c++/9783: Can't forward reference class in argument to templated method.

c++/9783: Can't forward reference class in argument to templated method.

[mleone]

>Number:         9783
>Category:       c++
>Synopsis:       Can't forward reference class in argument to templated method.
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Thu Feb 20 23:26:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     Mark Leone
>Release:        g++ 3.2
>Organization:
>Environment:
RedHat 7.2, i686 multiprocessor
>Description:
The following fails to compile.  Workaround is to declare forward reference to class outside the template.

template<class Info>
class Table {
  public:
    bool Lookup(int name, class Detail* detail, Info* info) const;
    void Insert(int name, class Detail* detail, Info  info);
};

class Detail {
  public:
    int stuff;
};

template<class Info>
bool Table<Info>::Lookup(int name, Detail* detail, Info* info) const {
    return true;
}

template<class Info>
void Table<Info>::Insert(int name, Detail* detail, Info info) {
}
>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:

Re: c++/9783: Can't forward reference class in argument to templated method.

[bangerth]

Synopsis: Can't forward reference class in argument to templated method.

State-Changed-From-To: open->analyzed
State-Changed-By: bangerth
State-Changed-When: Thu Feb 20 23:57:45 2003
State-Changed-Why:
    Confirmed. Here's a simpler testcase:
    --------------------------
    template <typename T>
    struct C {
        void foo (struct X *);
    };
    
    struct X {};
    
    template <typename T>
    void C<T>::foo(struct X *) {}
    -------------------------------
    It's rejected by all versions of gcc. However, if
    one makes C a non-template, then it is accepted. Strange.
    
    I suspect that the language actually mandates this behavior,
    since both icc and cxx (well, both EDG based after all)
    have this behavior as well. I don't know what is right in
    this case.
    
    W.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9783