rust-lang / rust-lang/rustc_codegen_cranelift
-Zcoverage is unimplemented
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Description
I've tried to use the cranlift rust backend for a project that records code coverage for tests. For this I run the following command:
RUSTFLAGS="-Zcodegen-backend=cranelift" cargo +nightly llvm-cov test -j 1
which resulted in the following error:
Compiling proc-macro2 v1.0.78
error: -Zcoverage is unimplemented
stmt Coverage::CounterIncrement(0)
fn main() -> () {
let mut _0: ();
// … more MIR
I expected that this would likely not work. I was just surprised that there is no issue for this yet, so I filled that one.
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the reported command with the Cranelift backend and tracing where the -Zcoverage option reaches the backend. Review the emitted Coverage::CounterIncrement MIR shown in the report; done means coverage instrumentation works without the unimplemented error and the relevant behavior is tested.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 25/100