[PATCH] D62116: [Sema] raise nullptr check to cover additional uses

[Nick Desaulniers via Phabricator via cfe-commits]

nickdesaulniers added inline comments.


================
Comment at: clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:557-558
+            dyn_cast_or_null<CXXRecordDecl>(ND->getDeclContext());
+        CXXThisScopeRAII ThisScope(*this, ThisContext, Qualifiers(),
+                                   ND->isCXXInstanceMember());
+      }
----------------
rsmith wrote:
> The purpose of creating this is to change the type of `this` in the scope of the instantiation below, so this change is incorrect. The right fix would be to change the initializer of `ThisContext` to handle `ND` being null. (I suspect that actually can't happen at the moment because we happen to only attach late-parsed attributes to `NamedDecl`s, but I don't think there's any fundamental reason why that should be the case so it makes some sense to retain the check here.)
> The purpose of creating this is to change the type of this in the scope of the instantiation below, so this change is incorrect. 

In this case I agree.  The `}` added on L559 should be extended to L564.

> so it makes some sense to retain the check here

I assume PVS studio is complaining about dereferencing ND on L556, then doing what looks like a `nullptr` check on L558 (reminiscent of `-fno-delete-null-pointer-checks`).  I assume `dyn_cast` on L554 can fail at runtime and return `nullptr`?  Should that happen, how should we proceed?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D62116/new/

https://reviews.llvm.org/D62116