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* [Bug c++/54912] New: [C++11] Non-type argument to alias template is not a constant expression
@ 2012-10-12 16:11 lucdanton at free dot fr
2012-10-12 16:55 ` [Bug c++/54912] [4.8 Regression] " paolo.carlini at oracle dot com
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: lucdanton at free dot fr @ 2012-10-12 16:11 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54912
Bug #: 54912
Summary: [C++11] Non-type argument to alias template is not a
constant expression
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: lucdanton@free.fr
gcc version 4.8.0 20121008 (experimental) with flags
-Wall -pedantic -std=c++11
complains when fed the following program:
template<bool B>
using Bool = int;
template<typename T>
void foo()
{
using bar = Bool<(sizeof(T) >= 0)>; // line 7
}
int main()
{
foo<int>();
}
Compiler output:
main.cpp: In substitution of 'template<bool B> using Bool = int [with bool B =
(sizeof (T) >= 0)]':
main.cpp:7:38: required from here
main.cpp:7:38: error: integral expression '(sizeof (T) >= 0)' is not constant
using bar = Bool<(sizeof(T) >= 0)>;
^
main.cpp:7:38: error: trying to instantiate 'template<bool B> using Bool =
int'
Using the sizeof expression as the non-type parameter of a class template with
the same template parameter list as the alias template is accepted. That same
expression can also be used to initialize e.g. a constexpr bool variable, which
will in fact in turn be accepted as a parameter to Bool.
Previous snapshots of GCC used to accept this kind of code.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/54912] [4.8 Regression] Non-type argument to alias template is not a constant expression
2012-10-12 16:11 [Bug c++/54912] New: [C++11] Non-type argument to alias template is not a constant expression lucdanton at free dot fr
@ 2012-10-12 16:55 ` paolo.carlini at oracle dot com
2012-10-12 17:08 ` paolo.carlini at oracle dot com
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: paolo.carlini at oracle dot com @ 2012-10-12 16:55 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54912
Paolo Carlini <paolo.carlini at oracle dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2012-10-12
Summary|[C++11] Non-type argument |[4.8 Regression] Non-type
|to alias template is not a |argument to alias template
|constant expression |is not a constant
| |expression
Ever Confirmed|0 |1
--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-10-12 16:54:53 UTC ---
Confirmed as a regression, 4_7-branch is fine.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/54912] [4.8 Regression] Non-type argument to alias template is not a constant expression
2012-10-12 16:11 [Bug c++/54912] New: [C++11] Non-type argument to alias template is not a constant expression lucdanton at free dot fr
2012-10-12 16:55 ` [Bug c++/54912] [4.8 Regression] " paolo.carlini at oracle dot com
@ 2012-10-12 17:08 ` paolo.carlini at oracle dot com
2012-10-21 22:52 ` paolo.carlini at oracle dot com
2012-10-21 22:53 ` paolo.carlini at oracle dot com
3 siblings, 0 replies; 5+ messages in thread
From: paolo.carlini at oracle dot com @ 2012-10-12 17:08 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54912
Paolo Carlini <paolo.carlini at oracle dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jason at gcc dot gnu.org
--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-10-12 17:07:56 UTC ---
Most likely a Dup of PR54859, also regressed with 191412.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/54912] [4.8 Regression] Non-type argument to alias template is not a constant expression
2012-10-12 16:11 [Bug c++/54912] New: [C++11] Non-type argument to alias template is not a constant expression lucdanton at free dot fr
2012-10-12 16:55 ` [Bug c++/54912] [4.8 Regression] " paolo.carlini at oracle dot com
2012-10-12 17:08 ` paolo.carlini at oracle dot com
@ 2012-10-21 22:52 ` paolo.carlini at oracle dot com
2012-10-21 22:53 ` paolo.carlini at oracle dot com
3 siblings, 0 replies; 5+ messages in thread
From: paolo.carlini at oracle dot com @ 2012-10-21 22:52 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54912
Paolo Carlini <paolo.carlini at oracle dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |pkeir at outlook dot com
--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-10-21 22:51:44 UTC ---
*** Bug 55013 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/54912] [4.8 Regression] Non-type argument to alias template is not a constant expression
2012-10-12 16:11 [Bug c++/54912] New: [C++11] Non-type argument to alias template is not a constant expression lucdanton at free dot fr
` (2 preceding siblings ...)
2012-10-21 22:52 ` paolo.carlini at oracle dot com
@ 2012-10-21 22:53 ` paolo.carlini at oracle dot com
3 siblings, 0 replies; 5+ messages in thread
From: paolo.carlini at oracle dot com @ 2012-10-21 22:53 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54912
Paolo Carlini <paolo.carlini at oracle dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |DUPLICATE
--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-10-21 22:53:20 UTC ---
Dup.
*** This bug has been marked as a duplicate of bug 54859 ***
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-10-21 22:53 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2012-10-12 16:11 [Bug c++/54912] New: [C++11] Non-type argument to alias template is not a constant expression lucdanton at free dot fr
2012-10-12 16:55 ` [Bug c++/54912] [4.8 Regression] " paolo.carlini at oracle dot com
2012-10-12 17:08 ` paolo.carlini at oracle dot com
2012-10-21 22:52 ` paolo.carlini at oracle dot com
2012-10-21 22:53 ` paolo.carlini at oracle dot com
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