[cfe-commits] patch for llvm.org/pr8207

[Nico Weber]

Hi,

the attached patch fixes llvm.org/pr8207 (and potentially more). The
reason the bug happens is the following code in CodeGenModule:

LangOptions::VisibilityMode
CodeGenModule::getDeclVisibilityMode(const Decl *D) const {
  // ...

  if (getLangOptions().CPlusPlus) {
    // Entities subject to an explicit instantiation declaration get default
    // visibility.
    if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D)) {
      // ...
    } else if (const ClassTemplateSpecializationDecl *ClassSpec
                              = dyn_cast<ClassTemplateSpecializationDecl>(D)) {
      if (ClassSpec->getSpecializationKind()
                                        == TSK_ExplicitInstantiationDeclaration)
        return LangOptions::Default;
    } else if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
      if (Record->getTemplateSpecializationKind()
                                        == TSK_ExplicitInstantiationDeclaration)
        return LangOptions::Default;
    } else if (const VarDecl *Var = dyn_cast<VarDecl>(D)) {
      // ...
    }

    // ...
  }

  // If this decl is contained in a class, it should have the same visibility
  // as the parent class.
  if (const DeclContext *DC = D->getDeclContext())
    if (DC->isRecord())
      return getDeclVisibilityMode(cast<Decl>(DC));

  return getLangOptions().getVisibilityMode();
}


When a template specialization declaration is overridden with a
template specialization definition, the template specialization kind
of inner structs was not updated. Hence, when the function above
checked the visibility of the inner struct's function, it would look
in the parent class (== the inner struct) because of the code at the
end of the function, and then would return LangOptions::Default,
because the inner struct would still have specialization kind
TSK_ExplicitInstantiationDeclaration.

The fix is to correctly re-set the specialization kind of inner
structs on the TSK_ExplicitInstantiationDeclaration ->
TSK_ExplicitInstantiationDefinition transition on the base class.

Nico


ps: I'm not sure if the call to MarkVTableUsed is needed, but it's
called further up in that file when
TSK_ExplicitInstantiationDefinition is set too.
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