# Bug: branch checkout is detached if the case doesn't match 6 messages from 2021-06-20 to 2021-06-23. Participants: Tim Hutt, Ævar Arnfjörð Bjarmason, brian m. carlson. Thread: https://gitlist.dev/t/55971 ## Tim Hutt, 2021-06-20 19:45 Subject: Bug: branch checkout is detached if the case doesn't match Message-ID: URL: https://gitlist.dev/e/CAKuVd4DfvEhXDUvxaU_jjNk8JSZANM8jpSEOxi1cbSAp23ohjg%40mail.gmail.com ``` If you try to switch to a branch (e.g. `master`), but get the case wrong, e.g: git switch MASTER git checkout MASTER git switch Master git checkout Master etc. then it autocorrects the case (bad idea but ok), but it also enables the `--detach` flag! In other words git switch Master acts like git switch -d master Very unexpected! Cheers, Tim [System Info] git version: git version 2.32.0 cpu: x86_64 no commit associated with this build sizeof-long: 8 sizeof-size_t: 8 shell-path: /bin/sh uname: Darwin 20.4.0 Darwin Kernel Version 20.4.0: Fri Mar 5 01:14:14 PST 2021; root:xnu-7195.101.1~3/RELEASE_X86_64 x86_64 compiler info: clang: 12.0.5 (clang-1205.0.22.9) libc info: no libc information available $SHELL (typically, interactive shell): /bin/zsh [Enabled Hooks] ``` ## Ævar Arnfjörð Bjarmason, 2021-06-20 22:03 Subject: Re: Bug: branch checkout is detached if the case doesn't match Message-ID: <87czsg429h.fsf@evledraar.gmail.com> URL: https://gitlist.dev/e/87czsg429h.fsf%40evledraar.gmail.com In-Reply-To: ``` On Sun, Jun 20 2021, Tim Hutt wrote: > If you try to switch to a branch (e.g. `master`), but get the case wrong, e.g: > > git switch MASTER > git checkout MASTER > git switch Master > git checkout Master > > etc. then it autocorrects the case (bad idea but ok), but it also > enables the `--detach` flag! In other words > > git switch Master > > acts like > > git switch -d master > > Very unexpected! This behavior isn't intentionaly, but ultimately isn't with Git, but with your running of Git on a filesystem that doesn't respect POSIX semantics. The default FS on OSX is case insensitive, we store the "master" reference (unpacked) under that name on the FS, so this is emergent behavior. Can you reproduce this after a: git pack-refs --all ? Even after that we'll have a .git/HEAD, and I know on OSX e.g. "git log head..." unintentionally resolved to "HEAD" too at some point (probably still). There's various workarounds in git's code to deal with funny behavior on OSX, but it's hard to catch them all as it means having to second-guess standard library calls. I think you're best off creating a case-sensitive partition on your computer and using git there if you want to avoid these cases entirely. > [System Info] > git version: > git version 2.32.0 > cpu: x86_64 > no commit associated with this build > sizeof-long: 8 > sizeof-size_t: 8 > shell-path: /bin/sh > uname: Darwin 20.4.0 Darwin Kernel Version 20.4.0: Fri Mar 5 01:14:14 > PST 2021; root:xnu-7195.101.1~3/RELEASE_X86_64 x86_64 > compiler info: clang: 12.0.5 (clang-1205.0.22.9) > libc info: no libc information available > $SHELL (typically, interactive shell): /bin/zsh > > [Enabled Hooks] ``` ## Tim Hutt, 2021-06-21 17:20 Subject: Re: Bug: branch checkout is detached if the case doesn't match Message-ID: URL: https://gitlist.dev/e/CAKuVd4Bfykm0xe0P5FMy3W8HuECJHqP-RGo%2BT_VK4hn43sgEpg%40mail.gmail.com In-Reply-To: <87czsg429h.fsf@evledraar.gmail.com> ``` Ah of course! > git pack-refs --all Yeah that "fixes" things so you get `fatal: invalid reference: MASTER`. I guess `git checkout` checks whether `MASTER` exists (yes, according to MacOS), but git log checks whether the current branch (`MASTER`) matches `master` (it doesn't). Very unfortunate, but I guess it's not worth fixing. Cheers, Tim On Sun, 20 Jun 2021 at 23:09, Ævar Arnfjörð Bjarmason wrote: > > > On Sun, Jun 20 2021, Tim Hutt wrote: > > > If you try to switch to a branch (e.g. `master`), but get the case wrong, e.g: > > > > git switch MASTER > > git checkout MASTER > > git switch Master > > git checkout Master > > > > etc. then it autocorrects the case (bad idea but ok), but it also > > enables the `--detach` flag! In other words > > > > git switch Master > > > > acts like > > > > git switch -d master > > > > Very unexpected! > > This behavior isn't intentionaly, but ultimately isn't with Git, but > with your running of Git on a filesystem that doesn't respect POSIX > semantics. > > The default FS on OSX is case insensitive, we store the "master" > reference (unpacked) under that name on the FS, so this is emergent > behavior. Can you reproduce this after a: > > git pack-refs --all > > ? > > Even after that we'll have a .git/HEAD, and I know on OSX e.g. "git log > head..." unintentionally resolved to "HEAD" too at some point > (probably still). > > There's various workarounds in git's code to deal with funny behavior on > OSX, but it's hard to catch them all as it means having to second-guess > standard library calls. I think you're best off creating a > case-sensitive partition on your computer and using git there if you > want to avoid these cases entirely. > > > [System Info] > > git version: > > git version 2.32.0 > > cpu: x86_64 > > no commit associated with this build > > sizeof-long: 8 > > sizeof-size_t: 8 > > shell-path: /bin/sh > > uname: Darwin 20.4.0 Darwin Kernel Version 20.4.0: Fri Mar 5 01:14:14 > > PST 2021; root:xnu-7195.101.1~3/RELEASE_X86_64 x86_64 > > compiler info: clang: 12.0.5 (clang-1205.0.22.9) > > libc info: no libc information available > > $SHELL (typically, interactive shell): /bin/zsh > > > > [Enabled Hooks] > ``` ## brian m. carlson, 2021-06-23 02:38 Subject: Re: Bug: branch checkout is detached if the case doesn't match Message-ID: URL: https://gitlist.dev/e/YNKeq5mSu3f0A%2F5I%40camp.crustytoothpaste.net In-Reply-To: ``` On 2021-06-21 at 17:20:28, Tim Hutt wrote: > Ah of course! > > > git pack-refs --all > > Yeah that "fixes" things so you get `fatal: invalid reference: MASTER`. > > I guess `git checkout` checks whether `MASTER` exists (yes, according > to MacOS), but git log checks whether the current branch (`MASTER`) > matches `master` (it doesn't). > > Very unfortunate, but I guess it's not worth fixing. I should point out that there is work underway to add a ref backend called reftable that doesn't store things in the file system and hence doesn't suffer from this problem. It's just a big project and it involves touching a lot of code, so it's slow going, but when it's completed, people who are using that won't have this problem ("MASTER" will be rejected if the branch is "master"). You aren't the first person to report this problem in some variation (it comes up quite frequently); we've known about it a long time, but fixing it just isn't trivial. In the mean time, you may prefer to adopt a naming convention for your project branches; for example, even though I use Linux and don't have this problem, I always use lowercase, which makes things easier for colleagues on other systems (and is also easier to type). -- brian m. carlson (he/him or they/them) Toronto, Ontario, CA ``` ## Tim Hutt, 2021-06-23 11:00 Subject: Re: Bug: branch checkout is detached if the case doesn't match Message-ID: URL: https://gitlist.dev/e/CAKuVd4D1qeuY_4%2B4eXQsU-q5oNw0%2B40PP46y_65GiNZdSgddCA%40mail.gmail.com In-Reply-To: ``` On Wed, 23 Jun 2021 at 03:38, brian m. carlson wrote: > I should point out that there is work underway to add a ref backend > called reftable that doesn't store things in the file system and hence > doesn't suffer from this problem. Ah nice - good luck! ``` ## Ævar Arnfjörð Bjarmason, 2021-06-23 13:00 Subject: Re: Bug: branch checkout is detached if the case doesn't match Message-ID: <87wnqk20qv.fsf@evledraar.gmail.com> URL: https://gitlist.dev/e/87wnqk20qv.fsf%40evledraar.gmail.com In-Reply-To: ``` On Wed, Jun 23 2021, brian m. carlson wrote: > [...] In the mean time, you may prefer to adopt a naming convention > for your project branches; for example, even though I use Linux and > don't have this problem, I always use lowercase, which makes things > easier for colleagues on other systems (and is also easier to type). The reported issue is one that doesn't have to do with the naming of the branch itself, but git accepting it due to how the ref backend interacts with the FS. As noted I've run into e.g. people writing unportable "head.." code, which we happily resolve to "HEAD"., ditto "master", "Master", "MASTER" etc. on OSX. ```