[PATCH] D13419: Fix several problems at the intersection of template instantiations and visibility

[Richard Smith via cfe-commits]

rsmith added a comment.

Please factor out the fix for `getTemplateInstantiationPattern` and commit it separately. https://reviews.llvm.org/D25942 has a testcase for that portion of this change.



================
Comment at: lib/AST/Decl.cpp:1057-1058
+        RD->getTemplateInstantiationPattern();
+    if (!InstantiatedFrom)
+      InstantiatedFrom = RD->getInstantiatedFromMemberClass();
     if (InstantiatedFrom)
----------------
This doesn't seem to match GCC; GCC seems to do this for all kinds of member specialization, not just for member class specialization:

```
template<typename T> struct A {
  template<typename U> struct __attribute__((visibility("hidden"))) B;
};
template<> template<typename U> struct A<int>::B { virtual void f() {} };
void g() { A<int>::B<int>().f(); }
```

Here, A<int>::B<int> gets hidden visibility, even though it was instantiated from the member template specialization `A<int>::B` which had no visibility attribute.

I don't know what the underlying logic is here -- does GCC look at the visibility on the enclosing class when computing visibility for a member class? -- but I don't think this one special case covers it.


================
Comment at: lib/AST/Decl.cpp:1096-1097
+    FunctionDecl *InstantiatedFrom = fn->getTemplateInstantiationPattern();
+    if (!InstantiatedFrom)
+      InstantiatedFrom = fn->getInstantiatedFromMemberFunction();
 
----------------
Likewise.


================
Comment at: lib/AST/DeclCXX.cpp:1349-1354
+      while (!CTD->isMemberSpecialization()) {
+        auto *NewCTD = CTD->getInstantiatedFromMemberTemplate();
+        if (!NewCTD)
           break;
         CTD = NewCTD;
       }
----------------
The same bug exists in `VarDecl::getTemplateInstantiationPattern`; can you fix it there too?


Repository:
  rL LLVM

https://reviews.llvm.org/D13419