Fix closure bug with nested pass-through frames

src/codegen/ast_interpreter.cpp

@@ -814,7 +814,14 @@ Value ASTInterpreter::visit_makeClass(AST_MakeClass* mkclass) {
     for (AST_expr* d : node->decorator_list)
         decorators.push_back(visit_expr(d).o);
 
-    BoxedClosure* closure = scope_info->takesClosure() ? created_closure : 0;
+    BoxedClosure* closure = NULL;
+    if (scope_info->takesClosure()) {
+        if (this->scope_info->passesThroughClosure())
+            closure = passed_closure;
+        else
+            closure = created_closure;
+        assert(closure);
+    }
     CLFunction* cl = wrapFunction(node, nullptr, node->body, source_info);
 
     Box* passed_globals = NULL;

src/codegen/irgen/irgenerator.cpp

@@ -1273,7 +1273,12 @@ private:
         // TODO duplication with _createFunction:
         CompilerVariable* created_closure = NULL;
         if (scope_info->takesClosure()) {
-            created_closure = symbol_table[internString(CREATED_CLOSURE_NAME)];
+            if (irstate->getScopeInfo()->createsClosure()) {
+                created_closure = symbol_table[internString(CREATED_CLOSURE_NAME)];
+            } else {
+                assert(irstate->getScopeInfo()->passesThroughClosure());
+                created_closure = symbol_table[internString(PASSED_CLOSURE_NAME)];
+            }
             assert(created_closure);
         }
 

test/tests/closure_test.py

@@ -69,3 +69,16 @@ def f6():
 
     print (lambda a=1: x)()
 f6()
+
+
+# Regression test: make sure we can handle two pass-through-closure frames in a row
+def f7(n):
+    class C(object):
+        class D(object):
+            def foo(self):
+                return n
+
+    return C.D
+
+c = f7(5)()
+print c.foo()