Rollup merge of rust-lang#133092 - madsmtm:bootstrap-deployment-target, r=Mark-Simulacrum

Always set the deployment target when building std

`cc` has [a bug/feature](rust-lang/cc-rs#1171) (I guess depending on how you look at it) where the default deployment target is taken from the SDK instead of from `rustc`. This causes `compiler-builtins` to build `compiler-rt` with the wrong deployment target on iOS.

I've been meaning to change how `cc` works in this regard, but that's a lengthy process, so let's fix it in bootstrap for now.

The behaviour be seen locally with `./x build library --set build.optimized-compiler-builtins=true` for various target triples, and then inspecting with `otool -l build/host/stage1/lib/rustlib/*/lib/libcompiler_builtins-*.rlib | rg 'minos|version'`. I have added a rmake test that ensures that we now have the same version everywhere.

Fixes rust-lang#128419
Fixes rust-lang/compiler-builtins#650
See also rust-lang/cargo#13115

`@rustbot` label O-apple

Author: Zalathar

src/bootstrap/src/core/build_steps/compile.rs

@@ -462,8 +462,63 @@ fn compiler_rt_for_profiler(builder: &Builder<'_>) -> PathBuf {
 /// Configure cargo to compile the standard library, adding appropriate env vars
 /// and such.
 pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, cargo: &mut Cargo) {
-    if let Some(target) = env::var_os("MACOSX_STD_DEPLOYMENT_TARGET") {
-        cargo.env("MACOSX_DEPLOYMENT_TARGET", target);
+    // rustc already ensures that it builds with the minimum deployment
+    // target, so ideally we shouldn't need to do anything here.
+    //
+    // However, `cc` currently defaults to a higher version for backwards
+    // compatibility, which means that compiler-rt, which is built via
+    // compiler-builtins' build script, gets built with a higher deployment
+    // target. This in turn causes warnings while linking, and is generally
+    // a compatibility hazard.
+    //
+    // So, at least until https://github.com/rust-lang/cc-rs/issues/1171, or
+    // perhaps https://github.com/rust-lang/cargo/issues/13115 is resolved, we
+    // explicitly set the deployment target environment variables to avoid
+    // this issue.
+    //
+    // This place also serves as an extension point if we ever wanted to raise
+    // rustc's default deployment target while keeping the prebuilt `std` at
+    // a lower version, so it's kinda nice to have in any case.
+    if target.contains("apple") && !builder.config.dry_run() {
+        // Query rustc for the deployment target.
+        let mut cmd = command(builder.rustc(cargo.compiler()));
+        cmd.arg("--target").arg(target.rustc_target_arg());
+        cmd.arg("--print=deployment-target");
+        let output = cmd.run_capture_stdout(builder).stdout();
+
+        let value = output.split('=').last().unwrap().trim();
+
+        // FIXME: Simplify after https://github.com/rust-lang/rust/pull/133041
+        let env_var = if target.contains("apple-darwin") {
+            "MACOSX_DEPLOYMENT_TARGET"
+        } else if target.contains("apple-ios") {
+            "IPHONEOS_DEPLOYMENT_TARGET"
+        } else if target.contains("apple-tvos") {
+            "TVOS_DEPLOYMENT_TARGET"
+        } else if target.contains("apple-watchos") {
+            "WATCHOS_DEPLOYMENT_TARGET"
+        } else if target.contains("apple-visionos") {
+            "XROS_DEPLOYMENT_TARGET"
+        } else {
+            panic!("unknown target OS for apple target");
+        };
+
+        // Unconditionally set the env var (if it was set in the environment
+        // already, rustc should've picked that up).
+        cargo.env(env_var, value);
+
+        // Allow CI to override the deployment target for `std` on macOS.
+        //
+        // This is useful because we might want the host tooling LLVM, `rustc`
+        // and Cargo to have a different deployment target than `std` itself
+        // (currently, these two versions are the same, but in the past, we
+        // supported macOS 10.7 for user code and macOS 10.8 in host tooling).
+        //
+        // It is not necessary on the other platforms, since only macOS has
+        // support for host tooling.
+        if let Some(target) = env::var_os("MACOSX_STD_DEPLOYMENT_TARGET") {
+            cargo.env("MACOSX_DEPLOYMENT_TARGET", target);
+        }
     }
 
     // Paths needed by `library/profiler_builtins/build.rs`.
@@ -1564,7 +1619,8 @@ pub fn compiler_file(
         return PathBuf::new();
     }
     let mut cmd = command(compiler);
-    cmd.args(builder.cflags(target, GitRepo::Rustc, c));
+    cmd.args(builder.default_cflags(target, c));
+    cmd.args(builder.extra_cflags(target, GitRepo::Rustc, c));
     cmd.arg(format!("-print-file-name={file}"));
     let out = cmd.run_capture_stdout(builder).stdout();
     PathBuf::from(out.trim())

src/bootstrap/src/core/build_steps/llvm.rs

@@ -534,7 +534,7 @@ impl Step for Llvm {
             cfg.define("LLVM_VERSION_SUFFIX", suffix);
         }
 
-        configure_cmake(builder, target, &mut cfg, true, ldflags, &[]);
+        configure_cmake(builder, target, &mut cfg, true, ldflags);
         configure_llvm(builder, target, &mut cfg);
 
         for (key, val) in &builder.config.llvm_build_config {
@@ -623,7 +623,6 @@ fn configure_cmake(
     cfg: &mut cmake::Config,
     use_compiler_launcher: bool,
     mut ldflags: LdFlags,
-    suppressed_compiler_flag_prefixes: &[&str],
 ) {
     // Do not print installation messages for up-to-date files.
     // LLVM and LLD builds can produce a lot of those and hit CI limits on log size.
@@ -757,17 +756,8 @@ fn configure_cmake(
     }
 
     cfg.build_arg("-j").build_arg(builder.jobs().to_string());
-    let mut cflags: OsString = builder
-        .cflags(target, GitRepo::Llvm, CLang::C)
-        .into_iter()
-        .filter(|flag| {
-            !suppressed_compiler_flag_prefixes
-                .iter()
-                .any(|suppressed_prefix| flag.starts_with(suppressed_prefix))
-        })
-        .collect::<Vec<String>>()
-        .join(" ")
-        .into();
+    let mut cflags: OsString =
+        builder.extra_cflags(target, GitRepo::Llvm, CLang::C).join(" ").into();
     if let Some(ref s) = builder.config.llvm_cflags {
         cflags.push(" ");
         cflags.push(s);
@@ -777,17 +767,8 @@ fn configure_cmake(
         cflags.push(format!(" --target={target}"));
     }
     cfg.define("CMAKE_C_FLAGS", cflags);
-    let mut cxxflags: OsString = builder
-        .cflags(target, GitRepo::Llvm, CLang::Cxx)
-        .into_iter()
-        .filter(|flag| {
-            !suppressed_compiler_flag_prefixes
-                .iter()
-                .any(|suppressed_prefix| flag.starts_with(suppressed_prefix))
-        })
-        .collect::<Vec<String>>()
-        .join(" ")
-        .into();
+    let mut cxxflags: OsString =
+        builder.extra_cflags(target, GitRepo::Llvm, CLang::Cxx).join(" ").into();
     if let Some(ref s) = builder.config.llvm_cxxflags {
         cxxflags.push(" ");
         cxxflags.push(s);
@@ -950,7 +931,7 @@ impl Step for Enzyme {
         // FIXME(ZuseZ4): Find a nicer way to use Enzyme Debug builds
         //cfg.profile("Debug");
         //cfg.define("CMAKE_BUILD_TYPE", "Debug");
-        configure_cmake(builder, target, &mut cfg, true, LdFlags::default(), &[]);
+        configure_cmake(builder, target, &mut cfg, true, LdFlags::default());
 
         // Re-use the same flags as llvm to control the level of debug information
         // generated for lld.
@@ -1065,7 +1046,7 @@ impl Step for Lld {
             ldflags.push_all("-Wl,-rpath,'$ORIGIN/../../../'");
         }
 
-        configure_cmake(builder, target, &mut cfg, true, ldflags, &[]);
+        configure_cmake(builder, target, &mut cfg, true, ldflags);
         configure_llvm(builder, target, &mut cfg);
 
         // Re-use the same flags as llvm to control the level of debug information
@@ -1164,20 +1145,7 @@ impl Step for Sanitizers {
         // Unfortunately sccache currently lacks support to build them successfully.
         // Disable compiler launcher on Darwin targets to avoid potential issues.
         let use_compiler_launcher = !self.target.contains("apple-darwin");
-        // Since v1.0.86, the cc crate adds -mmacosx-version-min to the default
-        // flags on MacOS. A long-standing bug in the CMake rules for compiler-rt
-        // causes architecture detection to be skipped when this flag is present,
-        // and compilation fails. https://github.com/llvm/llvm-project/issues/88780
-        let suppressed_compiler_flag_prefixes: &[&str] =
-            if self.target.contains("apple-darwin") { &["-mmacosx-version-min="] } else { &[] };
-        configure_cmake(
-            builder,
-            self.target,
-            &mut cfg,
-            use_compiler_launcher,
-            LdFlags::default(),
-            suppressed_compiler_flag_prefixes,
-        );
+        configure_cmake(builder, self.target, &mut cfg, use_compiler_launcher, LdFlags::default());
 
         t!(fs::create_dir_all(&out_dir));
         cfg.out_dir(out_dir);

src/bootstrap/src/core/build_steps/test.rs

@@ -2014,14 +2014,18 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
         // Only pass correct values for these flags for the `run-make` suite as it
         // requires that a C++ compiler was configured which isn't always the case.
         if !builder.config.dry_run() && mode == "run-make" {
+            let mut cflags = builder.default_cflags(target, CLang::C);
+            cflags.extend(builder.extra_cflags(target, GitRepo::Rustc, CLang::C));
+            let mut cxxflags = builder.default_cflags(target, CLang::Cxx);
+            cxxflags.extend(builder.extra_cflags(target, GitRepo::Rustc, CLang::Cxx));
             cmd.arg("--cc")
                 .arg(builder.cc(target))
                 .arg("--cxx")
                 .arg(builder.cxx(target).unwrap())
                 .arg("--cflags")
-                .arg(builder.cflags(target, GitRepo::Rustc, CLang::C).join(" "))
+                .arg(cflags.join(" "))
                 .arg("--cxxflags")
-                .arg(builder.cflags(target, GitRepo::Rustc, CLang::Cxx).join(" "));
+                .arg(cxxflags.join(" "));
             copts_passed = true;
             if let Some(ar) = builder.ar(target) {
                 cmd.arg("--ar").arg(ar);

src/bootstrap/src/core/builder/cargo.rs

@@ -122,6 +122,10 @@ impl Cargo {
         cargo
     }
 
+    pub fn compiler(&self) -> Compiler {
+        self.compiler
+    }
+
     pub fn into_cmd(self) -> BootstrapCommand {
         self.into()
     }
@@ -307,7 +311,7 @@ impl Cargo {
             let cc = ccacheify(&builder.cc(target));
             self.command.env(format!("CC_{triple_underscored}"), &cc);
 
-            let cflags = builder.cflags(target, GitRepo::Rustc, CLang::C).join(" ");
+            let cflags = builder.extra_cflags(target, GitRepo::Rustc, CLang::C).join(" ");
             self.command.env(format!("CFLAGS_{triple_underscored}"), &cflags);
 
             if let Some(ar) = builder.ar(target) {
@@ -319,7 +323,7 @@ impl Cargo {
 
             if let Ok(cxx) = builder.cxx(target) {
                 let cxx = ccacheify(&cxx);
-                let cxxflags = builder.cflags(target, GitRepo::Rustc, CLang::Cxx).join(" ");
+                let cxxflags = builder.extra_cflags(target, GitRepo::Rustc, CLang::Cxx).join(" ");
                 self.command
                     .env(format!("CXX_{triple_underscored}"), &cxx)
                     .env(format!("CXXFLAGS_{triple_underscored}"), cxxflags);

src/bootstrap/src/lib.rs

@@ -250,6 +250,7 @@ impl Mode {
     }
 }
 
+#[derive(Debug, Hash, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub enum CLang {
     C,
     Cxx,
@@ -1187,9 +1188,9 @@ Executed at: {executed_at}"#,
         self.cc.borrow()[&target].path().into()
     }
 
-    /// Returns a list of flags to pass to the C compiler for the target
-    /// specified.
-    fn cflags(&self, target: TargetSelection, which: GitRepo, c: CLang) -> Vec<String> {
+    /// Returns C flags that `cc-rs` thinks should be enabled for the
+    /// specified target by default.
+    fn default_cflags(&self, target: TargetSelection, c: CLang) -> Vec<String> {
         if self.config.dry_run() {
             return Vec::new();
         }
@@ -1198,14 +1199,18 @@ Executed at: {executed_at}"#,
             CLang::Cxx => self.cxx.borrow()[&target].clone(),
         };
 
-        // Filter out -O and /O (the optimization flags) that we picked up from
-        // cc-rs because the build scripts will determine that for themselves.
-        let mut base = base
-            .args()
+        // Filter out -O and /O (the optimization flags) that we picked up
+        // from cc-rs, that's up to the caller to figure out.
+        base.args()
             .iter()
             .map(|s| s.to_string_lossy().into_owned())
             .filter(|s| !s.starts_with("-O") && !s.starts_with("/O"))
-            .collect::<Vec<String>>();
+            .collect::<Vec<String>>()
+    }
+
+    /// Returns extra C flags that `cc-rs` doesn't handle.
+    fn extra_cflags(&self, target: TargetSelection, which: GitRepo, c: CLang) -> Vec<String> {
+        let mut base = Vec::new();
 
         // If we're compiling C++ on macOS then we add a flag indicating that
         // we want libc++ (more filled out than libstdc++), ensuring that

src/bootstrap/src/utils/cc_detect.rs

@@ -132,7 +132,8 @@ pub fn find_target(build: &Build, target: TargetSelection) {
     };
 
     build.cc.borrow_mut().insert(target, compiler.clone());
-    let cflags = build.cflags(target, GitRepo::Rustc, CLang::C);
+    let mut cflags = build.default_cflags(target, CLang::C);
+    cflags.extend(build.extra_cflags(target, GitRepo::Rustc, CLang::C));
 
     // If we use llvm-libunwind, we will need a C++ compiler as well for all targets
     // We'll need one anyways if the target triple is also a host triple
@@ -158,7 +159,8 @@ pub fn find_target(build: &Build, target: TargetSelection) {
     build.verbose(|| println!("CC_{} = {:?}", target.triple, build.cc(target)));
     build.verbose(|| println!("CFLAGS_{} = {cflags:?}", target.triple));
     if let Ok(cxx) = build.cxx(target) {
-        let cxxflags = build.cflags(target, GitRepo::Rustc, CLang::Cxx);
+        let mut cxxflags = build.default_cflags(target, CLang::Cxx);
+        cxxflags.extend(build.extra_cflags(target, GitRepo::Rustc, CLang::Cxx));
         build.verbose(|| println!("CXX_{} = {cxx:?}", target.triple));
         build.verbose(|| println!("CXXFLAGS_{} = {cxxflags:?}", target.triple));
     }

tests/run-make/apple-deployment-target/rmake.rs

@@ -7,7 +7,11 @@
 
 //@ only-apple
 
-use run_make_support::{apple_os, cmd, run_in_tmpdir, rustc, target};
+use std::collections::HashSet;
+
+use run_make_support::{
+    apple_os, cmd, has_extension, path, regex, run_in_tmpdir, rustc, shallow_find_files, target,
+};
 
 /// Run vtool to check the `minos` field in LC_BUILD_VERSION.
 ///
@@ -156,4 +160,21 @@ fn main() {
         rustc().env_remove(env_var).run();
         minos("foo.o", default_version);
     });
+
+    // Test that all binaries in rlibs produced by `rustc` have the same version.
+    // Regression test for https://github.com/rust-lang/rust/issues/128419.
+    let sysroot = rustc().print("sysroot").run().stdout_utf8();
+    let target_sysroot = path(sysroot.trim()).join("lib/rustlib").join(target()).join("lib");
+    let rlibs = shallow_find_files(&target_sysroot, |path| has_extension(path, "rlib"));
+
+    let output = cmd("otool").arg("-l").args(rlibs).run().stdout_utf8();
+    let re = regex::Regex::new(r"(minos|version) ([0-9.]*)").unwrap();
+    let mut versions = HashSet::new();
+    for (_, [_, version]) in re.captures_iter(&output).map(|c| c.extract()) {
+        versions.insert(version);
+    }
+    // FIXME(madsmtm): See above for aarch64-apple-watchos.
+    if versions.len() != 1 && target() != "aarch64-apple-watchos" {
+        panic!("std rlibs contained multiple different deployment target versions: {versions:?}");
+    }
 }