rustc/tests/coverage-map/README.md

The tests in ./status-quo were copied from tests/run-coverage in order to capture the current behavior of the instrumentor on non-trivial programs. The actual mappings have not been closely inspected.

Maintenance note

These tests can be sensitive to small changes in MIR spans or MIR control flow, especially in HIR-to-MIR lowering or MIR optimizations.

If you haven't touched the coverage code directly, and the run-coverage test suite still works, then it should usually be OK to just --bless these coverage mapping tests as necessary, without worrying too much about the exact changes.