unexpand: prevent overflow on over-large tab stop values - #14409
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In write_tabs, tabstop target arithmetic previously added without overflow checks, panicking in debug builds and wrapping in release builds when a tabstop near usize::MAX is specified. Use checked_add and saturating_add in write_tabs and column tracking so over-large tabstops are handled cleanly without panic or runaway loops.
Merging this PR will improve performance by 15.31%
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GNU testsuite comparison: |
sylvestre
reviewed
Sep 6, 2026
| // a tab, unless it's at the start of the line. | ||
| let ai = print_state.leading || amode; | ||
| if (ai && print_state.pctype != CharType::Tab && print_state.col > print_state.scol + 1) | ||
| if (ai |
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this if is now too complex
could you please refactor it a bit ?
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In
write_tabs, tabstop target arithmetic previously added without overflow checks (print_state.scol + ntsandprint_state.scol + 1), causing debug builds with overflow checks to panic and release builds to wrap around when an over-large tabstop nearusize::MAXis used. Furthermore, column tracking inunexpand_bufperformed unguarded additions that could overflow if a character followed a large tab stop.Use
checked_addandsaturating_addinwrite_tabsandunexpand_bufso over-large tab stop values are handled cleanly without panic or runaway loops, and add regression tests covering over-large tab stop arguments.Fixes #14378