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April 30, 2015 15:06
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This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode charactersOriginal file line number Diff line number Diff line change @@ -0,0 +1,122 @@ Suppose there is a commit `C` which have a single parent commit `P`. Let's say that `TC` and `TP` are the corresponding tree objects. Why `git diff P C` is not always equal to `git diff-tree TP TC -p`? ---- ## Why they should be equal? According to a git protocol specification, each commit object is pointing on only one tree objects. Different commit objects could use the same tree object, but not vice-versa. ## Any example? For instance, let's take this public repo : `[email protected]:dmalikov/dotfiles.git`. Here is some commit object: >> git cat-file -p 67019a5daef556ef5c3e2bea4f425d9a5044bc44 tree 1e9c97a5f0da406f4e74d02897393606e902408d parent 435f7e6a78d5c5797c0997c1ad73f11d38d89d7a author Dmitry Malikov <[email protected]> 1374867081 +0400 committer Dmitry Malikov <[email protected]> 1374867754 +0400 Vifm: cue2tracks mapping Here is parent commit: >> git cat-file -p 435f7e6a78d5c5797c0997c1ad73f11d38d89d7a tree eb00b6ee310bda76280c515c5bd698e3247d3416 parent 00a1c0f55cd6c9eaa6621b0c7799c56d6bf76df5 author Dmitry Malikov <[email protected]> 1374831285 +0400 committer Dmitry Malikov <[email protected]> 1374834097 +0400 Vim: correct tabs for js and eruby Commits' diff: >> git diff 435f7e6a78d5c5797c0997c1ad73f11d38d89d7a 67019a5daef556ef5c3e2bea4f425d9a5044bc44 --stat configs/vifm/vifmrc | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) Trees' diff: >> git diff-tree eb00b6ee310bda76280c515c5bd698e3247d3416 1e9c97a5f0da406f4e74d02897393606e902408d --stat configs/vifm/vifmrc | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) Unfortunately they're are different. Let's take a closer look again >> git diff 435f7e6a78d5c5797c0997c1ad73f11d38d89d7a 67019a5daef556ef5c3e2bea4f425d9a5044bc44 diff --git a/configs/vifm/vifmrc b/configs/vifm/vifmrc index 95b540d..a41bd54 100644 --- a/configs/vifm/vifmrc +++ b/configs/vifm/vifmrc @@ -167,14 +167,15 @@ filetype *.ssh FUSE_MOUNT2|sshfs %PARAM %DESTINATION_DIR set vifminfo=bookmarks " Sample mappings +nmap ,c :!cue2tracks -RF<CR> -nmap s :shell<cr> -nmap S :sort<cr> -nmap w :view<cr> -nmap o :!gvim --remote-tab-silent %f<cr> -nmap O :!gvim %f<cr> -" open file in the background using its default program -nmap gb :file &<cr>l +" nmap s :shell<cr> +" nmap S :sort<cr> +" nmap w :view<cr> +" nmap o :!gvim --remote-tab-silent %f<cr> +" nmap O :!gvim %f<cr> +" " open file in the background using its default program +" nmap gb :file &<cr>l nmap <f3> :!less %f<cr> nmap <f4> :edit<cr> And a trees' analogue: >> git diff-tree eb00b6ee310bda76280c515c5bd698e3247d3416 1e9c97a5f0da406f4e74d02897393606e902408d -p diff --git a/configs/vifm/vifmrc b/configs/vifm/vifmrc index 95b540d..a41bd54 100644 --- a/configs/vifm/vifmrc +++ b/configs/vifm/vifmrc @@ -167,14 +167,15 @@ filetype *.ssh FUSE_MOUNT2|sshfs %PARAM %DESTINATION_DIR set vifminfo=bookmarks " Sample mappings - -nmap s :shell<cr> -nmap S :sort<cr> -nmap w :view<cr> -nmap o :!gvim --remote-tab-silent %f<cr> -nmap O :!gvim %f<cr> -" open file in the background using its default program -nmap gb :file &<cr>l +nmap ,c :!cue2tracks -RF<CR> + +" nmap s :shell<cr> +" nmap S :sort<cr> +" nmap w :view<cr> +" nmap o :!gvim --remote-tab-silent %f<cr> +" nmap O :!gvim %f<cr> +" " open file in the background using its default program +" nmap gb :file &<cr>l nmap <f3> :!less %f<cr> nmap <f4> :edit<cr> So what we have here is some kind of different difference strategies used for calculating diff. ## How often this issue occurs? For a repository mentioned above there are 10 commits with the issue out of 735 commits. ---- ## Finally What is the difference between `diff` and `diff-tree` commands?