grep -v -f file and rg -v -f file differ

[BurntSushi]

While I don't maintain any guarantees with grep specifically, it was my intent to match its behavior here. Moreover, ripgrep's behavior is internally inconsistent:

$ echo wat | rg -f /dev/null
$ echo wat | rg -v -f /dev/null
$ echo wat | grep -f /dev/null
$ echo wat | grep -v -f /dev/null
wat
$ echo wat | rg -f <(echo)
wat
$ echo wat | rg -v -f <(echo)
$ echo wat | grep -f <(echo)
wat
$ echo wat | grep -v -f <(echo)
$

Specifically, the fact that the first two commands above both report no results is wrong.

Discussed in #3000

^{Originally posted by datatraveller1 February 26, 2025}
I want to list all found values from a search and all not found values from a search.
The following is a simplified example. The values searched for are listed in the file search_for.txt.

search_for.txt:

1
2
3

The file in which these values are searched is named searched_in.txt.

searched_in.txt:

item 1
item 2

I use the following commands (note that I'm on MS Windows):

find entries of file search_for.txt:

rg --file=search_for.txt --only-matching searched_in.txt > found.txt

not found entries of file search_for.txt:

rg --invert-match --file=found.txt search_for.txt > not_found.txt

The result is correct:

found.txt:

1
2

not_found.txt:

3

Great so far.
However, if I change the content of file search_for.txt so nothing is found...
search_for.txt:

4
5
6

... with the two above commands, the file found.txt gets created as a 0 bytes file (which is correct, because nothing is found) but the file not_found.txt gets also created as a 0 bytes file which doesn't match my expectations.
I have wished to see all values of file search_for.txt as result for the command
rg --invert-match --file=found.txt search_for.txt > not_found.txt
not_found.txt, wished result:

4
5
6

Isn't the inversion of nothing everything?
If this is the expected behaviour, is there a special flag to achieve what I want for --file and 0 bytes content of this file?