[vim/vim] regex: case-insensitive match fails on multi-byte string with re=1 (PR #21212)
Volodymyr Chernetskyi
Problem: With 'regexpengine' set to 1 a case-insensitive match against
a literal string fails when the string starts with a
multi-byte character that is longer than a character following
it, so the two regexp engines disagree (after v9.1.0645).
Solution: In cstrncmp() advance by the length of the character at the
current position instead of always measuring the first
character of "s1".
cstrncmp() walks "s1" to find how many characters make up "*n" bytes, so that it can measure out the same number of characters in "s2". The loop decremented the remaining byte count by mb_ptr2len(s1), which always returns the length of the first character, rather than the length of the character at the current position "p".
When the first character is longer than a later one the byte count runs out too early, the character count comes up short, and MB_STRNICMP2() is handed a length for "s2" that is too small, so the comparison fails. For example matching "\cüber" against "Überraschung": "über" is five bytes, but each iteration subtracts two (the length of "ü"), so the loop runs three times instead of four.
:set regexpengine=1
echo matchstr('Überraschung', '\cüber')
returns an empty string, while 'regexpengine' set to 2 correctly returns "Über". The default value of 0 uses the NFA engine and is unaffected.
You can view, comment on, or merge this pull request online at:
https://github.com/vim/vim/pull/21212
Commit Summary
- 34b9a81 regex: case-insensitive match fails on multi-byte string with re=1
File Changes
(2 files)
- M src/regexp.c (2)
- M src/testdir/test_regexp_utf8.vim (6)
Patch Links:
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Christian Brabandt
chrisbra left a comment (vim/vim#21212)thanks, obviously correct.
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