re PR fortran/85735 (f951 crashes on empty input)

	PR fortran/85735
	* options.c (gfc_post_options): Set main_input_filename.

From-SVN: r260120

gcc/fortran/ChangeLog

+2018-05-10  Marek Polacek  <polacek@redhat.com>
+
+	PR fortran/85735
+	* options.c (gfc_post_options): Set main_input_filename.
+
 2018-05-10  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR fortran/54613

gcc/fortran/options.c

@@ -313,6 +313,7 @@ gfc_post_options (const char **pfilename)
       if (gfc_current_form == FORM_UNKNOWN)
 	{
 	  gfc_current_form = FORM_FREE;
+	  main_input_filename = filename;
 	  gfc_warning_now (0, "Reading file %qs as free form", 
 			   (filename[0] == '\0') ? "<stdin>" : filename);
 	}