Crash in CompoundExpression::evaluate due iOS Maps SDK XCTests

[julianrex]

Detected some crashes from device testing a nightly build generated from mapbox/mapbox-gl-native-ios@e403a069f0 (post 5.7.0-beta.1) / PR mapbox/mapbox-gl-native-ios#179.

The above pins mapbox-gl-native at d85ce77 (on release-unicorn branch).

5 tests out of 545 tests failed (over 5 devices), attached 3 symbolicated crashes below:

Some of the crashes look to have happened as the associated XCTest is being shutdown; this feels like a thread clean-up issue. Although the crashes appear expression evaluation related, the offsets are large, and I suspect that there might have been an issue with the symbolication.

• From Crash 1, Crash 2:

  mbgl::style::expression::CompoundExpression::evaluate(mbgl::style::expression::EvaluationContext const&) const + 1858788 (compound_expression.cpp:1158)
  Crash 1 is identified as a segfault

• From Crash 3:

  mbgl::style::expression::BasicComparison::evaluate(mbgl::style::expression::EvaluationContext const&) const + 1809700 (comparison.cpp:105)

/cc @tmpsantos @pozdnyakov

[1ec5]

Any idea what expression may have been evaluated at the time of the crash? The offsets are large, but the file names and line numbers seem to check out.

[alexshalamov]

@julianrex is there a way to run tests / reproduce an issue locally?

[julianrex]

I have not tried locally; I'll send you more info.

[julianrex]

I'm 95% certain this was due to a retain cycle that kept the MGLMapView alive as the tests were shutting down. Going to close this issue as solved, but should we able to support calling exit while a map is still active @tmpsantos ?