Update code coverage

[Chralt98]

Hey,

could you please update the code coverage functionality? It's unfortunately not possible to get coverage reports with using the necessary compiler flags with cargo-fuzz.

This doesn't work:

RUSTFLAGS="-C instrument-coverage" LLVM_PROFILE_FILE="json5format-%m.profraw" cargo fuzz ...

So the users need to use cargo fuzz coverage ...

The library uses the deprecated -Z flag.

[fitzgen]

I personally am not super up to date with how code coverage works in rustc, and don't have the time to dig into that right now. If you do, I'd be happy to review a pull request fixing this!

[Chralt98]

Sorry, I have no capacities for this at the moment.

[folkertdev]

I suspect that this has now been fixed? I did need to run a cargo install cargo-fuzz to update my installation to get the fix