swift-api-digester: refine diagnostic messages for removed type alias.

Framework authors can use SwiftWraper:none to bring back string enums
to type alias of String. When diagnosing source breaking changes, these
type alias are shown as removed. Therefore, it's hard to tell whether these
changes are automatically migratable. This patch refines the
removed-type-alias by further analyzing whether a
RawRepresentable with the same usr appeared in the later version of
SDK. If there is, another kind of message is emitted for differentiation.

test/api-digester/Inputs/APINotesRight/APINotesTest.apinotes

@@ -5,3 +5,10 @@ Globals:
 Protocols:
   - Name: TypeWithMethod
     SwiftName: SwiftTypeWithMethodRight
+
+SwiftVersions:
+- Version: 3
+  Typedefs:
+  - Name: AnimalAttributeName
+    SwiftName: AnimalAttributeName
+    SwiftWrapper: none

test/api-digester/Outputs/Cake.txt

@@ -1,4 +1,6 @@
 
+/* RawRepresentable Changes */
+
 /* Removed Decls */
 cake1: Constructor Somestruct2.init(_:) has been removed
 cake1: Func C4.foo() has been removed

test/api-digester/Outputs/apinotes-diags-3-4.txt

@@ -0,0 +1,14 @@
+
+/* RawRepresentable Changes */
+APINotesTest(APINotesTest.h): TypeAlias AnimalAttributeName(NSString) is now String representable
+
+/* Removed Decls */
+
+/* Moved Decls */
+
+/* Renamed Decls */
+
+/* Type Changes */
+APINotesTest(APINotesTest.h): Func AnimalStatusDescriptor.addingAttributes(_:) has parameter 0 type change from [String : Any] to [AnimalAttributeName : Any]
+
+/* Decl Attribute changes */

test/api-digester/Outputs/apinotes-diags.txt

@@ -1,4 +1,6 @@
 
+/* RawRepresentable Changes */
+
 /* Removed Decls */
 APINotesTest(APINotesTest.h): Func ObjcProt.protMemberFunc2() has been removed
 APINotesTest(APINotesTest.h): Func ObjcProt.protMemberFunc3() has been removed

test/api-digester/apinotes-diags.swift

@@ -2,7 +2,10 @@
 // RUN: %empty-directory(%t.mod)
 // RUN: %empty-directory(%t.sdk)
 // RUN: %empty-directory(%t.module-cache)
-// RUN: %api-digester %clang-importer-sdk-nosource -dump-sdk -module APINotesTest -o %t.dump1.json -module-cache-path %t.module-cache -swift-version 3 -I %S/Inputs/APINotesLeft
+// RUN: %api-digester %clang-importer-sdk-nosource -dump-sdk -module APINotesTest -o %t.dump1.json -module-cache-path %t.module-cache -swift-version 4 -I %S/Inputs/APINotesLeft
 // RUN: %api-digester %clang-importer-sdk-nosource -dump-sdk -module APINotesTest -o %t.dump2.json -module-cache-path %t.module-cache -swift-version 3 -I %S/Inputs/APINotesRight
-// RUN: %api-digester -diagnose-sdk -print-module -input-paths %t.dump1.json -input-paths %t.dump2.json > %t.result
+// RUN: %api-digester %clang-importer-sdk-nosource -dump-sdk -module APINotesTest -o %t.dump3.json -module-cache-path %t.module-cache -swift-version 4 -I %S/Inputs/APINotesRight
+// RUN: %api-digester -diagnose-sdk -print-module -input-paths %t.dump1.json -input-paths %t.dump3.json > %t.result
 // RUN: diff -u %S/Outputs/apinotes-diags.txt %t.result
+// RUN: %api-digester -diagnose-sdk -print-module -input-paths %t.dump2.json -input-paths %t.dump3.json > %t.result
+// RUN: diff -u %S/Outputs/apinotes-diags-3-4.txt %t.result

test/api-digester/apinotes-migrator-gen.swift

@@ -2,7 +2,7 @@
 // RUN: %empty-directory(%t.mod)
 // RUN: %empty-directory(%t.sdk)
 // RUN: %empty-directory(%t.module-cache)
-// RUN: %api-digester -dump-sdk -module APINotesTest -o %t.dump1.json -module-cache-path %t.module-cache %clang-importer-sdk-nosource -swift-version 3 -I %S/Inputs/APINotesLeft
-// RUN: %api-digester -dump-sdk -module APINotesTest -o %t.dump2.json -module-cache-path %t.module-cache %clang-importer-sdk-nosource -swift-version 3 -I %S/Inputs/APINotesRight
+// RUN: %api-digester -dump-sdk -module APINotesTest -o %t.dump1.json -module-cache-path %t.module-cache %clang-importer-sdk-nosource -swift-version 4 -I %S/Inputs/APINotesLeft
+// RUN: %api-digester -dump-sdk -module APINotesTest -o %t.dump2.json -module-cache-path %t.module-cache %clang-importer-sdk-nosource -swift-version 4 -I %S/Inputs/APINotesRight
 // RUN: %api-digester -compare-sdk --input-paths %t.dump1.json -input-paths %t.dump2.json -o %t.result -json
 // RUN: diff -u %S/Outputs/apinotes-migrator-gen.json %t.result

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

@@ -179,6 +179,7 @@ bool contains(ArrayRef<T> container, T instance) {
 class SDKNode;
 typedef SDKNode* NodePtr;
 typedef std::map<NodePtr, NodePtr> ParentMap;
+typedef std::map<NodePtr, NodePtr> NodeMap;
 typedef std::vector<NodePtr> NodeVector;
 
 // The interface used to visit the SDK tree.
@@ -231,6 +232,7 @@ class SDKContext {
   llvm::StringSet<> TextData;
   llvm::BumpPtrAllocator Allocator;
   UpdatedNodesMap UpdateMap;
+  NodeMap TypeAliasUpdateMap;
 
 public:
   llvm::BumpPtrAllocator &allocator() {
@@ -242,6 +244,10 @@ public:
   UpdatedNodesMap &getNodeUpdateMap() {
     return UpdateMap;
   }
+  NodeMap &getTypeAliasUpdateMap() {
+    return TypeAliasUpdateMap;
+  }
+
 };
 
 // A node matcher will traverse two trees of SDKNode and find matched nodes
@@ -838,6 +844,15 @@ public:
     return None;
   }
 
+  SDKNodeType *getRawValueType() const {
+    if (isConformingTo(KnownProtocolKind::RawRepresentable)) {
+      if (auto RV = lookupChildByPrintedName("rawValue")) {
+        return (*(*RV)->getChildBegin())->getAs<SDKNodeType>();
+      }
+    }
+    return nullptr;
+  }
+
   bool isConformingTo(KnownProtocolKind Kind) const {
     StringRef Usr;
     switch (Kind) {
@@ -855,6 +870,9 @@ class SDKNodeTypeAlias : public SDKNodeDecl {
 public:
   SDKNodeTypeAlias(SDKNodeInitInfo Info) : SDKNodeDecl(Info,
                                                        SDKNodeKind::TypeAlias) {}
+  const SDKNodeType* getUnderlyingType() const {
+    return getOnlyChild()->getAs<SDKNodeType>();
+  }
   static bool classof(const SDKNode *N);
 };
 
@@ -1592,8 +1610,8 @@ public:
 
   // After collecting decls, either from imported modules or from a previously
   // serialized JSON file, using this function to get the root of the SDK.
-  NodePtr getSDKRoot() {
-    return RootNode;
+  SDKNodeRoot* getSDKRoot() {
+    return static_cast<SDKNodeRoot*>(RootNode);
   }
 
   void printTopLevelNames() {
@@ -2517,6 +2535,57 @@ private:
 
 };
 
+/// This is to find type alias of raw types being changed to RawRepresentable.
+/// e.g. AttributeName was a typealias of String in the old SDK however it becomes
+/// a RawRepresentable struct in the new SDK.
+/// This happens typically when we use apinotes to preserve API stability by
+/// using SwiftWrapper:none in the old SDK.
+class TypeAliasDiffFinder: public SDKNodeVisitor {
+  SDKNodeRoot *leftRoot;
+  SDKNodeRoot *rightRoot;
+  NodeMap &result;
+
+  static bool checkTypeMatch(const SDKNodeType* aliasType,
+      const SDKNodeType* rawType) {
+    StringRef Left = aliasType->getPrintedName();
+    StringRef Right = rawType->getPrintedName();
+    if (Left == "NSString" && Right == "String")
+      return true;
+    if (Left == "String" && Right == "String")
+      return true;
+    if (Left == "Int" && Right == "Int")
+      return true;
+    if (Left == "UInt" && Right == "UInt")
+      return true;
+    return false;
+  }
+
+  void visit(NodePtr node) override {
+    auto alias = dyn_cast<SDKNodeTypeAlias>(node);
+    if (!alias)
+      return;
+    const SDKNodeType* aliasType = alias->getUnderlyingType();
+    for (auto *counter: rightRoot->getDescendantsByUsr(alias->getUsr())) {
+      if (auto DT = dyn_cast<SDKNodeTypeDecl>(counter)) {
+        if (auto *rawType = DT->getRawValueType()) {
+          if (checkTypeMatch(aliasType, rawType)) {
+            result.insert({alias, DT});
+            return;
+          }
+        }
+      }
+    }
+  }
+public:
+  TypeAliasDiffFinder(SDKNodeRoot *leftRoot, SDKNodeRoot *rightRoot,
+    NodeMap &result): leftRoot(leftRoot), rightRoot(rightRoot),
+      result(result) {}
+
+  void search() {
+    SDKNode::preorderVisit(leftRoot, *this);
+  }
+};
+
 // Given a condition, search whether a node satisfies that condition exists
 // in a tree.
 class SearchVisitor : public SDKNodeVisitor {
@@ -2999,21 +3068,47 @@ class DiagnosisEmitter : public SDKNodeVisitor {
     static void theme(raw_ostream &OS) { OS << "Type Changes"; };
   };
 
+  struct RawRepresentableChangeDiag: public DiagBase {
+    DeclKind Kind;
+    StringRef DeclName;
+    StringRef UnderlyingType;
+    StringRef RawTypeName;
+    RawRepresentableChangeDiag(MetaInfo Info, DeclKind Kind, StringRef DeclName,
+        StringRef UnderlyingType, StringRef RawTypeName): DiagBase(Info),
+        Kind(Kind), DeclName(DeclName), UnderlyingType(UnderlyingType),
+        RawTypeName(RawTypeName) {}
+    bool operator<(RawRepresentableChangeDiag Other) const {
+      if (Kind != Other.Kind)
+        return Kind < Other.Kind;
+      return DeclName.compare(Other.DeclName) < 0;
+    }
+    void output() const override {
+      llvm::outs() << Kind << " " << printName(DeclName)
+        << "(" << UnderlyingType << ")"
+        << " is now " << RawTypeName << " representable\n";
+    }
+    static void theme(raw_ostream &OS) { OS << "RawRepresentable Changes"; };
+  };
+
   std::set<SDKNodeDecl*> AddedDecls;
   DiagBag<DeclAttrDiag> AttrChangedDecls;
   DiagBag<DeclTypeChangeDiag> TypeChangedDecls;
   DiagBag<RenamedDeclDiag> RenamedDecls;
   DiagBag<MovedDeclDiag> MovedDecls;
   DiagBag<RemovedDeclDiag> RemovedDecls;
+  DiagBag<RawRepresentableChangeDiag> RawRepresentableDecls;
 
   UpdatedNodesMap &UpdateMap;
+  NodeMap &TypeAliasUpdateMap;
   TypeMemberDiffVector &MemberChanges;
-  DiagnosisEmitter(UpdatedNodesMap &UpdateMap,
-                   TypeMemberDiffVector &MemberChanges):
-                     UpdateMap(UpdateMap), MemberChanges(MemberChanges) {}
+  DiagnosisEmitter(SDKContext &Ctx, TypeMemberDiffVector &MemberChanges):
+    UpdateMap(Ctx.getNodeUpdateMap()),
+    TypeAliasUpdateMap(Ctx.getTypeAliasUpdateMap()),
+    MemberChanges(MemberChanges){}
+
 public:
   static void diagnosis(NodePtr LeftRoot, NodePtr RightRoot,
-                        UpdatedNodesMap &UpdateMap);
+                        SDKContext &Ctx);
 };
 
 void DiagnosisEmitter::collectAddedDecls(NodePtr Root,
@@ -3130,11 +3225,11 @@ void DiagnosisEmitter::DeclAttrDiag::output() const {
 }
 
 void DiagnosisEmitter::diagnosis(NodePtr LeftRoot, NodePtr RightRoot,
-                                 UpdatedNodesMap &UpdateMap) {
+                                 SDKContext &Ctx) {
   // Find member hoist changes to help refine diagnostics.
   TypeMemberDiffVector MemberChanges;
   findTypeMemberDiffs(LeftRoot, RightRoot, MemberChanges);
-  DiagnosisEmitter Emitter(UpdateMap, MemberChanges);
+  DiagnosisEmitter Emitter(Ctx, MemberChanges);
   collectAddedDecls(RightRoot, Emitter.AddedDecls);
   SDKNode::postorderVisit(LeftRoot, Emitter);
 }
@@ -3171,6 +3266,19 @@ void DiagnosisEmitter::handle(const SDKNodeDecl *Node, NodeAnnotation Anno) {
       return;
     }
 
+    // If a type alias of a raw type has been changed to a struct/enum that
+    // conforms to RawRepresentable in the later version of SDK, we show the
+    // refine diagnostics message instead of showing the type alias has been
+    // removed.
+    if (TypeAliasUpdateMap.find((SDKNode*)Node) != TypeAliasUpdateMap.end()) {
+      RawRepresentableDecls.Diags.emplace_back(ScreenInfo, Node->getDeclKind(),
+        Node->getFullyQualifiedName(),
+        Node->getAs<SDKNodeTypeAlias>()->getUnderlyingType()->getPrintedName(),
+        TypeAliasUpdateMap[(SDKNode*)Node]->getAs<SDKNodeTypeDecl>()->
+          getRawValueType()->getPrintedName());
+      return;
+    }
+
     // We should exlude those declarations that are pulled up to the super classes.
     bool FoundInSuperclass = false;
     if (auto PD = dyn_cast<SDKNodeDecl>(Node->getParent())) {
@@ -3438,11 +3546,13 @@ static int diagnoseModuleChange(StringRef LeftPath, StringRef RightPath) {
   RightCollector.deSerialize(RightPath);
   auto LeftModule = LeftCollector.getSDKRoot();
   auto RightModule = RightCollector.getSDKRoot();
+  TypeAliasDiffFinder(LeftModule, RightModule,
+                      Ctx.getTypeAliasUpdateMap()).search();
   PrunePass Prune(Ctx.getNodeUpdateMap());
   Prune.pass(LeftModule, RightModule);
   ChangeRefinementPass RefinementPass(Ctx.getNodeUpdateMap());
   RefinementPass.pass(LeftModule, RightModule);
-  DiagnosisEmitter::diagnosis(LeftModule, RightModule, Ctx.getNodeUpdateMap());
+  DiagnosisEmitter::diagnosis(LeftModule, RightModule, Ctx);
   return 0;
 }