[Bug c++/115000] New: Confusing 'cannot convert to 'int' in initialization' error message

[Bug c++/115000] New: Confusing 'cannot convert to 'int' in initialization' error message

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115000

            Bug ID: 115000
           Summary: Confusing 'cannot convert to 'int' in initialization'
                    error message
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

Consider the following:

#include <ranges>

struct S {
  S() = default;
  S(S&&) = default;
};

S s;
std::ranges::single_view<S> r{s};

https://godbolt.org/z/65nvdaTfP

GCC reports constraints not satisfied which is correct, however, there is more:

<source>:9:31: error: cannot convert 'S' to 'int' in initialization
    9 | std::ranges::single_view<S> r{s};
      |                               ^
      |                               |
      |                               S

This is confusing since there is nothing to do with 'int'.

[Bug c++/115000] Confusing 'cannot convert to 'int' in initialization' error message

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115000

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2024-05-09
           Keywords|                            |error-recovery
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed. There is another issue like this. Basically the C++ front-end uses
int as a valid type after an error.

[Bug c++/115000] Confusing 'cannot convert to 'int' in initialization' error message

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115000

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced:
```
template<class T>
concept bool c = false;

template<c T>
struct ts{};
struct S {};
S s;
ts<S> t33{s};
```

[Bug c++/115000] Confusing 'cannot convert to 'int' in initialization' error message

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115000

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I suspect all of the see also bugs here are the same issue, I described my try
of fixing that in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104113#c8 .