By using gcc 3.4.6 version, the following errors are not reported by the
Warnings plugin :
/dir1/dir2/file.c:12:15: file.h: No such file or directory
/dir1/dir3/file.cpp:233: undefined reference to `MyInterface::getValue() const'

It seems with previous version of gcc the output format was not exactly the same.

I had a look on the Hudson plugin code and I think the regular expression can be
replaced by the following one :

/^(.\.[CHPSOLAXchpsolax0-9]+)?\d)?:\d*.(warning|error|undefined
reference to|No such file or directory|cannot find):?)(.*)$

NB: I did not test it with Hudson