Stefan Monnier <monnier@iro.umontreal.ca> writes:

> The case-fold-search variable is pretty low-level and applies to
> functions like re-search-forward.  Maybe it shouldn't be customizable to
> avoid such confusion.

As a first step toward this, the attached patch creates an option for
`isearch-case-fold-search'.  The possible values for this option are:

                t : isearch ignores case
              nil : isearch does not ignore case
             'yes : isearch ignores mixed case
'case-fold-search : isearch uses the local case-fold-search

Is it okay to apply this?