In asking this, I'm particularly puzzled by code like this in
build_base_path in cp/class.c:
/* Don't bother with the calculations inside sizeof; they'll ICE if the
source type is incomplete and the pointer value doesn't matter. */
if (skip_evaluation)
{
expr = build_nop (build_pointer_type (target_type), expr);
if (!want_pointer)
expr = build_indirect_ref (EXPR_LOCATION (expr), expr, NULL);
return expr;
}
Presumably the early return is OK within a sizeof expression; it is OK
within an expression like (0 ? x : y)?
From reading the code, I'd say yes. The bug that Jason fixed is
related to stuff that cannot appear within a constant expression except
within sizeof -- for example
struct B {};
struct D : public B {
static const int i = sizeof((B*)(D*)0);
};
struct Z {};
struct A : Z {};
Z* implicitToZ (Z*);
struct B : A {
static const int i = sizeof(implicitToZ((B*)0));
};
struct B {};
struct D;
D* p;
struct D: public B {
static const int i = sizeof ((B*)p);
};
(see PR27177). All of these would still be forbidden within (0?x:y).
Paolo
