todo: more

1 files changed, 19 insertions, 0 deletions

diff --git a/TODO b/TODO
index 5b3c670e..0f53ed8a 100644
--- a/TODO
+++ b/TODO
@@ -672,6 +672,25 @@ participate in the count.
 Do we want to disallow terminal start symbols?  The limitation is not
 technical.  Can it be useful to someone to "parse" a token?
 
+*** Fix default_reduction_only_for_accept
+In src/lalr.c:
+
+  /* We need a lookahead either to distinguish different reductions
+     (i.e., there are two or more), or to distinguish a reduction from a
+     shift.  Otherwise, it is straightforward, and the state is
+     'consistent'.  However, do not treat a state with any reductions as
+     consistent unless it is the accepting state (because there is never
+     a lookahead token that makes sense there, and so no lookahead token
+     should be read) if the user has otherwise disabled default
+     reductions.  */
+  s->consistent =
+    !(reds->num > 1
+      || (reds->num == 1 && trans->num && TRANSITION_IS_SHIFT (trans, 0))
+      || (reds->num == 1 && reds->rules[0]->number != 0
+          && default_reduction_only_for_accept));
+
+We should have a test for "is accepting rule".
+
 ** %include
 This is a popular demand.  We already made many changes in the parser that
 should make this reasonably easy to implement.