fix(MD049,MD037): Preserve inline code inside emphasis during auto-fix#652
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rvben merged 1 commit intoJun 2, 2026
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Both rules detect emphasis on a copy of the line where inline code spans are masked with equal-length runs of 'X' (and inline math with 'M'), so backtick or dollar contents are not mistaken for emphasis markers. The auto-fix then reused the emphasis content taken from that masked copy, so the placeholder characters leaked into the written file and permanently replaced the original inline code. This corrupts content and affects fix/fmt only, not check. Slice the replacement content from the original line at the span's byte offsets instead. Masking is length-preserving, so the offsets stay valid. - MD049: build emphasis content from the original line in collect_emphasis_from_line rather than the masked copy. - MD037: slice the trimmed content from the original line when building the space-fixed replacement. - Add regression tests for inline code inside emphasized spans in both rules (both directions for MD049), asserting no placeholder leakage.
Owner
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Thanks @thegeorgeliu, for both the clear bug report in #651 and the fix. Nicely scoped, with good regression tests. Merging now; it'll ship in the next patch release. |
Contributor
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Happy to contribute @rvben! Thanks for all your great work on rumdl, I've been using it for a while now throughout all my personal and work projects! |
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Description
To detect emphasis markers reliably,
MD049andMD037first build a throwaway copy of each line with every inline code span replaced by an equal-length sequence ofXcharacters (and inline math byM). This prevents backtick or dollar contents from being misread as emphasis markers. The auto-fix, however, reused the emphasis text taken from that masked copy, so theX/Mplaceholders leaked into the written file and permanently replaced the original inline code.The fix takes the replacement text from the original line at the span's byte offsets instead. Because masking replaces each span with a sequence of the same byte length, those offsets remain valid against the original line.
Example before this fix (
rumdl fmtwith MD049style = "asterisk"):- _An item withinline codeinside._- *An item with XXXXXXXXXXXXX inside.*After the fix the inline code is preserved:
- *An item withinline codeinside.*. Onlyfmt/--fixwas affected;checkdoes not modify files.MD050(strong style) was not affected.Type of Change
Testing
cargo nextestfor md049/md037/emphasis/reflow/md013/formatter_idempotency, and fullcargo test --lib(5810 passed)rumdl fmton the repro is now lossless and idempotentChecklist
cargo fmt --checkclean; CI clippy gate-D warnings -D clippy::uninlined_format_argsclean)Closes #651