erichkeane added a comment.
This likely also needs a Release Note.
================
Comment at: clang/lib/AST/ASTContext.cpp:2697
int64_t FieldSizeInBits =
Context.toBits(Context.getTypeSizeInChars(Field->getType()));
if (Field->isBitField()) {
----------------
MitalAshok wrote:
> erichkeane wrote:
> > This answer ends up being wrong in the case of _BitInt, consider
> > _BitInt(7). Its field-size would be 7, yet this would result in 8. I'm
> > not sure of the fallout of this though.
> The field size should be 8 for _BitInt(7), since it takes 8 bits in the
> struct (including the padding bit). It is filtered out later with
> "hasUniqueObjectRepresentations" on line 2709 if it wasn't in a bit field
I see, thanks for the explanation.
================
Comment at: clang/test/SemaCXX/has_unique_object_reps_bitint.cpp:7
+static_assert(__has_unique_object_representations(_BitInt(sizeof(int) * 8u)));
+static_assert(sizeof(_BitInt(24)) != 4 ||
!__has_unique_object_representations(_BitInt(24)));
+
----------------
MitalAshok wrote:
> erichkeane wrote:
> > Whats going on here? I don't particularly get the condition.
> sizeof(_BitInt(24)) == sizeof(int32_t) (4) since we align to the next larger
> builtin integer type. But if that weren't the case for some reason (i.e.,
> that changes in the future, I don't know if _BitInt is ABI stable), this
> wouldn't start failing for unrelated reasons
I see! Can you clarify that with a comment here?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D125802/new/
https://reviews.llvm.org/D125802
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