The trim_trailing_whitespace option changes the last substitute string at every file save

[sroccaserra]

What I experienced

While editing a file, I started to do some substitutions with :s/o/x. I tested it on one line, saved the file, and tried to apply it to the whole file with g&.

What I expected: all "o" chars changing to "x" chars in the file.
What happened: all the "o" chars of the file disapeared.

I had the editorconfig active, with the trim_trailing_whitespace active.

What I suppose

• when I saved, the editorconfig plugin applied the trim_trailing_whitespace, using a %s/\s\+$//e substitute
• the subsitute string was changed to '' and not restored
• the search pattern was restored
• when I tried to apply g&, it applied s/o// instead of s/o/x

To reproduce the bug

In an empty directory, add this simple .editorconfig file:

[*]
trim_trailing_whitespace = true

Then:

• open a new file
• type some text, for example hello world
• make a subsitution, for example :s/o/x, the text is now hellx world
• save the file with :w (this also applies the trim_trailing_whitespace rule)
• repeat the last substitution with & or g& or :s
• instead of hellx wxrld, the text is hellx wrld: this is a symptom of the bug: the last substitute used is now '' instead of 'x'.

What I tried & explored

• Using :@: (execute last command) seems to work as I expect, it replaces "o" chars by "x" chars in my example
• Commenting the trim_trailing_whitespace rule removes the bug
• Commenting this line removes the bug: https://github.com/editorconfig/editorconfig-vim/blob/f305bc7/plugin/editorconfig.vim#L510

I saw in the code that the view is saved and restored by s:TrimTrailingWhitespace(), apparently this does not restore the substitute string.

According to this documentation, The last used search pattern and the redo command "." will not be changed by the function

• https://vimhelp.org/eval.txt.html#function%2dsearch%2dundo

So maybe this is a Vim limitation, unlike the search pattern, the subsitute string is changed by the function and not restored?

[sroccaserra]

This is different (search pattern vs substitution is changed), but might be related to: #94

[cxw42]

Thanks very much for reporting!

I can reproduce if the "open a new file" step in your original post is vim bar.txt. However, if I just say vim and then :w foo.txt, the issue does not appear:
.
That might be yet another issue :) .

I agree this behaviour should be changed if possible, to avoid surprising the user.