[all-commits] [llvm/llvm-project] 7f4705: [Driver][MinGW] Always put libc argument last, eve...

[Keno Fischer via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7f470586e10543aa12efc7e04d4d4ac814eaca35
      https://github.com/llvm/llvm-project/commit/7f470586e10543aa12efc7e04d4d4ac814eaca35
  Author: Keno Fischer <keno at juliahub.com>
  Date:   2025-07-30 (Wed, 30 Jul 2025)

  Changed paths:
    M clang/lib/Driver/ToolChains/MinGW.cpp
    M clang/test/Driver/mingw-msvcrt.c

  Log Message:
  -----------
  [Driver][MinGW] Always put libc argument last, even if non-standard (#149434)

I was attempting to build openblas with clang in msys2's `ucrt64`
environment (I'm aware of the `clang64` environment, but I wanted
libstdc++). The openblas link failed with the following:

```
clang -march=native -mtune=native -m64  -O2 -fno-asynchronous-unwind-tables -O2 -DSMALL_MATRIX_OPT -DMS_ABI -DMAX_STACK_ALLOC=2048 -Wall -m64 -DF_INTERFACE_GFORT -DDYNAMIC_ARCH -DSMP_SERVER -DNO_WARMUP -DMAX_CPU_NUMBER=512 -DMAX_PARALLEL_NUMBER=1 -DBUILD_SINGLE=1 -DBUILD_DOUBLE=1 -DBUILD_COMPLEX=1 -DBUILD_COMPLEX16=1 -DVERSION=\"0.3.29\" -UASMNAME -UASMFNAME -UNAME -UCNAME -UCHAR_NAME -UCHAR_CNAME -DASMNAME= -DASMFNAME=_ -DNAME=_ -DCNAME= -DCHAR_NAME=\"_\" -DCHAR_CNAME=\"\" -DNO_AFFINITY -I..  libopenblas64_.def dllinit.obj \
-shared -o ../libopenblas64_.dll -Wl,--out-implib,../libopenblas64_.dll.a \
-Wl,--whole-archive ../libopenblas64_p-r0.3.29.a -Wl,--no-whole-archive -LC:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/15.1.0 -LC:/msys64/ucrt64/bin/../lib/gcc -LC:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/15.1.0/../../../../x86_64-w64-mingw32/lib/../lib -LC:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/15.1.0/../../../../lib -LC:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/15.1.0/../../../../x86_64-w64-mingw32/lib -LC:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/15.1.0/../../..  -lgfortran -lmingwex -lmsvcrt -lquadmath -lm -lpthread -lmingwex -lmsvcrt  -defaultlib:advapi32 -lgfortran -defaultlib:advapi32 -lgfortran

C:/msys64/ucrt64/bin/ld: C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/15.1.0/../../../../lib/libmingw32.a(lib64_libmingw32_a-pseudo-reloc.o): in function `__report_error':
D:/W/B/src/mingw-w64/mingw-w64-crt/crt/pseudo-reloc.c:157:(.text+0x59): undefined reference to `abort'
C:/msys64/ucrt64/bin/ld: C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/15.1.0/../../../../lib/libmingw32.a(lib64_libmingw32_a-tlsthrd.o): in function `___w64_mingwthr_add_key_dtor':
D:/W/B/src/mingw-w64/mingw-w64-crt/crt/tlsthrd.c:48:(.text+0xa5): undefined reference to `calloc'
C:/msys64/ucrt64/bin/ld: C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/15.1.0/../../../../lib/libmingw32.a(lib64_libmingw32_a-pesect.o): in function `_FindPESectionByName':
D:/W/B/src/mingw-w64/mingw-w64-crt/crt/pesect.c:79:(.text+0xfd): undefined reference to `strncmp'
```

These symbols come from the `-lmingw32` dep that the driver added and
are ordinarily found in `-lmsvcrt`, which got skipped here, because
openblas passed `-lmsvcrt` explicitly earlier in the link line. Since we
always add these libraries at the end here, I think that clang is "at
fault" (as opposed to a user or packaging mistake) and should have added
some crt here.

To preserve the intent of letting the user override which crt is chosen,
duplicate the (first) user chosen crt `-l` into this position, although
we should perhaps consider an explicit `-mcrtdll` like gcc has as well.



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