[PATCH v2 27/28] configure: remove overly restrictive check for clang

[H.J. Lu]

On Wed, Oct 29, 2025 at 1:13 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
> The clang support is still experimental and not all testcase build
> or run correctly.  Only clang 18 and onwards is supported and only
> for x86_64-linux-gnu and aarch64-linux-gnu.
> ---
>  NEWS         | 5 +++++
>  configure    | 4 ++--
>  configure.ac | 4 ++--
>  3 files changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/NEWS b/NEWS
> index 244f7613d8..b4348ac51b 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -13,6 +13,11 @@ Major new features:
>
>  * The ISO C23 memalignment function has been added.
>
> +* Initial support for building with clang has been added.  It requires
> +  at least clang version 18, aarch64-linux-gnu or x86_64-linux-gnu
> +  targets, and libgcc compatible runtime (including libgcc_s.so for
> +  pthread cancellation and backtrace runtime support).
> +
>  Deprecated and removed features, and other changes affecting compatibility:
>
>  * Support for dumped heaps has been removed - malloc_set_state() now always
> diff --git a/configure b/configure
> index 3c926be3ec..a21ce56302 100755
> --- a/configure
> +++ b/configure
> @@ -5799,7 +5799,7 @@ int
>  main (void)
>  {
>
> -#if !defined __GNUC__ || __GNUC__ < 12 || (__GNUC__ == 12 && __GNUC_MINOR__ < 1)
> +#if (!defined __GNUC__ || __GNUC__ < 12 || (__GNUC__ == 12 && __GNUC_MINOR__ < 1)) && (!defined __clang__ || __clang_major__ < 18)
>  #error insufficient compiler
>  #endif
>    ;
> @@ -7642,7 +7642,7 @@ else case e in #(
>  extern char *strstr (const char *, const char *) __asm ("my_strstr");
>  char *foo (const char *a, const char *b)
>  {
> -  return __builtin_strstr (a, b);
> +  return strstr (a, b);
>  }
>  EOF
>  if { ac_try='${CC-cc} -O3 -S conftest.c -o - | grep -F "my_strstr" > /dev/null'
> diff --git a/configure.ac b/configure.ac
> index 890f1b1c9c..29c45632fd 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -585,7 +585,7 @@ AC_CHECK_PROG_VER(BISON, bison, --version,
>  # Require GCC 12.1 to build.
>  AC_CACHE_CHECK([if $CC is sufficient to build libc], libc_cv_compiler_ok, [
>  AC_PREPROC_IFELSE([AC_LANG_PROGRAM([[]], [[
> -#if !defined __GNUC__ || __GNUC__ < 12 || (__GNUC__ == 12 && __GNUC_MINOR__ < 1)
> +#if (!defined __GNUC__ || __GNUC__ < 12 || (__GNUC__ == 12 && __GNUC_MINOR__ < 1)) && (!defined __clang__ || __clang_major__ < 18)
>  #error insufficient compiler

This change doesn't match the subject which should require clang 18 or above.

>  #endif]])],
>                [libc_cv_compiler_ok=yes],
> @@ -1474,7 +1474,7 @@ cat > conftest.c <<\EOF
>  extern char *strstr (const char *, const char *) __asm ("my_strstr");
>  char *foo (const char *a, const char *b)
>  {
> -  return __builtin_strstr (a, b);
> +  return strstr (a, b);

This should be a separate patch with a clear explanation.

>  }
>  EOF
>  dnl
> --
> 2.43.0
>


-- 
H.J.