swift-module-digester: changing open class members to public can be source-breaking.

Author: nkcsgexi

include/swift/AST/DiagnosticsModuleDiffer.def

@@ -78,6 +78,8 @@ ERROR(optional_req_changed,none,"%0 is %select{now|no longer}1 an optional requi
 
 ERROR(var_let_changed,none,"%0 changes from %select{var|let}1 to %select{let|var}1", (StringRef, bool))
 
+ERROR(no_longer_open,none,"%0 is no longer open for subclassing", (StringRef))
+
 #ifndef DIAG_NO_UNDEF
 # if defined(DIAG)
 #  undef DIAG

test/api-digester/Inputs/cake1.swift

@@ -114,3 +114,9 @@ public protocol ObjCProtocol {
 
 public let GlobalLetChangedToVar = 1
 public var GlobalVarChangedToLet = 1
+
+public class ClassWithOpenMember {
+  open class func foo() {}
+  open var property: Int {get { return 1}}
+  open func bar() {}
+}

test/api-digester/Inputs/cake2.swift

@@ -123,4 +123,10 @@ public protocol ObjCProtocol {
 }
 
 public var GlobalLetChangedToVar = 1
-public let GlobalVarChangedToLet = 1
+public let GlobalVarChangedToLet = 1
+
+public class ClassWithOpenMember {
+  public class func foo() {}
+  public var property: Int {get { return 1}}
+  public func bar() {}
+}

test/api-digester/Outputs/Cake.txt

@@ -54,3 +54,6 @@ cake2: Var RequiementChanges.addedVar has been added as a protocol requirement
 cake1: Class C4 has changed its super class from OldType to NewType
 cake1: Class SubGenericClass has changed its super class from GenericClass<P1> to GenericClass<P2>
 cake1: Class SuperClassRemoval has removed its super class C3
+cake1: Func ClassWithOpenMember.bar() is no longer open for subclassing
+cake1: Func ClassWithOpenMember.foo() is no longer open for subclassing
+cake1: Var ClassWithOpenMember.property is no longer open for subclassing

tools/swift-api-digester/ModuleAnalyzerNodes.cpp

@@ -690,7 +690,8 @@ bool SDKNode::operator==(const SDKNode &Other) const {
         return false;
       if (Left->getGenericSignature() != Right->getGenericSignature())
         return false;
-
+      if (Left->isOpen() != Right->isOpen())
+        return false;
       LLVM_FALLTHROUGH;
     }
     case SDKNodeKind::Root: {

tools/swift-api-digester/ModuleAnalyzerNodes.h

@@ -318,6 +318,7 @@ class SDKNodeDecl: public SDKNode {
   bool isStatic() const { return IsStatic; };
   bool isOverriding() const { return IsOverriding; };
   bool isOptional() const { return hasDeclAttribute(DeclAttrKind::DAK_Optional); }
+  bool isOpen() const { return IsOpen; }
   StringRef getGenericSignature() const { return GenericSig; }
   StringRef getScreenInfo() const;
   virtual void jsonize(json::Output &Out) override;

tools/swift-api-digester/ModuleDiagsConsumer.cpp

@@ -63,6 +63,7 @@ static StringRef getCategoryName(uint32_t ID) {
     return "/* Protocol Requirement Change */";
   case LocalDiagID::super_class_removed:
   case LocalDiagID::super_class_changed:
+  case LocalDiagID::no_longer_open:
     return "/* Class Inheritance Change */";
   default:
     return StringRef();

tools/swift-api-digester/swift-api-digester.cpp

@@ -727,6 +727,9 @@ static void detectDeclChange(NodePtr L, NodePtr R, SDKContext &Ctx) {
   auto &Diags = Ctx.getDiags();
   if (auto LD = dyn_cast<SDKNodeDecl>(L)) {
     auto *RD = R->getAs<SDKNodeDecl>();
+    if (!Ctx.checkingABI() && LD->isOpen() && !RD->isOpen()) {
+      Diags.diagnose(SourceLoc(), diag::no_longer_open, LD->getScreenInfo());
+    }
 
     // Diagnose static attribute change.
     if (LD->isStatic() ^ RD->isStatic()) {