Browse Source
"git rebase" behaved slightly differently depending on which one of the three backends gets used; this has been documented and an effort to make them more uniform has begun. * en/rebase-consistency: git-rebase: make --allow-empty-message the default t3401: add directory rename testcases for rebase and am git-rebase.txt: document behavioral differences between modes directory-rename-detection.txt: technical docs on abilities and limitations git-rebase.txt: address confusion between --no-ff vs --force-rebase git-rebase: error out when incompatible options passed t3422: new testcases for checking when incompatible options passed git-rebase.sh: update help messages a bit git-rebase.txt: document incompatible optionsmaint
Junio C Hamano
7 years ago
7 changed files with 462 additions and 42 deletions
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|
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Directory rename detection |
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========================== |
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|
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Rename detection logic in diffcore-rename that checks for renames of |
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individual files is aggregated and analyzed in merge-recursive for cases |
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where combinations of renames indicate that a full directory has been |
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renamed. |
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Scope of abilities |
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------------------ |
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It is perhaps easiest to start with an example: |
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* When all of x/a, x/b and x/c have moved to z/a, z/b and z/c, it is |
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likely that x/d added in the meantime would also want to move to z/d by |
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taking the hint that the entire directory 'x' moved to 'z'. |
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More interesting possibilities exist, though, such as: |
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* one side of history renames x -> z, and the other renames some file to |
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x/e, causing the need for the merge to do a transitive rename. |
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* one side of history renames x -> z, but also renames all files within |
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x. For example, x/a -> z/alpha, x/b -> z/bravo, etc. |
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* both 'x' and 'y' being merged into a single directory 'z', with a |
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directory rename being detected for both x->z and y->z. |
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* not all files in a directory being renamed to the same location; |
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i.e. perhaps most the files in 'x' are now found under 'z', but a few |
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are found under 'w'. |
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* a directory being renamed, which also contained a subdirectory that was |
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renamed to some entirely different location. (And perhaps the inner |
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directory itself contained inner directories that were renamed to yet |
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other locations). |
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* combinations of the above; see t/t6043-merge-rename-directories.sh for |
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various interesting cases. |
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Limitations -- applicability of directory renames |
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------------------------------------------------- |
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In order to prevent edge and corner cases resulting in either conflicts |
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that cannot be represented in the index or which might be too complex for |
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users to try to understand and resolve, a couple basic rules limit when |
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directory rename detection applies: |
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1) If a given directory still exists on both sides of a merge, we do |
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not consider it to have been renamed. |
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2) If a subset of to-be-renamed files have a file or directory in the |
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way (or would be in the way of each other), "turn off" the directory |
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rename for those specific sub-paths and report the conflict to the |
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user. |
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3) If the other side of history did a directory rename to a path that |
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your side of history renamed away, then ignore that particular |
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rename from the other side of history for any implicit directory |
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renames (but warn the user). |
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Limitations -- detailed rules and testcases |
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------------------------------------------- |
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|
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t/t6043-merge-rename-directories.sh contains extensive tests and commentary |
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which generate and explore the rules listed above. It also lists a few |
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additional rules: |
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a) If renames split a directory into two or more others, the directory |
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with the most renames, "wins". |
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b) Avoid directory-rename-detection for a path, if that path is the |
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source of a rename on either side of a merge. |
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c) Only apply implicit directory renames to directories if the other side |
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of history is the one doing the renaming. |
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Limitations -- support in different commands |
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-------------------------------------------- |
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Directory rename detection is supported by 'merge' and 'cherry-pick'. |
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Other git commands which users might be surprised to see limited or no |
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directory rename detection support in: |
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* diff |
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Folks have requested in the past that `git diff` detect directory |
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renames and somehow simplify its output. It is not clear whether this |
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would be desirable or how the output should be simplified, so this was |
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simply not implemented. Further, to implement this, directory rename |
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detection logic would need to move from merge-recursive to |
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diffcore-rename. |
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* am |
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git-am tries to avoid a full three way merge, instead calling |
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git-apply. That prevents us from detecting renames at all, which may |
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defeat the directory rename detection. There is a fallback, though; if |
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the initial git-apply fails and the user has specified the -3 option, |
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git-am will fall back to a three way merge. However, git-am lacks the |
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necessary information to do a "real" three way merge. Instead, it has |
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to use build_fake_ancestor() to get a merge base that is missing files |
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whose rename may have been important to detect for directory rename |
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detection to function. |
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* rebase |
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Since am-based rebases work by first generating a bunch of patches |
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(which no longer record what the original commits were and thus don't |
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have the necessary info from which we can find a real merge-base), and |
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then calling git-am, this implies that am-based rebases will not always |
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successfully detect directory renames either (see the 'am' section |
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above). merged-based rebases (rebase -m) and cherry-pick-based rebases |
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(rebase -i) are not affected by this shortcoming, and fully support |
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directory rename detection. |
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#!/bin/sh |
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test_description='git rebase + directory rename tests' |
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. ./test-lib.sh |
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. "$TEST_DIRECTORY"/lib-rebase.sh |
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test_expect_success 'setup testcase' ' |
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test_create_repo dir-rename && |
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( |
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cd dir-rename && |
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mkdir x && |
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test_seq 1 10 >x/a && |
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test_seq 11 20 >x/b && |
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test_seq 21 30 >x/c && |
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test_write_lines a b c d e f g h i >l && |
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git add x l && |
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git commit -m "Initial" && |
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git branch O && |
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git branch A && |
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git branch B && |
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git checkout A && |
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git mv x y && |
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git mv l letters && |
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git commit -m "Rename x to y, l to letters" && |
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git checkout B && |
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echo j >>l && |
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test_seq 31 40 >x/d && |
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git add l x/d && |
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git commit -m "Modify l, add x/d" |
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) |
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' |
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test_expect_success 'rebase --interactive: directory rename detected' ' |
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( |
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cd dir-rename && |
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git checkout B^0 && |
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set_fake_editor && |
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FAKE_LINES="1" git rebase --interactive A && |
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git ls-files -s >out && |
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test_line_count = 5 out && |
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test_path_is_file y/d && |
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test_path_is_missing x/d |
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) |
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' |
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|
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test_expect_failure 'rebase (am): directory rename detected' ' |
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( |
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cd dir-rename && |
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git checkout B^0 && |
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git rebase A && |
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git ls-files -s >out && |
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test_line_count = 5 out && |
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test_path_is_file y/d && |
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test_path_is_missing x/d |
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) |
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' |
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test_expect_success 'rebase --merge: directory rename detected' ' |
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( |
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cd dir-rename && |
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git checkout B^0 && |
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git rebase --merge A && |
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git ls-files -s >out && |
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test_line_count = 5 out && |
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test_path_is_file y/d && |
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test_path_is_missing x/d |
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) |
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' |
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test_expect_failure 'am: directory rename detected' ' |
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( |
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cd dir-rename && |
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git checkout A^0 && |
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git format-patch -1 B && |
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git am --3way 0001*.patch && |
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git ls-files -s >out && |
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test_line_count = 5 out && |
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test_path_is_file y/d && |
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test_path_is_missing x/d |
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) |
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' |
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test_done |
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#!/bin/sh |
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|
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test_description='test if rebase detects and aborts on incompatible options' |
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. ./test-lib.sh |
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test_expect_success 'setup' ' |
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test_seq 2 9 >foo && |
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git add foo && |
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git commit -m orig && |
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|
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git branch A && |
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git branch B && |
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|
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git checkout A && |
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test_seq 1 9 >foo && |
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git add foo && |
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git commit -m A && |
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|
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git checkout B && |
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echo "q qfoo();" | q_to_tab >>foo && |
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git add foo && |
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git commit -m B |
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' |
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|
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# |
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# Rebase has lots of useful options like --whitepsace=fix, which are |
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# actually all built in terms of flags to git-am. Since neither |
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# --merge nor --interactive (nor any options that imply those two) use |
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# git-am, using them together will result in flags like --whitespace=fix |
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# being ignored. Make sure rebase warns the user and aborts instead. |
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# |
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|
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test_rebase_am_only () { |
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opt=$1 |
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shift |
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test_expect_success "$opt incompatible with --merge" " |
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git checkout B^0 && |
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test_must_fail git rebase $opt --merge A |
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" |
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|
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test_expect_success "$opt incompatible with --strategy=ours" " |
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git checkout B^0 && |
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test_must_fail git rebase $opt --strategy=ours A |
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" |
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|
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test_expect_success "$opt incompatible with --strategy-option=ours" " |
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git checkout B^0 && |
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test_must_fail git rebase $opt --strategy-option=ours A |
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" |
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|
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test_expect_success "$opt incompatible with --interactive" " |
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git checkout B^0 && |
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test_must_fail git rebase $opt --interactive A |
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" |
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|
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test_expect_success "$opt incompatible with --exec" " |
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git checkout B^0 && |
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test_must_fail git rebase $opt --exec 'true' A |
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" |
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|
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} |
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|
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test_rebase_am_only --whitespace=fix |
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test_rebase_am_only --ignore-whitespace |
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test_rebase_am_only --committer-date-is-author-date |
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test_rebase_am_only -C4 |
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|
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test_expect_success '--preserve-merges incompatible with --signoff' ' |
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git checkout B^0 && |
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test_must_fail git rebase --preserve-merges --signoff A |
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' |
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|
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test_expect_success '--preserve-merges incompatible with --rebase-merges' ' |
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git checkout B^0 && |
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test_must_fail git rebase --preserve-merges --rebase-merges A |
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' |
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|
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test_expect_success '--rebase-merges incompatible with --strategy' ' |
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git checkout B^0 && |
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test_must_fail git rebase --rebase-merges -s resolve A |
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' |
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|
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test_expect_success '--rebase-merges incompatible with --strategy-option' ' |
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git checkout B^0 && |
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test_must_fail git rebase --rebase-merges -Xignore-space-change A |
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' |
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|
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test_done |
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Reference in new issue