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Merge branch 'maint'

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* maint:
  Documentation/git-read-tree: clarify 2-tree merge
  Documentation/git-read-tree: fix table layout
This commit is contained in:
Junio C Hamano 2010-03-16 19:30:37 -07:00
commit 60dafdd37d
1 changed files with 24 additions and 22 deletions
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46
Documentation/git-read-tree.txt
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@ -130,7 +130,7 @@ Single Tree Merge
~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~
If only 1 tree is specified, 'git read-tree' operates as if the user did not If only 1 tree is specified, 'git read-tree' operates as if the user did not
specify `-m`, except that if the original index has an entry for a specify `-m`, except that if the original index has an entry for a
given pathname, and the contents of the path matches with the tree given pathname, and the contents of the path match with the tree
being read, the stat info from the index is used. (In other words, the being read, the stat info from the index is used. (In other words, the
index's stat()s take precedence over the merged tree's). index's stat()s take precedence over the merged tree's).
@ -154,40 +154,42 @@ When two trees are specified, the user is telling 'git read-tree'
the following: the following:
1. The current index and work tree is derived from $H, but 1. The current index and work tree is derived from $H, but
the user may have local changes in them since $H; the user may have local changes in them since $H.
2. The user wants to fast-forward to $M. 2. The user wants to fast-forward to $M.
In this case, the `git read-tree -m $H $M` command makes sure In this case, the `git read-tree -m $H $M` command makes sure
that no local change is lost as the result of this "merge". that no local change is lost as the result of this "merge".
Here are the "carry forward" rules: Here are the "carry forward" rules, where "I" denotes the index,
"clean" means that index and work tree coincide, and "exists"/"nothing"
refer to the presence of a path in the specified commit:
I (index) H M Result I H M Result
------------------------------------------------------- -------------------------------------------------------
0 nothing nothing nothing (does not happen) 0 nothing nothing nothing (does not happen)
1 nothing nothing exists use M 1 nothing nothing exists use M
2 nothing exists nothing remove path from index 2 nothing exists nothing remove path from index
3 nothing exists exists, use M if "initial checkout" 3 nothing exists exists, use M if "initial checkout",
H == M keep index otherwise H == M keep index otherwise
exists fail exists, fail
H != M H != M
clean I==H I==M clean I==H I==M
------------------ ------------------
4 yes N/A N/A nothing nothing keep index 4 yes N/A N/A nothing nothing keep index
5 no N/A N/A nothing nothing keep index 5 no N/A N/A nothing nothing keep index
6 yes N/A yes nothing exists keep index 6 yes N/A yes nothing exists keep index
7 no N/A yes nothing exists keep index 7 no N/A yes nothing exists keep index
8 yes N/A no nothing exists fail 8 yes N/A no nothing exists fail
9 no N/A no nothing exists fail 9 no N/A no nothing exists fail
10 yes yes N/A exists nothing remove path from index 10 yes yes N/A exists nothing remove path from index
11 no yes N/A exists nothing fail 11 no yes N/A exists nothing fail
12 yes no N/A exists nothing fail 12 yes no N/A exists nothing fail
13 no no N/A exists nothing fail 13 no no N/A exists nothing fail
clean (H=M) clean (H==M)
------ ------
14 yes exists exists keep index 14 yes exists exists keep index
15 no exists exists keep index 15 no exists exists keep index
@ -202,26 +204,26 @@ Here are the "carry forward" rules:
21 no yes no exists exists fail 21 no yes no exists exists fail
In all "keep index" cases, the index entry stays as in the In all "keep index" cases, the index entry stays as in the
original index file. If the entry were not up to date, original index file. If the entry is not up to date,
'git read-tree' keeps the copy in the work tree intact when 'git read-tree' keeps the copy in the work tree intact when
operating under the -u flag. operating under the -u flag.
When this form of 'git read-tree' returns successfully, you can When this form of 'git read-tree' returns successfully, you can
see what "local changes" you made are carried forward by running see which of the "local changes" that you made were carried forward by running
`git diff-index --cached $M`. Note that this does not `git diff-index --cached $M`. Note that this does not
necessarily match `git diff-index --cached $H` would have necessarily match what `git diff-index --cached $H` would have
produced before such a two tree merge. This is because of cases produced before such a two tree merge. This is because of cases
18 and 19 --- if you already had the changes in $M (e.g. maybe 18 and 19 --- if you already had the changes in $M (e.g. maybe
you picked it up via e-mail in a patch form), `git diff-index you picked it up via e-mail in a patch form), `git diff-index
--cached $H` would have told you about the change before this --cached $H` would have told you about the change before this
merge, but it would not show in `git diff-index --cached $M` merge, but it would not show in `git diff-index --cached $M`
output after two-tree merge. output after the two-tree merge.
Case #3 is slightly tricky and needs explanation. The result from this Case 3 is slightly tricky and needs explanation. The result from this
rule logically should be to remove the path if the user staged the removal rule logically should be to remove the path if the user staged the removal
of the path and then switching to a new branch. That however will prevent of the path and then switching to a new branch. That however will prevent
the initial checkout from happening, so the rule is modified to use M (new the initial checkout from happening, so the rule is modified to use M (new
tree) only when the contents of the index is empty. Otherwise the removal tree) only when the content of the index is empty. Otherwise the removal
of the path is kept as long as $H and $M are the same. of the path is kept as long as $H and $M are the same.
3-Way Merge 3-Way Merge