[Bug c++/104823] New: [12 Regression] narrowing conversion inside non-dependent decltype operand silently accepted ever since r12-6075

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104823

            Bug ID: 104823
           Summary: [12 Regression] narrowing conversion inside
                    non-dependent decltype operand silently accepted ever
                    since r12-6075
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ppalka at gcc dot gnu.org
  Target Milestone: ---

struct S { S(int); };

int id(int v);
double id(double v);

template<class> auto f(double v) -> decltype(S{id(v)});


GCC 11 correctly issues a narrowing conversion warning for this testcase ever
since r11-434:

<stdin>:6:50: warning: narrowing conversion of ‘id(v)’ from ‘double’ to ‘int’
[-Wnarrowing]

But in GCC 12 the warning is gone.