[Sema] Fix crash in getConstructorName.

[ilya-biryukov]

Summary

Can happen when getConstructorName is called on invalid decls,
specifically the ones that do not have the injected class name.

[rsmith]

Looks fine, but please put the test case somewhere more appropriate (under SemaCXX, for instance).

lib/Sema/SemaExprCXX.cpp

118

We would be able to recover in more cases if we only bail out when the InjectedClassName is not found. Maybe instead of this change, you could weaken the assertion to only fail if the class is valid, and return ParsedType here if we don't find an InjectedClassName.

[ilya-biryukov]

• Better recovery for invalid decls that do have an injected class name
• Move the test to SemaCXX

[ilya-biryukov]

Thanks for taking a look!

lib/Sema/SemaExprCXX.cpp

ParsedType Sema::getConstructorName(IdentifierInfo &II,
   CXXRecordDecl *InjectedClassName = nullptr;
   for (NamedDecl *ND : CurClass->lookup(&II)) {
     auto *RD = dyn_cast<CXXRecordDecl>(ND);
     if (RD && RD->isInjectedClassName()) {
       InjectedClassName = RD;
       break;
     }
   }
+  if (!InjectedClassName && CurClass->isInvalidDecl())
+    return ParsedType();
   assert(InjectedClassName && "couldn't find injected class name");
 
   QualType T = Context.getTypeDeclType(InjectedClassName);
   DiagnoseUseOfDecl(InjectedClassName, NameLoc);
   MarkAnyDeclReferenced(NameLoc, InjectedClassName, /*OdrUse=*/false);
 
   return ParsedType::make(T);
 }
 

test/SemaCXX/injected-class-name-crash.cpp

+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+template <class T>
+struct X : public Foo<Bar { // expected-error {{unknown template name 'Foo'}} expected-error {{use of undeclared identifier 'Bar'}}
+  X();
+}; // expected-error {{expected '{' after base class list}}
+
+
+template <class T>
+X<T>::X() {
+}