[Bug c++/32058] New: invalid computed void parameter in template

[paul_m_doc at hotmail dot com]

Can't return void from type function instantiation with dependent args for use
in function declaration.

all versions from 3.4 to the latest 4.3.0 build on x86 cygwin/linux complain
with:

error: invalid parameter type 'void'
...

=

template 
struct F { typedef void Type; };

template 
struct X {

   // does not accept dependent computed type void!
   // (void* is fine as is non-dependent F<0>::Type)

   typedef typename F::Type ParmT;

   static int func(ParmT) { return 1; }
};

int main()
{
   int i = X<0>::func();
}



The VisualC++ compilers are fine.


-- 
   Summary: invalid computed void parameter in template
   Product: gcc
   Version: 4.3.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: paul_m_doc at hotmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32058

[Bug c++/9278] Illegal use of typedef to "void"

[paul_m_doc at hotmail dot com]

--- Comment #27 from paul_m_doc at hotmail dot com  2007-05-25 13:11 ---
(In reply to comment #26)
> *** Bug 32058 has been marked as a duplicate of this bug. ***

Sigh :(. The response at the October 2006 to DR 577 is enough to make any
template meta-programmer bang their head against the wall in despair.

This is the language that, according to its creator as a design goal should
'trust the programmer', right?

I certainly have a formal position on this and many other similar issues that
affect TMP.

This should have been at most a warning with the option to turn it off.

The Visual C++ compilers may be less fussy than gcc but at least they tend to
do the sensible thing.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9278