"Files are identical" should be "You are comparing the same one file" if both files are the same file

Consider this example:

echo hello > a.txt
echo hello > b.txt
meld a.txt b.txt

Meld will show "Files are identical" which is correct. But when I do this:

meld a.txt a.txt

Meld will also show "Files are identical", which is technically correct, but I obviously made a mistake. Meld should tell in (in bright red color) that "Hey, you probably made a mistake. You are not comparing 2 files, you accidentally typed filename twice".

This is a common footgun and meld has a chance to spot it. I think it should.

There are some edge cases to consider (like absolute vs. relative path, symlinks, etc.) but I think it should be simple to implement and it would help prevent stupid mistakes.