Merge pull request #37443 from egorzhdan/cxx-namespace-alias

C++ Interop: import namespace aliases

Author: zoecarver

lib/ClangImporter/ImportDecl.cpp

@@ -2590,8 +2590,42 @@ namespace {
     }
 
     Decl *VisitNamespaceAliasDecl(const clang::NamespaceAliasDecl *decl) {
-      // FIXME: Implement once Swift has namespaces.
-      return nullptr;
+      Optional<ImportedName> correctSwiftName;
+      auto importedName = importFullName(decl, correctSwiftName);
+      auto name = importedName.getDeclName().getBaseIdentifier();
+      if (name.empty())
+        return nullptr;
+
+      if (correctSwiftName)
+        return importCompatibilityTypeAlias(decl, importedName,
+                                            *correctSwiftName);
+
+      auto dc =
+          Impl.importDeclContextOf(decl, importedName.getEffectiveContext());
+      if (!dc)
+        return nullptr;
+
+      auto aliasedDecl =
+          Impl.importDecl(decl->getAliasedNamespace(), getActiveSwiftVersion());
+      if (!aliasedDecl)
+        return nullptr;
+
+      Type aliasedType;
+      if (auto aliasedTypeDecl = dyn_cast<TypeDecl>(aliasedDecl))
+        aliasedType = aliasedTypeDecl->getDeclaredInterfaceType();
+      else if (auto aliasedExtDecl = dyn_cast<ExtensionDecl>(aliasedDecl))
+        // This happens if the alias points to its parent namespace.
+        aliasedType = aliasedExtDecl->getExtendedType();
+      else
+        return nullptr;
+
+      auto result = Impl.createDeclWithClangNode<TypeAliasDecl>(
+          decl, AccessLevel::Public, Impl.importSourceLoc(decl->getBeginLoc()),
+          SourceLoc(), name, Impl.importSourceLoc(decl->getLocation()),
+          /*GenericParams=*/nullptr, dc);
+      result->setUnderlyingType(aliasedType);
+
+      return result;
     }
 
     Decl *VisitLabelDecl(const clang::LabelDecl *decl) {

test/Interop/Cxx/namespace/Inputs/classes.h

@@ -40,4 +40,35 @@ struct BasicStruct {
 };
 } // namespace ClassesNS3
 
+namespace GlobalAliasToNS1 = ClassesNS1;
+
+namespace ClassesNS4 {
+namespace AliasToGlobalNS1 = ::ClassesNS1;
+namespace AliasToGlobalNS2 = ::ClassesNS1::ClassesNS2;
+
+namespace ClassesNS5 {
+struct BasicStruct {};
+} // namespace ClassesNS5
+
+namespace AliasToInnerNS5 = ClassesNS5;
+namespace AliasToNS2 = ClassesNS1::ClassesNS2;
+
+namespace AliasChainToNS1 = GlobalAliasToNS1;
+namespace AliasChainToNS2 = AliasChainToNS1::ClassesNS2;
+} // namespace ClassesNS4
+
+namespace ClassesNS5 {
+struct BasicStruct {};
+namespace AliasToAnotherNS5 = ClassesNS4::ClassesNS5;
+
+namespace ClassesNS5 {
+struct BasicStruct {};
+namespace AliasToNS5NS5 = ClassesNS5;
+} // namespace ClassesNS5
+
+namespace AliasToGlobalNS5 = ::ClassesNS5;
+namespace AliasToLocalNS5 = ClassesNS5;
+namespace AliasToNS5 = ::ClassesNS5::ClassesNS5;
+} // namespace ClassesNS5
+
 #endif // TEST_INTEROP_CXX_NAMESPACE_INPUTS_CLASSES_H

test/Interop/Cxx/namespace/classes-irgen.swift

@@ -6,6 +6,7 @@ import Classes
 // CHECK: call i8* @{{_ZN10ClassesNS111BasicStruct11basicMemberEv|"\?basicMember@BasicStruct@ClassesNS1@@QEAAPEBDXZ"}}(%"struct.ClassesNS1::BasicStruct"*
 // CHECK: call i8* @{{_ZN10ClassesNS110ClassesNS211BasicStruct11basicMemberEv|"\?basicMember@BasicStruct@ClassesNS2@ClassesNS1@@QEAAPEBDXZ"}}(%"struct.ClassesNS1::ClassesNS2::BasicStruct"*
 // CHECK: call i8* @{{_ZN10ClassesNS311BasicStruct11basicMemberEv|"\?basicMember@BasicStruct@ClassesNS3@@QEAAPEBDXZ"}}(%"struct.ClassesNS3::BasicStruct"*
+// CHECK: call i8* @{{_ZN10ClassesNS111BasicStruct11basicMemberEv|"\?basicMember@BasicStruct@ClassesNS1@@QEAAPEBDXZ"}}(%"struct.ClassesNS1::BasicStruct"*
 // CHECK: ret void
 public func basicTests() {
   var basicStructInst = ClassesNS1.BasicStruct()
@@ -16,6 +17,9 @@ public func basicTests() {
 
   var siblingBasicStruct = ClassesNS3.BasicStruct()
   siblingBasicStruct.basicMember()
+
+  var basicStructViaAlias = ClassesNS4.AliasToGlobalNS1.BasicStruct()
+  basicStructViaAlias.basicMember()
 }
 
 // CHECK-LABEL: define {{.*}}void @"$s4main15forwardDeclaredyyF"()

test/Interop/Cxx/namespace/classes-module-interface.swift

@@ -32,3 +32,34 @@
 // CHECK:   }
 // CHECK: }
 // CHECK-NOT: extension
+
+// CHECK: typealias GlobalAliasToNS1 = ClassesNS1
+// CHECK: extension ClassesNS4 {
+// CHECK:   typealias AliasToGlobalNS1 = ClassesNS1
+// CHECK:   typealias AliasToGlobalNS2 = ClassesNS1.ClassesNS2
+// CHECK:   typealias AliasToInnerNS5 = ClassesNS4.ClassesNS5
+// CHECK:   typealias AliasToNS2 = ClassesNS1.ClassesNS2
+// CHECK:   typealias AliasChainToNS1 = ClassesNS1
+// CHECK:   typealias AliasChainToNS2 = ClassesNS1.ClassesNS2
+// CHECK: }
+// CHECK: extension ClassesNS4.ClassesNS5 {
+// CHECK:   struct BasicStruct {
+// CHECK:     init()
+// CHECK:   }
+// CHECK: }
+// CHECK: extension ClassesNS5 {
+// CHECK:   struct BasicStruct {
+// CHECK:     init()
+// CHECK:   }
+// CHECK:   typealias AliasToAnotherNS5 = ClassesNS4.ClassesNS5
+// CHECK:   typealias AliasToGlobalNS5 = ClassesNS5
+// CHECK:   typealias AliasToLocalNS5 = ClassesNS5.ClassesNS5
+// CHECK:   typealias AliasToNS5 = ClassesNS5.ClassesNS5
+// CHECK: }
+// CHECK: extension ClassesNS5.ClassesNS5 {
+// CHECK:   struct BasicStruct {
+// CHECK:     init()
+// CHECK:   }
+// CHECK:   typealias AliasToNS5NS5 = ClassesNS5.ClassesNS5
+// CHECK: }
+// CHECK-NOT: extension

test/Interop/Cxx/namespace/classes.swift

@@ -20,6 +20,10 @@ NamespacesTestSuite.test("Basic classes") {
   var siblingBasicStruct = ClassesNS3.BasicStruct()
   let siblingMemberCString = siblingBasicStruct.basicMember()
   expectEqual(String(cString: siblingMemberCString!), "ClassesNS3::BasicStruct::basicMember")
+
+  var basicStructViaAlias = ClassesNS4.AliasToGlobalNS1.BasicStruct()
+  let basicMemberViaAliasCString = basicStructViaAlias.basicMember()
+  expectEqual(String(cString: basicMemberViaAliasCString!), "ClassesNS1::BasicStruct::basicMember")
 }
 
 NamespacesTestSuite.test("Forward declared classes") {