swift-module-digester: when we have multiple extensions to a single external type, we should synthesize only one type decl node.

Author: nkcsgexi

test/api-digester/Inputs/cake.swift

@@ -48,3 +48,5 @@ public struct fixedLayoutStruct {
   private var b = 2
   var c = 3
 }
+
+extension Int: P1 { public func bar() {} }

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

@@ -983,6 +983,7 @@
         "Strideable",
         "ExpressibleByIntegerLiteral",
         "FixedWidthInteger",
+        "P1",
         "Encodable",
         "Decodable",
         "Hashable",
@@ -1012,6 +1013,22 @@
               "printedName": "()"
             }
           ]
+        },
+        {
+          "kind": "Function",
+          "name": "bar",
+          "printedName": "bar()",
+          "declKind": "Func",
+          "usr": "s:Si4cakeE3baryyF",
+          "location": "",
+          "moduleName": "cake",
+          "children": [
+            {
+              "kind": "TypeNominal",
+              "name": "Void",
+              "printedName": "()"
+            }
+          ]
         }
       ]
     }

test/api-digester/Outputs/cake.json

@@ -859,6 +859,7 @@
         "Strideable",
         "ExpressibleByIntegerLiteral",
         "FixedWidthInteger",
+        "P1",
         "Encodable",
         "Decodable",
         "Hashable",
@@ -888,6 +889,22 @@
               "printedName": "()"
             }
           ]
+        },
+        {
+          "kind": "Function",
+          "name": "bar",
+          "printedName": "bar()",
+          "declKind": "Func",
+          "usr": "s:Si4cakeE3baryyF",
+          "location": "",
+          "moduleName": "cake",
+          "children": [
+            {
+              "kind": "TypeNominal",
+              "name": "Void",
+              "printedName": "()"
+            }
+          ]
         }
       ]
     }

tools/swift-api-digester/ModuleAnalyzerNodes.cpp

@@ -1216,13 +1216,16 @@ static SDKNode *constructTypeDeclNode(SDKContext &Ctx, NominalTypeDecl *NTD,
 /// synthesize this type node to include those extension members, since these
 /// extension members are legit members of the module.
 static SDKNode *constructExternalExtensionNode(SDKContext &Ctx, SDKNode *Root,
-                                               ExtensionDecl *Ext,
+                                               NominalTypeDecl *NTD,
+                                               ArrayRef<ExtensionDecl*> AllExts,
                                         std::set<ExtensionDecl*> &HandledExts) {
-  auto *TypeNode = SDKNodeInitInfo(Ctx, Ext->getSelfNominalTypeDecl())
-      .createSDKNode(SDKNodeKind::DeclType);
+  auto *TypeNode = SDKNodeInitInfo(Ctx, NTD).createSDKNode(SDKNodeKind::DeclType);
 
-  // The members of the extension are the only members of this synthesized type.
-  addMembersToRoot(Ctx, TypeNode, Ext, HandledExts);
+  // The members of the extensions are the only members of this synthesized type.
+  for (auto *Ext: AllExts) {
+    HandledExts.insert(Ext);
+    addMembersToRoot(Ctx, TypeNode, Ext, HandledExts);
+  }
   return TypeNode;
 }
 
@@ -1302,16 +1305,20 @@ void SwiftDeclCollector::lookupVisibleDecls(ArrayRef<ModuleDecl *> Modules) {
   for (auto *VD : ClangMacros)
     processDecl(VD);
 
-  // For all known decls, collect those unhandled extensions and handle them
-  // separately.
+  // Collect extensions to types from other modules and synthesize type nodes
+  // for them.
+  llvm::MapVector<NominalTypeDecl*, llvm::SmallVector<ExtensionDecl*, 4>> ExtensionMap;
   for (auto *D: KnownDecls) {
     if (auto *Ext = dyn_cast<ExtensionDecl>(D)) {
       if (HandledExtensions.find(Ext) == HandledExtensions.end()) {
-        RootNode->addChild(constructExternalExtensionNode(Ctx, RootNode, Ext,
-                                                          HandledExtensions));
+        ExtensionMap[Ext->getExtendedNominal()].push_back(Ext);
       }
     }
   }
+  for (auto Pair: ExtensionMap) {
+    RootNode->addChild(constructExternalExtensionNode(Ctx, RootNode,
+      Pair.first, Pair.second, HandledExtensions));
+  }
 }
 
 void SwiftDeclCollector::processDecl(ValueDecl *VD) {

tools/swift-api-digester/ModuleAnalyzerNodes.h

@@ -495,7 +495,7 @@ class SwiftDeclCollector: public VisibleDeclConsumer {
   SDKContext &Ctx;
   std::vector<std::unique_ptr<llvm::MemoryBuffer>> OwnedBuffers;
   SDKNode *RootNode;
-  llvm::DenseSet<Decl*> KnownDecls;
+  llvm::SetVector<Decl*> KnownDecls;
   // Collected and sorted after we get all of them.
   std::vector<ValueDecl *> ClangMacros;
   std::set<ExtensionDecl*> HandledExtensions;