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c++/8280: friend declaration introduces class name into namespace scope
- From: dbaron at fas dot harvard dot edu
- To: gcc-gnats at gcc dot gnu dot org
- Date: 18 Oct 2002 23:48:33 -0000
- Subject: c++/8280: friend declaration introduces class name into namespace scope
- Reply-to: dbaron at fas dot harvard dot edu
>Number: 8280
>Category: c++
>Synopsis: friend declaration introduces class name into namespace scope
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: accepts-illegal
>Submitter-Id: net
>Arrival-Date: Fri Oct 18 16:56:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: dbaron@fas.harvard.edu
>Release: 3.2
>Organization:
>Environment:
Configured with: ../gcc-3.2/configure --prefix=/usr/local/gcc-3.2 --enable-languages=c++ --enable-__cxa_atexit
Thread model: posix
gcc version 3.2
(on Linux 2.4.18-17.8.0smp i686, i.e., RedHat 8.0)
Also present on gcc trunk:
gcc version 3.3 20021007 (experimental)
>Description:
According to section 7.3.1.2, clause 3, of the C++
standard:
If a |friend| declaration in a non-local class first
declares a class or function the friend class or
function is a member of the innermost enclosing
namespace. The name of the friend is not found
by simple name lookup until a matching declaration
is provided in that namespace scope (either before
or after then class declaration granting friendship).
In other words (I think), |friend class B| is allowed
even if B hasn't been declared yet, but it doesn't
declare B.
I have been told that this was not true in older
drafts of the standard.
>How-To-Repeat:
The following source code is sufficient to reproduce
the problem:
-----
class A { friend class B; };
// The name |B| should not be found yet, so this
// should not compile.
B* null_b() { return 0; }
int main() { return 0; }
-----
Compile with:
g++ -o friend -ansi -pedantic test.cpp
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: