[PATCH] D134286: [C2x] implement typeof and typeof_unqual

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added inline comments.


================
Comment at: clang/lib/AST/ASTContext.cpp:12910-12916
+    // FIXME:: is this assumption correct or do we need to do work here to find
+    // the common type sugar regarding the stripped qualifiers if only one side
+    // is unqual?
+    assert(cast<TypeOfType>(X)->isUnqual() == cast<TypeOfType>(Y)->isUnqual() &&
+           "typeof vs typeof_unqual mismatch?");
+    return Ctx.getTypeOfType(Ctx.getQualifiedType(Underlying),
+                             cast<TypeOfType>(X)->isUnqual());
----------------
mizvekov wrote:
> mizvekov wrote:
> > erichkeane wrote:
> > > I'm unfamiliar with this function, but I would expect you MIGHT need to?  If only because they are the same AST node.  Should 'unqual' version be its own node?  I'm on the fence, as it is a LOT of code to do so, but also ends up being simpler in many places.
> > A qualified and an unqualified typeof could have the same underlying type, so this assert can trip.
> > 
> > I think what makes most sense is to unify them to a qualified typeof in case they differ, as that holds the underlying type unchanged:
> > ```
> >     return Ctx.getTypeOfType(Ctx.getQualifiedType(Underlying),
> >                              cast<TypeOfType>(X)->isUnqual() && cast<TypeOfType>(Y)->isUnqual());
> > ```
> By the way, one thing to notice is the confusion regarding what is the underlying type of this node, the result of `desugar()` or the result of `getUnderlyingType()`?
> 
> On my previous post, I meant the former.
> 
> Maybe this is a good reason to rename `getUnderlyingType()` to `getUnmodifiedType()` or something similar?
FWIW: I still have to address these comments in the patch, but I'll do that tomorrow.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D134286/new/

https://reviews.llvm.org/D134286