git with Beyond Compare (4) on WSL2 Windows 11 not opening the repo version

Question

Trying to get git and Beyond Compare to place nicely together on WSL. Here is the output from git config --list:

diff.tool=bc3
difftool.prompt=false
difftool.bc3.path=/mnt/c/Program Files/Beyond Compare 4/BComp.exe
merge.tool=bc3
mergetool.prompt=false
mergetool.bc3.trustexitcode=true
mergetool.bc3.path=/mnt/c/Program Files/Beyond Compare 4/BComp.exe

Here is my ~/.gitconfig:

[diff]
    tool = bc3
[difftool]
    prompt = false
[difftool "bc3"]
    path = /mnt/c/Program Files/Beyond Compare 4/BComp.exe
[merge]
    tool = bc3
[mergetool]
    prompt = false
[mergetool "bc3"]
    trustExitCode = true
    path = /mnt/c/Program Files/Beyond Compare 4/BComp.exe

my git --version is:

git version 2.25.1

When I try git difftool file_in_git_repo Beyond Compare opens with the current version in the left pane, but nothing in the right pane (I have confirmed the file exists in the git repo.)

.git/config has no entries referencing diff or merge

Any suggestions would be most welcome

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Similar to VonC's suggestion, I was able to get it working with this in my .gitconfig file (disclaimer - I have not used the mergetool with this new method):

[diff]
    tool = bc3
[difftool]
    prompt = false
[difftool "bc3"]
    cmd = '/mnt/c/Program Files/Beyond Compare 4/BComp.exe'   \"$(wslpath -aw $LOCAL)\" \"$(wslpath -aw $REMOTE)\"
[merge]
    tool = bc3
[mergetool]
    prompt = false
[mergetool "bc3"]
    trustExitCode = true
    cmd = '/mnt/c/Program Files/Beyond Compare 4/BComp.exe'   \"$(wslpath -aw $LOCAL)\" \"$(wslpath -aw $REMOTE)\"

Answer 1

Check if this configuration might work in your case:

I managed to get it working using the built-in wslpath command which comes with new WSL versions!

My git config on WSL linux side:

difftool.bc3.cmd=BComp.exe "$(wslpath -aw $LOCAL)" "$(wslpath -aw $REMOTE)"
mergetool.bc3.cmd=BComp.exe "$(wslpath -aw $LOCAL)" "$(wslpath -aw $REMOTE)" "$(wslpath -aw $BASE)" "$(wslpath -aw $MERGED)"

BComp.exe is in my $PATH.
I'm using WSL2 on Windows version 2004 (build 19041), and this works both inside the WSL filesystem and also for the mounted Windows filesystem.

The new wslpath -aw converts the Linux paths like this:

$ wslpath -aw /home/
\\wsl$\Debian\home

And Windows paths like this:

$ wslpath -aw /mnt/c/Users/
C:\Users

This makes them both work perfectly with the Windows version of BC when launched from Linux.