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d90fd027c8
When MIR is built for an if-not expression, the `!` part of the condition doesn't correspond to any MIR statement, so coverage instrumentation normally can't see it. We can fix that by deliberately injecting a dummy statement whose sole purpose is to associate that span with its enclosing block.
The tests in this directory are shared by two different test modes, and can be run in multiple different ways:
./x.py test coverage-map(compiles to LLVM IR and checks coverage mappings)./x.py test coverage-run(runs a test binary and checks its coverage report)./x.py test coverage(runs bothcoverage-mapandcoverage-run)
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 tests still pass in
coverage-run mode, then it should usually be OK to just re-bless the mappings
as necessary with ./x.py test coverage-map --bless, without worrying too much
about the exact changes.