[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

117

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,
   // When naming a constructor as a member of a dependent context (eg, in a
   // friend declaration or an inherited constructor declaration), form an
   // unresolved "typename" type.
   if (CurClass->isDependentContext() && !EnteringContext) {
     QualType T = Context.getDependentNameType(ETK_None, SS.getScopeRep(), &II);
     return ParsedType::make(T);
   }
 
-  if (SS.isNotEmpty() && RequireCompleteDeclContext(SS, CurClass))
+  if ((SS.isNotEmpty() && RequireCompleteDeclContext(SS, CurClass)) ||
+      CurClass->isInvalidDecl())
     return ParsedType();
 
   // Find the injected-class-name declaration. Note that we make no attempt to
   // diagnose cases where the injected-class-name is shadowed: the only
   // declaration that can validly shadow the injected-class-name is a
   // non-static data member, and if the class contains both a non-static data
   // member and a constructor then it is ill-formed (we check that in
   // CheckCompletedCXXClass).
   CXXRecordDecl *InjectedClassName = nullptr;
   for (NamedDecl *ND : CurClass->lookup(&II)) {
     auto *RD = dyn_cast<CXXRecordDecl>(ND);
     if (RD && RD->isInjectedClassName()) {
       InjectedClassName = RD;
       break;
     }
   }
   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/Sema/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() {
+}