rogfer01 marked 4 inline comments as done.
================
Comment at: lib/Sema/SemaExpr.cpp:10527
@@ +10526,3 @@
+ ME->getMemberDecl()->hasAttr<PackedAttr>()) {
+ Diag(OpLoc, diag::warn_taking_address_of_packed_member)
+ << ME->getMemberDecl() << RD;
----------------
aaron.ballman wrote:
> I wonder if we should diagnose only when the resulting pointer is actually
> misaligned. For instance, the following code should be just fine:
> ```
> struct __attribute__((packed)) S {
> int i;
> };
>
> void f(S s) {
> int *ip = &s.i; // Why should this warn?
> }
> ```
> Have you run this patch over any large code bases to see how high the
> false-positive rate is? How do you envision users silencing this diagnostic
> if they have a false-positive? Something like `&(s.x)` (since I you're not
> ignoring paren imp casts)?
I think it should warn because in this case &s == &s.i and the alignment of the
whole struct is 1 (due to the packed attribute) so s.i is also aligned to 1
which would not be the suitable alignment for an int.
I'm currently building Firefox, I'll add a comment once it ends.
Regarding silencing the diagnostic: -Wno-address-of-packed-member should do but
I understand it might be too coarse in some cases.
http://reviews.llvm.org/D20561
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