Unset "ignorecase" only in insert-mode completion?

[François Ingelrest]

Hi all,

This is something that has annoyed me for quite some time and I can't
seem to fix it. I :set ignorecase, as it's a great feature for
searching without caring about the case of the actual searched text.
My problem is that this option is also used for insert-mode completion
and when it's on I can't find a way to achieve completion the way I
want it.

If I set :infercase and try to complete "he" while the only possible
completion is "Hello", then the exiting string "he" will be completed
to "hello", a non-existing word in the completion list. This is quite
annoying when programming.

Now if I :set noinfercase, "he" is changed to "He" and completed to
"Hello" which actually exists, but does not match my initial string
"he".

I know this is caused by :set ignorecase, so what I want is having
this option on when searching but off when completing. Is there a way
to fix this problem?

Thanks.