Re: Puzzling error message about templates (gcc 3.4.0)

[Paul Koning <pkoning at equallogic dot com>]

Following up on my own message:

> From: Paul Koning <pkoning@equallogic.com>
> To: gcc@gcc.gnu.org
> Date: Thu, 10 Jun 2004 15:07:33 -0400
> Subject: Puzzling error message about templates (gcc 3.4.0)
> 
> GCC 3.4 objects to this (GCC 3.3 does not):
> 
> template <class Type> class Test
> {
> public:
> 	Test(void);
> 	~Test(void);
> 	static bool probe(void *addr);
> };
> 
> template <class Type> inline bool Test<Type>::probe(void *addr)
> {}
> 
> template <class Type> inline Test<Type>::Test<Type>(void)
> {}
> 
> template <class Type> inline Test<Type>::~Test<Type>(void)
> {}
> 
> The error messages is:
> 
> foo.cc:15: error: non-template `Test' used as template
> foo.cc:15: error: (use `Test<Type>::template Test' to indicate that it is a template)
> foo.cc:15: error: expected class-name at end of input
> foo.cc:15: error: expected init-declarator at end of input
> foo.cc:15: error: expected `;' at end of input
> 
> I can't figure out what the suggestion is trying to suggest (in other
> words, I can't tell what the proposed replacement source would look
> like).
> 
> But what's really puzzling is that it only complains about the
> destructor, even though the other two methods have the identical
> pattern.  Parser bug?

Not a parser bug, but a very confusing message.

The correct syntax for template class constructors/destructors is (as
far as I can fathom from my textbooks)

template <class Type> inline Test<Type>::Test(void) {}

template <class Type> inline Test<Type>::~Test(void) {}

without the extra <Type> just before the (void).  The other form was
accepted by the old parser, and it's a natural mistake to make because
constructor names are "the name of the class" -- and one might figure
that "Test<Type>" is that name.

Anyway, the message doesn't say that.  It's also doubly confusing
because the (presumably) incorrect constructor syntax is silently
accepted while the destructor causes the error messages.

	 paul