[SE-0160] Swift 3: Downgrade error about non-ObjC @(IB|GK)Inspectable properties

include/swift/AST/DiagnosticsSema.def

@@ -3080,6 +3080,10 @@ ERROR(objc_extension_not_class,none,
 // If you change this, also change enum ObjCReason
 #define OBJC_ATTR_SELECT "select{marked @_cdecl|marked dynamic|marked @objc|marked @IBOutlet|marked @IBAction|marked @NSManaged|a member of an @objc protocol|implicitly @objc|an @objc override|an implementation of an @objc requirement|marked @IBInspectable|marked @GKInspectable|in an @objc extension of a class (without @nonobjc)}"
 
+WARNING(attribute_meaningless_when_nonobjc,none,
+        "'@%0' attribute is meaningless on a property that cannot be "
+        "represented in Objective-C", (StringRef))
+
 ERROR(objc_invalid_on_var,none,
       "property cannot be %" OBJC_ATTR_SELECT "0 "
       "because its type cannot be represented in Objective-C", (unsigned))

lib/Sema/TypeCheckDecl.cpp

@@ -2366,8 +2366,10 @@ static Optional<ObjCReason> shouldMarkAsObjC(TypeChecker &TC,
   // explicitly declared @objc.
   if (VD->getAttrs().hasAttribute<ObjCAttr>())
     return ObjCReason::ExplicitlyObjC;
-  // @IBOutlet, @IBAction, @IBInspectable, @NSManaged, and @GKInspectable
-  // imply @objc.
+  // @IBOutlet, @IBAction, @NSManaged, and @GKInspectable imply @objc.
+  //
+  // @IBInspectable and @GKInspectable imply @objc quietly in Swift 3
+  // (where they warn on failure) and loudly in Swift 4 (error on failure).
   if (VD->getAttrs().hasAttribute<IBOutletAttr>())
     return ObjCReason::ExplicitlyIBOutlet;
   if (VD->getAttrs().hasAttribute<IBActionAttr>())
@@ -2735,7 +2737,7 @@ void swift::markAsObjC(TypeChecker &TC, ValueDecl *D,
   // could be overridden by @nonobjc. If we see a @nonobjc and we are trying
   // to add an @objc for whatever reason, diagnose an error.
   if (auto *attr = D->getAttrs().getAttribute<NonObjCAttr>()) {
-    if (!shouldDiagnoseObjCReason(*isObjC))
+    if (!shouldDiagnoseObjCReason(*isObjC, TC.Context))
       isObjC = ObjCReason::ImplicitlyObjC;
 
     TC.diagnose(D->getStartLoc(), diag::nonobjc_not_allowed,
@@ -5113,7 +5115,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
             // complain.
             auto storageObjCAttr = storage->getAttrs().getAttribute<ObjCAttr>();
             if (storageObjCAttr->isSwift3Inferred() &&
-                shouldDiagnoseObjCReason(*isObjC)) {
+                shouldDiagnoseObjCReason(*isObjC, TC.Context)) {
               TC.diagnose(storage, diag::accessor_swift3_objc_inference,
                           storage->getDescriptiveKind(), storage->getFullName(),
                           isa<SubscriptDecl>(storage), FD->isSetter())
@@ -7282,6 +7284,24 @@ void TypeChecker::validateDecl(ValueDecl *D) {
 
         markAsObjC(*this, VD, isObjC);
 
+        // Under the Swift 3 inference rules, if we have @IBInspectable or
+        // @GKInspectable but did not infer @objc, warn that the attribute is
+        if (!isObjC && Context.LangOpts.EnableSwift3ObjCInference) {
+          if (auto attr = VD->getAttrs().getAttribute<IBInspectableAttr>()) {
+            diagnose(attr->getLocation(),
+                     diag::attribute_meaningless_when_nonobjc,
+                     attr->getAttrName())
+              .fixItRemove(attr->getRange());
+          }
+
+          if (auto attr = VD->getAttrs().getAttribute<GKInspectableAttr>()) {
+            diagnose(attr->getLocation(),
+                     diag::attribute_meaningless_when_nonobjc,
+                     attr->getAttrName())
+              .fixItRemove(attr->getRange());
+          }
+        }
+
         // Infer 'dynamic' before touching accessors.
         inferDynamic(Context, VD);
 

lib/Sema/TypeCheckType.cpp

@@ -3145,7 +3145,7 @@ static void describeObjCReason(TypeChecker &TC, const ValueDecl *VD,
 static void diagnoseFunctionParamNotRepresentable(
     TypeChecker &TC, const AbstractFunctionDecl *AFD, unsigned NumParams,
     unsigned ParamIndex, const ParamDecl *P, ObjCReason Reason) {
-  if (!shouldDiagnoseObjCReason(Reason))
+  if (!shouldDiagnoseObjCReason(Reason, TC.Context))
     return;
 
   if (NumParams == 1) {
@@ -3171,7 +3171,7 @@ static bool isParamListRepresentableInObjC(TypeChecker &TC,
                                            ObjCReason Reason) {
   // If you change this function, you must add or modify a test in PrintAsObjC.
 
-  bool Diagnose = shouldDiagnoseObjCReason(Reason);
+  bool Diagnose = shouldDiagnoseObjCReason(Reason, TC.Context);
 
   bool IsObjC = true;
   unsigned NumParams = PL->size();
@@ -3180,7 +3180,7 @@ static bool isParamListRepresentableInObjC(TypeChecker &TC,
 
     // Swift Varargs are not representable in Objective-C.
     if (param->isVariadic()) {
-      if (Diagnose && shouldDiagnoseObjCReason(Reason)) {
+      if (Diagnose && shouldDiagnoseObjCReason(Reason, TC.Context)) {
         TC.diagnose(param->getStartLoc(), diag::objc_invalid_on_func_variadic,
                     getObjCDiagnosticAttrKind(Reason))
           .highlight(param->getSourceRange());
@@ -3267,7 +3267,7 @@ static bool checkObjCInExtensionContext(TypeChecker &tc,
 static bool checkObjCWithGenericParams(TypeChecker &TC,
                                        const AbstractFunctionDecl *AFD,
                                        ObjCReason Reason) {
-  bool Diagnose = shouldDiagnoseObjCReason(Reason);
+  bool Diagnose = shouldDiagnoseObjCReason(Reason, TC.Context);
 
   if (AFD->getGenericParams()) {
     // Diagnose this problem, if asked to.
@@ -3288,7 +3288,7 @@ static bool checkObjCWithGenericParams(TypeChecker &TC,
 static bool checkObjCInForeignClassContext(TypeChecker &TC,
                                            const ValueDecl *VD,
                                            ObjCReason Reason) {
-  bool Diagnose = shouldDiagnoseObjCReason(Reason);
+  bool Diagnose = shouldDiagnoseObjCReason(Reason, TC.Context);
 
   auto type = VD->getDeclContext()->getDeclaredInterfaceType();
   if (!type)
@@ -3356,7 +3356,7 @@ bool TypeChecker::isRepresentableInObjC(
 
   // If you change this function, you must add or modify a test in PrintAsObjC.
 
-  bool Diagnose = shouldDiagnoseObjCReason(Reason);
+  bool Diagnose = shouldDiagnoseObjCReason(Reason, Context);
 
   if (checkObjCInForeignClassContext(*this, AFD, Reason))
     return false;
@@ -3688,7 +3688,7 @@ bool TypeChecker::isRepresentableInObjC(const VarDecl *VD, ObjCReason Reason) {
   }
   bool Result = T->isRepresentableIn(ForeignLanguage::ObjectiveC,
                                      VD->getDeclContext());
-  bool Diagnose = shouldDiagnoseObjCReason(Reason);
+  bool Diagnose = shouldDiagnoseObjCReason(Reason, Context);
 
   if (Result && checkObjCInExtensionContext(*this, VD, Diagnose))
     return false;
@@ -3719,7 +3719,7 @@ bool TypeChecker::isRepresentableInObjC(const SubscriptDecl *SD,
                                         ObjCReason Reason) {
   // If you change this function, you must add or modify a test in PrintAsObjC.
 
-  bool Diagnose = shouldDiagnoseObjCReason(Reason);
+  bool Diagnose = shouldDiagnoseObjCReason(Reason, Context);
 
   if (checkObjCInForeignClassContext(*this, SD, Reason))
     return false;

lib/Sema/TypeChecker.h

@@ -551,7 +551,8 @@ enum class ObjCReason {
 
 /// Determine whether we should diagnose conflicts due to inferring @objc
 /// with this particular reason.
-static inline bool shouldDiagnoseObjCReason(ObjCReason reason) {
+static inline bool shouldDiagnoseObjCReason(ObjCReason reason,
+                                            ASTContext &ctx) {
   switch(reason) {
   case ObjCReason::ExplicitlyCDecl:
   case ObjCReason::ExplicitlyDynamic:
@@ -563,11 +564,13 @@ static inline bool shouldDiagnoseObjCReason(ObjCReason reason) {
   case ObjCReason::OverridesObjC:
   case ObjCReason::WitnessToObjC:
   case ObjCReason::ImplicitlyObjC:
-  case ObjCReason::ExplicitlyIBInspectable:
-  case ObjCReason::ExplicitlyGKInspectable:
   case ObjCReason::MemberOfObjCExtension:
     return true;
 
+  case ObjCReason::ExplicitlyIBInspectable:
+  case ObjCReason::ExplicitlyGKInspectable:
+    return !ctx.LangOpts.EnableSwift3ObjCInference;
+
   case ObjCReason::MemberOfObjCSubclass:
   case ObjCReason::MemberOfObjCMembersClass:
   case ObjCReason::Accessor:

test/attr/attr_objc.swift

@@ -1672,9 +1672,6 @@ class HasIBAction {
 class HasIBInspectable {
   @IBInspectable var goodProperty: AnyObject?
   // CHECK: {{^}}  @IBInspectable @objc var goodProperty: AnyObject?
-
-  @IBInspectable var badProperty: PlainStruct?
-  // expected-error@-1{{property cannot be marked @IBInspectable because its type cannot be represented in Objective-C}}
 }
 
 //===---
@@ -1685,9 +1682,6 @@ class HasIBInspectable {
 class HasGKInspectable {
   @GKInspectable var goodProperty: AnyObject?
   // CHECK: {{^}}  @GKInspectable @objc var goodProperty: AnyObject?
-
-  @GKInspectable var badProperty: PlainStruct?
-  // expected-error@-1{{property cannot be marked @GKInspectable because its type cannot be represented in Objective-C}}
 }
 
 //===---

test/attr/attr_objc_swift3_deprecated_uses.swift

@@ -3,6 +3,8 @@
 
 import Foundation
 
+struct SwiftStruct { }
+
 class ObjCSubclass : NSObject {
   func foo() { } // expected-note 2{{add '@objc' to expose this instance method to Objective-C}}{{3-3=@objc }}
   var bar: NSObject? = nil // expected-note 2{{add '@objc' to expose this var to Objective-C}}{{3-3=@objc }}
@@ -22,6 +24,9 @@ class ObjCSubclass : NSObject {
 
     set { }
   }
+
+  @IBInspectable var ibvar: SwiftStruct = SwiftStruct() // expected-warning{{'@IBInspectable' attribute is meaningless on a property that cannot be represented in Objective-C}}{{3-18=}}
+  @GKInspectable var gkvar: SwiftStruct = SwiftStruct() // expected-warning{{'@GKInspectable' attribute is meaningless on a property that cannot be represented in Objective-C}}{{3-18=}}
 }
 
 class DynamicMembers {

test/attr/attr_objc_swift4.swift

@@ -20,3 +20,13 @@ func test(sc: ObjCSubclass, dm: DynamicMembers) {
   _ = #selector(getter: dm.bar)
   _ = #keyPath(DynamicMembers.bar)
 }
+
+struct PlainStruct { }
+
+class BadInSwift4 {
+  @IBInspectable var badIBInspectable: PlainStruct?
+  // expected-error@-1{{property cannot be marked @IBInspectable because its type cannot be represented in Objective-C}}
+
+  @GKInspectable var badGKInspectable: PlainStruct?
+  // expected-error@-1{{property cannot be marked @GKInspectable because its type cannot be represented in Objective-C}}
+}