Implement raw-dylib on Mach-O

[madsmtm]

Implements #146356 by adding the raw_dylib_macho feature flag.

@Noratrieb sniped me at RustWeek few months back to investigate this, never got around to finishing it.

This is a draft because I found out (after being 80% done with the impl) that using LLVM's TextAPI is probably not going to fly if we want to support other codegen backends, we'll need to write .tbd stubs ourselves.

TODO:

• Figure out which TextAPI version to support (should at least support our minimum host tooling).
• Write some hacky code to output the yaml manually (we probably don't want to pull in a whole yaml library). Alternatively, emit a Mach-O stub file using object.
• Replace the LLVM TextAPI stuff I've done already.
• Write a properly detailed PR description.
• Add a bunch more tests in different scenarios.

r? bjorn3
CC @Noratrieb @thomcc @roblabla

[rust-log-analyzer]

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tidy check Checking tidy rustdoc_json... No error code explanation was removed! tidy: Skipping binary file check, read-only filesystem ##[error]tidy error: /checkout/compiler/rustc_codegen_ssa/src/back/link/raw_dylib.rs:135: TODO is used for tasks that should be done before merging a PR; If you want to leave a message in the codebase use FIXME ##[error]tidy error: /checkout/compiler/rustc_codegen_ssa/src/back/link/raw_dylib.rs:142: TODO is used for tasks that should be done before merging a PR; If you want to leave a message in the codebase use FIXME ##[error]tidy error: /checkout/compiler/rustc_codegen_ssa/src/back/link/raw_dylib.rs:154: TODO is used for tasks that should be done before merging a PR; If you want to leave a message in the codebase use FIXME ##[error]tidy error: /checkout/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp:1968: TODO is used for tasks that should be done before merging a PR; If you want to leave a message in the codebase use FIXME removing old virtual environment creating virtual environment at '/checkout/obj/build/venv' using 'python3.10' and 'venv' creating virtual environment at '/checkout/obj/build/venv' using 'python3.10' and 'virtualenv' Requirement already satisfied: pip in ./build/venv/lib/python3.10/site-packages (25.2) linting python files --- ^ /checkout/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp:1963:29: error: code should be clang-formatted [-Wclang-format-violations] uint32_t CurrentVersion, ^ /checkout/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp:1965:43: error: code should be clang-formatted [-Wclang-format-violations] const LLVMRustMachOTbdExport *Exports, ^ /checkout/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp:1981:72: error: code should be clang-formatted [-Wclang-format-violations] File.addSymbol(Exports[i].kind, StringRef(Exports[i].name), Target, Exports[i].flags); ^ /checkout/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp:1994:67: error: code should be clang-formatted [-Wclang-format-violations] if (Error Err = MachO::TextAPIWriter::writeToStream(OS, File)) { ^ /checkout/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp:1995:62: error: code should be clang-formatted [-Wclang-format-violations] LLVMRustSetLastError(toString(std::move(Err)).c_str()); ^ clang-format linting failed! Printing diff suggestions: --- /checkout/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp (actual) +++ /checkout/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp (formatted) @@ -1956,15 +1956,11 @@ MachO::EncodeKind kind; }; extern "C" uint8_t LLVMRustMachoTbdWrite( - const char *Path, - const char *LLVMTargetName, - const char *InstallName, - uint32_t CurrentVersion, - uint32_t CompatibilityVersion, - const LLVMRustMachOTbdExport *Exports, - size_t NumExports) { + const char *Path, const char *LLVMTargetName, const char *InstallName, + uint32_t CurrentVersion, uint32_t CompatibilityVersion, + const LLVMRustMachOTbdExport *Exports, size_t NumExports) { MachO::InterfaceFile File; File.setFileType(MachO::FileType::TBD_V1); // TODO File.setInstallName(StringRef(InstallName)); @@ -1977,9 +1973,10 @@ MachO::Target Target{Triple(LLVMTargetName)}; File.addTarget(Target); for (size_t i = 0; i < NumExports; i++) { - File.addSymbol(Exports[i].kind, StringRef(Exports[i].name), Target, Exports[i].flags); + File.addSymbol(Exports[i].kind, StringRef(Exports[i].name), Target, + Exports[i].flags); } std::string ErrorInfo; std::error_code EC; @@ -1991,10 +1988,10 @@ return -1; } if (Error Err = MachO::TextAPIWriter::writeToStream(OS, File)) { - LLVMRustSetLastError(toString(std::move(Err)).c_str()); - return -1; + LLVMRustSetLastError(toString(std::move(Err)).c_str()); + return -1; } return 0; } some tidy checks failed tidy error: checks with external tool 'clang-format' failed Bootstrap failed while executing `test src/tools/tidy tidyselftest --extra-checks=py,cpp,js,spellcheck` Command `/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-tools-bin/rust-tidy /checkout /checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo /checkout/obj/build 4 /node/bin/npm --extra-checks=py,cpp,js,spellcheck` failed with exit code 1 Created at: src/bootstrap/src/core/build_steps/tool.rs:1550:23 Executed at: src/bootstrap/src/core/build_steps/test.rs:1281:29 Command has failed. Rerun with -v to see more details. Build completed unsuccessfully in 0:01:18 local time: Tue Sep 9 02:00:13 UTC 2025 network time: Tue, 09 Sep 2025 02:00:13 GMT ##[error]Process completed with exit code 1. Post job cleanup. 

[bors]

☔ The latest upstream changes (presumably #146636) made this pull request unmergeable. Please resolve the merge conflicts.