From: Alan T. DeKok <aland@freeradius.org>
Date: Thu, 23 Oct 2025 09:51:31 +0000 (+0200)
Subject: use -std=c23 if it's available, otherwise use -std=c11
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=1bd7a59004d6c463937acafb3ad8bdd5fa16d619;p=thirdparty%2Ffreeradius-server.git

use -std=c23 if it's available, otherwise use -std=c11

the "configure" script was not yet updated
---

diff --git a/configure.ac b/configure.ac
index 754d4c52f1..f2cd044e89 100644
--- a/configure.ac
+++ b/configure.ac
@@ -341,11 +341,16 @@ else
   AC_SUBST(clang_path, "")
 fi
 
-AX_CC_STD_C11
-if test "x$ax_cv_cc_std_c11_flag" != x; then
-  CFLAGS="$CFLAGS $ax_cv_cc_std_c11_flag"
+AX_CC_STD_C23
+if test "x$ax_cv_cc_std_c23_flag" != x; then
+  CFLAGS="$CFLAGS $ax_cv_cc_std_c23_flag"
 else
-  AC_MSG_ERROR([FreeRADIUS requires a C11 compiler])
+  AX_CC_STD_C11
+  if test "x$ax_cv_cc_std_c11_flag" != x; then
+    CFLAGS="$CFLAGS $ax_cv_cc_std_c11_flag"
+  else
+    AC_MSG_ERROR([FreeRADIUS requires a C11 compiler])
+  fi
 fi
 
 dnl #
diff --git a/m4/ax_cc.m4 b/m4/ax_cc.m4
index 88b69875e5..8e712562cb 100644
--- a/m4/ax_cc.m4
+++ b/m4/ax_cc.m4
@@ -15,6 +15,31 @@ AC_DEFUN([AX_CC_IS_CLANG],[
   ])
 ])
 
+AC_DEFUN([AX_CC_STD_C23],[
+  AC_CACHE_CHECK([for the compiler flag to enable C23 support], [ax_cv_cc_std_c23_flag],[
+    ax_cv_cc_std_c23_flag=
+
+    CFLAGS_SAVED=$CFLAGS
+    CFLAGS="$CFLAGS -Werror -std=c23"
+
+    AC_LANG_PUSH(C)
+    AC_TRY_COMPILE(
+      [],
+      [
+        struct foo {
+          union {
+            int a;
+            int b;
+          };
+        } bar;
+      ],
+      [ax_cv_cc_std_c23_flag="-std=c23"])
+
+    AC_LANG_POP
+    CFLAGS="$CFLAGS_SAVED"
+  ])
+])
+
 dnl #
 dnl # clang and gcc originally used different flags to specify c11 support
 dnl #