[Bug c++/11119] New: using forward declared classes in templates

[lars@trolltech.com]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11119

           Summary: using forward declared classes in templates
           Product: gcc
           Version: 3.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: lars@trolltech.com
                CC: gcc-bugs@gcc.gnu.org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu

Hi, 
 
using gcc cvs from Jun 06. 
 
not sure this is really a bug, but it's behavior is at least different from earlier gcc 
versions and somewhat inconsistent. The code below compiles on all versions < 3.4, 
as the template only needs the full class declaration of Bar when the method Foo::foo() 
gets instantiated. 3.4 gives a compile error for the function call, but not when using the 
operator notation. 
 
 
class Bar; 
 
template <typename T> class Foo 
{ 
public: 
    void foo(const Bar &b) { 
	// this compiles 
	T t; 
	b << t; 
	// these don't compile in 3.4 
	b.operator<<(t); 
	b.bar(t) 
    } 
}; 
 
 
[lars@binky gcc-bugs]$ gcc -c forward_decl.cpp 
forward_decl.cpp: In member function `void Foo<T>::foo(const Bar&)': 
forward_decl.cpp:11: error: invalid use of undefined type `const struct Bar' 
forward_decl.cpp:1: error: forward declaration of `const struct Bar' 
[lars@binky gcc-bugs]$ gcc -v 
Reading specs from /home/lars/gcc/lib/gcc-lib/i686-pc-linux-gnu/3.4/specs 
Configured with: ../gcc/configure --prefix=/home/lars/gcc --disable-libgcj 
Thread model: posix 
gcc version 3.4 20030605 (experimental) 
 
 
Cheers, 
Lars