The problem is that diagnostic_action_after_output tries to delete the active

The problem is that diagnostic_action_after_output tries to delete the active
pretty-printer which tries to delete its output_buffer, which is normally
dynamically allocated via placement-new, but the output_buffer used by the
error_buffer of Fortran is statically allocated. Being statically allocated
simplifies a lot pushing/poping several instances of error_buffer.

The solution is to reset the active output_buffer back to the default one
before calling diagnostic_action_after_output. This is a bit ugly, because this
function does use the output_buffer, however, at the point that Fortran calls
it, both are in an equivalent state, thus there is no visible difference.

gcc/testsuite/ChangeLog:

2015-06-24  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR fortran/66528
	* gfortran.dg/maxerrors.f90: New test.

gcc/fortran/ChangeLog:

2015-06-24  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR fortran/66528
	* error.c (gfc_warning_check): Restore the default output_buffer
	before calling diagnostic_action_after_output.
	(gfc_error_check): Likewise.
	(gfc_diagnostics_init): Add comment.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@224926 138bc75d-0d04-0410-961f-82ee72b054a4