Symbol features are not returned by `queryRenderedFeatures`

[lucaswoj]

GL JS master isn't returning any symbol features from Map#queryRenderedFeatures. Why isn't this causing any test-suite failures? The bug bisects to #3478.

cc @jfirebaugh @mourner @mapsam

mapbox-gl-js version: master as of 46a73c4 / #3478

Steps to Trigger Behavior

call Map#queryRenderedFeatures at a point with a symbol feature

(tricky to provide a jsbin because this bug occurs only in master)

Expected Behavior

the symbol feature is returned

Actual Behavior

the symbol feature is not returned

[jfirebaugh]

I can take a look later today. I believe all of the query tests are for very simple styles, usually with only one layer. One thing I would check is if this only shows up if there are other layers present with the symbol layer.

[lucaswoj]

Debugging Notes

• the bug was introduced in Encapsulate SymbolBucket's unique requirements #3478
• the bug does not manifest itself on a map with only symbol layers & background layers
• the bug does manifest itself on a map with a symbol layer and a line or fill layer
• the symbol in the StructArray returned by CollisionTile#queryRendered has an incorrect bucketIndex

Diagnosis

As of #3478, SymbolBucket no longer inherits from Bucket.

Most of the constructor logic from Bucket was copied to SymbolBucket but the initialization of the index property was not https://github.com/mapbox/mapbox-gl-js/pull/3478/files#diff-621f09c210ab28c3dbf7bc1f0f03c6b2R116

Next Steps

• initialize index within the SymbolBucket constructor
• add a regression test to mapbox-gl-test-suite
• 🚢