• Junio C Hamano's avatar
    apply --ignore-space-change: lines with and without leading whitespaces do not match · 14d3bb49
    Junio C Hamano authored
    The fuzzy_matchlines() function is used when attempting to resurrect
    a patch that is whitespace-damaged, or when applying a patch that
    was produced against an old codebase to the codebase after
    indentation change.
    
    The patch may want to change a line "a_bc" ("_" is used throught
    this description for a whitespace to make it stand out) in the
    original into something else, and we may not find "a_bc" in the
    current source, but there may be "a__bc" (two spaces instead of one
    the whitespace-damaged patch claims to expect).  By ignoring the
    amount of whitespaces, it forces "git apply" to consider that "a_bc"
    in the broken patch meant to refer to "a__bc" in reality.
    
    However, the implementation special cases a run of whitespaces at
    the beginning of a line and makes "abc" match "_abc", even though a
    whitespace in the middle of string never matches a 0-width gap,
    e.g. "a_bc" does not match "abc".  A run of whitespace at the end of
    one string does not match a 0-width end of line on the other line,
    either, e.g. "abc_" does not match "abc".
    
    Fix this inconsistency by making the code skip leading whitespaces
    only when both strings begin with a whitespace.  This makes the
    option mean the same as the option of the same name in "diff" and
    "git diff".
    
    Note that I am not sure if anybody sane should use this option in
    the first place.  The fuzzy match logic may be able to find the
    original line that the patch author may have meant to touch because
    it does not fully trust what the original lines say (i.e. context
    lines prefixed by " " and old lines prefixed by "-" does not have to
    exactly match the contents the patch is applied to).  There is no
    reason for us to trust what the replacement lines (i.e. new lines
    prefixed by "+") say, either, but with this option enabled, we end
    up copying these new lines with suspicious whitespace distributions
    literally into the patched result.  But as long as we keep it, we
    should make it do its insane thing consistently.
    Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
    14d3bb49
t4107-apply-ignore-whitespace.sh 3.7 KB