[Bug c++/51501] decltype over-agressive SFINAE

2012-12-14 Thread jason at gcc dot gnu.org 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51501



--- Comment #7 from Jason Merrill jason at gcc dot gnu.org 2012-12-15 
04:08:09 UTC ---

This is core issue 1433, classified as an extension in Kona.  I don't know if

EWG has taken a look at it yet.

[Bug c++/51501] decltype over-agressive SFINAE

2012-08-18 Thread dave at boostpro dot com 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51501

--- Comment #6 from Dave Abrahams dave at boostpro dot com 2012-08-18 
23:18:21 UTC ---
Jason, are you submitting (or is there already) an issue for this?

[Bug c++/51501] decltype over-agressive SFINAE

2011-12-19 Thread jason at gcc dot gnu.org 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51501

Jason Merrill jason at gcc dot gnu.org changed:

   What|Removed |Added

 Status|UNCONFIRMED |ASSIGNED
   Last reconfirmed||2011-12-19
 CC||jason at gcc dot gnu.org
 AssignedTo|unassigned at gcc dot   |jason at gcc dot gnu.org
   |gnu.org |
 Ever Confirmed|0   |1

--- Comment #4 from Jason Merrill jason at gcc dot gnu.org 2011-12-19 
21:51:21 UTC ---
Reduced:

template class T T list(T x);

template class H, class ...T
auto list(H h, T ...args) - decltype(list(args...));

auto list3 = list(1, 2, 3);

[Bug c++/51501] decltype over-agressive SFINAE

2011-12-19 Thread jason at gcc dot gnu.org 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51501

Jason Merrill jason at gcc dot gnu.org changed:

   What|Removed |Added

 Status|ASSIGNED|SUSPENDED

--- Comment #5 from Jason Merrill jason at gcc dot gnu.org 2011-12-19 
22:06:03 UTC ---
The problem here is that the variadic 'list' is not in scope when the
trailing-return-type is parsed.  3.3.2 says,

The point of declaration for a name is immediately after its complete
declarator 

and the declarator includes the trailing-return-type.  And then since all the
arguments are integers, no argument-dependent lookup is done, so the call in
the trailing-return-type doesn't find the right template, and fails.

The versions of EDG and Clang that I have handy seem to reject this testcase on
the same basis.

This seems like a flaw in the standard.

[Bug c++/51501] decltype over-agressive SFINAE

2011-12-11 Thread marc.glisse at normalesup dot org 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51501

Marc Glisse marc.glisse at normalesup dot org changed:

   What|Removed |Added

 CC||marc.glisse at normalesup
   ||dot org

--- Comment #2 from Marc Glisse marc.glisse at normalesup dot org 2011-12-11 
09:41:00 UTC ---
Could this be related to Bug 45873?

[Bug c++/51501] decltype over-agressive SFINAE

2011-12-11 Thread dave at boostpro dot com 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51501

--- Comment #3 from Dave Abrahams dave at boostpro dot com 2011-12-11 
10:32:25 UTC ---
(In reply to comment #2)
 Could this be related to Bug 45873?

Not if your explanation in http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45873#c2
is correct, I think.  This is a straightforward pack expansion with no change
in the number of arguments.

[Bug c++/51501] decltype over-agressive SFINAE

2011-12-10 Thread dave at boostpro dot com 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51501

--- Comment #1 from Dave Abrahams dave at boostpro dot com 2011-12-10 
21:06:14 UTC ---
Created attachment 26045
  -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=26045
test case

compile with -std=c++11 to see the failure.  Additionally add -DWORKAROUND to
demonstrate why it ought to work.