Fix assertion failure importing NS_OPTION with differing Swift name across versions

At the call sites of `findAnonymousEnumForTypedef` we often wish to
import the returned enum declaration and return the type the declaration
creates.

Prior to this patch, we assumed that the enum declaration would be
imported as a `NominalTypeDecl`. This is not always the case. For
whatever reason, sometimes in typechecking we import a declaration
for various different naming versions. If the Swift name for an imported
enum differs between the canonical name version, and currently
requested name version, we import the enum as a `TypeAliasDecl` instead.

Prior to this patch, this meant we would hit asserts importing some
components of UIKit.

This patch relaxes the assumption that the import is a `NominalTypeDecl`
to just a `TypeDecl`, which as of yet, seems to be true.

Author: NuriAmari

lib/ClangImporter/ImportDecl.cpp

@@ -5756,7 +5756,8 @@ SwiftDeclConverter::getImplicitProperty(ImportedName importedName,
         assert(clangEnum.value()->getIntegerType()->getCanonicalTypeInternal() ==
                typedefType->getCanonicalTypeInternal());
         if (auto swiftEnum = Impl.importDecl(*clangEnum, Impl.CurrentVersion)) {
-          importedType = {cast<NominalTypeDecl>(swiftEnum)->getDeclaredType(), false};
+          importedType = {cast<TypeDecl>(swiftEnum)->getDeclaredInterfaceType(),
+                          false};
         }
       }
     }

lib/ClangImporter/ImportType.cpp

@@ -2134,7 +2134,7 @@ ImportedType ClangImporter::Implementation::importFunctionReturnType(
         assert(clangEnum.value()->getIntegerType()->getCanonicalTypeInternal() ==
                typedefType->getCanonicalTypeInternal());
         if (auto swiftEnum = importDecl(*clangEnum, CurrentVersion)) {
-          return {cast<NominalTypeDecl>(swiftEnum)->getDeclaredType(), false};
+          return {cast<TypeDecl>(swiftEnum)->getDeclaredInterfaceType(), false};
         }
       }
     }
@@ -2200,7 +2200,8 @@ ImportedType ClangImporter::Implementation::importFunctionParamsAndReturnType(
         assert(clangEnum.value()->getIntegerType()->getCanonicalTypeInternal() ==
                typedefType->getCanonicalTypeInternal());
         if (auto swiftEnum = importDecl(*clangEnum, CurrentVersion)) {
-          importedType = {cast<NominalTypeDecl>(swiftEnum)->getDeclaredType(), false};
+          importedType = {cast<TypeDecl>(swiftEnum)->getDeclaredInterfaceType(),
+                          false};
         }
       }
     }
@@ -2301,7 +2302,7 @@ ClangImporter::Implementation::importParameterType(
                    ->getCanonicalTypeInternal() ==
                typedefType->getCanonicalTypeInternal());
         if (auto swiftEnum = importDecl(*clangEnum, CurrentVersion)) {
-          swiftParamTy = cast<NominalTypeDecl>(swiftEnum)->getDeclaredType();
+          swiftParamTy = cast<TypeDecl>(swiftEnum)->getDeclaredInterfaceType();
         }
       }
     }
@@ -2892,7 +2893,8 @@ ImportedType ClangImporter::Implementation::importMethodParamsAndReturnType(
         assert(clangEnum.value()->getIntegerType()->getCanonicalTypeInternal() ==
                typedefType->getCanonicalTypeInternal());
         if (auto swiftEnum = importDecl(*clangEnum, CurrentVersion)) {
-          importedType = {cast<NominalTypeDecl>(swiftEnum)->getDeclaredType(), false};
+          importedType = {cast<TypeDecl>(swiftEnum)->getDeclaredInterfaceType(),
+                          false};
         }
       }
     }

test/Interop/Cxx/enum/Inputs/CenumsNSOptions.apinotes

@@ -11,8 +11,12 @@ Enumerators:
 Tags:
 - Name: UIPrinterJobTypes
   SwiftName: UIPrinter.JobTypes
+- Name: Baz
+  SwiftName: CurrentBazVersion
 SwiftVersions:
 - Version: 4
   Tags:
   - Name: UIPrinterJobTypes
     SwiftName: UIPrinterJobTypes
+  - Name: Baz
+    SwiftName: BazVersion4

test/Interop/Cxx/enum/Inputs/c-enums-NS_OPTIONS.h

@@ -78,3 +78,13 @@ typedef NS_OPTIONS(NSUInteger, Bar) {
   API_NOTES_NAMED_OptionFour = API_NOTES_NAMED_OptionOne |
                                API_NOTES_NAMED_OptionTwo
 };
+
+typedef NS_OPTIONS(NSUInteger, Baz) { Baz1, Baz2 };
+
+Baz CFunctionReturningNSOption();
+void CFunctionTakingNSOption(Baz);
+
+@interface NSOptionTypeCheckTest
++ (Baz)methodReturningNSOption;
++ (void)methodTakingNSOption:(Baz)baz;
+@end

test/Interop/Cxx/enum/c-enums-NS_OPTIONS-typecheck-name-differs-between-versions.swift

@@ -0,0 +1,9 @@
+// RUN: %target-swift-frontend -I %S/Inputs -enable-experimental-cxx-interop -typecheck %s
+// REQUIRES: objc_interop
+
+import CenumsNSOptions
+
+let foo = CFunctionReturningNSOption()
+CFunctionTakingNSOption(foo)
+let foo2 = NSOptionTypeCheckTest.methodReturningNSOption()
+NSOptionTypeCheckTest.methodTakingNSOption(foo)