[PATCH] D52598: [OpenCL] Fixed address space cast in C style cast of C++ parsing

[John McCall via Phabricator via cfe-commits]

rjmccall added inline comments.


================
Comment at: lib/Sema/SemaCast.cpp:2288
+      SrcType->isPointerType()) {
+    const PointerType *DestPtr = DestType->getAs<PointerType>();
+    if (!DestPtr->isAddressSpaceOverlapping(*SrcType->getAs<PointerType>())) {
----------------
Anastasia wrote:
> Anastasia wrote:
> > rjmccall wrote:
> > > Please test the result of `getAs` instead of separately testing `isPointerType`.
> > > 
> > > Why is this check OpenCL-specific?  Address spaces are a general language feature.
> > I think mainly because I am factoring out from the existing OpenCL check. But it probably makes sense that the semantics of this is not different in other languages. I will update it! Thanks!
> After playing with this for a bit longer I discovered that I have to keep the OpenCL check unfortunately.
> 
> I found this old commit (`d4c5f84`/`r129583`) that says:
>   C-style casts can add/remove/change address spaces through the reinterpret_cast mechanism.
> That's not the same as in OpenCL because it seems for C++ you can cast any AS to any other AS. Therefore, no checks are needed at all. I am not sure if we can come up with a common function for the moment.
> 
> The following  tests are checking this:
>    CodeGenCXX/address-space-cast.cpp
>    SemaCXX/address-space-conversion.cpp
> 
> Do you think it would make sense to rename this method with OpenCL-something or keep in case may be CUDA or some other languages might need similar functionality...
> 
I think you can leave it alone for now, but please add a comment explaining the reasoning as best you see it, and feel free to express uncertainty about the right rule.

Don't take `QualType` by `const &`, by the way.  It's a cheap-to-copy value type and should always be passed by value.


https://reviews.llvm.org/D52598