[PATCH] D112765: [AST] injected-class-name is not a redecl, even in template specializations

[Sam McCall via Phabricator via cfe-commits]

sammccall added inline comments.


================
Comment at: clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:1841-1842
+                                   /*DelayTypeCreation=*/IsInjectedClassName);
+  if (IsInjectedClassName)
+    SemaRef.Context.getTypeDeclType(Record, cast<CXXRecordDecl>(Owner));
 
----------------
hokein wrote:
> aaron.ballman wrote:
> > Why is this call needed? (It seems strange to me that we call it and ignore the return value.)
> my understanding is
>   - `getTypeDeclType` is more than a getter, it also has a side-effort -- if the type of the passed `Record` is empty, it creates a type, and propagates the type to `Record->TypeForDecl`;
>   - from the above line, we delay the type creation when `IsInjectedClassName` is true;
>   - so we need to create a type for the `Record` by invoking `getTypeDeclType`;
> 
> might be worth a comment.
> 
That's exactly right. The injected-class-name is an independent decl but yields the same RecordType, and getTypeDeclType has a hacky interface so we can force this link.
(It wasn't needed in the old version of the code, because when it was a redecl getTypeDeclType would yield the same type in any case)

I should have mentioned this is all derived from the injected-class-name handling in Sema::ActOnStartCXXMemberDeclarations(). It lacks comments, but I'll add a few while here.


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Comment at: clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:1910
 
+  if (IsInjectedClassName)
+    assert(Record->isInjectedClassName() && "Broken injected-class-name");
----------------
hokein wrote:
> it is unclear to me what's the intention of the assertion.
We needed to do a few weird things (and to assume some things about the input) to initialize the injected-class-name, it verifies we got them all right.

(This assertion is also in ActOnStartCXXMemberDeclarations())


Repository:
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  https://reviews.llvm.org/D112765/new/

https://reviews.llvm.org/D112765