bug#20322: 25.0.50; indent-tabs-mode should default to nil

[Dmitry Gutov <dgutov@yandex.ru>]

On 04/15/2015 04:19 AM, Stefan Monnier wrote:
>> However, the implementation seems to do the right thing:
>
>> https://github.com/outsideris/popularconvention/blob/master/src/parser/js-parser.coffee#L99-L100
>
> This seems to count the number of lines which start with a SPC and those
> which start with a TAB.

That sounds right. But I'd say the projects that mix tabs and spaces 
must be a minority among those that use tabs at all.

> If your indentation rules use an indentation step of 2, you'd likely get
> many more lines that start with SPC regardless of indent-tabs-mode
> (just because most lines of code are less indented than 8 columns).

I don't actually recall seeing code intentionally mixing tabs and spaces 
like that, ever, before looking at Emacs's sources.

> So, I don't think it does the right test.  I think the right test would be
>
>    tab = /^\t/
>    space = /^\s\s\s\s\s\s\s\s/

That would be more correct indeed. Again, if you think the results of 
this can matter in some future decision, I can spend the time to apply 
the fix, deploy it myself and rerun the analysis.