-Zinstrument-coverage and matches!()

[scole66]

When using -Zinstrument-coverage on a recent (first-week-of-May-2021) nightly, the matches! macro is no longer marked covered. (This is likely related to macro coverage rules recently adjusted.) The macro was marked covered earlier in April.

  | res::scanner::tests::template_test_09:
  | 2957|      1|    fn template_test_09() {
  | 2958|      1|        let r = scan_token(&Scanner::new(), "`\\", ScanGoal::InputElementRegExp);
  | 2959|      1|        let (token, scanner) = r;
  | 2960|      1|        assert_eq!(scanner, Scanner { line: 1, column: 1, start_idx: 0 });
  | 2961|      1|        assert!(matches!(token, Token::Error(_)));
  |                              ^0
  | 2962|      1|    }

Meta

rustc --version --verbose:

rustc 1.54.0-nightly (716394d65 2021-05-03)
binary: rustc
commit-hash: 716394d6581b60c75cfdd88b8e5b876f2db88b62
commit-date: 2021-05-03
host: x86_64-unknown-linux-gnu
release: 1.54.0-nightly
LLVM version: 12.0.0

[scole66]

/cc @richkadel

[Enselic]

Triage: Can you still reproduce this? If yes, can you add a minimal reproducer please?

[scole66]

yes, I can still repro this. I don't have a minimized reproducer though; that'll take a half an hour maybe tomorrow...

[kpreid]

Triage: Relabeling issues which don't have a runnable reproduction (as opposed to having a non-minimized one) to the new label S-needs-repro.
@rustbot label +S-needs-repro -E-needs-mcve

[scole66]

Minimal Reproducer:

main.rs:

fn main() {
    assert!(matches!(Some(10), Some(_)));
}

#[cfg(test)]
#[test]
fn run() {
    main()
}

Test runner bash script:

output=cov-testcase.profdata;
function tst ()
{
    rm -f cov-testcase-*.profraw
    RUST_BACKTRACE=1 LLVM_PROFILE_FILE="cov-testcase-%m.profraw" RUSTFLAGS="-Cinstrument-coverage" cargo test
    local covstatus=$?
    if [ $covstatus -eq 0 ]; then
        cargo profdata -- merge cov-testcase-*.profraw --output="$output"
    fi
    return $covstatus
}
function objects() {
    for file in $( \
        LLVM_PROFILE_FILE="cov-testcase-%m.profraw" RUSTFLAGS="-Cinstrument-coverage" cargo test --no-run --message-format=json 2> /dev/null | \
            jq -r "select(.profile.test == true) | .filenames[]" | \
            grep -v dSYM - \
        ); do
        /bin/echo -n "-object $file ";
    done
    echo
}
tst
cargo cov -- show \
    --instr-profile="$output" \
    $(objects) \
    --show-line-counts-or-regions \
    --name main \
    -Xdemangler=rustfilt

Output:

$ ./doit.sh 
    Finished test [unoptimized + debuginfo] target(s) in 0.00s
     Running unittests src/main.rs (target/debug/deps/cov_testcase-c24dc8f1fbb12e98)

running 1 test
test run ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

cov_testcase::main:
    1|      1|fn main() {
    2|      1|    assert!(matches!(Some(10), Some(_)));
                          ^0
    3|      1|}

[scole66]

@rustbot label -S-needs-repro