Rust Coverage not working if macros are formatted across multiple lines
Open
Nobody has claimed this yet.
A-code-coverage
C-bug
S-needs-repro
T-compiler
- Dominant language
- Rust
- Stars
- 119k
- Forks
- 16.1k
- PR merge metrics
- PR metrics pending
Description
I tried this code:
log::info!(
"hello world {} 12323123123123123123123123123123123123123123123123",
"Testing"
);
I expected all lines to be covered. However, only the first line
log::info!(
All other lines are not covered
rustc --version --verbose:
rustc 1.86.0 (05f9846f8 2025-03-31)
binary: rustc
commit-hash: 05f9846f893b09a1be1fc8560e33fc3c815cfecb
commit-date: 2025-03-31
host: x86_64-unknown-linux-gnu
release: 1.86.0
LLVM version: 19.1.7
Contributor guide
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 report with the multiline log::info! example and the supplied rustc --version --verbose details. Trace how coverage maps macro-expanded source spans to lines, then verify that every line in the example is reported as covered. Done means multiline macro formatting no longer leaves the argument lines uncovered.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers, testing-qa
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100