Mercurial > cpython-lru_cache-weakref

diff Modules/parsermodule.c @ 20432:56141b86a7f2 legacy-trunk

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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)+ [',']]
author Guido van Rossum <guido@python.org>
date Mon, 15 Oct 2001 15:44:05 +0000
parents 5501958edc36
children 42d0819546d6
line wrap: on
line diff
--- a/Modules/parsermodule.c	Mon Oct 15 14:34:42 2001 +0000
+++ b/Modules/parsermodule.c	Mon Oct 15 15:44:05 2001 +0000
@@ -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;
 }