[Bug c++/55768] New: Use of unknown __attribute__ in function definition is flagged with an error

[dnovillo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55768

             Bug #: 55768
           Summary: Use of unknown __attribute__ in function definition is
                    flagged with an error
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dnovillo@gcc.gnu.org
                CC: jason@gcc.gnu.org


I am not sure whether this is a bug, but it is a behaviour change since 4.7.

The compiler usually rejects attributes applied to function definitions:

int foo(int x, int y) __attribute__((const))
{
  return x * y;
}
$ gcc47 -c a.cc
a.cc:1:23: error: attributes are not allowed on a function-definition
$

But if the compiler does not recognize the attribute, then it says nothing:

int foo(int x, int y) __attribute__((no_thread_safety_analysis))
{
  return x * y;
}
$ gcc47 -c a.cc
$

This has changed in 4.8.  We now emit an error even if we do not understand the
attribute:

a.cc:1:23: error: attributes are not allowed on a function-definition
 int foo(int x, int y) __attribute__((no_thread_safety_analysis))
                       ^

Is this a case where the user code should be changed to accomodate the rule of
not allowing attributes on function definitions?

In fact, shouldn't the compiler just allow attributes on function definitions?