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Date: Tue, 03 Feb 2004 20:29:00 -0000
From: "reichelt at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Message-ID: <20040203202940.14008.reichelt@gcc.gnu.org>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug c++/14008] New: Confusing diagnostic when ommitting a template parameter
X-Bugzilla-Reason: CC
X-SW-Source: 2004-02/txt/msg00437.txt.bz2
List-Id: <gcc-bugs.sourceware.org>

Here are two invalid code snippets where gcc gives misleading diagnostic:

=================================================
namespace N
{ 
    template<int> struct A {};
}

struct B
{
    N::A a;
};
=================================================

With mainline I get

bug1.cc:8: error: using-declaration for non-member at class scope
bug1.cc:8: error: expected `;' before "a"

but I fail to see a using declaration in the code.


If I write "typename N::A a;" instead and make "struct B" a template
like so

=================================================
namespace N
{ 
    template<int> struct A {};
}

template<int> struct B
{
    typename N::A a;
};
=================================================

I get

bug2.cc:8: error: no class template named `A' in `N'
bug2.cc:8: error: ISO C++ forbids declaration of `a' with no type

which is equally confusing, since 'A' *is* a class template in 'N'.

-- 
           Summary: Confusing diagnostic when ommitting a template parameter
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: reichelt at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14008