[Bug c++/45492] New: G++ permits function-to-data pointer conversions with __extension__ in functions, but not function templates

[jimb at red-bean dot com]

With trunk G++:

$ ~/gcc/bin/g++ --version
g++ (GCC) 4.6.0 20100901 (experimental)
Copyright (C) 2010 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ cat fdc.cc
extern void cf();

// no warning
void *f() { return __extension__ (void *) cf; }

// warning:
// ISO C++ forbids casting between pointer-to-function and pointer-to-object
template<bool flag>
void *ft() { return __extension__ (void *) cf; }

template void *ft<true>();
$ LD_LIBRARY_PATH=$HOME/gcc/lib ~/gcc/bin/g++ -Wall -pedantic -c fdc.cc
fdc.cc: In function ‘void* ft() [with bool flag = true]’:
fdc.cc:11:25:   instantiated from here
fdc.cc:9:44: warning: ISO C++ forbids casting between pointer-to-function and
pointer-to-object [enabled by default]

I would expect G++ to either complain about both casts, or neither; whether the
code appears in a function template shouldn't matter.


-- 
           Summary: G++ permits function-to-data pointer conversions with
                    __extension__ in functions, but not function templates
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jimb at red-bean dot com
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45492