diff options
Diffstat (limited to 'compiler/rustc_codegen_ssa/src')
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/back/link.rs | 48 | ||||
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/back/metadata.rs | 10 |
2 files changed, 48 insertions, 10 deletions
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs index a23cc512926..e7b1c63a822 100644 --- a/compiler/rustc_codegen_ssa/src/back/link.rs +++ b/compiler/rustc_codegen_ssa/src/back/link.rs @@ -2959,11 +2959,12 @@ pub(crate) fn are_upstream_rust_objects_already_included(sess: &Session) -> bool } } -/// We need to communicate four things to the linker on Apple/Darwin targets: +/// We need to communicate five things to the linker on Apple/Darwin targets: /// - The architecture. /// - The operating system (and that it's an Apple platform). -/// - The deployment target. /// - The environment / ABI. +/// - The deployment target. +/// - The SDK version. fn add_apple_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) { if !sess.target.is_like_osx { return; @@ -3039,7 +3040,38 @@ fn add_apple_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavo let (major, minor, patch) = current_apple_deployment_target(&sess.target); let min_version = format!("{major}.{minor}.{patch}"); - // Lie about the SDK version, we don't know it here + // 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.: + // <https://github.com/apple-oss-distributions/dyld/blob/dyld-1165.3/common/MachOFile.cpp#L3029> + // <https://github.com/apple-oss-distributions/dyld/blob/dyld-1165.3/common/MachOFile.cpp#L3738-L3857> + // - By system frameworks to change certain behaviour. For example, the default value of + // `-[NSView wantsBestResolutionOpenGLSurface]` is `YES` when the SDK version is >= 10.15. + // <https://developer.apple.com/documentation/appkit/nsview/1414938-wantsbestresolutionopenglsurface?language=objc> + // + // We do not currently know the actual SDK version though, so we have a few options: + // 1. Use the minimum version supported by rustc. + // 2. Use the same as the deployment target. + // 3. Use an arbitary recent version. + // 4. Omit the version. + // + // The first option is too low / too conservative, and means that users will not get the + // same behaviour from a binary compiled with rustc as with one compiled by clang. + // + // The second option is similarly conservative, and also wrong since if the user specified a + // higher deployment target than the SDK they're compiling/linking with, the runtime might + // make invalid assumptions about the capabilities of the binary. + // + // The third option requires that `rustc` is periodically kept up to date with Apple's SDK + // version, and is also wrong for similar reasons as above. + // + // The fourth option is bad because while `ld`, `otool`, `vtool` and such understand it to + // mean "absent" or `n/a`, dyld doesn't actually understand it, and will end up interpreting + // it as 0.0, which is again too low/conservative. + // + // Currently, we lie about the SDK version, and choose the second option. + // + // FIXME(madsmtm): Parse the SDK version from the SDK root instead. + // <https://github.com/rust-lang/rust/issues/129432> let sdk_version = &*min_version; // From the man page for ld64 (`man ld`): @@ -3053,11 +3085,13 @@ fn add_apple_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavo cmd.link_args(&["-platform_version", platform_name, &*min_version, sdk_version]); } else { // cc == Cc::Yes + // // We'd _like_ to use `-target` everywhere, since that can uniquely - // communicate all the required details, but that doesn't work on GCC, - // and since we don't know whether the `cc` compiler is Clang, GCC, or - // something else, we fall back to other options that also work on GCC - // when compiling for macOS. + // communicate all the required details except for the SDK version + // (which is read by Clang itself from the SDKROOT), but that doesn't + // work on GCC, and since we don't know whether the `cc` compiler is + // Clang, GCC, or something else, we fall back to other options that + // also work on GCC when compiling for macOS. // // Targets other than macOS are ill-supported by GCC (it doesn't even // support e.g. `-miphoneos-version-min`), so in those cases we can diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs index 06433484ea3..8857fda1e97 100644 --- a/compiler/rustc_codegen_ssa/src/back/metadata.rs +++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs @@ -402,13 +402,17 @@ fn macho_object_build_version_for_target(target: &Target) -> object::write::Mach let platform = rustc_target::spec::current_apple_platform(target).expect("unknown Apple target OS"); let min_os = rustc_target::spec::current_apple_deployment_target(target); - let (sdk_major, sdk_minor) = - rustc_target::spec::current_apple_sdk_version(platform).expect("unknown Apple target OS"); let mut build_version = object::write::MachOBuildVersion::default(); build_version.platform = platform; build_version.minos = pack_version(min_os); - build_version.sdk = pack_version((sdk_major, sdk_minor, 0)); + // The version here does not _really_ matter, since it is only used at runtime, and we specify + // it when linking the final binary, so we will omit the version. This is also what LLVM does, + // and the tooling also allows this (and shows the SDK version as `n/a`). Finally, it is the + // semantically correct choice, as the SDK has not influenced the binary generated by rustc at + // this point in time. + build_version.sdk = 0; + build_version } |