[ASTImporter] Import the default argument of NonTypeTemplateParmDecl

[teemperor]

Summary

The test case isn't using the AST matchers for all checks as there doesn't seem to be support for
matching NonTypeTemplateParmDecl default arguments. Otherwise this is simply importing the
default arguments.

[martong]

This looks good as well, thanks!

clang/lib/AST/ASTImporter.cpp

5225

Good catch!

[teemperor]

• Rebased

[shafik]

clang/unittests/AST/ASTImporterTest.cpp

933

Might make sense to test multiple default arguments and types.

clang/lib/AST/ASTImporter.cpp

ASTNodeImporter::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
   auto ToDeclName = importChecked(Err, D->getDeclName());
   auto ToLocation = importChecked(Err, D->getLocation());
   auto ToType = importChecked(Err, D->getType());
   auto ToTypeSourceInfo = importChecked(Err, D->getTypeSourceInfo());
   auto ToInnerLocStart = importChecked(Err, D->getInnerLocStart());
   if (Err)
     return std::move(Err);
 
-  // FIXME: Import default argument.
-
   NonTypeTemplateParmDecl *ToD = nullptr;
-  (void)GetImportedOrCreateDecl(
-      ToD, D, Importer.getToContext(),
+  if (GetImportedOrCreateDecl(ToD, D, Importer.getToContext(),
                               Importer.getToContext().getTranslationUnitDecl(),
                               ToInnerLocStart, ToLocation, D->getDepth(),
-      D->getPosition(), ToDeclName.getAsIdentifierInfo(), ToType,
-      D->isParameterPack(), ToTypeSourceInfo);
+                              D->getPosition(),
+                              ToDeclName.getAsIdentifierInfo(), ToType,
+                              D->isParameterPack(), ToTypeSourceInfo))
+    return ToD;
+
+  if (D->hasDefaultArgument()) {
+    ExpectedExpr ToDefaultArgOrErr = import(D->getDefaultArgument());
+    if (!ToDefaultArgOrErr)
+      return ToDefaultArgOrErr.takeError();
+    ToD->setDefaultArgument(*ToDefaultArgOrErr);
+  }
+
   return ToD;
 }
 
 ExpectedDecl
 ASTNodeImporter::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
   // Import the name of this declaration.
   auto NameOrErr = import(D->getDeclName());
   if (!NameOrErr)

clang/unittests/AST/ASTImporterTest.cpp

TEST_P(ASTImporterOptionSpecificTestBase, ImportBeginLocOfDeclRefExpr) {
   ASSERT_TRUE(To);
   ASSERT_TRUE(
       cast<CStyleCastExpr>(cast<CompoundStmt>(To->getBody())->body_front())
           ->getSubExpr()
           ->getBeginLoc()
           .isValid());
 }
 
+TEST_P(ASTImporterOptionSpecificTestBase, NonTypeTemplateParmDeclNoDefaultArg) {
+  Decl *FromTU = getTuDecl("template<int N> struct X {};", Lang_CXX03);
+  auto From = FirstDeclMatcher<NonTypeTemplateParmDecl>().match(
+      FromTU, templateTypeParmDecl(hasName("N")));
+  NonTypeTemplateParmDecl *To = Import(From, Lang_CXX03);
+  ASSERT_FALSE(To->hasDefaultArgument());
+}
+
+TEST_P(ASTImporterOptionSpecificTestBase, NonTypeTemplateParmDeclDefaultArg) {
+  Decl *FromTU = getTuDecl("template<int S = 1> struct X {};", Lang_CXX03);
+  auto From = FirstDeclMatcher<NonTypeTemplateParmDecl>().match(
+      FromTU, templateTypeParmDecl(hasName("N")));
+  NonTypeTemplateParmDecl *To = Import(From, Lang_CXX03);
+  ASSERT_TRUE(To->hasDefaultArgument());
+  Expr *ToArg = To->getDefaultArgument();
+  ASSERT_TRUE(isa<IntegerLiteral>(ToArg));
+  ASSERT_EQ(cast<IntegerLiteral>(ToArg)->getValue().getLimitedValue(), 1U);
+}
+
 TEST_P(ASTImporterOptionSpecificTestBase,
        ImportOfTemplatedDeclOfClassTemplateDecl) {
   Decl *FromTU = getTuDecl("template<class X> struct S{};", Lang_CXX03);
   auto From =
       FirstDeclMatcher<ClassTemplateDecl>().match(FromTU, classTemplateDecl());
   ASSERT_TRUE(From);
   auto To = cast<ClassTemplateDecl>(Import(From, Lang_CXX03));
   ASSERT_TRUE(To);
   Decl *ToTemplated = To->getTemplatedDecl();
   Decl *ToTemplated1 = Import(From->getTemplatedDecl(), Lang_CXX03);
   EXPECT_TRUE(ToTemplated1);
   EXPECT_EQ(ToTemplated1, ToTemplated);
 }
 
 TEST_P(ASTImporterOptionSpecificTestBase,
        ImportOfTemplatedDeclOfFunctionTemplateDecl) {
   Decl *FromTU = getTuDecl("template<class X> void f(){}", Lang_CXX03);
   auto From = FirstDeclMatcher<FunctionTemplateDecl>().match(
       FromTU, functionTemplateDecl());