Fix shadowed variable in mapillary/opensfm/opensfm/src/map/src/tracks…

…_manager.cc

Summary:
Our upcoming compiler upgrade will require us not to have shadowed variables. Such variables have a _high_ bug rate and reduce readability, so we would like to avoid them even if the compiler was not forcing us to do so.

This codemod attempts to fix an instance of a shadowed variable. Please review with care: if it's failed the result will be a silent bug.

**What's a shadowed variable?**

Shadowed variables are variables in an inner scope with the same name as another variable in an outer scope. Having the same name for both variables might be semantically correct, but it can make the code confusing to read! It can also hide subtle bugs.

This diff fixes such an issue by renaming the variable.

 - If you approve of this diff, please use the "Accept & Ship" button :-)

Reviewed By: palmje

Differential Revision: D64398698

fbshipit-source-id: e70f61a9337391e8357fff7a8d07c0b927c63b4d

opensfm/src/map/src/tracks_manager.cc

@@ -356,15 +356,15 @@ TracksManager::GetAllPairsConnectivity(
 TracksManager TracksManager::MergeTracksManager(
     const std::vector<const TracksManager*>& tracks_managers) {
   // Some typedefs claryfying the aggregations
-  using FeatureId = std::pair<ShotId, int>;
+  using FeatureId_2 = std::pair<ShotId, int>;
   using SingleTrackId = std::pair<TrackId, int>;
 
   // Union-find main data
   std::vector<std::unique_ptr<UnionFindElement<SingleTrackId>>>
       union_find_elements;
 
   // Aggregate tracks be merged using (shot_id, feature_id)
-  std::unordered_map<FeatureId, std::vector<int>, HashPair>
+  std::unordered_map<FeatureId_2, std::vector<int>, HashPair>
       observations_per_feature_id;
   for (int i = 0; i < tracks_managers.size(); ++i) {
     const auto& manager = tracks_managers[i];
@@ -387,7 +387,7 @@ TracksManager TracksManager::MergeTracksManager(
     return merged;
   }
 
-  // Union-find any two tracks sharing a common FeatureId
+  // Union-find any two tracks sharing a common FeatureId_2
   // For N tracks, make 0 the parent of [1, ... N-1[
   for (const auto& tracks_agg : observations_per_feature_id) {
     if (tracks_agg.second.empty()) {