On Tue, Jun 05, 2007 at 04:35:16PM +0200, Ion Gaztañaga wrote:
I just realized about this just after sending my previous mail. SunCC seems to use the classical cfront approach encoding a pointer to member as offset + 1. So it seems that parent_from_member detection is correct for SunCC.
Slightly off-topic, but: do you know the background WHY did they decide to implement ptr-to-member as offset +1?
boost/intrusive/detail/utilities.hpp in the member_value_traits class:
static node_ptr to_node_ptr(reference value) { MemberHookType* result = &(value.*P); return result->to_node_ptr(); }
I have tracked the conversion to here myself. I wondered whether this was a compiler bug, but the following simple program works, ie. it does NOT raise an assertion failure. I hope I managed to reproduce correctly the usage pattern of ptr-to-member.. == #include <assert.h> struct A { int x; int y; }; template<typename T, int T::*P> struct setter { static void f(T &t) { t.*P = 42; } }; int main(void) { A a; a.x = a.y = 0; assert((a.x == 0) && (a.y == 0)); setter<A, &A::y>::f(a); assert((a.x == 0) && (a.y == 42)); setter<A, &A::x>::f(a); assert((a.x == 42) && (a.y == 42)); return 0; } == I'm kinda clueless as how to proceed from here. If it _is_ a genuine compiler bug, we need a more complex test-case, which I'm unable to produce myself (as I don't know how many intermediate instantiation steps there are in the intrusive library).