When I search a word, the search engine fail to find the same word when it has an apostrophe before, so a search for "apostrophe" doesn't find "L'apostrophe" occurrence.
In French the apostrophe is not part of the word, its a contraction for "La apostrophe".
For example :
https://en.wikipedia.org/w/index.php?title=Special%3ASearch&profile=default&search=Arc-en-Ciel&fulltext=Search
"Arc-en-Ciel" doesn't match any "L'Arc-en-Ciel" (with L') directly.
Compare with a search "L'Arc-en-Ciel"
https://en.wikipedia.org/w/index.php?search=L%27Arc-en-Ciel&title=Special%3ASearch&fulltext=1
In French, like in English, apostrophe should be not indexed as part of the word.
Note : its the same bug than https://bugzilla.wikimedia.org/show_bug.cgi?id=9598 (old)
See also a different apostrophe usage in Ukrainian https://bugzilla.wikimedia.org/show_bug.cgi?id=21002
Version: unspecified
Severity: normal