Sets sw=6, ts=8 when file uses tabs

[HaleTom]

Here's the file:

https://raw.githubusercontent.com/git/git/master/git-add--interactive.perl

I was expecting sw=4, ts=4 (preferred) or a least sw=8, ts=8.

[HaleTom]

Perhaps a user-settable variable to allow a person do define 2, 4, or 8 (etc) spaces as default if there are only TABs?

[HaleTom]

This may help detecting the causes in the provided file:

roryokane/detectindent#18

[tpope]

We do respect 'tabstop' if there are nothing but tabs. Unfortunately, there's a single line that starts with 6 spaces:

https://github.com/git/git/blob/abe6bb3905392d5eb6b01fa6e54d7e784e0522aa/git-add--interactive.perl#L481

I'm not seeing an obvious fix here. While a single line 6 space indent is almost certainly spurious, that's not very far from a sole pair of 4 space indents, which is valid:

class MixedFile {
    public static void main(String[] args) {
	System.out.println("This file uses sw=4 ts=8 noet");
    }
}

Where do we draw the line?

I do have a fix coming for this particular example in the form of EditorConfig support. The repository in question has a .editorconfig with relevant settings:

[*.{c,h,sh,perl,pl,pm,txt}]
indent_style = tab
tab_width = 8

[tpope]

Looks like disallowing 6 as a valid indent level does allow it to detect this file as shiftwidth=8 tabstop=8, so I've gone ahead and done that. Unfortunately, this still won't allow shiftwidth=0 like it would with a purely tab indented file.

Specifically, I changed the even number requirement to a multiple of 4 requirement, and given precedence to 4 and 8 over the uncommon (but still occasionally used 3. I'm retaining support for large multiples of 4 because they have niche uses (e.g., I like sw=24 in Vim help files) and I don't think I've had any error reports of that nature.

[HaleTom]

Thanks for resolving this! 🎉🥳