[Bug c++/57765] [C++11] Variadic Template Specialization does not follow the INCITS/ISO​/IEC 14882-2011 standard

[Bug c++/57765] [C++11] Variadic Template Specialization does not follow the INCITS/ISO​/IEC 14882-2011 standard

[trashyankes at wp dot pl]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57765

trashyankes at wp dot pl changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |trashyankes at wp dot pl

--- Comment #1 from trashyankes at wp dot pl ---
In version of C++0x standard I have (not final, 2011-02-28 N3225) section 14.1
paragraph 11:
"If a template-parameter of a class template has a default template-argument,
each subsequent template-parameter shall either have a default
template-argument supplied or be a template parameter pack. If a
template-parameter of a primary class template is a template parameter pack, it
shall be the last template-parameter. [ Note: These are not requirements for
function templates or class template partial specializations
because template arguments can be deduced (...) — end note ]"
If this is not changed then first example is valid and second isnt because you
cant deduced value of `int`.
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From: "dominiq at lps dot ens.fr" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug fortran/54788] ICE on pointer-array element assignment
Date: Mon, 01 Jul 2013 09:33:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idT788

--- Comment #9 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Thanks for the commit.

[Bug c++/57765] [C++11] Variadic Template Specialization does not follow the INCITS/ISO​/IEC 14882-2011 standard

[aaronngray.lists at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57765

--- Comment #2 from AaronNGray <aaronngray.lists at gmail dot com> ---
Interesting ...from the standard, not in braces :-
"A template parameter pack of a function template shall not be followed by
another template parameter unless that template parameter can be deduced or has
a default argument"

The two paragraphs in full :-

14.1 [11] If a template-parameter of a class template or alias template has a
default template-argument, each subsequent template-parameter shall either have
a default template-argument supplied or be a template parameter pack. If a
template-parameter of a primary class template or alias template is a template
parameter pack, it shall be the last template-parameter. A template parameter
pack of a function template shall not be followed by another template parameter
unless that template parameter can be deduced or has a default argument
(14.8.2).

14.1 [15] If a template-parameter is a type-parameter with an ellipsis prior to
its optional identifier or is a parameter-declaration that declares a parameter
pack (8.3.5), then the template-parameter is a template parameter pack
(14.5.3). A template parameter pack that is a parameter-declaration whose type
contains one or more unexpanded parameter packs is a pack expansion. Similarly,
a template parameter pack that is a type-parameter with a
template-parameter-list containing one or more unexpanded parameter packs is a
pack expansion. A template parameter pack that is a pack expansion shall not
expand a parameter pack declared in the same template-parameter-list.

[Bug c++/57765] [C++11] Variadic Template Specialization does not follow the INCITS/ISO​/IEC 14882-2011 standard

[trashyankes at wp dot pl]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57765

--- Comment #3 from trashyankes at wp dot pl ---
I see, they fix wording in final version, but meaning didnt change (at last if
I understand it correctly).

"(...) primary class template or alias template is a template parameter pack,
it shall be the last template-parameter"


    template <typename ... Ts> //<-this is a "primary class template" 
    class Foo { };

    template <typename TR, typename ... Ts, TR (&f)(Ts...)> 
        //   ^-- this isnt a "primary class template"
    struct OpF<TR (Ts...), f> //<-this is a "primary class template"
    { };

"(...) function template shall not be followed by another template parameter
unless that template parameter can be deduced (...)"

    template < typename TR, typename ... Ts, int i> TR tester(Ts...);
                   //      cant be deduced --^

[Bug c++/57765] [C++11] Variadic Template Specialization does not follow the INCITS/ISO​/IEC 14882-2011 standard

[aaronngray.lists at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57765

AaronNGray <aaronngray.lists at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #4 from AaronNGray <aaronngray.lists at gmail dot com> ---
If a template-parameter of a primary class template or alias template is a
template parameter pack, it shall be the last template-parameter.

template <typename TR, typename ... Ts, TR (&f)(Ts...)> struct
 OpF<TR (Ts...), f> { };