cmFileAPICodemodel: Build map from each target to its index

Source/cmFileAPICodemodel.cxx

@@ -46,6 +46,9 @@
 
 namespace {
 
+using TargetIndexMapType =
+  std::unordered_map<cmGeneratorTarget const*, Json::ArrayIndex>;
+
 class Codemodel
 {
   cmFileAPI& FileAPI;
@@ -94,6 +97,8 @@ class CodemodelConfig
     ProjectMap;
   std::vector<Project> Projects;
 
+  TargetIndexMapType TargetIndexMap;
+
   void ProcessDirectories();
 
   Json::ArrayIndex GetDirectoryIndex(cmLocalGenerator const* lg);
@@ -663,6 +668,8 @@ Json::Value CodemodelConfig::DumpTarget(cmGeneratorTarget* gt,
   target["projectIndex"] = pi;
   this->Projects[pi].TargetIndexes.append(ti);
 
+  this->TargetIndexMap[gt] = ti;
+
   return target;
 }