The current behavior is intentional, for obvious reasons.
If we start expanding special symbols in user inputs, the users will have to manually escape every ! there, or funny things will happen.

The current behavior is intentional, for obvious reasons. If we start expanding special symbols in user inputs, the users will have to manually escape every ! there, or funny things will happen.

No. With this patch, diff !& expands to e.g. git diff "panel.cpp" "infolist.cpp"
Without this patch diff !& is executed as is:

git.cmd diff !&
fatal: ambiguous argument '!': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'

With this patch, diff !& expands

Exactly, but not only !&.

Guess what will happen when you paste names like Wham! - Last Christmas.mp3 or S01E04 - M. Night Shaym-Aliens!.mkv or Readme!.txt into the input box.

Guess what will happen when you paste names like Wham! - Last Christmas.mp3 or S01E04 - M. Night Shaym-Aliens!.mkv or Readme!.txt into the input box.

ok. created file Readme!.txt, selected it, called menu item: git diff !&

git diff "Readme!.txt" "panel.cpp" "infolist.cpp"

It works as intended, nothing wrong is happened.

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

Good to know, but it's not what I asked.

Just in case if it's still not obvious what is wrong with this approach:

1. Extract gh-966.zip somewhere.
2. Put the cursor on _readme!.txt
3. F2, Enter, Enter

I'm not against expanding special symbols in user inputs in principle, but we cannot break the processing of random files that just happen to have ! somewhere in the name.
Yes, perhaps picking ! for Long file name without extension was a horrible design mistake in the first place, but that ship has sailed.
It has to be either some new, non-conflicting syntax or opt-in, e.g. a checkbox "Expand special symbols" in the dialog or something.