`raw-dylib` usage in std broke thumbv7a-*-windows-msvc targets

[bdbai]

Starting from nightly-2024-02-26 rust version 1.78.0-nightly (0ecbd0605 2024-02-25), std for thumbv7a-uwp-windows-msvc no longer builds:

cargo +nightly-2024-02-26 build -Z build-std=std,panic_abort --target thumbv7a-uwp-windows-msvc --release

Output:

...
error: could not compile `std` (lib)                                                                                                                           

Caused by:
  process didn't exit successfully: `C:\Users\bdbai\.rustup\toolchains\nightly-2024-02-26-x86_64-pc-windows-msvc\bin\rustc.exe --crate-name std --edition=2021 C:\Users\bdbai\.rustup\toolchains\nightly-2024-02-26-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\std\src\lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=158 --crate-type rlib --emit=dep-info,metadata,link -C opt-level=3 -C embed-bitcode=no --cfg "feature=\"addr2line\"" --cfg "feature=\"backtrace\"" --cfg "feature=\"gimli-symbolize\"" --cfg "feature=\"miniz_oxide\"" --cfg "feature=\"object\"" --cfg "feature=\"panic_unwind\"" --cfg "feature=\"std_detect_dlsym_getauxval\"" --cfg "feature=\"std_detect_file_io\"" -C metadata=e432070f6e8a70e3 -C extra-filename=-e432070f6e8a70e3 --out-dir C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps --target thumbv7a-uwp-windows-msvc -Z force-unstable-if-unmarked -L dependency=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps -L dependency=C:\project_dir\target\release\deps --extern priv:addr2line=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libaddr2line-08740835d495a638.rmeta --extern alloc=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\liballoc-ffcd7e68b1b4d768.rmeta --extern priv:cfg_if=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libcfg_if-ed9aa18cde72cb83.rmeta --extern priv:compiler_builtins=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libcompiler_builtins-4dc2d4fb24785f49.rmeta --extern core=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libcore-e9d96bbb4564a7c8.rmeta --extern priv:hashbrown=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libhashbrown-bbafedfdf9ba97f2.rmeta --extern libc=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\liblibc-b57e343fcebc03aa.rmeta --extern priv:miniz_oxide=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libminiz_oxide-58abf01af28732ef.rmeta --extern priv:object=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libobject-d7dbd142c5e57f98.rmeta --extern priv:panic_abort=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libpanic_abort-d509d9c2350c464a.rmeta --extern priv:panic_unwind=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libpanic_unwind-ba05a49921f1f9c0.rmeta --extern priv:rustc_demangle=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\librustc_demangle-d8165352be6fe153.rmeta --extern priv:std_detect=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libstd_detect-937e46cacab5d26e.rmeta --extern priv:unwind=C:\project_dir\target\thumbv7a-uwp-windows-msvc\release\deps\libunwind-bd6619bcb4fe0878.rmeta -Z unstable-options --cap-lints allow --cfg backtrace_in_libstd` (exit code: 0xc000001d, STATUS_ILLEGAL_INSTRUCTION)
warning: build failed, waiting for other jobs to finish...
...

This looks very similar to the error reported in #120921 , which indicates somewhere in std is using raw-dylib already and triggers the same issue within llvm. Looks like #121337 is the first PR that introduces raw-dylib and so far there are a handful of other places (like f68529f) using it as well. Given llvm is having issues for this particular platform, can we consider excluding thumbv7a from using raw-dylib in std, or at least there would be a way to workaround this?

Ping @ChrisDenton @bjorn3

[bjorn3]

Is this still an issue? The import library writer has been rewritten into Rust rather than using the LLVM version. And if it is still an issue, what is the panic message?