c++/10530: [3.4 regression] Cannot access non-dependent type within nested template

c++/10530: [3.4 regression] Cannot access non-dependent type within nested template

[giovannibajo]

>Number:         10530
>Category:       c++
>Synopsis:       [3.4 regression] Cannot access non-dependent type within nested template
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Mon Apr 28 23:36:01 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     Giovanni Bajo
>Release:        3.4 i686-pc-cygwin
>Organization:
>Environment:
Reading specs from /usr/local/lib/gcc-lib/i686-pc-cygwin/3.4/specs
Configured with: ../gcc/configure --program-suffix=-3.4 --enable-languages=c,c++

Thread model: single
gcc version 3.4 20030413 (experimental)
>Description:
GCC 3.4 does not compile the following legal snippet:

---------------------------------
template <typename T>
struct Foo
{
    template <typename Q>
    struct Inner
    {
        typedef int type;
    };
};

struct Bar
{
    template <typename A>
    void func(void)
    {
        typedef typename
            Foo<int>
            ::Inner<int>
            ::type type;
    }
};

int main()
{
    Bar b;
    b.func<int>();
}
---------------------------------
newbug.cpp: In member function `void Bar::func()':
newbug.cpp:19: error: no type named `type' in `struct Foo<int>::Inner<int>'
newbug.cpp:19: error: ISO C++ forbids declaration of `type' with no type


I also tried adding the nested template keyword (which is unneeded because the postfix-expression is clearly non-dependent) but it does not help.

Previous GCCs compile the above correctly.
>How-To-Repeat:
Compile the snippet
>Fix:
No known workaround
>Release-Note:
>Audit-Trail:
>Unformatted:

Re: c++/10530: [3.4 regression] Cannot access non-dependent type within nested template

[bangerth]

Synopsis: [3.4 regression] Cannot access non-dependent type within nested template

State-Changed-From-To: open->analyzed
State-Changed-By: bangerth
State-Changed-When: Tue Apr 29 00:19:14 2003
State-Changed-Why:
    Correct. Even smaller:
    --------------------------
    template <typename T>
    struct Foo {
        struct Inner {
            typedef int type;
        };
    };
    
    template <typename A> struct Bar {
        typedef typename Foo<int>::Inner::type type;
    };
    ------------------------------
    
    This won't compile with present mainline:
    g/x> /home/bangerth/bin/gcc-3.4-pre/bin/c++ -c x.cc
    x.cc:9: error: no type named `type' in `struct Foo<int>::Inner'
    x.cc:9: error: ISO C++ forbids declaration of `type' with no type
    
    If now someone (probably rightfully) argues that the
    "typename" is not necessary here -- this is what we get
    in that case:
    g/x> /home/bangerth/bin/gcc-3.4-pre/bin/c++ -c x.cc
    x.cc:9: error: type `Foo<int>::Inner' is not derived from type `Bar<A>'
    x.cc:9: error: ISO C++ forbids declaration of `type' with no type
    x.cc:9: error: expected `;'
    
    Ups, that's even worse...
    
    For the record: icc7 compiles it with and without the
    typename stuff. So does gcc3.3, so this is indeed a regression.
    
    W.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10530