[Bug c/53182] New: GNU C: attributes without underscores should be discouraged / no longer be documented e.g. as examples

[vincent-gcc at vinc17 dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53182

             Bug #: 53182
           Summary: GNU C: attributes without underscores should be
                    discouraged / no longer be documented e.g. as examples
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: vincent-...@vinc17.net


Attributes without underscores can conflict with the ISO C standard. For
instance, if the C11 <stdnoreturn.h> header is included, this breaks GCC's

  __attribute__ ((noreturn))

(such problems may occur in particular if different libraries, with different
expectations, are used). To avoid such a clash, only the __noreturn__ version
should be used. Other attributes without __ may also lead to conflicts with a
future C standard. You can see

  http://lists.gnu.org/archive/html/bug-gnulib/2012-05/msg00024.html

and the corresponding discussion, from which I've reported this bug.

I suggest the following changes:

* Fix the GCC manual: the versions without __ should be discouraged (explain
why) and the examples should always use the __ version, e.g. change

          void fatal () __attribute__ ((noreturn));

to

          void fatal () __attribute__ ((__noreturn__));

* Possibly issue a warning if an attribute without __ is used.