Possibly a "Save unquoted" checkbox?
That would be the obvious solution, but since we allow a total of 13 (6 predefined and 7 custom) fields per variable, we would need something like 7 checkboxes. It's pretty safe to assume that the predefined fields are pathnames, but any of the custom fields could be either a single path, several paths, or something else.
As far as quoted paths and compiler options go, shouldn't it be possible to do...
-I "C:\My Dev Stuff\include"?
Yes, but the problem is that the most common usage scenario is rather something like
-I $foo or
-I $#bar, i.e. it's the IDE who must supply quotes if necessary. I'm not sure if the regex matches inside quotes either (it shouldn't, unless I made it buggy), and writing something like
-I "$foo" shouldn't expand.
Whatever it is, one must also consider that there are a few thousand people who have been using this for half a decade on some hundred thousand projects, thus we cannot easily change the behaviour, or we risk well-deserved hate mail.
Personally, I'd puke if I'd have to manually edit each and every project from the last 5 years just because someone decided to change program behaviour. Likely, a lot of users will be like that, too.
The only thing I could think of which would be realistic to implement and safe enough for backwards compatibility would be to decide for a "literal string" marker, and that can be harder than it sounds.
Such a thing must be easy to type on any keyboard, regardless of localization, and won't occur in a filename or a commandline option, so for example something like
!!!. Then again, under some operating systems, it is perfectly legal to have a file named
!!! or
*/?...