[Accepted as a DR at the November, 2023 meeting.]

The message of a static_assert declaration is a conditional-expression and thus is not manifestly constant evaluated. Consider this example:

  struct X {
    std::string s;
    const char *p;
  };
  consteval X f() { return {.s = "some long string that requires a heap allocation", .p = "hello"}; }

  static_assert(cond, f().p);

The example is ill-formed, because the immediate invocation f() lets a pointer to the heap escape.