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...

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.

From-SVN: r224926

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.
+
 2015-06-23  Andre Vehreschild  <vehre@gmx.de>
 
 	PR fortran/64674

gcc/fortran/error.c

@@ -1249,7 +1249,6 @@ gfc_clear_warning (void)
 void
 gfc_warning_check (void)
 {
-  /* This is for the new diagnostics machinery.  */
   if (! gfc_output_buffer_empty_p (pp_warning_buffer))
     {
       pretty_printer *pp = global_dc->printer;
@@ -1259,10 +1258,10 @@ gfc_warning_check (void)
       warningcount += warningcount_buffered;
       werrorcount += werrorcount_buffered;
       gcc_assert (warningcount_buffered + werrorcount_buffered == 1);
+      pp->buffer = tmp_buffer;
       diagnostic_action_after_output (global_dc, 
 				      warningcount_buffered 
 				      ? DK_WARNING : DK_ERROR);
-      pp->buffer = tmp_buffer;
     }
 }
 
@@ -1381,8 +1380,8 @@ gfc_error_check (void)
       pp_really_flush (pp);
       ++errorcount;
       gcc_assert (gfc_output_buffer_empty_p (pp_error_buffer));
-      diagnostic_action_after_output (global_dc, DK_ERROR);
       pp->buffer = tmp_buffer;
+      diagnostic_action_after_output (global_dc, DK_ERROR);
       return true;
     }
 
@@ -1472,6 +1471,8 @@ gfc_diagnostics_init (void)
   global_dc->caret_chars[1] = '2';
   pp_warning_buffer = new (XNEW (output_buffer)) output_buffer ();
   pp_warning_buffer->flush_p = false;
+  /* pp_error_buffer is statically allocated.  This simplifies memory
+     management when using gfc_push/pop_error. */
   pp_error_buffer = &(error_buffer.buffer);
   pp_error_buffer->flush_p = false;
 }

gcc/testsuite/ChangeLog

+2015-06-24  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	PR fortran/66528
+	* gfortran.dg/maxerrors.f90: New test.
+
 2015-06-08  DJ Delorie  <dj@redhat.com>
 
 	* gcc.dg/torture/pr66345.c: Fix assumption about size_t type.

gcc/testsuite/gfortran.dg/maxerrors.f90

+! { dg-do compile }
+! { dg-options "-fmax-errors=1" }
+! PR66528
+! { dg-prune-output "compilation terminated" }
+program main
+  read (*,*) n
+  if (n<0) then
+    print *,foo
+  end ! { dg-error "END IF statement expected" }
+    print *,bar
+end program main
+