0a2562bf4d
Add `#[no_coverage]` to the test harness's `fn main` There are two main motivations for adding `#[no_coverage]` to the test harness's entry point: - The entry point is trivial compiler-generated code that doesn't correspond to user source, and it always runs, so there's no value in instrumenting it for coverage. - Because it has dummy spans, it causes the instrumentor implementation to emit invalid coverage mappings that confuse `llvm-cov` and result in strange coverage reports. Fixes #110749.