I am having a problem with octopus merges when symbolic links are involved. I'm not completely convinced this is a bug in git, but I'm also not convinced that it's _not_. (If it's not, my apologies; I often find it very hard to track down the answers to complicated git questions on the internet.) There is a minimal reproducer available at https://github.com/mmcclimon/git-merge-problem-demo. Fetch all the branches there. The main branch contains a directory (dir1) with a single file (file.txt), plus a symlink (dir2), which links to dir1. branch1 replaces this symlink with a copy of the files that were linked to. (This was accomplished with: rm dir2; cp -r dir1 dir2.) branch2 and branch3 do not touch this directory at all. Merging these three branches fails: $ git merge branch1 branch2 branch3 Fast-forwarding to: branch1 Trying simple merge with branch2 Simple merge did not work, trying automatic merge. Trying simple merge with branch3 error: Entry 'dir2/file.txt' not uptodate. Cannot merge. Merge with strategy octopus failed. The order here matters! Here is every permutation (1 here is the symlink change) to git merge; only the first two fail, all the others work. 1 2 3 FAIL 1 3 2 FAIL 2 1 3 PASS 2 3 1 PASS 3 1 2 PASS 3 2 1 PASS 1 2 PASS 2 1 PASS 2 3 PASS 3 2 PASS 1 3 PASS 3 1 PASS I tracked this down as best I could (I am not a C programmer), by adding `set -x` to my copy of git-octopus-merge.sh. I determined that the line is failing is toward the very bottom of the main loop there: git read-tree -u -m --aggressive $common $MRT $SHA1 I had a read of the index-format.txt and then the git read-tree docs, and I confess that I don't _totally_ follow the latter. But, I wonder if maybe --aggressive is perhaps not aggressive enough if the parts of the index that store symbolic link data aren't taken into account, when it's changed between two versions and the blobs involved aren't actually different. I recognize that replacing a symlink with real files under the same name is a weird thing to do, but this is a pared-down example of a thing that happens occasionally at $work, where we regularly octopus-merge 15+ heads into development branches. I would also be happy to know, if this isn't a bug, if there's some other workaround! The only way I know to fix this case is to merge the symlink change, then rebase all in-flight branches against it. That is often extremely time-consuming and tedious, though, and requires a human to be involved (all the other merging is done by CI.) Thanks! Michael Please review the rest of the bug report below. You can delete any lines you don't wish to share. [System Info] git version: git version 2.34.1 cpu: x86_64 no commit associated with this build sizeof-long: 8 sizeof-size_t: 8 shell-path: /bin/sh uname: Darwin 20.6.0 Darwin Kernel Version 20.6.0: Wed Jun 23 00:26:31 PDT 2021; root:xnu-7195.141.2~5/RELEASE_X86_64 x86_64 compiler info: clang: 13.0.0 (clang-1300.0.29.3) libc info: no libc information available $SHELL (typically, interactive shell): /bin/zsh [Enabled Hooks] -- Michael McClimon michael@xxxxxxxxxxxx
