[Bug c++/114183] New: Lambda constexpr works in msvc but not in gcc

[Bug c++/114183] New: Lambda constexpr works in msvc but not in gcc

[jlame646 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114183

            Bug ID: 114183
           Summary: Lambda constexpr works in msvc but not in gcc
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jlame646 at gmail dot com
  Target Milestone: ---

The following valid(afaik) program is rejected by gcc:
https://godbolt.org/z/xhes5fvoc

```
int main() {
    constexpr auto func = []()constexpr { return 1; };
    auto i = []{return func();};
}   

```

GCC says:

```
<source>: In lambda function:
<source>:3:28: error: 'func' is not captured
    3 |     auto i = []{return func();};
      |                        ~~~~^~
<source>:3:15: note: the lambda has no capture-default
    3 |     auto i = []{return func();};
      |               ^
<source>:2:20: note: 'constexpr const main()::<lambda()> func' declared here
    2 |     constexpr auto func = []()constexpr { return 1; };
      |
```

https://en.cppreference.com/w/cpp/language/lambda says:

> A lambda expression can read the value of a variable without capturing it if the variable
> is constexpr and has no mutable members.

[Bug c++/114183] [11/12/13/14 Regression] Lambda constexpr works in msvc but not in gcc

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114183

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |7.5.0
      Known to fail|                            |8.1.0
   Target Milestone|---                         |11.5
            Summary|Lambda constexpr works in   |[11/12/13/14 Regression]
                   |msvc but not in gcc         |Lambda constexpr works in
                   |                            |msvc but not in gcc

[Bug c++/114183] [11/12/13/14 Regression] Lambda constexpr works in msvc but not in gcc

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114183

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
https://github.com/llvm/llvm-project/issues/83569 was closed so this is not a
bug?

[Bug c++/114183] [11/12/13/14 Regression] Lambda constexpr works in msvc but not in gcc

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114183

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

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

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Invalid for the same reason as the clang issue is invalid.