[ASTImporter] Fix import of NestedNameSpecifierLoc.

[balazske]

Summary

Import type location in case of TypeSpec and TypeSpecWithTemplate.
Without this fix the imported NespedNameSpecifierLoc will have an
invalid begin location.

[martong]

Ping

[a_sidorin]

Looks good!

[balazske]

Rebase.

lib/AST/ASTImporter.cpp

while (!NestedNames.empty()) {
 
     case NestedNameSpecifier::NamespaceAlias:
       Builder.Extend(getToContext(), Spec->getAsNamespaceAlias(),
                      ToLocalBeginLoc, ToLocalEndLoc);
       break;
 
     case NestedNameSpecifier::TypeSpec:
     case NestedNameSpecifier::TypeSpecWithTemplate: {
+      SourceLocation ToTLoc;
+      if (Error Err = importInto(ToTLoc, NNS.getTypeLoc().getBeginLoc()))
+        return std::move(Err);
       TypeSourceInfo *TSI = getToContext().getTrivialTypeSourceInfo(
-            QualType(Spec->getAsType(), 0));
+            QualType(Spec->getAsType(), 0), ToTLoc);
       Builder.Extend(getToContext(), ToLocalBeginLoc, TSI->getTypeLoc(),
                      ToLocalEndLoc);
       break;
     }
 
     case NestedNameSpecifier::Global:
       Builder.MakeGlobal(getToContext(), ToLocalBeginLoc);
       break;

unittests/AST/ASTImporterTest.cpp

testImport(
       "template<typename T, int Size> class declToImport {"
       "  T data[Size];"
       "};",
       Lang_CXX, "", Lang_CXX, Verifier,
       classTemplateDecl(has(cxxRecordDecl(
           has(fieldDecl(hasType(dependentSizedArrayType())))))));
 }
 
+TEST_P(ASTImporterOptionSpecificTestBase, ImportBeginLocOfDeclRefExpr) {
+  Decl *FromTU = getTuDecl(
+      "class A { public: static int X; }; void f() { (void)A::X; }", Lang_CXX);
+  auto From = FirstDeclMatcher<FunctionDecl>().match(
+      FromTU, functionDecl(hasName("f")));
+  ASSERT_TRUE(From);
+  ASSERT_TRUE(
+      cast<CStyleCastExpr>(cast<CompoundStmt>(From->getBody())->body_front())
+          ->getSubExpr()
+          ->getBeginLoc()
+          .isValid());
+  FunctionDecl *To = Import(From, Lang_CXX);
+  ASSERT_TRUE(To);
+  ASSERT_TRUE(
+      cast<CStyleCastExpr>(cast<CompoundStmt>(To->getBody())->body_front())
+          ->getSubExpr()
+          ->getBeginLoc()
+          .isValid());
+}
+
 TEST_P(ASTImporterOptionSpecificTestBase,
        ImportOfTemplatedDeclOfClassTemplateDecl) {
   Decl *FromTU = getTuDecl("template<class X> struct S{};", Lang_CXX);
   auto From =
       FirstDeclMatcher<ClassTemplateDecl>().match(FromTU, classTemplateDecl());
   ASSERT_TRUE(From);
   auto To = cast<ClassTemplateDecl>(Import(From, Lang_CXX));
   ASSERT_TRUE(To);