Now mise works fine in git-bash, but the installed tool bash can't be found

There are subtlety in GitBash's paths that "manual' transformations like the sed | tr above does not capture: i.e. some paths must be converted differently than others.
That subtelty, and probably others, are well handled by the cygpath command, as shown below

When the argument is a LIST of path, then adding the -p option let cygpath convert Windows (;) separator to Unix separator (:):

Also, it is nice to know that cygpath -u -F <number> return the path to some well known directories on Windows (cuts down on guesswork).

How about, in the output of mise activate bash, an if branch for -n "$MSYSTEM" that would then apply cygpath to all paths ? (Similarly for zsh and other shells available under MSYS2, but Git's MSYS2 Bash being most popular).

See #6633

I put some comments onto #6633, also explaining how to support busybox.exe bash, another bash-on-Windows option.

So for Git Bash instead of MSYS2 ZSH it would comes down to something like

    _MISE_EXE_UNIX="$(cygpath -u "$(command -v mise.exe)")"
    mise() { command "$_MISE_EXE_UNIX" "$@"; }
    export MISE_EXE="$_MISE_EXE_UNIX"
    export MISE_SHELL=bash

    mise_activate_script="$(mise activate bash)"
    mise_path_line="$(printf '%s\n' "$mise_activate_script" | sed -n 's/^export PATH="\([^"]*\)".*$/\1/p')"
    if [[ -n "$mise_path_line" ]]; then
      mise_path_line="$(cygpath -u -p "$mise_path_line")"
      mise_activate_script="$(printf '%s\n' "$mise_activate_script" \
        | awk -v newpath="$mise_path_line" 'BEGIN{done=0} { if (!done && $0 ~ /^export PATH=/) { print "export PATH=\"" newpath "\""; done=1; } else { print $0; } }')"
    fi

    mise_activate_script="$(printf '%s\n' "$mise_activate_script" \
      | sed -E "s@[A-Za-z]:\\\\[^\"']*\\\\mise\.exe@$_MISE_EXE_UNIX@g")"

    eval "$mise_activate_script"

?

ugh... even this isn't always sufficient if you also have mise activation in your powershell profile. I haven't quite worked out the exact steps to reproduce, but what I've seen on my system is that sometimes (but not always), this happens:

1. user decides to launch git bash
2. Windows decides to use powershell to launch git bash (note: I haven't fully pinned down how exactly this decision is made)
3. powershell profile activates mise. stuff gets added to PATH using Windows path syntax (root is C:\, file separator is \ , path separator is ;)
4. powershell launches git bash
5. git bash updates PATH to use unix path syntax (root becomes /c, file separator is /, path separator is :).

At this point, things should be correct, and running mise activate bash will mess things up.

The easiest way to tell if you're in this scenario is, in your bash profile, check for $__MISE_ORIG_PATH before you do anything else:

if [ -n "$__MISE_ORIG_PATH" ]; then
    echo "mise already activated"
else
    echo "activating mise"
    # contents of @ericis's gist above
fi

This way, if you have somehow found yourself in the weird scenario of git bash having been launched from powershell, you skip over mise activation and just let git bash fix up the paths. If it's not already been activated, then you'll activate it correctly under bash rules.

See my gist for Windows 11, Git BASH, zsh, and mise configuration.

The message and gist have been edited to include Git Bash, but only with ZSH installed overriding Bash? A try for those bound to Git Bash

If you use ZSH (MSYS2) on Windows, then the suggestions here have found their way into the ZIM module https://github.com/joke/zim-mise

For fish shell (MSYS2) this one is workaround:

function mise_activate
    mise activate fish | perl -pe '
        s/hook-env -s fish \| source/hook-env -s bash | source \&\& export PATH=(\/usr\/bin\/cygpath -u -p "\$PATH")/g;
        s/'\''C:/'\''\/c/g;
        s/\\\\/\//g;
    ' | source
end


function mise_deactivate
    set -gx PATH $__MISE_ORIG_PATH
    functions --erase __mise_env_eval
    functions --erase __mise_env_eval_2
    functions --erase __mise_cd_hook
    functions --erase mise
    set -e MISE_SHELL
    set -e __MISE_DIFF
    set -e __MISE_SESSION
    set -e __MISE_ORIG_PATH
end

I don't know why, but command mise deactivate gives an error:

mise deactivate
fish: Unknown command: rm
fish:
        command rm $filename
                ^^
in function '__fish_psub_24442' with arguments 'JOB_EXIT -1 0'

Thank you, would you mind explaining the OLDPATH logic?

What could be an issue down the road is that these scripts depend on Mise's shell script internal variables and functions such as __MISE_ORIG_PATH

The OLDPATH thing snuck in from a previous version while I was figuring out how stuff works; I've removed it. And yes, it does depend on those things, but if they change I'll just have to figure it out again. It's not like I'm planning to update it daily. scoop reset makes it easy to revert to an older version if necessary, as well.