[Bug c++/103212] New: requires expression with lambda fails

[Bug c++/103212] New: requires expression with lambda fails

[egor.pugin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103212

            Bug ID: 103212
           Summary: requires expression with lambda fails
           Product: gcc
           Version: 11.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: egor.pugin at gmail dot com
  Target Milestone: ---

---
constexpr bool test = requires { [](auto o){}(0); };
static_assert(test);
---

gives

<source>:1:37: error: expected primary-expression before 'auto'
    1 | constexpr bool test = requires { [](auto o){}(0); };
      |                                     ^~~~

Also see for compiler comparison:
https://godbolt.org/z/zYGa733d4

msvc fails that condition, clang compiles ok.

[Bug c++/103212] requires expression with lambda fails

[egor.pugin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103212

--- Comment #1 from Egor Pugin <egor.pugin at gmail dot com> ---
Original code was closer to something like this:

---
#include <memory>
constexpr bool test = requires { [](auto o) {}(std::unique_ptr<int>{}); };
static_assert(test);
---

[Bug c++/103212] requires expression with lambda inside causes a parse error

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103212

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-11-12
            Summary|requires expression with    |requires expression with
                   |lambda fails                |lambda inside causes a
                   |                            |parse error
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Simplified testcase:
static_assert(requires { [](int){}(0); });

Note even though MSVC parses this code correctly, it still says the
static_assert is valid which is obviously wrong :).

[Bug c++/103212] requires expression with lambda inside causes a parse error

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103212

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |12.1.0
      Known to work|                            |12.2.0
           Keywords|                            |needs-bisection

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Looks like this has been fixed.

[Bug c++/103212] requires expression with lambda inside causes a parse error

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103212

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
           Keywords|needs-bisection             |
         Resolution|---                         |DUPLICATE
                 CC|                            |ppalka at gcc dot gnu.org

--- Comment #4 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fully fixed for GCC 12.2+ by the fixes for PR101677 / PR105541 it seems.  This
is close enough to a dup of the latter.

*** This bug has been marked as a duplicate of bug 105541 ***