rtk-ai/rtk · error

--format=%B must parse

Error message

--format=%B must parse

What it means

The test `git_show_format_B` in src/cmds/git/diff_cmd.rs calls `condense_unified_diff_strict(b).expect("--format=%B must parse")`. `condense_unified_diff_strict` (diff_cmd.rs:2083) returns `Option<String>` and yields `None` whenever the strict unified-diff state machine decides a stream is not a parseable diff (unsupported line shapes, prose misclassification, unterminated regions). The panic means the strict parser rejected the `git show --format=%B` fixture instead of condensing it to `[file] w.txt (+1 -0)`. The fixture's body prose starting with `diff ` is designed to exercise the GNU-latch rules; a parser regression re-arms the latch and the stream is sent raw or rejected.

Solutions

1. Run `cargo test git_show_format_B` with a debug print inside condense_unified_diff_strict to find the line where parsing bails to None
2. Check the GNU latch (`gnu_diff_r`) state transitions around the `diff ` line in the fixture message body
3. Verify the fixture still matches real `git show --format=%B` output; regenerate with `git show --format=%B <sha>` if it drifted
4. Diff recent commits touching diff_cmd.rs rules 5/8 and revert the offending state-machine change

Example fix

// before
let out = condense_unified_diff_strict(b).expect("--format=%B must parse");
// after (diagnosing, keep expect in final code)
let out = match condense_unified_diff_strict(b) {
    Some(o) => o,
    None => panic!("strict parser returned None for git_show_format_B fixture"),
};

// Before running the full suite, check the fixture still parses:
let b = include_str!("../../../tests/fixtures/diff/git_show_format_B_raw.txt");
if condense_unified_diff_strict(b).is_none() {
    eprintln!("git_show_format_B fixture no longer parses");
}

// Isolate the failure with a descriptive panic instead of a bare expect:
let out = condense_unified_diff_strict(b).unwrap_or_else(||
    panic!("strict parser returned None for git_show_format_B_raw fixture"));

When it happens

Trigger: Running `cargo test` when condense_unified_diff_strict returns None for tests/fixtures/diff/git_show_format_B_raw.txt. Happens after edits to the parser's GNU latch, mbox message region, or file-header recognition rules in diff_cmd.rs.

Common situations: A contributor refactors the diff condensing rules and breaks recognition of `git show --format=%B` output whose commit body contains a line starting with `diff `; a fixture is regenerated with content the strict parser no longer accepts.

Related errors

• --stat -p must parse
• a bodyless region of prose must not force raw
• a table in the message must not force raw
• f.txt entry
• filter(s) have no inline tests (use --require-all in CI)

AI-assisted analysis of rtk-ai/rtk@0924356b4c (2026-09-19). Data as JSON: /api/errors/3d76e1109b5ef41e. Report an issue: GitHub.

Appendix: source

Thrown at src/cmds/git/diff_cmd.rs:6386

        assert!(
            out.contains("[file] \"caf\\351.txt\" (+1 -1)"),
            "got:\n{out}"
        );
        assert!(!out.contains('\u{FFFD}'), "got:\n{out}");
    }

    #[test]
    fn git_stat_separator_and_format_b_prose_condense() {
        // Real `git log --stat -p`: a bare `---` between the message and
        // the diffstat used to read as lost content.
        let stat = include_str!("../../../tests/fixtures/diff/git_log_p_stat_raw.txt");
        let out = condense_unified_diff_strict(stat).expect("--stat -p must parse");
        assert!(out.contains("[file] i.py (+1 -1)"), "got:\n{out}");
        assert!(out.contains("[file] m.txt (mode changed)"), "got:\n{out}");
        // Real `git show --format=%B`: body prose starting with `diff `
        // used to arm the GNU latch and send the stream raw.
        let b = include_str!("../../../tests/fixtures/diff/git_show_format_B_raw.txt");
        let out = condense_unified_diff_strict(b).expect("--format=%B must parse");
        assert_eq!(out, "[file] w.txt (+1 -0)\n+zz");
    }

    #[test]
    fn combined_diffs_with_three_parents_parse() {
        // Real octopus merge: `@@@@` with three old ranges, via `git show
        // --cc` and via `git diff-tree -c` (`diff --combined`).
        for fixture in [
            include_str!("../../../tests/fixtures/diff/git_show_cc_octopus_raw.txt"),
            include_str!("../../../tests/fixtures/diff/git_diff_tree_combined_raw.txt"),
        ] {
            let out = condense_unified_diff_strict(fixture).expect("must parse");
            assert_eq!(out, "[file] x.txt (+1 -1)\n---2\n+++EVIL");
        }
    }

    #[test]
    fn svn_copy_target_without_content_is_listed() {

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