Hi,
I'm compiling gnulib 23eecb48e39afd0d267d64d40ba6bf97aa865e13 with gcc-4.6,
and using it from a C++ project compiled with g++-4.6 -std=c++0x
When I attempt to include argp.h, compilation fails:
% cat foo.cc
#include "config.h"
#include "argp.h"
% g++-4.6 -DHAVE_CONFIG_H -Ilib -Wall -Werror -std=c++0x -c foo.cc
In file included from foo.cc:2:0:
lib/argp.h:623:1: error: ‘__leaf__’ attribute has no effect on unit
local functions [-Werror=attributes]
lib/argp.h:635:1: error: ‘__leaf__’ attribute has no effect on unit
local functions [-Werror=attributes]
Looking at the preprocessed output, I can see that the two functions
: ARGP_EI int
: __NTH (__option_is_short (const struct argp_option *__opt))
: /* ... */
: ARGP_EI int
: __NTH (__option_is_end (const struct argp_option *__opt))
were expanded as:
: static __attribute__ ((__unused__)) int
: __attribute__ ((__leaf__)) _option_is_short (const struct
argp_option *__opt) throw ()
: /* ... */
: static __attribute__ ((__unused__)) int
: __attribute__ ((__leaf__)) _option_is_end (const struct argp_option
*__opt) throw ()
So __leaf__ was indeed applied to a static function. This "static" comes from
the expansion of ARGP_EI:
#define ARGP_EI _GL_INLINE /* in argp.h */
#define _GL_INLINE static _GL_UNUSED /* in config.h */
#define _GL_UNUSED __attribute__ ((__unused__)) /* in config.h */
The warning disappears if I use g++-4.6 without the -std=c++0x option. In this
case these prototypes become:
: extern inline __attribute__ ((__gnu_inline__)) int
: __attribute__ ((__leaf__)) _option_is_short (const struct
argp_option *__opt) throw ()
: /* ... */
: extern inline __attribute__ ((__gnu_inline__)) int
: __attribute__ ((__leaf__)) _option_is_end (const struct argp_option
*__opt) throw ()
because now config.h has
#define _GL_INLINE extern inline __attribute__ ((__gnu_inline__))
The warning also disappear if I use g++-4.7 -std=c++0x. Then we get:
: inline int
: __attribute__ ((__leaf__)) _option_is_short (const struct
argp_option *__opt) throw ()
: /* ... */
: inline int
: __attribute__ ((__leaf__)) _option_is_end (const struct argp_option
*__opt) throw ()
with
#define _GL_INLINE inline /* in config.h */
(The difference between 4.6 -std=c++0x and 4.7 -std=c++0x is that the
former defines __GNUC_GNU_INLINE__ while the latter defines
__GNUC_STDC_INLINE__.)
Comments:
1. I do not understand the effect of marking an inline function as leaf, or
as nothrow. Shouldn't these attributes be only used to help the
compiler when
a function is declared, but its body is unknown?
2. Shouldn't _GL_INLINE/_GL_EXTERN_INLINE simply always expand to
'inline' in C++?
I've patched my copy of argp.h as suggested in point 1 above to fix my
compilation issue (patch attached). But as the implication of __NTH in
conjunction with _GL_INLINE is unclear to me, I'm not sure whether
this is sane.
--
Alexandre Duret-Lutz
From c072aaf3ed47169105fbb23dec64644e4277d9ec Mon Sep 17 00:00:00 2001
From: Alexandre Duret-Lutz <a...@lrde.epita.fr>
Date: Wed, 18 Dec 2013 13:35:21 +0100
Subject: [PATCH] argp: fix compilation with g++-4.6 -std=c++0x.
* lib/argp.h (__option_is_short, __option_is_end) Do not declare
with __NTH. The 'leaf' attribute is unwelcome in the case ARGP_EI
is implemented with 'static' (this occurs when compiling argp.hh
with g++-4.6 -std=c++0x).
---
ChangeLog | 9 +++++++++
lib/argp.h | 4 ++--
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 1753c8e..8dbcdf3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2013-12-18 Alexandre Duret-Lutz <a...@lrde.epita.fr>
+
+ argp: fix compilation with g++-4.6 -std=c++0x.
+
+ * lib/argp.h (__option_is_short, __option_is_end) Do not declare
+ with __NTH. The 'leaf' attribute is unwelcome in the case ARGP_EI
+ is implemented with 'static' (this occurs when compiling argp.hh
+ with g++-4.6 -std=c++0x).
+
2013-12-17 Paul Eggert <egg...@cs.ucla.edu>
gettimeofday: port recent C++ fix to Emacs
diff --git a/lib/argp.h b/lib/argp.h
index a5f686a..99ea26a 100644
--- a/lib/argp.h
+++ b/lib/argp.h
@@ -620,7 +620,7 @@ __argp_usage (const struct argp_state *__state)
}
ARGP_EI int
-__NTH (__option_is_short (const struct argp_option *__opt))
+__option_is_short (const struct argp_option *__opt)
{
if (__opt->flags & OPTION_DOC)
return 0;
@@ -632,7 +632,7 @@ __NTH (__option_is_short (const struct argp_option *__opt))
}
ARGP_EI int
-__NTH (__option_is_end (const struct argp_option *__opt))
+__option_is_end (const struct argp_option *__opt)
{
return !__opt->key && !__opt->name && !__opt->doc && !__opt->group;
}
--
1.8.5.1
