic)]
-pub(crate) enum AppleDeploymentTarget {
-    #[diag(codegen_ssa_apple_deployment_target_invalid)]
-    Invalid { env_var: &'static str, error: ParseIntError },
-    #[diag(codegen_ssa_apple_deployment_target_too_low)]
-    TooLow { env_var: &'static str, version: String, os_min: String },
-}
-
-#[derive(Diagnostic)]
 #[diag(codegen_ssa_read_file)]
 pub(crate) struct ReadFileError {
     pub message: std::io::Error,
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index f36e42cc6b9..67217927a87 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/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)]