[Bug c++/96396] New: initializer_list in `-fconcepts -std=c++11` reports internal compiler error

[Bug c++/96396] New: initializer_list in `-fconcepts -std=c++11` reports internal compiler error

[gcc at mailinator dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96396

            Bug ID: 96396
           Summary: initializer_list in `-fconcepts -std=c++11` reports
                    internal compiler error
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc at mailinator dot com
  Target Milestone: ---

Program:

```
#include<initializer_list>

int main(){
        for(auto it:{1, 2}){
        }
}
```

Compiler flag: `-fconcepts -std=c++11`

Godbolt link: https://cpp.godbolt.org/z/K7e5rh (version: x84-64 gcc 10.2 or
trunk)

Compiler output:

```
<source>: In function 'int main()':

<source>:4:26: internal compiler error: in type_unification_real, at
cp/pt.c:21786

    4 |         for(auto it:{1, 2}){

      |                          ^

Please submit a full bug report,

with preprocessed source if appropriate.

See <https://gcc.gnu.org/bugs/> for instructions.
```

[Bug c++/96396] initializer_list in `-fconcepts -std=c++11` reports internal compiler error

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96396

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mpolacek at gcc dot gnu.org
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2020-08-03
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed.

[Bug c++/96396] initializer_list in `-fconcepts -std=c++11` reports internal compiler error

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96396

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2020-08-03 00:00:00         |2021-7-22

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
'-fconcepts -std=c++17' works though.

[Bug c++/96396] initializer_list in `-fconcepts -std=c++11` reports internal compiler error

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96396

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |needs-bisection

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Seems fixed in GCC 13+

[Bug c++/96396] initializer_list in `-fconcepts -std=c++11` reports internal compiler error

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96396

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|needs-bisection             |

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed by r13-3639

  c++: change -fconcepts to mean C++20 concepts

  It was always weird that -fconcepts in C++17 mode meant the same thing as
  -fconcepts-ts in C++20 mode; this patch harmonizes the flags so that for TS
  concepts you always need to write -fconcepts-ts.

  In the unlikely event anyone is still using -fconcepts in C++17 mode, they
  can either fix their code to work with C++20 concepts or adjust the compiler
  flag.


It still ICEs with -fconcepts-ts -std=c++11

But I'm not surprised that combination doesn't work, the Concepts TS is
supposed to be used with C++17.