From fd70a41ac6df0c3c19458cd9fb9ebcc5c54b8c84 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Diego=20=27Flameeyes=27=20Petten=C3=B2?=
 <flameeyes@gmail.com>
Date: Fri, 16 Mar 2007 20:12:41 +0000
Subject: Add a check if the compiler supports weak aliases, to add FreeBSD
 support to Real codecs.

CVS patchset: 8680
CVS date: 2007/03/16 20:12:41
---
 m4/attributes.m4 | 81 +++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 71 insertions(+), 10 deletions(-)

(limited to 'm4')

diff --git a/m4/attributes.m4 b/m4/attributes.m4
index fa00a95f8..a83390006 100644
--- a/m4/attributes.m4
+++ b/m4/attributes.m4
@@ -1,13 +1,42 @@
 # Functions to check for attributes support in compiler
 
+AC_DEFUN([CC_CHECK_CFLAGS], [
+	ac_save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $1"
+	AC_MSG_CHECKING([if compiler supports $1])
+	AC_COMPILE_IFELSE([int a;],
+		[cc_check_cflags=yes],
+		[cc_check_cflags=no])
+	AC_MSG_RESULT([$cc_check_cflags])
+	CFLAGS="$ac_save_CFLAGS"
+	
+	if test "x$cc_check_cflags" = "xyes"; then
+		true
+		$2
+	else
+		true
+		$3
+	fi
+])
+
+AC_DEFUN([CC_CHECK_WERROR], [
+	CC_CHECK_CFLAGS([-Werror], [werror=-Werror])
+
+	dnl This is for SUN Studio compiler
+	if test "x$werror" = "x"; then
+		CC_CHECK_CFLAGS([-errwarn=%all], [werror=-errwarn=%all])
+	fi
+])
+
 AC_DEFUN([CC_ATTRIBUTE_CONSTRUCTOR], [
+	AC_REQUIRE([CC_CHECK_WERROR])
 	ac_save_CFLAGS="$CFLAGS"
-	CFLAGS="$CFLAGS -Werror"
+	CFLAGS="$CFLAGS $werror"
 	AC_CACHE_CHECK([if compiler supports __attribute__((constructor))],
 		[cc_cv_attribute_constructor],
 		[AC_COMPILE_IFELSE([
 			void ctor() __attribute__((constructor));
-			void ctor() { };
+			void ctor() { int a; };
 			],
 			[cc_cv_attribute_constructor=yes],
 			[cc_cv_attribute_constructor=no])
@@ -24,8 +53,9 @@ AC_DEFUN([CC_ATTRIBUTE_CONSTRUCTOR], [
 ])
 
 AC_DEFUN([CC_ATTRIBUTE_FORMAT], [
+	AC_REQUIRE([CC_CHECK_WERROR])
 	ac_save_CFLAGS="$CFLAGS"
-	CFLAGS="$CFLAGS -Werror"
+	CFLAGS="$CFLAGS $werror"
 	AC_CACHE_CHECK([if compiler supports __attribute__((format(printf, n, n)))],
 		[cc_cv_attribute_format],
 		[AC_COMPILE_IFELSE([
@@ -46,8 +76,9 @@ AC_DEFUN([CC_ATTRIBUTE_FORMAT], [
 ])
 
 AC_DEFUN([CC_ATTRIBUTE_FORMAT_ARG], [
+	AC_REQUIRE([CC_CHECK_WERROR])
 	ac_save_CFLAGS="$CFLAGS"
-	CFLAGS="$CFLAGS -Werror"
+	CFLAGS="$CFLAGS $werror"
 	AC_CACHE_CHECK([if compiler supports __attribute__((format_arg(printf)))],
 		[cc_cv_attribute_format_arg],
 		[AC_COMPILE_IFELSE([
@@ -68,8 +99,9 @@ AC_DEFUN([CC_ATTRIBUTE_FORMAT_ARG], [
 ])
 
 AC_DEFUN([CC_ATTRIBUTE_VISIBILITY], [
+	AC_REQUIRE([CC_CHECK_WERROR])
 	ac_save_CFLAGS="$CFLAGS"
-	CFLAGS="$CFLAGS -Werror"
+	CFLAGS="$CFLAGS $werror"
 	AC_CACHE_CHECK([if compiler supports __attribute__((visibility("...")))],
 		[cc_cv_attribute_visibility],
 		[AC_COMPILE_IFELSE([
@@ -92,8 +124,9 @@ AC_DEFUN([CC_ATTRIBUTE_VISIBILITY], [
 ])
 
 AC_DEFUN([CC_FLAG_VISIBILITY], [
+	AC_REQUIRE([CC_CHECK_WERROR])
 	ac_save_CFLAGS="$CFLAGS"
-	CFLAGS="$CFLAGS -Werror"
+	CFLAGS="$CFLAGS $werror"
 	AC_CACHE_CHECK([if compiler supports -fvisibility=hidden],
 		[cc_cv_flag_visibility],
 		[
@@ -116,8 +149,9 @@ AC_DEFUN([CC_FLAG_VISIBILITY], [
 ])
 
 AC_DEFUN([CC_ATTRIBUTE_NONNULL], [
+	AC_REQUIRE([CC_CHECK_WERROR])
 	ac_save_CFLAGS="$CFLAGS"
-	CFLAGS="$CFLAGS -Werror"
+	CFLAGS="$CFLAGS $werror"
 	AC_CACHE_CHECK([if compiler supports __attribute__((nonnull()))],
 		[cc_cv_attribute_nonnull],
 		[AC_COMPILE_IFELSE([
@@ -139,8 +173,9 @@ AC_DEFUN([CC_ATTRIBUTE_NONNULL], [
 ])
 
 AC_DEFUN([CC_ATTRIBUTE_UNUSED], [
+	AC_REQUIRE([CC_CHECK_WERROR])
 	ac_save_CFLAGS="$CFLAGS"
-	CFLAGS="$CFLAGS -Werror"
+	CFLAGS="$CFLAGS $werror"
 	AC_CACHE_CHECK([if compiler supports __attribute__((unused))],
 		[cc_cv_attribute_unused],
 		[AC_COMPILE_IFELSE([
@@ -161,8 +196,9 @@ AC_DEFUN([CC_ATTRIBUTE_UNUSED], [
 ])
 
 AC_DEFUN([CC_FUNC_EXPECT], [
+	AC_REQUIRE([CC_CHECK_WERROR])
 	ac_save_CFLAGS="$CFLAGS"
-	CFLAGS="$CFLAGS -Werror"
+	CFLAGS="$CFLAGS $werror"
 	AC_CACHE_CHECK([if compiler has __builtin_expect function],
 		[cc_cv_func_expect],
 		[AC_COMPILE_IFELSE([
@@ -187,8 +223,9 @@ AC_DEFUN([CC_FUNC_EXPECT], [
 ])
 
 AC_DEFUN([CC_ATTRIBUTE_SENTINEL], [
+	AC_REQUIRE([CC_CHECK_WERROR])
 	ac_save_CFLAGS="$CFLAGS"
-	CFLAGS="$CFLAGS -Werror"
+	CFLAGS="$CFLAGS $werror"
 	AC_CACHE_CHECK([if compiler supports __attribute__((sentinel))],
 		[cc_cv_attribute_sentinel],
 		[AC_COMPILE_IFELSE([
@@ -207,3 +244,27 @@ AC_DEFUN([CC_ATTRIBUTE_SENTINEL], [
 		$2
 	fi
 ])
+
+AC_DEFUN([CC_ATTRIBUTE_ALIAS], [
+	AC_REQUIRE([CC_CHECK_WERROR])
+	ac_save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $werror"
+	AC_CACHE_CHECK([if compiler supports __attribute__((weak, alias))],
+		[cc_cv_attribute_alias],
+		[AC_COMPILE_IFELSE([
+			void other_function(void *foo) { }
+			void some_function(void *foo) __attribute__((weak, alias("other_function")));
+			],
+			[cc_cv_attribute_alias=yes],
+			[cc_cv_attribute_alias=no])
+		])
+	CFLAGS="$ac_save_CFLAGS"
+	
+	if test "x$cc_cv_attribute_alias" = "xyes"; then
+		AC_DEFINE([SUPPORT_ATTRIBUTE_ALIAS], 1, [Define this if the compiler supports the alias attribute])
+		$1
+	else
+		true
+		$2
+	fi
+])
-- 
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