ABI/API checker: diagnose adding new designated initializers to open classes

If client's subclass provides an implementation of all of its superclass designated
initializers, it automatically inherits all of the superclass convenience initializers.
This means if a new designated init is added to the base class, the inherited
convenience init may be missing and cause breakage.

SR-11454

Author: nkcsgexi

include/swift/AST/DiagnosticsModuleDiffer.def

@@ -98,6 +98,8 @@ ERROR(new_decl_without_intro,none,"%0 is a new API without @available attribute"
 
 ERROR(objc_name_change,none,"%0 has ObjC name change from %1 to %2", (StringRef, StringRef, StringRef))
 
+ERROR(desig_init_added,none,"%0 has been added as a designated initializer to an open class", (StringRef))
+
 #ifndef DIAG_NO_UNDEF
 # if defined(DIAG)
 #  undef DIAG

include/swift/IDE/DigesterEnums.def

@@ -152,6 +152,7 @@ KEY_STRING(IntrotvOS, intro_tvOS)
 KEY_STRING(IntrowatchOS, intro_watchOS)
 KEY_STRING(Introswift, intro_swift)
 KEY_STRING(ObjCName, objc_name)
+KEY_STRING(InitKind, init_kind)
 
 KEY_STRING_ARR(SuperclassNames, superclassNames)
 KEY_STRING_ARR(ToolArgs, tool_arguments)

test/api-digester/Inputs/cake_baseline/cake.swift

@@ -201,3 +201,12 @@ public class SwiftObjcClass {
   @objc(OldObjCFool:OldObjCA:OldObjCB:)
   public func foo(a:Int, b:Int, c: Int) {}
 }
+
+@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
+open class AddingNewDesignatedInit {
+  public init() {}
+  public convenience init(foo: Int) {
+    self.init()
+    print(foo)
+  }
+}

test/api-digester/Inputs/cake_current/cake.swift

@@ -208,3 +208,13 @@ public class SwiftObjcClass {
   @objc(NewObjCFool:NewObjCA:NewObjCB:)
   public func foo(a:Int, b:Int, c: Int) {}
 }
+
+@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
+open class AddingNewDesignatedInit {
+  public init(_ b: Bool) {}
+  public init() {}
+  public convenience init(foo: Int) {
+    self.init()
+    print(foo)
+  }
+}

test/api-digester/Outputs/Cake-abi.txt

@@ -115,3 +115,4 @@ cake: Var RequiementChanges.addedVar has been added as a protocol requirement
 cake: Class C4 has changed its super class from APINotesTest.OldType to APINotesTest.NewType
 cake: Class SubGenericClass has changed its super class from cake.GenericClass<cake.P1> to cake.GenericClass<cake.P2>
 cake: Class SuperClassRemoval has removed its super class cake.C3
+cake: Constructor AddingNewDesignatedInit.init(_:) has been added as a designated initializer to an open class

test/api-digester/Outputs/Cake.txt

@@ -64,6 +64,7 @@ cake: Accessor ClassWithOpenMember.property.Get() is no longer open for subclass
 cake: Class C4 has changed its super class from APINotesTest.OldType to APINotesTest.NewType
 cake: Class SubGenericClass has changed its super class from cake.GenericClass<cake.P1> to cake.GenericClass<cake.P2>
 cake: Class SuperClassRemoval has removed its super class cake.C3
+cake: Constructor AddingNewDesignatedInit.init(_:) has been added as a designated initializer to an open class
 cake: Func ClassWithOpenMember.bar() is no longer open for subclassing
 cake: Func ClassWithOpenMember.foo() is no longer open for subclassing
 cake: Var ClassWithOpenMember.property is no longer open for subclassing

test/api-digester/Outputs/cake-abi.json

@@ -564,7 +564,8 @@
           "implicit": true,
           "declAttributes": [
             "Inlinable"
-          ]
+          ],
+          "init_kind": "Designated"
         },
         {
           "kind": "Var",
@@ -1823,5 +1824,5 @@
       ]
     }
   ],
-  "json_format_version": 5
+  "json_format_version": 6
 }

test/api-digester/Outputs/cake.json

@@ -584,7 +584,8 @@
           "implicit": true,
           "declAttributes": [
             "Inlinable"
-          ]
+          ],
+          "init_kind": "Designated"
         },
         {
           "kind": "Var",
@@ -1674,5 +1675,5 @@
       ]
     }
   ],
-  "json_format_version": 5
+  "json_format_version": 6
 }

test/api-digester/Outputs/clang-module-dump.txt

@@ -105,7 +105,8 @@
             "Override",
             "ObjC",
             "Dynamic"
-          ]
+          ],
+          "init_kind": "Designated"
         }
       ],
       "declKind": "Class",
@@ -183,5 +184,5 @@
       ]
     }
   ],
-  "json_format_version": 5
+  "json_format_version": 6
 }

test/api-digester/Outputs/empty-baseline.json

@@ -2,5 +2,5 @@
   "kind": "Root",
   "name": "TopLevel",
   "printedName": "TopLevel",
-  "json_format_version": 5
+  "json_format_version": 6
 }

tools/swift-api-digester/ModuleAnalyzerNodes.cpp

@@ -132,7 +132,7 @@ SDKNodeDeclFunction::SDKNodeDeclFunction(SDKNodeInitInfo Info):
   FuncSelfKind(Info.FuncSelfKind) {}
 
 SDKNodeDeclConstructor::SDKNodeDeclConstructor(SDKNodeInitInfo Info):
-  SDKNodeDeclAbstractFunc(Info, SDKNodeKind::DeclConstructor) {}
+  SDKNodeDeclAbstractFunc(Info, SDKNodeKind::DeclConstructor), InitKind(Info.InitKind) {}
 
 SDKNodeDeclAccessor::SDKNodeDeclAccessor(SDKNodeInitInfo Info):
   SDKNodeDeclAbstractFunc(Info, SDKNodeKind::DeclAccessor),
@@ -1271,6 +1271,30 @@ static std::vector<DeclAttrKind> collectDeclAttributes(Decl *D) {
   return Results;
 }
 
+CtorInitializerKind SDKNodeDeclConstructor::getInitKind() const {
+#define CASE(KIND) if (InitKind == #KIND) return CtorInitializerKind::KIND;
+  CASE(Designated)
+  CASE(Convenience)
+  CASE(ConvenienceFactory)
+  CASE(Factory)
+#undef CASE
+  llvm_unreachable("unhandled init kind");
+}
+
+StringRef SDKContext::getInitKind(Decl *D) {
+  if (auto *CD = dyn_cast<ConstructorDecl>(D)) {
+    switch(CD->getInitKind()) {
+#define CASE(KIND) case CtorInitializerKind::KIND: return #KIND;
+    CASE(Designated)
+    CASE(Convenience)
+    CASE(ConvenienceFactory)
+    CASE(Factory)
+#undef CASE
+    }
+  }
+  return StringRef();
+}
+
 SDKNodeInitInfo::SDKNodeInitInfo(SDKContext &Ctx, Decl *D):
       Ctx(Ctx), DKind(D->getKind()),
       Location(calculateLocation(Ctx, D)),
@@ -1285,6 +1309,7 @@ SDKNodeInitInfo::SDKNodeInitInfo(SDKContext &Ctx, Decl *D):
       IntrowatchOS(Ctx.getPlatformIntroVersion(D, PlatformKind::watchOS)),
       Introswift(Ctx.getLanguageIntroVersion(D)),
       ObjCName(Ctx.getObjcName(D)),
+      InitKind(Ctx.getInitKind(D)),
       IsImplicit(D->isImplicit()),
       IsDeprecated(D->getAttrs().getDeprecated(D->getASTContext())),
       IsABIPlaceholder(isABIPlaceholderRecursive(D)),
@@ -1916,6 +1941,11 @@ void SDKNodeDeclFunction::jsonize(json::Output &out) {
   output(out, KeyKind::KK_funcSelfKind, FuncSelfKind);
 }
 
+void SDKNodeDeclConstructor::jsonize(json::Output &out) {
+  SDKNodeDeclAbstractFunc::jsonize(out);
+  output(out, KeyKind::KK_init_kind, InitKind);
+}
+
 void SDKNodeDeclType::jsonize(json::Output &out) {
   SDKNodeDecl::jsonize(out);
   output(out, KeyKind::KK_superclassUsr, SuperclassUsr);

tools/swift-api-digester/ModuleAnalyzerNodes.h

@@ -62,7 +62,7 @@ namespace api {
 ///
 /// When the json format changes in a way that requires version-specific handling, this number should be incremented.
 /// This ensures we could have backward compatibility so that version changes in the format won't stop the checker from working.
-const uint8_t DIGESTER_JSON_VERSION = 5; // Populate ObjC, Dynamic and Final to attribute list
+const uint8_t DIGESTER_JSON_VERSION = 6; // Add initkind for constructors
 const uint8_t DIGESTER_JSON_DEFAULT_VERSION = 0; // Use this version number for files before we have a version number in json.
 
 class SDKNode;
@@ -218,6 +218,7 @@ class SDKContext {
   StringRef getPlatformIntroVersion(Decl *D, PlatformKind Kind);
   StringRef getLanguageIntroVersion(Decl *D);
   StringRef getObjcName(Decl *D);
+  StringRef getInitKind(Decl *D);
   bool isEqual(const SDKNode &Left, const SDKNode &Right);
   bool checkingABI() const { return Opts.ABI; }
   AccessLevel getAccessLevel(const ValueDecl *VD) const;
@@ -677,9 +678,12 @@ class SDKNodeDeclFunction: public SDKNodeDeclAbstractFunc {
 };
 
 class SDKNodeDeclConstructor: public SDKNodeDeclAbstractFunc {
+  StringRef InitKind;
 public:
   SDKNodeDeclConstructor(SDKNodeInitInfo Info);
   static bool classof(const SDKNode *N);
+  CtorInitializerKind getInitKind() const;
+  void jsonize(json::Output &Out) override;
 };
 
 class SDKNodeDeclAccessor: public SDKNodeDeclAbstractFunc {

tools/swift-api-digester/ModuleDiagsConsumer.cpp

@@ -73,6 +73,7 @@ static StringRef getCategoryName(uint32_t ID) {
   case LocalDiagID::super_class_removed:
   case LocalDiagID::super_class_changed:
   case LocalDiagID::no_longer_open:
+  case LocalDiagID::desig_init_added:
     return "/* Class Inheritance Change */";
   default:
     return StringRef();

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

@@ -1144,6 +1144,18 @@ class PrunePass : public MatchedNodeListener, public SDKTreeDiffPass {
           }
         }
       }
+      if (auto *CD = dyn_cast<SDKNodeDeclConstructor>(Right)) {
+        if (auto *TD = dyn_cast<SDKNodeDeclType>(Right->getParent())) {
+          if (TD->isOpen() && CD->getInitKind() == CtorInitializerKind::Designated) {
+            // If client's subclass provides an implementation of all of its superclass designated
+            // initializers, it automatically inherits all of the superclass convenience initializers.
+            // This means if a new designated init is added to the base class, the inherited
+            // convenience init may be missing and cause breakage.
+            CD->emitDiag(diag::desig_init_added);
+          }
+        }
+      }
+
       return;
     case NodeMatchReason::Removed:
       assert(!Right);