----- Original Message -----
From: Jay Soffian
Date: 6/25/2012 2:48 PM
I was using a "fast-export | <filter program> | fast-import" as a much
faster filter-branch --env-filter (I needed to rewrite
author/committer email-addresses) and was surprised that after the
pipeline was done, the new ref's trees didn't match the old ref's
trees. i.e.:
$ cmp <(git log old-ref --pretty='%T') <(git log --pretty='%T' new-ref)
didn't return 0. Comparing one of the differing tree-pairs indicated
it was due to a case-difference in a file which had been renamed.
After some experimenting I finally tracked this down to having
core.ignorecase set to "true" on the repo in which I was running the
pipeline. By setting it to "false" the filtering pipeline completes
with new-ref (and all its ancestors) being tree-identical to old-ref.
Is there any reason for fast-import to honor ignorecase?
I provided this change in ac1c80f7645b6fa90534890e1f83005d40d98281.
In my mind, core.ignorecase=true means that the file system cannot
handle case-sensitive filenames. Files held in the repository should
conform to a single case.
When I was getting a 'fast export' of our Perforce repository, I found
file case was all over the map. Perforce internally handles its files
for a case preserving case insensitive file system in a case insensitive
manner. File case can change from changelist to changelist! The
fast-exported file was a mess. In the original fast-imported version,
'git status' thought that one case of file was modified when another
case of the same file was the same. Git could not follow the history
over all of the filename case changes.
The case folding patches were created to handle this. Specifically, the
fast-import patch serves as a catch-all to handle repositories that do
not conform to a single case as they were created and in operation. It
folds the incoming file case to match that of what is in the existing
repository. The end result is a clean repository with one file case for
a given filename. 'git status' works. File history can be followed.
'git add' knows which name to match against.
(I am a firm believer that Git should handle *all* case _internally_ as
insensitive when core.ignorecase=true, and I have work-in-progress
patches that illustrate this behavior. Others here (particularly on the
msysgit mailing list) are adamantly against those patches. Nonetheless,
there would be no need to fold case if the Git internals handled
comparisons in a case insensitive fashion.)
I do understand your point above, and I have no good answer. Your file
case was changed during a rename. The fast-import core.ignorecase=true
process did not preserve that case change despite it being right and
appropriate for your repository. core.ignorecase=false did preserve the
case. I guess the solution here depends on what core.ignorecase=true
should mean.
Nevertheless, I am certain Git fast-import needs to retain the case
folding behavior during fast-import, even if it means enabling it via a
command-line flag instead of core.ignorecase=true.
-Josh
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