LLVM build failures on Windows/Mac

[Hoverbear]

Summary

On Windows and Mac, x.py build src/llvm-project can fail when download-ci-llvm = false is set in the config.toml.

Command used

Clone the rust repo, then copy the config.example.toml to config.toml and set the following:

[llvm]
download-ci-llvm = false

Then run:

x.py build src/llvm-project

Expected behaviour

A successful build, exiting 0.

Actual behaviour

On Mac, the result is:

-- Installing: /Users/ana/git/ferrocene/ferrocene/build/aarch64-apple-darwin/lld/lib/cmake/lld/LLDConfigVersion.cmake
cargo:root=/Users/ana/git/ferrocene/ferrocene/build/aarch64-apple-darwin/lld
        finished in 31.764 seconds
Building crtbegin.o and crtend.o for aarch64-apple-darwin
cargo:warning=/Users/ana/git/ferrocene/ferrocene/src/llvm-project/compiler-rt/lib/builtins/crtbegin.c:15:28: error: argument to 'section' attribute is not valid for this target: mach-o section specifier requires a segment and section separated by a comma
cargo:warning=   15 |     __attribute__((section(".eh_frame"), aligned(sizeof(void *)))) = {};
cargo:warning=      |                            ^
cargo:warning=/Users/ana/git/ferrocene/ferrocene/src/llvm-project/compiler-rt/lib/builtins/crtbegin.c:49:24: error: argument to 'section' attribute is not valid for this target: mach-o section specifier requires a segment and section separated by a comma
cargo:warning=   49 | __attribute__((section(".init_array"),
cargo:warning=      |                        ^
cargo:warning=/Users/ana/git/ferrocene/ferrocene/src/llvm-project/compiler-rt/lib/builtins/crtbegin.c:106:24: error: argument to 'section' attribute is not valid for this target: mach-o section specifier requires a segment and section separated by a comma
cargo:warning=  106 | __attribute__((section(".fini_array"),
cargo:warning=      |                        ^
cargo:warning=3 errors generated.


error occurred: Command env -u IPHONEOS_DEPLOYMENT_TARGET "cc" "-O3" "-ffunction-sections" "-fdata-sections" "-fPIC" "--target=arm64-apple-macosx15.2" "-std=c11" "-DCRT_HAS_INITFINI_ARRAY" "-DEH_USE_FRAME_REGISTRY" "-o" "/Users/ana/git/ferrocene/ferrocene/build/aarch64-apple-darwin/native/crt/df7af2d07715af86-crtbegin.o" "-c" "/Users/ana/git/ferrocene/ferrocene/src/llvm-project/compiler-rt/lib/builtins/crtbegin.c" with args cc did not execute successfully (status code exit status: 1).

On Windows, the result is:

-- Installing: D:/git/ferrocene/ferrocene/build/x86_64-pc-windows-msvc/llvm/include/llvm/Config/llvm-config.h
-- Installing: D:/git/ferrocene/ferrocene/build/x86_64-pc-windows-msvc/llvm/include/llvm/Support/VCSRevision.h
-- Installing: D:/git/ferrocene/ferrocene/build/x86_64-pc-windows-msvc/llvm/lib/cmake/llvm/LLVMConfigExtensions.cmake

cargo:root=D:\git\ferrocene\ferrocene\build\x86_64-pc-windows-msvc\llvm
        finished in 1242.431 seconds
Building crtbegin.o and crtend.o for x86_64-pc-windows-msvc



cargo:warning=cl : Command line warning D9002 : ignoring unknown option '-std=c11'
crtbegin.c
D:\git\ferrocene\ferrocene\src/llvm-project/compiler-rt/lib/builtins/crtbegin.c(9): fatal error C1034: stddef.h: no include path set


error occurred: Command "C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\MSVC\\14.40.33807\\bin\\HostX64\\x64\\cl.exe" "-nologo" "-MD" "-O2" "-Brepro" "-std=c11" "-DCRT_HAS_INITFINI_ARRAY" "-DEH_USE_FRAME_REGISTRY" "-FoD:\\git\\ferrocene\\ferrocene\\build\\x86_64-pc-windows-msvc\\native\\crt\\89a91fa0b39682bb-crtbegin.o" "-c" "D:\\git\\ferrocene\\ferrocene\\src/llvm-project/compiler-rt/lib/builtins/crtbegin.c" with args cl.exe did not execute successfully (status code exit code: 2).


Build completed unsuccessfully in 0:39:09

Bootstrap configuration (config.toml)

The same as the config.example.toml but:

[llvm]
download-ci-llvm = false

Operating system

This is happening on, as far as I know, all Windows and Mac targets. I tested on Mac 15.2 and Windows 11 24H2.

HEAD

bcd0683 and 6a64e3b both display the issue

Additional context

After discussing with @japaric, I believe that these steps (building crtbegin.o and crtend.o) are unnecessary, bootstrap seems to claim that these steps are for cross compiling to MUSL.

We believe the issue happened sometime between #134839 (where the problem is not present) and #134987 (where the problem is now present)

(Build logs excluded as they are longer than the Github Issues limit)

windows-log.txt

mac-log.txt

[onur-ozkan]

#132994 might be related.

[japaric]

my observations so far

some recent change in bootstrap made it such that ./x build src/llvm-project now includes the CrtBeginEnd step (which is mapped to path src/llvm-project/compiler-rt/lib/crt). I don't think this change is wrong.

./x build src/llvm-project/compiler-rt/lib/crt will try to compile the CRT objects to the host triple. Those objects are meant to be cross compiled to MUSL as you can see in copy_self_contained_objects where the CrtBeginEnd build is guarded by a target.contains("musl") check. I think this is the part of the logic that's wrong.

I don't think the cc update is the problem because ./x build src/llvm-project/compiler-rt/lib/crt will configure cc::Build to compile to the host triple which then uses the wrong compiler (cl.exe on Windows and a machO-default gcc on macOS). Case in point, that ./x build src/llvm-project/compiler-rt/lib/crt command also tries to do native compilation (+) on revision 6e1c115 which does not include cc update PR

In conclusion, I think ./x build src/llvm-project/compiler-rt/lib/crt has been broken since a while ago and only now that has surfaced in ./x build src/llvm-project because of recent changes. I think that to fix this CrtBeginEnd::make_run should skip the actual build (CrtBeginEnd::run) if the target is not MUSL to match the logic in copy_self_contained_objects.

(+) I should mention that I only have a Linux box around so I can't actually repro the problem seen on macOS and Windows but if I add an assertion like assert!(self.target.triple.contains("musl")) to CrtBeginEnd::run then I can see the panic. self.target.triple is passed to cc::Build in that function and it's set to x86_64-linux (the host triple) when I run ./x build src/llvm-project/compiler-rt/lib/crt.

[Hoverbear]

@japaric asked me to repro the issue on Mac from checkout 6e1c11591fc7e98015f8e793a15c8faf0bda67f1. Here is the output of ./x build src/llvm-project/compiler-rt/lib/crt :

Submodule path 'src/llvm-project': checked out '104d0d16c3c7c3fef2435fef6efb2d57b70fff73'
downloading https://static.rust-lang.org/dist/2024-10-16/rustfmt-nightly-aarch64-apple-darwin.tar.xz
################################################################################################################################################################# 100.0%
extracting /Users/ana/git/rust-lang/rust/build/cache/2024-10-16/rustfmt-nightly-aarch64-apple-darwin.tar.xz to /Users/ana/git/rust-lang/rust/build/aarch64-apple-darwin/rustfmt
downloading https://static.rust-lang.org/dist/2024-10-16/rustc-nightly-aarch64-apple-darwin.tar.xz
################################################################################################################################################################# 100.0%
extracting /Users/ana/git/rust-lang/rust/build/cache/2024-10-16/rustc-nightly-aarch64-apple-darwin.tar.xz to /Users/ana/git/rust-lang/rust/build/aarch64-apple-darwin/rustfmt
Building crtbegin.o and crtend.o for aarch64-apple-darwin
cargo:warning=/Users/ana/git/rust-lang/rust/src/llvm-project/compiler-rt/lib/builtins/crtbegin.c:15:28: error: argument to 'section' attribute is not valid for this target: mach-o section specifier requires a segment and section separated by a comma
cargo:warning=   15 |     __attribute__((section(".eh_frame"), aligned(sizeof(void *)))) = {};
cargo:warning=      |                            ^
cargo:warning=/Users/ana/git/rust-lang/rust/src/llvm-project/compiler-rt/lib/builtins/crtbegin.c:49:24: error: argument to 'section' attribute is not valid for this target: mach-o section specifier requires a segment and section separated by a comma
cargo:warning=   49 | __attribute__((section(".init_array"),
cargo:warning=      |                        ^
cargo:warning=/Users/ana/git/rust-lang/rust/src/llvm-project/compiler-rt/lib/builtins/crtbegin.c:106:24: error: argument to 'section' attribute is not valid for this target: mach-o section specifier requires a segment and section separated by a comma
cargo:warning=  106 | __attribute__((section(".fini_array"),
cargo:warning=      |                        ^
cargo:warning=3 errors generated.


error occurred: Command env -u IPHONEOS_DEPLOYMENT_TARGET "cc" "-O3" "-ffunction-sections" "-fdata-sections" "-fPIC" "--target=arm64-apple-darwin" "-mmacosx-version-min=15.2" "-std=c11" "-DCRT_HAS_INITFINI_ARRAY" "-DEH_USE_FRAME_REGISTRY" "-o" "/Users/ana/git/rust-lang/rust/build/aarch64-apple-darwin/native/crt/201e8d6b412081ae-crtbegin.o" "-c" "/Users/ana/git/rust-lang/rust/src/llvm-project/compiler-rt/lib/builtins/crtbegin.c" with args cc did not execute successfully (status code exit status: 1).


Build completed unsuccessfully in 0:01:13
Took 1min 14sec 350ms