c/6904: GCC attribute syntax

[Matthias Klose]

>Number:         6904
>Category:       c
>Synopsis:       GCC attribute syntax
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    unassigned
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Sat Jun 01 15:46:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Ian Jackson <ian@davenant.greenend.org.uk>
>Release:        3.1 (Debian) (Debian unstable)
>Organization:
The Debian Project
>Environment:
System: Debian GNU/Linux (unstable)
Architecture: i686
	
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Installed/Config-files/Unpacked/Failed-config/Half-installed
|/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: uppercase=bad)
||/ Name           Version        Description
+++-==============-==============-============================================
ii  gcc-3.1        3.1-2          The GNU C compiler.
ii  binutils       2.12.90.0.7-1  The GNU assembler, linker and binary utiliti
ii  libc6          2.2.5-6        GNU C Library: Shared libraries and Timezone
host: i386-linux
configured with: /mnt/data/gcc-3.1/gcc-3.1-3.1ds2/src/configure -v --enable-languages=c,c++,java,f77,proto,objc,ada --prefix=/usr --mandir=$\(prefix\)/share/man --infodir=$\(prefix\)/share/info --with-gxx-include-dir=$\(prefix\)/include/g++-v3-3.1 --enable-shared --with-system-zlib --enable-long-long --enable-nls --without-included-gettext --enable-clocale=gnu --enable-threads=posix --enable-java-gc=boehm --enable-objc-gc i386-linux
>Description:
[ Reported to the Debian BTS as report #12253.
  Please CC 12253@bugs.debian.org on replies.
  Log of report can be found at http://bugs.debian.org/12253 ]

[ The documentation has been updated:
  http://gcc.gnu.org/ml/gcc-patches/2001-01/msg01683.html
  The "obvious" syntax isn't accepted. ]

The function __attribute__((...)) extension in GCC is very useful.
However, it has something of a niggle in its use.

If the relevant declaration of a function is also its definition then
you cannot use __attribute__ in the way suggested by the examples in
the GCC manual; GCC rejects the `obvious' usage with a syntax error.

The manual does not give a formal definition of where function
attributes may appear, but the examples are all like
          int square (int) __attribute__ ((const));
suggesting that in a definition it should appear between the argument
list and the opening brace.

However, GCC does not accept that syntax.  Experimenting shows that it
_does_ accept a syntax where the attributes appear immediately before
the function name (at least for functions with return values not of a
pointer type).

I think it would be useful to accept the `obvious' syntax (e.g., u.c
in my transcript below).  I also think the syntax which is accepted
should be specified; in particular, the locations where the
__attribute__ may appear should be specified.

Thanks,
Ian.

-davenant:~/junk> cat t.c
static void f(void) __attribute__((noreturn));
static void f(void) { }
-davenant:~/junk> gcc -Wall -O3 -c t.c
t.c: In function `f':
t.c:2: warning: `noreturn' function does return
-davenant:~/junk> cat u.c
static void f(void) __attribute__((noreturn)) { }
-davenant:~/junk> gcc -Wall -O3 -c u.c
u.c:1: parse error before `{'
u.c:1: warning: `f' declared `static' but never defined
-davenant:~/junk> cat v.c
static void __attribute__((noreturn)) f(void) { }
-davenant:~/junk> gcc -Wall -O3 -c v.c
v.c: In function `f':
v.c:1: warning: `noreturn' function does return
-davenant:~/junk> 

>How-To-Repeat:
	
>Fix:
	
>Release-Note:
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