bug#10113: 24.0.91; Isearch & `M-e'

[Juri Linkov]

>> Yes, this patch makes automatic toggling in both directions:
>> from case-insensitive to case-sensitive and back from case-sensitive
>> to case-insensitive.
>
> This was ten years ago, and isearch behaves the same, as far as I can
> tell.

This request is exactly as bug#14729 - to change the traditional behavior
of isearch for no gain, only for consistency with some abstract ideas.

>> Without this patch the current behavior is automatic toggling in one
>> direction: from case-insensitive to case-sensitive (on the first
>> encountered upper case letter).  Toggling back from case-sensitive
>> to case-insensitive is manual with `M-c', and this choice is remembered
>> with the value `yes' of `isearch-case-fold-search'.
>
> I think your patch makes sense -- make `M-c' toggle the case
> sensitivity in both directions, if I understand correctly?

The patch implemented automatic case-fold toggling in both directions,
where typing a letter re-evaluates case-sensitivity of the search string.
This might break some users' habits.  So another idea was to re-evaluate
case-sensitivity only in `isearch-edit-string' and `isearch-del-char'.
Still such change might be unexpected for some users.