[ExtractAPI] Include +/- symbols for ObjC methods (llvm#145035)

ObjC methods include a +/- prefix to indicate if they are a class or
instance method. This information is valuable, and must be included in
the navigator generated by ExtractAPI.

rdar://150870936

Author: snprajwal

clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp

@@ -344,6 +344,22 @@ Object serializeNames(const APIRecord *Record) {
   serializeArray(Names, "subHeading",
                  serializeDeclarationFragments(Record->SubHeading));
   DeclarationFragments NavigatorFragments;
+  // The +/- prefix for Objective-C methods is important information, and
+  // should be included in the navigator fragment. The entire subheading is
+  // not included as it can contain too much information for other records.
+  switch (Record->getKind()) {
+  case APIRecord::RK_ObjCClassMethod:
+    NavigatorFragments.append("+ ", DeclarationFragments::FragmentKind::Text,
+                              /*PreciseIdentifier*/ "");
+    break;
+  case APIRecord::RK_ObjCInstanceMethod:
+    NavigatorFragments.append("- ", DeclarationFragments::FragmentKind::Text,
+                              /*PreciseIdentifier*/ "");
+    break;
+  default:
+    break;
+  }
+
   NavigatorFragments.append(Record->Name,
                             DeclarationFragments::FragmentKind::Identifier,
                             /*PreciseIdentifier*/ "");

clang/test/ExtractAPI/objc_instancetype.m

@@ -157,6 +157,10 @@ - (id) reset;
       },
       "names": {
         "navigator": [
+          {
+            "kind": "text",
+            "spelling": "- "
+          },
           {
             "kind": "identifier",
             "spelling": "init"
@@ -228,6 +232,10 @@ - (id) reset;
       },
       "names": {
         "navigator": [
+          {
+            "kind": "text",
+            "spelling": "- "
+          },
           {
             "kind": "identifier",
             "spelling": "reset"