Re: [PATCH] fstatat: support NULL if AT_EMPTY_PATH

Paul Eggert wrote:
> diff --git a/m4/fstatat.m4 b/m4/fstatat.m4
> index d53e8d9196..ceeb211d34 100644
> --- a/m4/fstatat.m4
> +++ b/m4/fstatat.m4
...
> +           [gl_saved_CFLAGS=$CFLAGS
> +            CFLAGS="$CFLAGS -Wno-nonnull"
> +            AC_RUN_IFELSE(
...

I think two things are wrong here:

  - A missing statement
      CFLAGS=$gl_saved_CFLAGS
    after the AC_RUN_IFELSE macro.

  - The -Wno-nonnull option surely works only with gcc, clang, and
    compatible compilers. How about testing whether -Wno-nonnull
    works, first?

    AC_CACHE_CHECK([whether -Wnonnull is supported],
      [gl_cv_cc_nonnull_supported],
      [gl_saved_CFLAGS="$CFLAGS"
       CFLAGS="$CFLAGS -Wnonnull"
       AC_COMPILE_IFELSE(
         [AC_LANG_PROGRAM([[]], [[]])],
         [gl_cv_cc_nonnull_supported=yes],
         [gl_cv_cc_nonnull_supported=no])
       CFLAGS="$gl_saved_CFLAGS"
      ])

Bruno