majnemer added a comment. In http://reviews.llvm.org/D18596#392098, @andreybokhanko wrote:
> In http://reviews.llvm.org/D18596#388295, @aaron.ballman wrote: > > > Regression is a bit of a question mark, to me depending on the diagnostic. > > I think warning the user "this has absolutely no effect" is a reasonable > > diagnostic for that situation -- the user wrote something, possibly > > expecting it to have an effect, and it turns out that it does absolutely > > nothing (including in the compiler that implements the language extension). > > If MSVC were to ever add semantic effect in those cases (diverging from > > what Clang implements), the diagnostic becomes even more important for > > Clang users. So I think it's fine to accept __unaligned for non-pointer > > types, but issue an "attribute ignored" warning diagnostic. > > > As David wrote, __unaligned is a qualifier in MSVC, so MS accepts the > following: > > __unaligned int *p; > > as a correct usage (and does mangling for __unaligned). > > We model it as an attribute, so we create a new AttributedType for int, not > for the pointer. This is OK, since our mangling code takes PointeeType and > checks presence of the attribute. Unfortunately, this means that we can't > issue warnings, as it's impossible (to the best of my knowledge) to > distinguish between > > __unaligned int *p; > __unaligned int p; > > in processTypeAttrs function. > > As I said before, the purpose of this patch is to implement correct mangling > (and thus, improve object level compatibility with MSVC), not to provide a > fully correct implementation of __unaligned. > > Another alternative is to model __unaligned as a qualifier, but this would > require addition of an extra field to TypeBitfields. That's OK. We have plenty of bits in the "address_space" field to steal from. > Do we want to do this for an ignored qualifier? I don't see any practical > purpose. It's not ignored for Windows on ARM. > Andrey http://reviews.llvm.org/D18596 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
