ABI/API checker: add a version number for the json descriptors of APIs

Author: nkcsgexi

include/swift/IDE/DigesterEnums.def

@@ -156,6 +156,7 @@ KEY_STRING_ARR(ToolArgs, tool_arguments)
 
 KEY_UINT(SelfIndex, selfIndex)
 KEY_UINT(FixedBinaryOrder, fixedbinaryorder)
+KEY_UINT(JsonFormatVer, json_format_version)
 
 KEY(children)
 KEY(conformances)

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

@@ -1753,5 +1753,6 @@
         }
       ]
     }
-  ]
+  ],
+  "json_format_version": 1
 }

test/api-digester/Outputs/cake.json

@@ -1621,5 +1621,6 @@
         }
       ]
     }
-  ]
+  ],
+  "json_format_version": 1
 }

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

@@ -168,5 +168,6 @@
         "ObjC"
       ]
     }
-  ]
+  ],
+  "json_format_version": 1
 }

tools/swift-api-digester/ModuleAnalyzerNodes.cpp

@@ -80,7 +80,8 @@ SDKNode::SDKNode(SDKNodeInitInfo Info, SDKNodeKind Kind): Ctx(Info.Ctx),
   Name(Info.Name), PrintedName(Info.PrintedName), TheKind(unsigned(Kind)) {}
 
 SDKNodeRoot::SDKNodeRoot(SDKNodeInitInfo Info): SDKNode(Info, SDKNodeKind::Root),
-  ToolArgs(Info.ToolArgs) {}
+  ToolArgs(Info.ToolArgs),
+  JsonFormatVer(Info.JsonFormatVer.hasValue() ? *Info.JsonFormatVer : DIGESTER_JSON_DEFAULT_VERSION) {}
 
 SDKNodeDecl::SDKNodeDecl(SDKNodeInitInfo Info, SDKNodeKind Kind)
       : SDKNode(Info, Kind), DKind(Info.DKind), Usr(Info.Usr),
@@ -369,6 +370,7 @@ SDKNode *SDKNodeRoot::getInstance(SDKContext &Ctx) {
   Info.Name = Ctx.buffer("TopLevel");
   Info.PrintedName = Ctx.buffer("TopLevel");
   Info.ToolArgs = Ctx.getOpts().ToolArgs;
+  Info.JsonFormatVer = DIGESTER_JSON_VERSION;
   return Info.createSDKNode(SDKNodeKind::Root);
 }
 
@@ -1833,6 +1835,7 @@ void SDKNode::jsonize(json::Output &out) {
 
 void SDKNodeRoot::jsonize(json::Output &out) {
   SDKNode::jsonize(out);
+  out.mapRequired(getKeyContent(Ctx, KeyKind::KK_json_format_version).data(), JsonFormatVer);
   if (!Ctx.getOpts().AvoidToolArgs)
     out.mapOptional(getKeyContent(Ctx, KeyKind::KK_tool_arguments).data(), ToolArgs);
 }

tools/swift-api-digester/ModuleAnalyzerNodes.h

@@ -58,6 +58,13 @@ class Output;
 namespace ide {
 namespace api {
 
+/// Serialized json format  version number.
+///
+/// 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 = 1; // Adding digester_version to the format
+const uint8_t DIGESTER_JSON_DEFAULT_VERSION = 0; // Use this version number for files before we have a version number in json.
+
 class SDKNode;
 typedef SDKNode* NodePtr;
 typedef std::map<NodePtr, NodePtr> ParentMap;
@@ -387,13 +394,14 @@ class SDKNodeRoot: public SDKNode {
   llvm::StringMap<llvm::SmallSetVector<SDKNodeDecl*, 2>> DescendantDeclTable;
   /// The tool invocation arguments to generate this root node. We shouldn't need APIs for it.
   std::vector<StringRef> ToolArgs;
-
+  uint8_t JsonFormatVer;
 public:
   SDKNodeRoot(SDKNodeInitInfo Info);
   static SDKNode *getInstance(SDKContext &Ctx);
   static bool classof(const SDKNode *N);
   void registerDescendant(SDKNode *D);
   virtual void jsonize(json::Output &Out) override;
+  Optional<uint8_t> getJsonFormatVersion() const { return JsonFormatVer; }
   ArrayRef<SDKNodeDecl*> getDescendantsByUsr(StringRef Usr) {
     return DescendantDeclTable[Usr].getArrayRef();
   }