From 3addb4c1e8a50df7dcf4465a7f149f78bf5af78b Mon Sep 17 00:00:00 2001
From: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
Date: Sun, 26 Mar 2023 10:38:43 +0100
Subject: [PATCH] build: Improve `SECP_TRY_APPEND_DEFAULT_CFLAGS` macro

Co-authored-by: Tim Ruffing <crypto@timruffing.de>
---
 configure.ac | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/configure.ac b/configure.ac
index 1276dfaacd527..1722d0abd85dc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -88,11 +88,14 @@ esac
 AC_DEFUN([SECP_TRY_APPEND_DEFAULT_CFLAGS], [
     # GCC and compatible (incl. clang)
     if test "x$GCC" = "xyes"; then
-      # Try to append -Werror=unknown-warning-option to CFLAGS temporarily. Otherwise clang will
-      # not error out if it gets unknown warning flags and the checks here will always succeed
-      # no matter if clang knows the flag or not.
+      # Try to append -Werror to CFLAGS temporarily. Otherwise checks for some unsupported
+      # flags will succeed.
+      # Note that failure to append -Werror does not necessarily mean that -Werror is not
+      # supported. The compiler may already be warning about something unrelated, for example
+      # about some path issue. If that is the case, -Werror cannot be used because all
+      # of those warnings would be turned into errors.
       SECP_TRY_APPEND_DEFAULT_CFLAGS_saved_CFLAGS="$CFLAGS"
-      SECP_TRY_APPEND_CFLAGS([-Werror=unknown-warning-option], CFLAGS)
+      SECP_TRY_APPEND_CFLAGS([-Werror], CFLAGS)
 
       SECP_TRY_APPEND_CFLAGS([-std=c89 -pedantic -Wno-long-long -Wnested-externs -Wshadow -Wstrict-prototypes -Wundef], $1) # GCC >= 3.0, -Wlong-long is implied by -pedantic.
       SECP_TRY_APPEND_CFLAGS([-Wno-overlength-strings], $1) # GCC >= 4.2, -Woverlength-strings is implied by -pedantic.