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[RFC] gcc 4.8 vs glibc alias macros

Dunno if alpha is going to be the only glibc port to encounter this, if it should be considered a gcc bug, or what.

Without this patch, using mainline gcc, I get

./../include/libc-symbols.h:485:26: error: â__EI___isnanfâ aliased to external symbol â__GI___isnanfâ
   extern __typeof (name) __EI_##name \
./../include/libc-symbols.h:489:29: note: in expansion of macro '__hidden_ver1'
 #  define hidden_def(name)  __hidden_ver1(__GI_##name, name, name);
../ports/sysdeps/alpha/fpu/s_isnan.c:48:1: note: in expansion of macro 'hidden_def'
 hidden_def (__isnanf)

We get this because I chained aliases from __isnan to __isnanf to __GI___isnanf.

The patch works around this by defining both __isnanf and __GI___isnanf in terms of the original __isnan.

This isn't 100% correct since the __GI___isnanf symbol gets defined in the object file with visibility default, but it doesn't matter in practice because the users of the symbol still see the hidden_proto and so when the symbols are merged in the linker and link map applied, it acquires hidden visibility.

I'm looking for opinions as to whether (1) this is a gcc bug and (2) whether the patch should be applied to glibc regardless.

>From 9b0aca04145daf0d22d607e88d6fa2df8c49f11b Mon Sep 17 00:00:00 2001
From: Richard Henderson <>
Date: Thu, 30 Aug 2012 12:02:50 -0700
Subject: [PATCH] alpha: Work around gcc 4.8 aliasing difference/bug

 ports/ChangeLog.alpha             |  5 +++++
 ports/sysdeps/alpha/fpu/s_isnan.c | 12 +++++-------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/ports/ChangeLog.alpha b/ports/ChangeLog.alpha
index 19edf6f..9589dd3 100644
--- a/ports/ChangeLog.alpha
+++ b/ports/ChangeLog.alpha
@@ -1,3 +1,8 @@
+2012-08-30  Richard Henderson  <>
+	* sysdeps/alpha/fpu/s_isnan.c: Define all aliases in terms of
+	the original __isnan symbol.
 2012-08-27  Mike Frysinger  <>
 	[BZ #5400]
diff --git a/ports/sysdeps/alpha/fpu/s_isnan.c b/ports/sysdeps/alpha/fpu/s_isnan.c
index b18c7bb..1f239ac 100644
--- a/ports/sysdeps/alpha/fpu/s_isnan.c
+++ b/ports/sysdeps/alpha/fpu/s_isnan.c
@@ -28,11 +28,6 @@
 #undef isnanf
 #undef __GI___isnanf
-/* The hidden_proto in include/math.h was obscured by the macro hackery.  */
-__typeof (__isnan) __isnanf;
-hidden_proto (__isnanf)
 __isnan (double x)
@@ -45,8 +40,11 @@ weak_alias (__isnan, isnan)
 /* It turns out that the 'double' version will also always work for
    single-precision.  */
 strong_alias (__isnan, __isnanf)
-hidden_def (__isnanf)
-weak_alias (__isnanf, isnanf)
+weak_alias (__isnan, isnanf)
+/* ??? GCC 4.8 fails to look through chains of aliases with asm names
+   attached.  Work around this for now.  */
+hidden_ver (__isnan, __isnanf)
 strong_alias (__isnan, __isnanl)

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