Merge pull request #29679 from slavapestov/fix-enum-error-case-alias

ClangImporter: Fix importEnumCaseAlias() when the original is itself an alias

Author: slavapestov

lib/ClangImporter/ImportDecl.cpp

@@ -5823,23 +5823,38 @@ Decl *SwiftDeclConverter::importEnumCaseAlias(
   if (!importIntoDC)
     importIntoDC = importedEnum;
 
-  // Construct the original constant. Enum constants without payloads look
-  // like simple values, but actually have type 'MyEnum.Type -> MyEnum'.
-  auto constantRef =
-      new (Impl.SwiftContext) DeclRefExpr(original, DeclNameLoc(),
-                                          /*implicit*/ true);
-  constantRef->setType(original->getInterfaceType());
-
   Type importedEnumTy = importedEnum->getDeclaredInterfaceType();
-
   auto typeRef = TypeExpr::createImplicit(importedEnumTy, Impl.SwiftContext);
-  auto instantiate = new (Impl.SwiftContext)
-      DotSyntaxCallExpr(constantRef, SourceLoc(), typeRef);
-  instantiate->setType(importedEnumTy);
-  instantiate->setThrows(false);
+
+  Expr *result = nullptr;
+  if (auto *enumElt = dyn_cast<EnumElementDecl>(original)) {
+    assert(!enumElt->hasAssociatedValues());
+
+    // Construct the original constant. Enum constants without payloads look
+    // like simple values, but actually have type 'MyEnum.Type -> MyEnum'.
+    auto constantRef =
+        new (Impl.SwiftContext) DeclRefExpr(enumElt, DeclNameLoc(),
+                                            /*implicit*/ true);
+    constantRef->setType(enumElt->getInterfaceType());
+
+    auto instantiate = new (Impl.SwiftContext)
+        DotSyntaxCallExpr(constantRef, SourceLoc(), typeRef);
+    instantiate->setType(importedEnumTy);
+    instantiate->setThrows(false);
+
+    result = instantiate;
+  } else {
+    assert(isa<VarDecl>(original));
+
+    result =
+        new (Impl.SwiftContext) MemberRefExpr(typeRef, SourceLoc(),
+                                              original, DeclNameLoc(),
+                                              /*implicit*/ true);
+    result->setType(original->getInterfaceType());
+  }
 
   Decl *CD = Impl.createConstant(name, importIntoDC, importedEnumTy,
-                                 instantiate, ConstantConvertKind::None,
+                                 result, ConstantConvertKind::None,
                                  /*isStatic*/ true, alias);
   Impl.importAttributes(alias, CD);
   return CD;

test/ClangImporter/Inputs/custom-modules/AliasCaseErrorEnum/AliasCaseErrorEnum.apinotes

@@ -0,0 +1,5 @@
+---
+Name: AliasCaseErrorEnum
+Tags:
+- Name: AliasError
+  NSErrorDomain: AliasErrorDomain

test/ClangImporter/Inputs/custom-modules/AliasCaseErrorEnum/AliasCaseErrorEnum.h

@@ -0,0 +1,10 @@
+@import Foundation;
+
+#define kAliasErrorDomain "com.acme.AliasErrorDomain"
+
+extern NSString *const __nonnull AliasErrorDomain;
+
+typedef NS_ENUM(NSInteger, AliasError) {
+    AliasErrorRealName = 1,
+    AliasErrorFakeName = 1,
+};

test/ClangImporter/Inputs/custom-modules/AliasCaseErrorEnum/module.map

@@ -0,0 +1,4 @@
+module AliasCaseErrorEnum {
+  umbrella header "AliasCaseErrorEnum.h"
+  export *
+}

test/ClangImporter/enum-error-case-alias.swift

@@ -0,0 +1,11 @@
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -emit-sil %s -enable-objc-interop -I %S/Inputs/custom-modules/AliasCaseErrorEnum
+
+// REQUIRES: objc_interop
+
+import AliasCaseErrorEnum
+
+// Make sure that we can reference aliases defined in the wrapper type
+// which themselves point at aliases inside the nested 'Code' type.
+
+_ = AliasError.realName
+_ = AliasError.fakeName