[Bug c++/107791] New: Spurious -Wunused warning for artificial variable introduced for post contract

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107791

            Bug ID: 107791
           Summary: Spurious -Wunused warning for artificial variable
                    introduced for post contract
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

int f(int x) [[pre: x > 0]] [[post r: r > 0]]
{
  return -5;
}

int main()
{
  f(42);
}


$ g++20 fail.cc  -fcontracts  -Wunused
fail.cc: In function 'int f(int, int)':
fail.cc:1:45: warning: unused parameter '__r' [-Wunused-parameter]
    1 | int f(int x) [[pre: x > 0]] [[post r: r > 0]]
      |                                             ^