[glibc/azanella/clang] configure: Use -Wno-restrict iff compiler supports it

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b42d0f75b071481e8a4844b0887d229a21ee0c0e

commit b42d0f75b071481e8a4844b0887d229a21ee0c0e
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Thu Jul 27 15:49:52 2023 -0300

    configure: Use -Wno-restrict iff compiler supports it

Diff:
---
 configure      | 24 ++++++++++++++++++++++++
 configure.ac   |  8 ++++++++
 libio/Makefile |  4 ++--
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 04cefde3d3..07f5ddedc0 100755
--- a/configure
+++ b/configure
@@ -7214,6 +7214,30 @@ printf "%s\n" "$libc_cv_wno_maybe_uninitialized" >&6; }
 config_vars="$config_vars
 config-cflags-wno-maybe-uninitialized = $libc_cv_wno_maybe_uninitialized"
 
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for -Wno-restrict" >&5
+printf %s "checking for -Wno-restrict... " >&6; }
+if test ${libc_cv_wno_restrict+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+  		if { ac_try='${CC-cc} -Werror -Wno-restrict -xc /dev/null -S -o /dev/null'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then :
+  libc_cv_wno_restrict=-Wno-restrict
+else $as_nop
+  libc_cv_wno_restrict=
+fi
+
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_wno_restrict" >&5
+printf "%s\n" "$libc_cv_wno_restrict" >&6; }
+config_vars="$config_vars
+config-cflags-wno-restrict = $libc_cv_wno_restrict"
+
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for -fexcess-precision=standard" >&5
 printf %s "checking for -fexcess-precision=standard... " >&6; }
 if test ${libc_cv_fexcess_precision_standard+y}
diff --git a/configure.ac b/configure.ac
index f0ef446df3..fc50642673 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1394,6 +1394,14 @@ AC_CACHE_CHECK([for -Wno-maybe-uninitialized], libc_cv_wno_maybe_uninitialized,
 LIBC_CONFIG_VAR([config-cflags-wno-maybe-uninitialized],
 		[$libc_cv_wno_maybe_uninitialized])
 
+AC_CACHE_CHECK([for -Wno-restrict], libc_cv_wno_restrict, [dnl
+		LIBC_TRY_CC_OPTION([-Werror -Wno-restrict],
+				   [libc_cv_wno_restrict=-Wno-restrict],
+				   [libc_cv_wno_restrict=])
+])
+LIBC_CONFIG_VAR([config-cflags-wno-restrict],
+		[$libc_cv_wno_restrict])
+
 AC_CACHE_CHECK([for -fexcess-precision=standard], libc_cv_fexcess_precision_standard, [dnl
 		LIBC_TRY_CC_OPTION([-Werror -fexcess-precision=standard],
 				   [libc_cv_fexcess_precision_standard=-fexcess-precision=standard],
diff --git a/libio/Makefile b/libio/Makefile
index 287ec11338..549912a06c 100644
--- a/libio/Makefile
+++ b/libio/Makefile
@@ -187,8 +187,8 @@ CFLAGS-tst-bz24153.c += $(no-fortify-source)
 CFLAGS-tst_putwc.c += -DOBJPFX=\"$(objpfx)\"
 
 # These test cases intentionally use overlapping arguments
-CFLAGS-tst-sprintf-ub.c += -Wno-restrict $(no-fortify-source)
-CFLAGS-tst-sprintf-chk-ub.c += -Wno-restrict $(no-fortify-source)
+CFLAGS-tst-sprintf-ub.c += $(config-cflags-wno-restrict) $(no-fortify-source)
+CFLAGS-tst-sprintf-chk-ub.c += $(config-cflags-wno-restrict) $(no-fortify-source)
 
 LDFLAGS-tst-bz24228 = -Wl,--version-script=tst-bz24228.map