From: Alexander Miller <alex.miller@gmx.de>
Date: Thu, 30 Sep 2021 01:39:57 +0000 (+0200)
Subject: build: Allow building with -flto on gcc-10 and newer
X-Git-Tag: 0.11.4~15
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c7a5d780ae58b6f7ae7d814fd5bc53cf1f58ee5f;p=thirdparty%2Flibbsd.git

build: Allow building with -flto on gcc-10 and newer

Global asm statements (like .symver directives) do not work reliably
in gcc with link time optimization. Use the symver attribute introduced
with gcc-10 to set symbol versions instead, if available.

[guillem@hadrons.org:
 - Simplify by using __has_attribute fallback from <sys/cdefs.h>.
 - Coding style changes. ]

Signed-off-by: Guillem Jover <guillem@hadrons.org>
---

diff --git a/src/local-link.h b/src/local-link.h
index 55fd028..fd1949c 100644
--- a/src/local-link.h
+++ b/src/local-link.h
@@ -27,16 +27,28 @@
 #ifndef LIBBSD_LOCAL_LINK_H
 #define LIBBSD_LOCAL_LINK_H
 
+#include <sys/cdefs.h>
+
 #define libbsd_link_warning(symbol, msg) \
 	static const char libbsd_emit_link_warning_##symbol[] \
 		__attribute__((__used__,__section__(".gnu.warning." #symbol))) = msg
 
 #ifdef __ELF__
+#  if __has_attribute(symver)
+/* The symver attribute is supported since gcc 10.x. */
+#define libbsd_symver_default(alias, symbol, version) \
+	extern __typeof(symbol) symbol \
+		__attribute((__symver__(#alias "@@" #version)))
+#define libbsd_symver_variant(alias, symbol, version) \
+	extern __typeof(symbol) symbol \
+		__attribute((__symver__(#alias "@" #version)))
+#  else
 #define libbsd_symver_default(alias, symbol, version) \
 	__asm__(".symver " #symbol "," #alias "@@" #version)
 
 #define libbsd_symver_variant(alias, symbol, version) \
 	__asm__(".symver " #symbol "," #alias "@" #version)
+#  endif
 #else
 #define libbsd_symver_default(alias, symbol, version) \
 	extern __typeof(symbol) alias __attribute__((__alias__(#symbol)))