* src/location.h (boundary): Note that a line or column equal

to INT_MAX indicates an overflow.
* src/scan-gram.l: Include verify.h.  Don't include get-errno.h.
(rule_length_overflow, increment_rule_length, add_column_width):
New functions.
(<INITIAL>{id}, <SC_ESCAPED_STRING>"\"", <SC_ESCAPED_CHARACTER>"'"):
(<SC_BRACED_CODE>"}"):
Use increment_rule_length rather than incrementing it by hand.
(adjust_location, handle_syncline): Diagnose overflow.
(handle_action_dollar, handle_action_at):
Fix bug with monstrosities like $-2147483648.
Remove now-unnecessary checks.
(scan_integer): Verify assumptions and remove now-unnecessary checks.
(convert_ucn_to_byte): Verify assumptions.
(handle_syncline): New arg LOC.  All callers changed.
Don't store through a value derived from char const * pointer.

src/location.h

@@ -29,11 +29,13 @@ typedef struct
   /* The name of the file that contains the boundary.  */
   uniqstr file;
 
-  /* The (origin-1) line that contains the boundary.  */
+  /* The (origin-1) line that contains the boundary.
+     If this is INT_MAX, the line number has overflowed.  */
   int line;
 
   /* The (origin-1) column just after the boundary.  This is neither a
-     byte count, nor a character count; it is a column count.  */
+     byte count, nor a character count; it is a column count.
+     If this is INT_MAX, the column number has overflowed.  */
   int column;
 
 } boundary;