[PrintAsObjC] Hack: Assume all option sets have typedefs. (#3961)

...because otherwise option sets that get imported as members using
NS_SWIFT_NAME are printed with an 'enum' tag, and the definition of
NS_OPTIONS only declares the typedef under C++.

We should come back and figure out something more principled for this
later, but for now this solves an issue with generated headers
imported into C++ translation units.

rdar://problem/27130343
(cherry picked from commit 02d2517)

Author: jrose-apple

lib/ClangImporter/ImportDecl.cpp

@@ -2499,6 +2499,10 @@ namespace {
         if (!result)
           return nullptr;
 
+        // HACK: Make sure PrintAsObjC always omits the 'enum' tag for
+        // option set enums.
+        Impl.DeclsWithSuperfluousTypedefs.insert(decl);
+
         enumeratorContext = result;
         break;
       }

lib/PrintAsObjC/PrintAsObjC.cpp

@@ -97,9 +97,13 @@ static StringRef getNameForObjC(const ValueDecl *VD,
   if (customNamesOnly)
     return StringRef();
 
-  if (auto clangDecl = dyn_cast_or_null<clang::NamedDecl>(VD->getClangDecl()))
+  if (auto clangDecl = dyn_cast_or_null<clang::NamedDecl>(VD->getClangDecl())) {
     if (const clang::IdentifierInfo *II = clangDecl->getIdentifier())
       return II->getName();
+    if (auto *anonDecl = dyn_cast<clang::TagDecl>(clangDecl))
+      if (auto *anonTypedef = anonDecl->getTypedefNameForAnonDecl())
+        return anonTypedef->getIdentifier()->getName();
+  }
 
   return VD->getName().str();
 }

test/PrintAsObjC/Inputs/enums.h

@@ -0,0 +1,23 @@
+// This file is meant to be used with the mock SDK, not the real one.
+#import <Foundation.h>
+
+#define SWIFT_NAME(X) __attribute__((swift_name(#X)))
+
+@interface Wrapper : NSObject
+@end
+
+enum TopLevelRaw { TopLevelRawA };
+enum MemberRaw { MemberRawA } SWIFT_NAME(Wrapper.Raw);
+
+typedef enum { TopLevelAnonA } TopLevelAnon;
+typedef enum { MemberAnonA } MemberAnon SWIFT_NAME(Wrapper.Anon);
+typedef enum SWIFT_NAME(Wrapper.Anon2) { MemberAnon2A } MemberAnon2;
+
+typedef enum TopLevelTypedef { TopLevelTypedefA } TopLevelTypedef;
+typedef enum SWIFT_NAME(Wrapper.Typedef) MemberTypedef { MemberTypedefA } MemberTypedef;
+
+typedef NS_ENUM(long, TopLevelEnum) { TopLevelEnumA };
+typedef NS_ENUM(long, MemberEnum) { MemberEnumA } SWIFT_NAME(Wrapper.Enum);
+
+typedef NS_OPTIONS(long, TopLevelOptions) { TopLevelOptionsA = 1 };
+typedef NS_OPTIONS(long, MemberOptions) { MemberOptionsA = 1} SWIFT_NAME(Wrapper.Options);

test/PrintAsObjC/enums.swift

@@ -1,7 +1,7 @@
 // RUN: rm -rf %t
 // RUN: mkdir %t
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-source-import -emit-module -emit-module-doc -o %t %s -disable-objc-attr-requires-foundation-module
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -parse-as-library %t/enums.swiftmodule -parse -emit-objc-header-path %t/enums.h -import-objc-header %S/../Inputs/empty.h -disable-objc-attr-requires-foundation-module
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-source-import -emit-module -emit-module-doc -o %t %s -import-objc-header %S/Inputs/enums.h -disable-objc-attr-requires-foundation-module
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -parse-as-library %t/enums.swiftmodule -parse -emit-objc-header-path %t/enums.h -import-objc-header %S/Inputs/enums.h -disable-objc-attr-requires-foundation-module
 // RUN: FileCheck %s < %t/enums.h
 // RUN: FileCheck -check-prefix=NEGATIVE %s < %t/enums.h
 // RUN: %check-in-clang %t/enums.h
@@ -21,6 +21,8 @@ import Foundation
 // CHECK-NEXT: - (enum NegativeValues)takeAndReturnEnum:(enum FooComments)foo;
 // CHECK-NEXT: - (void)acceptPlainEnum:(enum NSMalformedEnumMissingTypedef)_;
 // CHECK-NEXT: - (enum ObjcEnumNamed)takeAndReturnRenamedEnum:(enum ObjcEnumNamed)foo;
+// CHECK-NEXT: - (void)acceptTopLevelImportedWithA:(enum TopLevelRaw)a b:(TopLevelEnum)b c:(TopLevelOptions)c d:(TopLevelTypedef)d e:(TopLevelAnon)e;
+// CHECK-NEXT: - (void)acceptMemberImportedWithA:(enum MemberRaw)a b:(enum MemberEnum)b c:(MemberOptions)c d:(enum MemberTypedef)d e:(MemberAnon)e ee:(MemberAnon2)ee;
 // CHECK: @end
 @objc class AnEnumMethod {
   @objc func takeAndReturnEnum(_ foo: FooComments) -> NegativeValues {
@@ -30,6 +32,9 @@ import Foundation
   @objc func takeAndReturnRenamedEnum(_ foo: EnumNamed) -> EnumNamed {
     return .A
   }
+
+  @objc func acceptTopLevelImported(a: TopLevelRaw, b: TopLevelEnum, c: TopLevelOptions, d: TopLevelTypedef, e: TopLevelAnon) {}
+  @objc func acceptMemberImported(a: Wrapper.Raw, b: Wrapper.Enum, c: Wrapper.Options, d: Wrapper.Typedef, e: Wrapper.Anon, ee: Wrapper.Anon2) {}
 }
 
 // CHECK-LABEL: typedef SWIFT_ENUM_NAMED(NSInteger, ObjcEnumNamed, "EnumNamed") {