[change-namespace] Fix crash when injected base-class name is used in friend declarations.

[hokein]

LGTM.

change-namespace/ChangeNamespace.cpp

if (const auto *Using = Result.Nodes.getNodeAs<UsingDecl>("using")) {
     // filtered by matchers in some cases, e.g. the type is templated. We should
     // handle the record type qualifier instead.
     TypeLoc Loc = *TLoc;
     while (Loc.getTypeLocClass() == TypeLoc::Qualified)
       Loc = Loc.getNextTypeLoc();
     if (Loc.getTypeLocClass() == TypeLoc::Elaborated) {
       NestedNameSpecifierLoc NestedNameSpecifier =
           Loc.castAs<ElaboratedTypeLoc>().getQualifierLoc();
+      // This happens for friend declaration of a base class with injected class
+      // name.
+      if (!NestedNameSpecifier.getNestedNameSpecifier())
+        return;
       const Type *SpecifierType =
           NestedNameSpecifier.getNestedNameSpecifier()->getAsType();
       if (SpecifierType && SpecifierType->isRecordType())
         return;
     }
     fixTypeLoc(Result, startLocationForType(Loc), endLocationForType(Loc), Loc);
   } else if (const auto *VarRef =
                  Result.Nodes.getNodeAs<DeclRefExpr>("var_ref")) {

unittests/change-namespace/ChangeNamespaceTests.cpp

std::string Expected = "namespace na {\n"
                          "  A& operator=(const A&) = delete;\n"
                          "};\n"
                          "void f() { A a; a = A(); A aa = A(); }\n"
                          "} // namespace y\n"
                          "} // namespace x\n";
   EXPECT_EQ(format(Expected), runChangeNamespaceOnCode(Code));
 }
 
+TEST_F(ChangeNamespaceTest, InjectedClassNameInFriendDecl) {
+  OldNamespace = "d";
+  NewNamespace = "e";
+  std::string Code = "namespace a{\n"
+                     "template <typename T>\n"
+                     "class Base {\n"
+                     " public:\n"
+                     "  void f() {\n"
+                     "    T t;\n"
+                     "    t.priv();\n"
+                     "  }\n"
+                     "};\n"
+                     "}  // namespace a\n"
+                     "namespace d {\n"
+                     "class D : public a::Base<D> {\n"
+                     " private:\n"
+                     "  friend class Base<D>;\n"
+                     "  void priv() {}\n"
+                     "  Base b;\n"
+                     "};\n"
+                     "\n"
+                     "void f() {\n"
+                     "  D d;\n"
+                     "  a:: Base<D> b;\n"
+                     "  b.f();\n"
+                     "}\n"
+                     "}  // namespace d\n";
+  std::string Expected = "namespace a{\n"
+                         "template <typename T>\n"
+                         "class Base {\n"
+                         " public:\n"
+                         "  void f() {\n"
+                         "    T t;\n"
+                         "    t.priv();\n"
+                         "  }\n"
+                         "};\n"
+                         "}  // namespace a\n"
+                         "\n"
+                         "namespace e {\n"
+                         "class D : public a::Base<D> {\n"
+                         " private:\n"
+                         "  friend class Base<D>;\n"
+                         "  void priv() {}\n"
+                         "  a::Base b;\n"
+                         "};\n"
+                         "\n"
+                         "void f() {\n"
+                         "  D d;\n"
+                         "  a::Base<D> b;\n"
+                         "  b.f();\n"
+                         "}\n"
+                         "}  // namespace e\n";
+  EXPECT_EQ(format(Expected), runChangeNamespaceOnCode(Code));
+}
 
 } // anonymous namespace
 } // namespace change_namespace
 } // namespace clang