Issue #2333: Backport set and dict comprehensions syntax.
diff --git a/Parser/Python.asdl b/Parser/Python.asdl
index ee6e999..54f5893 100644
--- a/Parser/Python.asdl
+++ b/Parser/Python.asdl
@@ -58,6 +58,8 @@
| Dict(expr* keys, expr* values)
| Set(expr* elts)
| ListComp(expr elt, comprehension* generators)
+ | SetComp(expr elt, comprehension* generators)
+ | DictComp(expr key, expr value, comprehension* generators)
| GeneratorExp(expr elt, comprehension* generators)
-- the grammar constrains where yield expressions can occur
| Yield(expr? value)