[Bug c++/100765] New: attribute incorrectly applied during type alias deduction

[Bug c++/100765] New: attribute incorrectly applied during type alias deduction

[rustamabd at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100765

            Bug ID: 100765
           Summary: attribute incorrectly applied during type alias
                    deduction
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rustamabd at gmail dot com
  Target Milestone: ---

template <typename T>
using vec __attribute__((vector_size(8))) = T;

template <typename T>
void test(vec<T> x) {}

int main() {
  test(vec<int>{1,2});
}

Compiles fine in Clang, but fails in GCC with:

In substitution of 'template<class T> using vec = T [with T = __vector(2)
int]':
   required by substitution of 'template<class T> void test(vec<T>) [with T =
__vector(2) int]'
   required from here
 error: invalid vector type for attribute 'vector_size'
    2 | using vec __attribute__((vector_size(8))) = T;
      |       ^~~

GCC seems to be applying __attribute__(vector_size) to int when deducing from
vec<int>.

Bypassing deduction makes the code compile:

  test<int>(vec<int>{1,2});

This issue seems to exist in all GCC versions starting from 4.7.0 until at
least the current (12.0) trunk.

[Bug c++/100765] attribute incorrectly applied during type alias deduction

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100765

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 100766 has been marked as a duplicate of this bug. ***

[Bug c++/100765] attribute incorrectly applied during type alias deduction

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100765

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-08-12
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug c++/100765] attribute incorrectly applied during type alias deduction

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100765

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
GNU++98 version:
#define vec __attribute__((vector_size(4)))
template <typename T>
vec T f(vec T);

vec int ff(vec int t)
{
    return f(t);
}

----- CUT ----
And one which rejects a different way:
#define vec __attribute__((vector_size(4)))
template <typename T>
vec T f(T a, vec T);

vec int ff(int a, vec int t)
{
    return f(a, t);
}

[Bug c++/100765] attribute incorrectly applied during type alias deduction

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100765

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gcc-bugzilla@richardebeling
                   |                            |.de

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 110140 has been marked as a duplicate of this bug. ***