commit ccc7b5148bdd9deb33f3cfa5a872a74634105021
author Johannes Schindelin <johannes.schindelin@gmx.de> Thu Jul 14 14:31:03 2022 +0000
committer Junio C Hamano <gitster@pobox.com> Thu Jul 14 10:37:44 2022 -0700
tree e9f0a5c16b0e6da1020cbfa515f4a4b83bd1d818
parent 980145f7470e20826ca22d7343494712eda9c81d

mergetool(vimdiff): allow paths to contain spaces again

In 0041797449d (vimdiff: new implementation with layout support,
2022-03-30), we introduced a completely new implementation of the
`vimdiff` backend for `git mergetool`.

In this implementation, we no longer call `vim` directly but we
accumulate in the variable `FINAL_CMD` an arbitrary number of commands
for `vim` to execute, which necessitates the use of `eval` to split the
commands properly into multiple command-line arguments.

That same `eval` command also needs to pass the paths to `vim`, and
while it looks as if they are quoted correctly, that quoting only
reaches the `eval` instruction and is lost after that, therefore paths
that contain whitespace characters (or other characters that are
interpreted by the POSIX shell) are handled incorrectly.

This is a simple reproducer:

	git init -b main bam-merge-fail
	cd bam-merge-fail
	echo a>"a file.txt"
	git add "a file.txt"
	git commit -m "added 'a file.txt'"
	echo b>"a file.txt"
	git add "a file.txt"
	git commit -m "diverged b 'a file.txt'"
	git checkout -b c HEAD~
	echo c>"a file.txt"
	git add "a file.txt"
	git commit -m "diverged c 'a file.txt'"
	git checkout main
	git merge c
	git mergetool --tool=vimdiff

With Git v2.37.0/v2.37.1, this will open 7 buffers, not four, and not
display the correct contents at all.

To fix this, let's not expand the variables containing the path
parameters before passing them to the `eval` command, but let that
command expand the variables instead.

This fixes https://github.com/git-for-windows/git/issues/3945

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>