How can I highlight misuse of tabs and spaces according to current configuration?

Question

I'm looking for a way that will highlight lines (or part of lines) that don't adhere to current tabs settings.

Say for instance, I have the following configuration in my .vimrc

tabstop=8 
softtabstop=8 
shiftwidth=8 
noexpandtab

Is it possible to highlight lines that don't adhere to the above settings ?

Answer 1

My IndentConsistencyCop plugin checks the consistency of the used indent, and compares this with the buffer's indent settings. With a companion plugin, it can be triggered automatically for configured filetypes. (The plugin page has links to alternative plugins.)

Answer 2

With those settings, a "line that doesn't adhere to current tabs settings" is basically "a line with spaces as indentation".

You can highlight such lines by searching:

/\v^\t* +\t*[^\s]

Broken down:

• \v − "very magic" mode so we don't have to use too many \ later (see :help /\v)
• ^ − anchor to the start of the line.
• \t* − match zero or more tab characters.
• + − match one or more space characters.
• \t* − match zero or more tab characters again.
• [^\s] − match anything except a space character.

Or if you want to highlight the entire line, add .* to the end to also match the rest of the line:

/\v^\t* +\t*[^\s].*

If you don't want to clobber your search history with this, you can use :match:

:match Error /\v^\t* +\t*[^\s].*/

See :help :match.