Jason, I just want to make sure we still want the -Wplacement-new option I added some time ago enabled by default.
I think I had initially intended it to be on because the original implementation was more permissive and didn't diagnose cases where (for example) the buffer spanned multiple members of the same struct, as in the example below. After our discussion of the patch where you pointed out that C++ is moving in the direction of increased strictness of aliasing requirements, I changed it to diagnose those cases. Can you please confirm that enabling -Wplacement-new by default is still appropriate? Thanks Martin struct S { int a; char b; } s; new (&s) char [sizeof s]; // accepted new (&s.a) char [sizeof s]; // diagnosed