bug#13594: 24.2.92; [PATCH] compilation-start doesn't consider nil OUTWIN

[Juri Linkov]

> 1. A new variable compilation-dont-display-buffer to prevent calling
>    display-buffer.

Some users of `async-shell-command' want the same feature of
not displaying the output buffer.  From the old discussion
I got the impression that such customization should be possible
by customizing `display-buffer-alist' and associating
the buffer name (such as *compilation* or *Async Shell Command*)
with an inaction to skip window display.

(But it still need to check `outwin' for null values in your patch
for the case when `display-buffer' will return nil.)

> 2. Display a message when calling compilation-next-error like this:
>    Error: 2/623

I think it would be nice to display the same in the mode line.

> Sadly this second patch doesn't account for the fact that some
> compilation messages are removed later on by font-lock.

`grep' used to remove parts of grep/compilation messages,
but now there shouldn't be such a problem in grep's font-lock.
Do you have a test case that would demonstrate this problem
in compilation's font-lock?