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
 }