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![Elijah Newren](/assets/img/avatar_default.png)
As noted in commit9822175d2b
("Ensure index matches head before invoking merge machinery, round N", 2019-08-17), we have had a very long history of problems with failing to enforce the requirement that index matches HEAD when starting a merge. One of the commits referenced in the long tale of issues arising from lax enforcement of this requirement was commit55f39cf755
("merge: fix misleading pre-merge check documentation", 2018-06-30), which tried to document the requirement and noted there were some exceptions. As mentioned in that commit message, the `resolve` strategy was the one strategy that did not have an explicit index matching HEAD check, and the reason it didn't was that I wasn't able to discover any cases where the implementation would fail to catch the problem and abort, and didn't want to introduce unnecessary performance overhead of adding another check. Well, today I discovered a testcase where the implementation does not catch the problem and so an explicit check is needed. Add a testcase that previously would have failed, and update git-merge-resolve.sh to have an explicit check. Note that the code is copied from3ec62ad9ff
("merge-octopus: abort if index does not match HEAD", 2016-04-09), so that we reuse the same message and avoid making translators need to translate some new message. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
65 lines
1.2 KiB
Bash
Executable file
65 lines
1.2 KiB
Bash
Executable file
#!/bin/sh
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#
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# Copyright (c) 2005 Linus Torvalds
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# Copyright (c) 2005 Junio C Hamano
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#
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# Resolve two trees, using enhanced multi-base read-tree.
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. git-sh-setup
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# Abort if index does not match HEAD
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if ! git diff-index --quiet --cached HEAD --
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then
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gettextln "Error: Your local changes to the following files would be overwritten by merge"
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git diff-index --cached --name-only HEAD -- | sed -e 's/^/ /'
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exit 2
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fi
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# The first parameters up to -- are merge bases; the rest are heads.
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bases= head= remotes= sep_seen=
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for arg
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do
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case ",$sep_seen,$head,$arg," in
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*,--,)
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sep_seen=yes
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;;
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,yes,,*)
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head=$arg
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;;
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,yes,*)
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remotes="$remotes$arg "
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;;
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*)
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bases="$bases$arg "
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;;
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esac
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done
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# Give up if we are given two or more remotes -- not handling octopus.
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case "$remotes" in
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?*' '?*)
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exit 2 ;;
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esac
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# Give up if this is a baseless merge.
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if test '' = "$bases"
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then
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exit 2
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fi
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git update-index -q --refresh
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git read-tree -u -m --aggressive $bases $head $remotes || exit 2
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echo "Trying simple merge."
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if result_tree=$(git write-tree 2>/dev/null)
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then
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exit 0
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else
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echo "Simple merge failed, trying Automatic merge."
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if git merge-index -o git-merge-one-file -a
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then
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exit 0
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else
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exit 1
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fi
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fi
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