[ClangImporter] Add support for 'SwiftImportAsNonGeneric' in API notes (#6962)

Generic Objective-C classes with this annotation will be imported as
non-generic in Swift. The Swift 3 behavior hardcoded a certain set of
class /hierarchies/ as permanently non-generic, and this is preserved
in Swift 3 mode.

Actually using this API note in a versioned way (as opposed to just
marking the class non-generic in all language versions) will cause
horrible source compatibility problems in the mix-and-match cases,
where Swift 3 code presents a non-generic type that Swift 4 expects to
be generic or vice versa.  Fixes for this will come later; right now
it's more important to add support for the feature at all.

To avoid unwanted changes in Swift 4, this commit also adds API notes
to make any existing classes in the previously-hardcoded set continue
to import as non-generic even in Swift 4. The difference is that
/subclasses/ of these classes may come in as generic. (If we want to
make a change here, that can be a separate commit.)

rdar://problem/31226414 (Swift side of rdar://problem/28455962)

apinotes/CMakeLists.txt

@@ -38,6 +38,7 @@ set(SWIFT_API_NOTES_INPUTS
   QuickLook
   SafariServices
   SceneKit
+  ScriptingBridge
   SpriteKit
   StoreKit
   TVMLKit

apinotes/Foundation.apinotes

@@ -5,6 +5,7 @@ Classes:
   SwiftBridge: AffineTransform
 - Name: NSArray
   SwiftBridge: Swift.Array
+  SwiftImportAsNonGeneric: true
   Methods:
   - Selector: 'pathsMatchingExtensions:'
     SwiftName: pathsMatchingExtensions(_:)
@@ -12,6 +13,15 @@ Classes:
   - Selector: 'filteredArrayUsingPredicate:'
     SwiftName: filtered(using:)
     MethodKind: Instance
+- Name: NSMutableArray
+  SwiftImportAsNonGeneric: true
+  Methods:
+  - Selector: 'removeObjectIdenticalTo:inRange:'
+    SwiftName: removeObject(identicalTo:in:)
+    MethodKind: Instance
+  - Selector: 'removeObjectIdenticalTo:'
+    SwiftName: removeObject(identicalTo:)
+    MethodKind: Instance
 - Name: NSCachedURLResponse
   SwiftName: CachedURLResponse
 - Name: NSCharacterSet
@@ -51,6 +61,8 @@ Classes:
   - Selector: 'hasMemberInPlane:'
     SwiftName: hasMemberInPlane(_:)
     MethodKind: Instance
+- Name: NSCountedSet
+  SwiftImportAsNonGeneric: true
 - Name: NSData
   SwiftBridge: Data
   Methods:
@@ -85,6 +97,8 @@ Classes:
   SwiftBridge: DateComponents
 - Name: NSDateInterval
   SwiftBridge: DateInterval
+- Name: NSEnumerator
+  SwiftImportAsNonGeneric: true
 - Name: NSError
   SwiftBridge: Swift.Error
   Methods:
@@ -93,12 +107,18 @@ Classes:
     MethodKind: Class
 - Name: NSDictionary
   SwiftBridge: Swift.Dictionary
+  SwiftImportAsNonGeneric: true
+- Name: NSMutableDictionary
+  SwiftImportAsNonGeneric: true
 - Name: NSSet
   SwiftBridge: Swift.Set
+  SwiftImportAsNonGeneric: true
   Methods:
   - Selector: 'filteredSetUsingPredicate:'
     SwiftName: filtered(using:)
     MethodKind: Instance
+- Name: NSMutableSet
+  SwiftImportAsNonGeneric: true
 - Name: NSString
   SwiftBridge: Swift.String
   Methods:
@@ -313,14 +333,7 @@ Classes:
     MethodKind: Instance
 - Name: NSMeasurement
   SwiftBridge: Measurement
-- Name: NSMutableArray
+  SwiftImportAsNonGeneric: true
-  Methods:
-  - Selector: 'removeObjectIdenticalTo:inRange:'
-    SwiftName: removeObject(identicalTo:in:)
-    MethodKind: Instance
-  - Selector: 'removeObjectIdenticalTo:'
-    SwiftName: removeObject(identicalTo:)
-    MethodKind: Instance
 - Name: NSMutableData
   Methods:
   - Selector: 'appendBytes:length:'
@@ -445,6 +458,7 @@ Classes:
   - Name: unsignedIntegerValue
     SwiftName: uintValue
 - Name: NSOrderedSet
+  SwiftImportAsNonGeneric: true
   Methods:
   - Selector: 'enumerateObjectsWithOptions:usingBlock:'
     SwiftName: enumerateObjects(options:using:)
@@ -470,6 +484,8 @@ Classes:
   - Selector: 'indexOfObjectWithOptions:passingTest:'
     SwiftName: index(_:ofObjectPassingTest:)
     MethodKind: Instance
+- Name: NSMutableOrderedSet
+  SwiftImportAsNonGeneric: true
 - Name: NSTask
   SwiftName: Process
   Methods:
@@ -932,6 +948,7 @@ Classes:
   SwiftName: ValueTransformer
 - Name: NSDirectoryEnumerator
   SwiftName: FileManager.DirectoryEnumerator
+  SwiftImportAsNonGeneric: true
 - Name: NSDimension
   SwiftName: Dimension
 - Name: NSUnit

apinotes/ScriptingBridge.apinotes

@@ -0,0 +1,5 @@
+---
+Name: ScriptingBridge
+Classes:
+- Name: SBElementArray
+  SwiftImportAsNonGeneric: true

lib/ClangImporter/ImportDecl.cpp

@@ -1713,7 +1713,14 @@ getAccessorPropertyType(const clang::FunctionDecl *accessor, bool isSetter,
 /// Whether we should suppress importing the Objective-C generic type params
 /// of this class as Swift generic type params.
 static bool
-shouldSuppressGenericParamsImport(const clang::ObjCInterfaceDecl *decl) {
+shouldSuppressGenericParamsImport(const LangOptions &langOpts,
+                                  const clang::ObjCInterfaceDecl *decl) {
+  if (decl->hasAttr<clang::SwiftImportAsNonGenericAttr>())
+    return true;
+
+  if (langOpts.isSwiftVersion3()) {
+    // In Swift 3 we used a hardcoded list of declarations, and made all of
+    // their subclasses drop their generic parameters when imported.
     while (decl) {
       StringRef name = decl->getName();
       if (name == "NSArray" || name == "NSDictionary" || name == "NSSet" ||
@@ -1723,6 +1730,8 @@ shouldSuppressGenericParamsImport(const clang::ObjCInterfaceDecl *decl) {
       }
       decl = decl->getSuperClass();
     }
+  }
+
   return false;
 }
 
@@ -6149,7 +6158,7 @@ Optional<GenericParamList *> SwiftDeclConverter::importObjCGenericParams(
   if (!typeParamList) {
     return nullptr;
   }
-  if (shouldSuppressGenericParamsImport(decl)) {
+  if (shouldSuppressGenericParamsImport(Impl.SwiftContext.LangOpts, decl)) {
     return nullptr;
   }
   assert(typeParamList->size() > 0);

test/APINotes/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Headers/APINotesFrameworkTest.apinotes

@@ -84,6 +84,8 @@ SwiftVersions:
           - Name: accessorsOnlyRenamedRetypedClass
             PropertyKind:    Class
             SwiftImportAsAccessors: true
+      - Name: NewlyGenericSub
+        SwiftImportAsNonGeneric: true
     Protocols:
       - Name: ProtoWithVersionedUnavailableMember
         Methods:

test/APINotes/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Headers/APINotesFrameworkTest.h

@@ -15,8 +15,13 @@ __attribute__((objc_root_class))
 -(nonnull id)methodWithA:(nonnull id)a;
 @end
 
+__attribute__((objc_root_class))
+@interface Base
+@end
+
 #endif // __OBJC__
 
+#import <APINotesFrameworkTest/Classes.h>
 #import <APINotesFrameworkTest/ImportAsMember.h>
 #import <APINotesFrameworkTest/Properties.h>
 #import <APINotesFrameworkTest/Protocols.h>

test/APINotes/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Headers/Classes.h

@@ -0,0 +1,9 @@
+#ifdef __OBJC__
+#pragma clang assume_nonnull begin
+
+@interface NewlyGenericSub<Element> : Base
++ (Element)defaultElement;
+@end
+
+#pragma clang assume_nonnull end
+#endif // __OBJC__

test/APINotes/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Headers/Properties.h

@@ -1,10 +1,6 @@
 #ifdef __OBJC__
 #pragma clang assume_nonnull begin
 
-__attribute__((objc_root_class))
-@interface Base
-@end
-
 @interface TestProperties: Base
 @property (nonatomic, readwrite, retain) id accessorsOnly;
 @property (nonatomic, readwrite, retain, class) id accessorsOnlyForClass;

test/APINotes/versioned-objc.swift

@@ -13,4 +13,14 @@ class ProtoWithVersionedUnavailableMemberImpl: ProtoWithVersionedUnavailableMemb
   func requirement() -> Any? { return nil }
 }
 
+func testNonGeneric() {
+  // CHECK-DIAGS-3:[[@LINE+1]]:{{[0-9]+}}: error: cannot convert value of type 'Any' to specified type 'Int'
+  let _: Int = NewlyGenericSub.defaultElement()
+  // CHECK-DIAGS-4:[[@LINE-1]]:{{[0-9]+}}: error: generic parameter 'Element' could not be inferred
+
+  // CHECK-DIAGS-3:[[@LINE+1]]:{{[0-9]+}}: error: cannot specialize non-generic type 'NewlyGenericSub'
+  let _: Int = NewlyGenericSub<Base>.defaultElement()
+  // CHECK-DIAGS-4:[[@LINE-1]]:{{[0-9]+}}: error: cannot convert value of type 'Base' to specified type 'Int'
+}
+
 let unrelatedDiagnostic: Int = nil