> Often compilation-mode displays wrong number of errors
> in the mode-line even when compilation is finished.
>
> compilation-mode is based on font-lock, so when the
> *compilation* buffer is not displayed during compilation,
> some parts of this buffer that contain error messages
> are not fontified, and thus these errors are not counted.
>
> This patch ensures the correct number of errors
> is displayed on the mode-line:

Actually maybe better to count errors not at the end
of compilation, but during compilation as output goes: