[Bug c++/11501] New: template environmet confuses g++, and prohibits compiling valid code

["eikescholz at gmx dot de" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11501

           Summary: template environmet confuses g++, and prohibits
                    compiling valid code
           Product: gcc
           Version: 3.2.3
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: eikescholz at gmx dot de
                CC: gcc-bugs at gcc dot gnu dot org

The following code: 

----------------------bug.cc ----------------------------

template< unsigned int flavor >
class A
{
  public:
                                                                                
                                                                                
    template<unsigned int _flavor> A<_flavor>& change_flavor()
    {
        typedef A<_flavor> new_flavor;
        return reinterpret_cast< new_flavor& >( *this );
    };
                                                                                
};                                                                                 
                                                                                
                                                                                
// this one compiles
int kungfoo()
{
                                                                                
    A<1> test;
    A<2> test2( test.change_flavor<2>() );
                                                                                
    return 1;
}
                                                                                
#if 1
// this one not
template<int k> int kungfoo_template()
{
                                                                                
    A<1> test;
    A<2> test2( test.change_flavor<2>() );
                                                                                
    return k;
}
#endif
                                                                                
int main()
{
      return kungfoo();
//    return kungfoo_template<1>();
}
------------------------- end bug.cc ----------------------

produces:

----
cptchaos@motion debug_g++ $ g++ bug.cc -o bug
bug.cc: In function `int kungfoo_template()':
bug.cc:31: syntax error before `)' token
----

with:

----
cptchaos@motion debug_g++ $ g++ --version
g++ (GCC) 3.2.3 20030422 (Gentoo Linux 1.4 3.2.3-r1, propolice)
Copyright (C) 2002 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.
----

if you change the #if 1 to #if 0 the file will compile.
Because off the fact, that the not templated function uses exact the same 
syntax like the templatet one, I assume that the systax errror is a false
positive, that prohibits compiling valid code.

I could reproduce the error with g++-2.95 and g++-3.3 on my debian system:

---
station% gcc-2.95 bug.cc
bug.cc: In function `int kungfoo_template()':
bug.cc:31: parse error before `('
station% gcc-2.95 --version
2.95.4


station% gcc-3.3 bug.cc
bug.cc: In function `int kungfoo_template()':
bug.cc:31: error: parse error before `)' token
station% gcc-3.3 --version
gcc-3.3 (GCC) 3.3 (Debian)
Copyright (C) 2003 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.
---


PS: I need this reinterpret_cast tric for some aggressive compile_time
optimisations, and I now what I am doing there, and it makes sense.