[Bug c++/127403] Internally surrounding a statement expression with #pragma's erroneously voids it in C++ mode

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127403

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
It certainly does insert one now, which is why you can't do:

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wc++17-extensions"
  if constexpr (cond)
#pragma GCC diagnostic pop
    statement;

because the pop is interpreted as the statement following the if.