Documentation/git-read-tree: clarify 2-tree merge
Clarify the description of the 2-tree merge by defining the terms which are used in the table, and by applying some small linguistic changes. Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Michael J Gruber committed
Mar 15, 2010 at 11:54 UTC
7325283987430f94712713313c5089e5143f2e17
1 file changed
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Documentation/git-read-tree.txt
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@@ -130,7 +130,7 @@ Single Tree Merge
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~~~~~~~~~~~~~~~~~
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If only 1 tree is specified, 'git read-tree' operates as if the user did not
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specify `-m`, except that if the original index has an entry for a
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-given pathname, and the contents of the path matches with the tree
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+given pathname, and the contents of the path match with the tree
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being read, the stat info from the index is used. (In other words, the
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index's stat()s take precedence over the merged tree's).
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@@ -154,22 +154,24 @@ When two trees are specified, the user is telling 'git read-tree'
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the following:
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1. The current index and work tree is derived from $H, but
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- the user may have local changes in them since $H;
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+ the user may have local changes in them since $H.
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2. The user wants to fast-forward to $M.
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In this case, the `git read-tree -m $H $M` command makes sure
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that no local change is lost as the result of this "merge".
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-Here are the "carry forward" rules:
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+Here are the "carry forward" rules, where "I" denotes the index,
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+"clean" means that index and work tree coincide, and "exists"/"nothing"
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+refer to the presence of a path in the specified commit:
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- I (index) H M Result
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+ I H M Result
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-------------------------------------------------------
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0 nothing nothing nothing (does not happen)
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1 nothing nothing exists use M
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2 nothing exists nothing remove path from index
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- 3 nothing exists exists, use M if "initial checkout"
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+ 3 nothing exists exists, use M if "initial checkout",
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H == M keep index otherwise
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- exists fail
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+ exists, fail
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H != M
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clean I==H I==M
@@ -187,7 +189,7 @@ Here are the "carry forward" rules:
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12 yes no N/A exists nothing fail
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13 no no N/A exists nothing fail
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- clean (H=M)
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+ clean (H==M)
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------
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14 yes exists exists keep index
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15 no exists exists keep index
@@ -202,26 +204,26 @@ Here are the "carry forward" rules:
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21 no yes no exists exists fail
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In all "keep index" cases, the index entry stays as in the
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-original index file. If the entry were not up to date,
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+original index file. If the entry is not up to date,
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'git read-tree' keeps the copy in the work tree intact when
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operating under the -u flag.
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When this form of 'git read-tree' returns successfully, you can
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-see what "local changes" you made are carried forward by running
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+see which of the "local changes" that you made were carried forward by running
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`git diff-index --cached $M`. Note that this does not
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-necessarily match `git diff-index --cached $H` would have
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+necessarily match what `git diff-index --cached $H` would have
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produced before such a two tree merge. This is because of cases
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18 and 19 --- if you already had the changes in $M (e.g. maybe
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you picked it up via e-mail in a patch form), `git diff-index
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--cached $H` would have told you about the change before this
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merge, but it would not show in `git diff-index --cached $M`
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-output after two-tree merge.
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+output after the two-tree merge.
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-Case #3 is slightly tricky and needs explanation. The result from this
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+Case 3 is slightly tricky and needs explanation. The result from this
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rule logically should be to remove the path if the user staged the removal
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of the path and then switching to a new branch. That however will prevent
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the initial checkout from happening, so the rule is modified to use M (new
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-tree) only when the contents of the index is empty. Otherwise the removal
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+tree) only when the content of the index is empty. Otherwise the removal
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of the path is kept as long as $H and $M are the same.
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3-Way Merge