1 files changed, 23 insertions, 0 deletions
diff --git a/Lib/compiler/misc.py b/Lib/compiler/misc.py
index 29ff866780..b834a2e677 100644
--- a/Lib/compiler/misc.py
+++ b/Lib/compiler/misc.py
@@ -39,3 +39,26 @@ class Stack:
         self.stack.append(elt)
     def top(self):
         return self.stack[-1]
+
+MANGLE_LEN = 256 # magic constant from compile.c
+
+def mangle(name, klass):
+    if not name.startswith('__'):
+        return name
+    if len(name) + 2 >= MANGLE_LEN:
+        return name
+    if name.endswith('__'):
+        return name
+    try:
+        i = 0
+        while klass[i] == '_':
+            i = i + 1
+    except IndexError:
+        return name
+    klass = klass[i:]
+
+    tlen = len(klass) + len(name)
+    if tlen > MANGLE_LEN:
+        klass = klass[:MANGLE_LEN-tlen]
+
+    return "_%s%s" % (klass, name)