------- Comment #88 from ian at airs dot com 2007-05-18 17:35 ------- Regarding comment #85, this again relies on the notion of dynamic type of a memory location such that the only possible end result is to eliminate TBAA when compiling C++. The only thing I can say about this sort of test case is that I agree that one can make an argument from the standard that this type of code is valid. However, as I've said before, e.g., in comment #76, I don't think that anybody really wants that end result.
Any example that inherently relies on a type cast is going to lead you straight to eliminating TBAA. And note that your example is clearly invalid in C. Adding the placement new doesn't really have anything to do with whether it is valid or invalid in C++. Can you show me a test case which my patch gets wrong which does not involve type casting outside of placement new itself? -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29286
