parser: fix a...b syntax error.

This issue has implications mainly for read/print consistency.
The (rcons a .b) expression prints a...b, but that doesn't
read back. The reason is that the . on .b isn't preceded by
whitespace, and so isn't the UREFDOT token recognized in
a n_expr. It's just the '.' token which is a syntax error
in that situation.

* parser.y (n_expr): New special case rule to handle the
phrase pattern n_expr DOTDOT '.' n_expr which is now
a syntax error.

1 files changed, 6 insertions, 0 deletions

diff --git a/parser.y b/parser.y
index 427a3fc1..a4a98300 100644
--- a/parser.y
+++ b/parser.y
@@ -986,6 +986,12 @@ n_expr : SYMTOK                 { $$ = symhlpr($1, t); }
        | n_expr DOTDOT n_expr   { uses_or2;
                                   $$ = rlcp(list(rcons_s, $1, $3, nao),
                                             or2($1, $3)); }
+       | n_expr DOTDOT '.' n_expr
+                                { uses_or2;
+                                  $$ = rlcp(list(rcons_s, $1,
+                                                          uref_helper(parser, $4),
+                                                          nao),
+                                            or2($1, $4)); }
        | n_expr '.' n_expr      { uses_or2;
                                   if (consp($3) && car($3) == qref_s) {
                                     rplacd($3, rlcp(cons($1, cdr($3)), $1));