swift-module-digester: diagnose optional protocol requirement changes.

Author: nkcsgexi

include/swift/AST/DiagnosticsModuleDiffer.def

@@ -74,6 +74,8 @@ ERROR(super_class_changed,none,"%0 has changed its super class from %1 to %2", (
 
 ERROR(nominal_type_kind_changed,none,"%0 has been changed to a %1", (StringRef, StringRef))
 
+ERROR(optional_req_changed,none,"%0 is %select{now|no longer}1 an optional requirement", (StringRef, bool))
+
 #ifndef DIAG_NO_UNDEF
 # if defined(DIAG)
 #  undef DIAG

test/api-digester/Inputs/cake1.swift

@@ -102,4 +102,12 @@ public class SuperClassChange: C7 {}
 
 public class GenericClass<T> {}
 
-public class SubGenericClass: GenericClass<P1> {}
+public class SubGenericClass: GenericClass<P1> {}
+
+@objc
+public protocol ObjCProtocol {
+  @objc
+  optional func removeOptional()
+  @objc
+  func addOptional()
+}

test/api-digester/Inputs/cake2.swift

@@ -113,3 +113,11 @@ public class SuperClassChange: C8 {}
 public class GenericClass<T> {}
 
 public class SubGenericClass: GenericClass<P2> {}
+
+@objc
+public protocol ObjCProtocol {
+  @objc
+  func removeOptional()
+  @objc
+  optional func addOptional()
+}

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

@@ -53,6 +53,8 @@ cake2: Var fixedLayoutStruct.c is added to a non-resilient type
 cake2: Var fixedLayoutStruct.lazy_d.storage is added to a non-resilient type
 
 /* Conformance changes */
+cake1: Func ObjCProtocol.addOptional() is now an optional requirement
+cake1: Func ObjCProtocol.removeOptional() is no longer an optional requirement
 cake1: Protocol P3 has added inherited protocol P4
 cake1: Protocol P3 has removed inherited protocol P2
 cake1: Struct fixedLayoutStruct has removed conformance to P1

test/api-digester/Outputs/Cake.txt

@@ -38,6 +38,7 @@ cake1: Var C1.CIIns1 changes from weak to strong
 cake1: Var C1.CIIns2 changes from strong to weak
 
 /* Conformance changes */
+cake1: Func ObjCProtocol.removeOptional() is no longer an optional requirement
 cake1: Protocol P3 has added inherited protocol P4
 cake1: Protocol P3 has removed inherited protocol P2
 cake1: Struct fixedLayoutStruct has removed conformance to P1

tools/swift-api-digester/ModuleAnalyzerNodes.h

@@ -317,6 +317,7 @@ class SDKNodeDecl: public SDKNode {
   bool isImplicit() const { return IsImplicit; };
   bool isStatic() const { return IsStatic; };
   bool isOverriding() const { return IsOverriding; };
+  bool isOptional() const { return hasDeclAttribute(DeclAttrKind::DAK_Optional); }
   StringRef getGenericSignature() const { return GenericSig; }
   StringRef getScreenInfo() const;
   virtual void jsonize(json::Output &Out) override;

tools/swift-api-digester/ModuleDiagsConsumer.cpp

@@ -55,6 +55,7 @@ static StringRef getCategoryName(uint32_t ID) {
     return "/* Fixed-layout Type Changes */";
   case LocalDiagID::conformance_added:
   case LocalDiagID::conformance_removed:
+  case LocalDiagID::optional_req_changed:
     return "/* Protocol Conformance Change */";
   case LocalDiagID::default_associated_type_removed:
   case LocalDiagID::protocol_req_added:

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

@@ -775,7 +775,17 @@ static void detectDeclChange(NodePtr L, NodePtr R, SDKContext &Ctx) {
       Diags.diagnose(SourceLoc(), diag::generic_sig_change, LD->getScreenInfo(),
         LD->getGenericSignature(), RD->getGenericSignature());
     }
-
+    if (LD->isOptional() != RD->isOptional()) {
+      if (Ctx.checkingABI()) {
+        // Both adding/removing optional is ABI-breaking.
+        Diags.diagnose(SourceLoc(), diag::optional_req_changed,
+                       LD->getScreenInfo(), LD->isOptional());
+      } else if (LD->isOptional()) {
+        // Removing optional is source-breaking.
+        Diags.diagnose(SourceLoc(), diag::optional_req_changed,
+                       LD->getScreenInfo(), LD->isOptional());
+      }
+    }
     if (auto *LDT = dyn_cast<SDKNodeDeclType>(L)) {
       if (auto *RDT = dyn_cast<SDKNodeDeclType>(R)) {
         diagnoseNominalTypeDeclChange(LDT, RDT);