rsmith added inline comments.
> SemaChecking.cpp:11053-11056
> + if ((RequiredAlignment > AlignRecord) ||
> + ((Context.toCharUnitsFromBits(
> + Context.getFieldOffset(cast<FieldDecl>(MD))) %
> + RequiredAlignment) != 0)) {
This doesn't seem to correctly handle the case where the base expression gives
you some guaranteed alignment; it only handles the case where the base
expression reduces the alignment. Suppose `__alignof__(double) == 8` and I have
this:
struct __attribute__((packed, aligned(1))) B { double d; };
struct __attribute__((aligned(8))) A { B b; };
A *p;
double *q = &p->b.d;
For the top `MemberExpr` here, we see `RequiredAlignment == AlignField == 8`,
`AlignRecord == 1`, and we report that we have a reference to a field with
reduced alignment. But we don't, because the reference is within an
8-byte-aligned `B` object within the enclosing `A` object.
Do you care about handling that case correctly? It seems like one way to handle
all the nontrivial cases here would be to recurse to the innermost
`MemberExpr`, accumulating an offset on the way, and then check that the
innermost expression's type implies a correct alignment and offset for the type
of `E`.
> SemaChecking.cpp:11069-11071
> + // If this field already has the least alignment possible it will
> never
> + // yield a misaligned pointer.
> + break;
Too much indentation.
> SemaChecking.cpp:11072
> + break;
> ME = dyn_cast<MemberExpr>(ME->getBase());
> }
You should at least `IgnoreParens` here, and maybe `IgnoreParenNoopCasts`.
https://reviews.llvm.org/D23657
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