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According to Bruno Haible on 12/15/2009 4:51 PM:
>>> to instead use
>>> #define func (GL_LINK_WARNING("..."),func)
>
> You would need that only for functions that take a variable number of
> arguments.
> Currently
> - openat, fprintf, printf, snprintf, fprintf are already using your proposed
> idiom,
> - ioctl is not, and should be changed.
openat was only half-using it. dprintf was also broken. I'm committing
this as a stop-gap measure, until I finish the much bigger job of the
attribute approach.
> - The trick is to write
> #if HAVE_DECL_FOO
> extern __typeof__(foo) foo __attribute__ ((__warning__ ("message")));
> #endif
Thanks for the tip. And you are right - as long as we depend on gcc, then
we can use __typeof__ to make applying the attribute typesafe via a single
reusable macro (where the macro takes two arguments: foo and "message"),
without needing to retype the parameter list for each function thus labeled.
> I like it. You can leave the old 'link-warning' module as it is; some other
> package may be using it.
Good point.
> About the name: GL_USAGE_WARNING? GL_USE_WARNING? I'm not an English speaker,
> but "usage" reminds me the --help explanations of every program.
But in English, USE_WARNING parses ambiguously - is it the active verb
(rhyming with "lose"), or the noun (rhyming with "loose")? With
_GL_ARG_NONNULL, we have noun-adjective; that is, the macro is telling us
that an ARG has the property of being NONNULL. We want the macro in
question to convey the fact that using a function will trigger a warning.
USAGE_WARNING always implies the noun. So I'm starting to think
_GL_WARN_ON_USE may be a better name.
> About the prefix: As discussed a couple of days ago, with arg-nonnull.h,
> better
> use the prefix _GL_ than GL_.
Agreed.
- --
Don't work too hard, make some time for fun as well!
Eric Blake e...@byu.net
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From c150f13de37b0881b46da70a6977cdce3ca67922 Mon Sep 17 00:00:00 2001
From: Eric Blake <e...@byu.net>
Date: Tue, 15 Dec 2009 06:51:24 -0700
Subject: [PATCH] fcntl-h, stdio, sys_ioctl: fix declarations
We cannot use a function-like macro to provide a link-time warning
of a variadic function during GNULIB_POSIXCHECK; at least, not
without assuming C99 variadic macros. We can, however,
use an object-like macro (as was already done for printf).
On the other hand, this patch is only a stop-gap measure to fix
an obvious bug; a more complete patch that switches from a
link-time warning (specific to GNU ld, gcc, and ELF image) to
a compile-time attribute is in the works.
* lib/stdio.in.h (dprintf): Use of link warning on a variadic
function must not take arguments.
* lib/sys_ioctl.in.h (ioctl): Likewise.
* lib/fcntl.in.h (openat): Likewise. Declare extern.
(open): Add a link warning.
Signed-off-by: Eric Blake <e...@byu.net>
---
ChangeLog | 11 ++++++++++-
lib/fcntl.in.h | 10 ++++++++--
lib/stdio.in.h | 4 ++--
lib/sys_ioctl.in.h | 4 ++--
4 files changed, 22 insertions(+), 7 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 7655b07..efa426c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2009-12-15 Eric Blake <e...@byu.net>
+
+ fcntl-h, stdio, sys_ioctl: fix declarations
+ * lib/stdio.in.h (dprintf): Use of link warning on a variadic
+ function must not take arguments.
+ * lib/sys_ioctl.in.h (ioctl): Likewise.
+ * lib/fcntl.in.h (openat): Likewise. Declare extern.
+ (open): Add a link warning.
+
2009-12-15 Jim Meyering <meyer...@redhat.com>
areadlink, areadlink-with-size: relax license to LGPLv2+
@@ -5,7 +14,7 @@
* modules/areadlink-with-size (License): Likewise.
2009-12-15 Joel E. Denny <jde...@clemson.edu>
- Bruno Haible <br...@clisp.org>
+ Bruno Haible <br...@clisp.org>
*printf: Fix memory leak.
* lib/fprintf.c (fprintf): Free memory allocated by vasnprintf.
diff --git a/lib/fcntl.in.h b/lib/fcntl.in.h
index 75e1b55..953e065 100644
--- a/lib/fcntl.in.h
+++ b/lib/fcntl.in.h
@@ -61,6 +61,12 @@ extern "C" {
# define open rpl_open
extern int open (const char *filename, int flags, ...) _GL_ARG_NONNULL ((1));
# endif
+#elif defined GNULIB_POSIXCHECK
+# undef open
+# define open \
+ (GL_LINK_WARNING ("open is not always POSIX compliant - " \
+ "use gnulib module open for portability"), \
+ open)
#endif
#if @GNULIB_OPENAT@
@@ -69,12 +75,12 @@ extern int open (const char *filename, int flags, ...)
_GL_ARG_NONNULL ((1));
# define openat rpl_openat
# endif
# if !...@have_openat@ || @REPLACE_OPENAT@
-int openat (int fd, char const *file, int flags, /* mode_t mode */ ...)
+extern int openat (int fd, char const *file, int flags, /* mode_t mode */ ...)
_GL_ARG_NONNULL ((2));
# endif
#elif defined GNULIB_POSIXCHECK
# undef openat
-# define openat(f,u,g) \
+# define openat \
(GL_LINK_WARNING ("openat is not portable - " \
"use gnulib module openat for portability"), \
openat)
diff --git a/lib/stdio.in.h b/lib/stdio.in.h
index 0bcf154..a52f65f 100644
--- a/lib/stdio.in.h
+++ b/lib/stdio.in.h
@@ -80,10 +80,10 @@ extern int dprintf (int fd, const char *format, ...)
# endif
#elif defined GNULIB_POSIXCHECK
# undef dprintf
-# define dprintf(d,f,a) \
+# define dprintf \
(GL_LINK_WARNING ("dprintf is unportable - " \
"use gnulib module dprintf for portability"), \
- dprintf (d, f, a))
+ dprintf)
#endif
#if @GNULIB_FCLOSE@
diff --git a/lib/sys_ioctl.in.h b/lib/sys_ioctl.in.h
index 55d3b35..dfcb54e 100644
--- a/lib/sys_ioctl.in.h
+++ b/lib/sys_ioctl.in.h
@@ -54,10 +54,10 @@ extern int ioctl (int fd, int request, ... /* {void *,char
*} arg */);
# define ioctl ioctl_used_without_requesting_gnulib_module_ioctl
#elif defined GNULIB_POSIXCHECK
# undef ioctl
-# define ioctl(f,c,a) \
+# define ioctl \
(GL_LINK_WARNING ("ioctl does not portably work on sockets - " \
"use gnulib module ioctl for portability"), \
- ioctl (f, c, a))
+ ioctl)
#endif
--
1.6.5.rc1
