------- Comment #13 from mmitchel at gcc dot gnu dot org 2009-01-28 23:56 ------- Actually, CLASSTYPE_EMPTY_P is probably a fine thing to use for C++. (It's of course C++ specific; you'd either need to access it via a hook, or promote to a language-independent bit.) CLASSTYPE_EMPTY_P will not capture an array of empty objects, but that's an extreme corner-case.
Note that CLASSTYPE_EMPTY_P classes may have arbitrary size. That's because of things like: struct A{}; struct B : public A {}; struct C : public A, public B {}; In C, you cannot put the B sub-object at the same address as the A sub-object since that would end up with two A sub-objects (the A-in-B-in-C subobject and A-in-C subobject) at the same address. So, C will be a two-byte structure. Obviously, you can generalize this to make arbitrarily huge empty classes. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908