vendored libelf compilation issue on ARM64 with clang

[KarstenB]

When I try to clippy the build with a vendored libelf on arm64 with clang:

sudo apt install  libclang-dev autopoint m4 flex bison gawk clang
export CC=clang
cargo clippy --all-targets --features=vendored-libelf

I get the following error:

 configure: WARNING: not running biarch tests, clang -m32 does not work
  error: unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
  error: unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
  error: unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
  make: *** [Makefile:497: xasprintf.o] Error 1
  make: *** Waiting for unfinished jobs....
  make: *** [Makefile:497: xstrdup.o] Error 1
  error: unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
  error: unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
  error: unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
  make: *** [Makefile:497: xstrndup.o] Error 1
  error: unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
  error: make: *** [Makefile:497: xmalloc.o] Error 1
  unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
  error: unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
  make: *** [Makefile:497: next_prime.o] Error 1
  make: *** [Makefile:497: crc32_file.o] Error 1
  error: unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
  make: *** [Makefile:497: error.o] Error 1
  make: *** [Makefile:497: crc32.o] Error 1
  make: *** [Makefile:497: color.o] Error 1
  make: *** [Makefile:497: printversion.o] Error 1

This is caused by this code, which when removed, works as expected:

    #[cfg(target_arch = "aarch64")]
    cflags.push_str(" -Wno-error=stringop-overflow");

When this code is removed, and I use GCC, it still compiles successfully. Maybe something that this was supposed to workaround has been fixed upstream?

[d-e-s-o]

It's from c043865. cc @mmullin-halcyon. Perhaps try with CFLAGS -Wno-unknown-warning-option.

[KarstenB]

My workaround is to simply export CC=gcc. I don't really care which compiler is used, and it works. But I feel like this code no longer serves any pupose, the commit is even labeled hotfix.