[Bug c++/66092] [c++-concepts] Concept can't check variadic template arguments
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66092 Jason Merrill jason at gcc dot gnu.org changed: What|Removed |Added Status|NEW |RESOLVED Resolution|--- |FIXED --- Comment #7 from Jason Merrill jason at gcc dot gnu.org --- Crash was fixed.
[Bug c++/66092] [c++-concepts] Concept can't check variadic template arguments
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66092 --- Comment #6 from Jason Merrill jason at gcc dot gnu.org --- Author: jason Date: Fri Jul 17 17:43:09 2015 New Revision: 225959 URL: https://gcc.gnu.org/viewcvs?rev=225959root=gccview=rev Log: PR c++/66092 PR c++/66834 * gcc/cp/pt.c (coerce_template_parms): Re-apply earlier change. Added: branches/c++-concepts/gcc/testsuite/g++.dg/concepts/dr1430.C Modified: branches/c++-concepts/ChangeLog.concepts branches/c++-concepts/gcc/cp/pt.c
[Bug c++/66092] [c++-concepts] Concept can't check variadic template arguments
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66092 --- Comment #5 from Jason Merrill jason at gcc dot gnu.org --- Author: jason Date: Tue Jul 14 04:11:11 2015 New Revision: 225758 URL: https://gcc.gnu.org/viewcvs?rev=225758root=gccview=rev Log: PR c++/66092 PR c++/66834 * gcc/cp/pt.c (coerce_template_parms): Revert earlier change. Removed: branches/c++-concepts/gcc/testsuite/g++.dg/concepts/dr1430.C Modified: branches/c++-concepts/ChangeLog.concepts branches/c++-concepts/gcc/cp/pt.c
[Bug c++/66092] [c++-concepts] Concept can't check variadic template arguments
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66092 --- Comment #4 from Jason Merrill jason at gcc dot gnu.org --- Author: jason Date: Fri Jul 10 07:25:49 2015 New Revision: 225649 URL: https://gcc.gnu.org/viewcvs?rev=225649root=gccview=rev Log: PR c++/66092 * gcc/cp/cp-tree.h (concept_template_p): New. * gcc/cp/pt.c (coerce_template_parms): Concepts are also affected by DR 1430. * gcc/cp/constraint.cc (lift_template_id): Use location_of. * gcc/cp/parser.c (cp_parser_template_id): SET_EXPR_LOCATION. Added: branches/c++-concepts/gcc/testsuite/g++.dg/concepts/dr1430.C Modified: branches/c++-concepts/ChangeLog.concepts branches/c++-concepts/gcc/cp/constraint.cc branches/c++-concepts/gcc/cp/cp-tree.h branches/c++-concepts/gcc/cp/parser.c branches/c++-concepts/gcc/cp/pt.c branches/c++-concepts/gcc/testsuite/g++.dg/concepts/var-concept3.C
[Bug c++/66092] [c++-concepts] Concept can't check variadic template arguments
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66092
Jason Merrill jason at gcc dot gnu.org changed:
What|Removed |Added
Status|UNCONFIRMED |NEW
Last reconfirmed||2015-07-10
CC||jason at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #3 from Jason Merrill jason at gcc dot gnu.org ---
(In reply to Andrew Sutton from comment #2)
I think that this should be ill-formed.
template typename T, typename U, typename... Args
concept bool Same()
{
return decltype(checkT, U, Args...())::value;
}
template typename... Args
requires SameArgs...()
void foo( Args... args ) {}
Template constraint processing requires that flatten (inline) the check for
SameArgs...(), but I don't see how we can substitute a dependent argument
pack into three distinct template parameters (T, U, and ...Args).
The wording prohibiting this is missing in the TS.
Agreed, this is basically the same issue as core issue 1430 for alias
templates. We can fix the crash on this testcase by adding concepts to the DR
1430 check in coerce_template_parms, but complain is tf_none at that point so
we don't get a helpful error message. Any thoughts on that? It seems to me
that we probably want to pass complain through the normalize/lift functions.
Is there something to address this in your latest draft?
[Bug c++/66092] [c++-concepts] Concept can't check variadic template arguments
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66092
Andrew Sutton andrew.n.sutton at gmail dot com changed:
What|Removed |Added
CC||andrew.n.sutton at gmail dot
com
--- Comment #2 from Andrew Sutton andrew.n.sutton at gmail dot com ---
I think that this should be ill-formed.
template typename T, typename U, typename... Args
concept bool Same()
{
return decltype(checkT, U, Args...())::value;
}
template typename... Args
requires SameArgs...()
void foo( Args... args ) {}
Template constraint processing requires that flatten (inline) the check for
SameArgs...(), but I don't see how we can substitute a dependent argument
pack into three distinct template parameters (T, U, and ...Args).
The wording prohibiting this is missing in the TS.
[Bug c++/66092] [c++-concepts] Concept can't check variadic template arguments
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66092
--- Comment #1 from Ying-Po Liao yingpo.liao at gmail dot com ---
Here's another implementation, which results in the same consequence.
template typename T, typename U, typename... Args
struct Checker
{
constexpr static decltype(auto) check( std::true_type )
{ return std::integral_constantbool, __is_same_as(T, U)(); }
constexpr static decltype(auto) check( std::false_type )
{ return std::integral_constantbool, __is_same_as(T, U)
CheckerU, Args...::value(); }
constexpr static bool value = decltype(
check( std::integral_constantbool, (sizeof...(Args)==0)() )
)::value;
};
template typename T, typename U, typename... Args
concept bool Same()
{
return CheckerT, U, Args...::value;
}
