Hi,

It might be interesting to add a "gcc-include" parser.
I noticed that Emacs does have a "gcc-include" parser (visible from its
"compilation-error-regexp-alist-alist" variable - highlights appearing in
compilation mode), which differs from its own GNU parser, that why I suggest
this enhancement.

The current regexp pattern in Emacs is the following :
"^(?:In file included| ) from (.)[0-9])(?|(,))?"

From the example below :
"
In file included from /usr/include/c++/3.3/backward/warn.h:4,
from /usr/include/c++/3.3/backward/iostream.h:31,
from test_clt.cc:1:
"
... Emacs will parse the two first line as "information" and the third line as
an "error".

If you think it's interesting to add this parser, the parsing could be
Priority.LOW for the two fist line and Priority.HIGH for the third line, or
whatever you think is better.