We should be running static analysis errors when building iOS engine. This will cause the build time to increase quite a lot, which should be evaluated.

I believe this can be done by passing --clang-static-analyzer into gn in the builder:
https://github.com/flutter/engine/blob/217d545631f9010d10f6f250422b6d18ba2b331c/ci/builders/mac_ios_engine.json#L31-L36
https://github.com/flutter/engine/blob/945a524bfc5c5eef25487ece2151db644d0eb256/tools/gn#L440