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authorJunio C Hamano <gitster@pobox.com>2014-06-16 17:05:37 (GMT)
committerJunio C Hamano <gitster@pobox.com>2014-06-16 17:05:38 (GMT)
commit79e539404c016e894d8a4db8f43762842a066afc (patch)
treeda07cd8e80c23c5c089ab1042c9e95d7bb1d6083 /Documentation
parent75cc6c67e25656c1b19c7c8f6ca29d1463aefef4 (diff)
parent8f2514e95fe142954d1dd4408cc7cb413a275844 (diff)
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Merge branch 'mt/patch-id-stable' (early part)
* 'mt/patch-id-stable' (early part): patch-id-test: test stable and unstable behaviour patch-id: make it stable against hunk reordering test doc: test_write_lines does not split its arguments test: add test_write_lines helper
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/git-patch-id.txt37
1 files changed, 32 insertions, 5 deletions
diff --git a/Documentation/git-patch-id.txt b/Documentation/git-patch-id.txt
index 312c3b1..31efc58 100644
--- a/Documentation/git-patch-id.txt
+++ b/Documentation/git-patch-id.txt
@@ -8,14 +8,14 @@ git-patch-id - Compute unique ID for a patch
SYNOPSIS
--------
[verse]
-'git patch-id' < <patch>
+'git patch-id' [--stable | --unstable] < <patch>
DESCRIPTION
-----------
-A "patch ID" is nothing but a SHA-1 of the diff associated with a patch, with
-whitespace and line numbers ignored. As such, it's "reasonably stable", but at
-the same time also reasonably unique, i.e., two patches that have the same "patch
-ID" are almost guaranteed to be the same thing.
+A "patch ID" is nothing but a sum of SHA-1 of the file diffs associated with a
+patch, with whitespace and line numbers ignored. As such, it's "reasonably
+stable", but at the same time also reasonably unique, i.e., two patches that
+have the same "patch ID" are almost guaranteed to be the same thing.
IOW, you can use this thing to look for likely duplicate commits.
@@ -27,6 +27,33 @@ This can be used to make a mapping from patch ID to commit ID.
OPTIONS
-------
+
+--stable::
+ Use a "stable" sum of hashes as the patch ID. With this option:
+ - Reordering file diffs that make up a patch does not affect the ID.
+ In particular, two patches produced by comparing the same two trees
+ with two different settings for "-O<orderfile>" result in the same
+ patch ID signature, thereby allowing the computed result to be used
+ as a key to index some meta-information about the change between
+ the two trees;
+
+ - Result is different from the value produced by git 1.9 and older
+ or produced when an "unstable" hash (see --unstable below) is
+ configured - even when used on a diff output taken without any use
+ of "-O<orderfile>", thereby making existing databases storing such
+ "unstable" or historical patch-ids unusable.
+
+ This is the default if patchid.stable is set to true.
+
+--unstable::
+ Use an "unstable" hash as the patch ID. With this option,
+ the result produced is compatible with the patch-id value produced
+ by git 1.9 and older. Users with pre-existing databases storing
+ patch-ids produced by git 1.9 and older (who do not deal with reordered
+ patches) may want to use this option.
+
+ This is the default.
+
<patch>::
The diff to create the ID of.