[patch, fortran] New take on PR 82373

[Thomas Koenig <tkoenig@netcologne.de>]

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Hello world,

after some thought, I think the PR can be fixed by something
far less invasive than my previous patch.

The new version of the patch simply issues an error for a
non-printable character (which should never be legal).
Anything else should be caught by other error reporting
routines.

OK for trunk?

Regards

	Thomas

2017-10-12  Thomas Koenig  <tkoenig@gcc.gnu.org>

         PR fortran/82372
         * fortran/scanner.c (last_error_char):  New global variable.
         (gfc_scanner_init_1): Set last_error_char to NULL.
         (gfc_gooble_whitespace): If a character not printable or
         not newline, issue an error.

2017-10-12  Thomas Koenig  <tkoenig@gcc.gnu.org>

         PR fortran/82372
         * gfortran.dg/illegal_char.f90: New test.

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Index: scanner.c
===================================================================
--- scanner.c	(Revision 253530)
+++ scanner.c	(Arbeitskopie)
@@ -80,6 +80,7 @@ static struct gfc_file_change
 size_t file_changes_cur, file_changes_count;
 size_t file_changes_allocated;
 
+static gfc_char_t *last_error_char;
 
 /* Functions dealing with our wide characters (gfc_char_t) and
    sequences of such characters.  */
@@ -269,6 +270,7 @@ gfc_scanner_init_1 (void)
   continue_line = 0;
 
   end_flag = 0;
+  last_error_char = NULL;
 }
 
 
@@ -1700,6 +1702,14 @@ gfc_gobble_whitespace (void)
     }
   while (gfc_is_whitespace (c));
 
+  if (!ISPRINT(c) && c != '\n' && last_error_char != gfc_current_locus.nextc)
+    {
+      char buf[20];
+      last_error_char = gfc_current_locus.nextc;
+      snprintf (buf, 20, "%2.2X", c);
+      gfc_error_now ("Invalid character 0x%s at %C", buf);
+    }
+
   gfc_current_locus = old_loc;
 }
 

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#include "illegal_char.f90"