Very subtle syntax change: in a list comprehension, the testlist in
"for <var> in <testlist> may no longer be a single test followed by
a comma. This solves SF bug #431886. Note that if the testlist
contains more than one test, a trailing comma is still allowed, for
maximum backward compatibility; but this example is not:
[(x, y) for x in range(10), for y in range(10)]
^
The fix involved creating a new nonterminal 'testlist_safe' whose
definition doesn't allow the trailing comma if there's only one test:
testlist_safe: test [(',' test)+ [',']]
diff --git a/Modules/parsermodule.c b/Modules/parsermodule.c
index bc82ce5..000e639 100644
--- a/Modules/parsermodule.c
+++ b/Modules/parsermodule.c
@@ -1039,6 +1039,14 @@
}
+static int
+validate_testlist_safe(node *tree)
+{
+ return (validate_repeating_list(tree, testlist_safe,
+ validate_test, "testlist_safe"));
+}
+
+
/* '*' NAME [',' '**' NAME] | '**' NAME
*/
static int
@@ -1218,7 +1226,7 @@
res = (validate_name(CHILD(tree, 0), "for")
&& validate_exprlist(CHILD(tree, 1))
&& validate_name(CHILD(tree, 2), "in")
- && validate_testlist(CHILD(tree, 3)));
+ && validate_testlist_safe(CHILD(tree, 3)));
return res;
}