From 4c9af8b6d183ba4f84564dda9c17303b6c10d6f8 Mon Sep 17 00:00:00 2001
From: Viktor Szakats <commit@vsz.me>
Date: Wed, 8 Apr 2026 03:18:11 +0200
Subject: [PATCH] configure: silence useless clang warnings in C89 builds

Syncing with CMake.

Follow-up to 43397b0283d4cdb10797e7ead6eacbe09f8a3e77 #21015
Follow-up to 09c9afdd711d0b2ee9f524a235803e755e1074b7 #20363

Closes #21263
---
 m4/curl-compilers.m4 | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/m4/curl-compilers.m4 b/m4/curl-compilers.m4
index 9fce552515..b37c53ce06 100644
--- a/m4/curl-compilers.m4
+++ b/m4/curl-compilers.m4
@@ -962,6 +962,17 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
               CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [c++-keyword])
             fi
           fi
+
+          case "$CFLAGS" in
+            *-std=c89*|*-std=c90*|*-std=gnu89*|*-std=gnu90*)
+              if test "$compiler_num" -ge "300"; then
+                tmp_CFLAGS="$tmp_CFLAGS -Wno-c99-extensions"  # Avoid: warning: '_Bool' is a C99 extension
+              fi
+              if test "$compiler_num" -ge "309"; then
+                tmp_CFLAGS="$tmp_CFLAGS -Wno-comma"  # Just silly
+              fi
+              ;;
+          esac
         fi
         ;;
         #