aaron.ballman added inline comments.
================
Comment at: lib/Sema/SemaExpr.cpp:10527
@@ +10526,3 @@
+ if (RD->hasAttr<PackedAttr>() ||
+ ME->getMemberDecl()->hasAttr<PackedAttr>()) {
+ Diag(OpLoc, diag::warn_taking_address_of_packed_member)
----------------
rogfer01 wrote:
> aaron.ballman wrote:
> > Ah, I forgot that the attribute also affected the alignment of the struct
> > itself. Amending my false-positive idea, the following should be fine,
> > shouldn't it?:
> > ```
> > struct __attribute__((packed)) S {
> > char c;
> > int i;
> > char c2;
> > };
> >
> > void f(S s) {
> > char *cp = &s.c;
> > char *cp2 = &s.c2;
> > }
> > ```
> > I think perhaps we should not diagnose if the member's type also has a
> > one-byte alignment (or, for instance, uses alignas(1) to achieve that).
> > What do you think?
> Yes. I like the idea since the packed attribute has no effect on already
> 1-aligned data (like char). But note that C++11 does not allow reducing the
> alignment through `alignas`.
Hmm, okay, I was not remembering properly; I thought one of `alignas`,
`__declspec(align)`, or `__attribute__((aligned))` allowed for decreasing the
alignment, but documentation implies otherwise.
http://reviews.llvm.org/D20561
_______________________________________________
cfe-commits mailing list
[email protected]
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
