'Call clzl check' breaks cross compilation (was: PATCH 13/22] Coarray caf_shmem final patch set)

Hi Jerry & Andre,

the commit r16-7734-g136940891b16ba breaks cross compilation:

Jerry D wrote:
> From: Andre Vehreschild<[email protected]>
> Date: Thu, 12 Feb 2026 11:17:47 -0800
> Subject: [PATCH] Fortran: Add a shared memory coarray implementation [PR88076]
>
> Add caf_shmem, a shared memory multi process coarray implementation.
> The library adheres to the existing coarray ABI and is controlled by
> environment variables for selecting the number of images and virtual
> memory size.
...
> libgfortran/ChangeLog:
>
> 	* Makefile.am: Add new library.
> 	* Makefile.in: Regenerated
> 	* acinclude.m4: Add check for reasonable clzl.
> 	* config.h.in: Regenerate.
> 	* configure: Regenerate.
> 	* configure.ac: Call clzl check.
* * *
> --- a/libgfortran/acinclude.m4
> +++ b/libgfortran/acinclude.m4
...
> +AC_DEFUN([LIBGFOR_CHECK_SANE_BUILTIN_CLZL], [
> +  AC_RUN_IFELSE([AC_LANG_PROGRAM([[
> +      int main()
> +      {
> +	return __builtin_clzl(256) != 8;
> +      }]], [[]])],
> +    AC_DEFINE(HAVE_SANE_BUILTIN_CLZL, 1,
> +      [Define if __builtin_clzl behaves as expected.])
> +    AM_CONDITIONAL([HAVE_SANE_BUILTIN_CLZL],true),
> +    [AM_CONDITIONAL([HAVE_SANE_BUILTIN_CLZL],false)])
> +])

This fails with:

configure: error: in build-gcc-trunk-offload-amdgcn/amdgcn-amdhsa/libgfortran'
configure: error: cannot run test program while cross compiling

Namely, the generated configure file contains:
> # Check if __builtin_clzl behaves (it doesn't on Msys2/ucrt64).
>
>    if test "$cross_compiling" = yes; then :
>    { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
> $as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
> as_fn_error $? "cannot run test program while cross compiling
> See \`config.log' for more details" "$LINENO" 5; }
> else

In the code, you can either use code like:
   if test "$cross_compiling" != no; then
for the current code and the following in an else branch.
Or just the following:

   case "${host}" in
   *-*-mingw32*)
       ....
     ;;
   *)
     ....
     ;;
   esac

In any case, AC_RUN_IFELSE is wrong for cross compilation,
AC_COMPILE_IFELSE is fine.

Tobias