According to https://godbolt.org/z/XzT1wz, compiles in 8.3 and trunk. Fails compilation on 9.2.

constexpr float f() { float x = 42; ++x; return x; }
void g() { constexpr float x = f(); }

<source>: In function 'void g()':
<source>:2:33:   in 'constexpr' expansion of 'f()'
<source>:2:34: error: '((float)1 + 4.2e+1f)' is not a constant expression
    2 | void g() { constexpr float x = f(); }
      |                                  ^