c++/5436: explicit instatiation

c++/5436: explicit instatiation

[kunert]

>Number:         5436
>Category:       c++
>Synopsis:       explicit instatiation
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Sun Jan 20 07:26:01 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     Thomas Kunert
>Release:        3.0.2, cvs 15.1.02
>Organization:
>Environment:
i586-pc-linux-gnu
>Description:
This code:

	template <class T>
	class A {
	    static const int a=17;  // #1
	    A( const A& );          // #2    
	};

	extern template class A<int>;
	template class A<int>;

generates the error messages:

	test.cc: In instantiation of `A<T>::A(const A<T>&) [with T = int]':
	test.cc:8:   instantiated from here
	test.cc:8: explicit instantiation of `A<T>::A(const A<T>&) [with T = int]' but
	   no definition available
	test.cc: In instantiation of `const int A<int>::a':
	test.cc:8:   instantiated from here
	test.cc:8: explicit instantiation of `A<int>::a' but no definition available

Without the `extern' declaration this error message disappears.

Line #1 is definitely legal and the corresponding 
error message is wrong.
I am not sure about #2, but it seems inconsistent that
the legality of this depends on the extern declaration.

Thomas Kunert

>How-To-Repeat:

>Fix:

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

Re: c++/5436: explicit instatiation

[nathan]

Synopsis: explicit instatiation

State-Changed-From-To: open->analyzed
State-Changed-By: nathan
State-Changed-When: Sun Sep 15 12:21:39 2002
State-Changed-Why:
    extern template is a g++ extension.
    definitely a bug. regardless of the extern template bit,
    the explicit instantiation should barf

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5436