Don't try to create generator closure for c[p]def functions

Cython/Compiler/ParseTreeTransforms.py

@@ -1885,7 +1885,7 @@ class MarkClosureVisitor(CythonTransform):
         return node
 
     def visit_CFuncDefNode(self, node):
-        self.visit_FuncDefNode(node)
+        self.visitchildren(node)
         if node.needs_closure:
             error(node.pos, "closures inside cdef functions not yet supported")
         return node

tests/errors/e_cdef_yield.pyx

+# mode: error
+
+cdef cdef_yield():
+    yield
+
+cpdef cpdef_yield():
+    yield
+
+_ERRORS = u"""
+4:4: 'yield' not supported here
+7:4: 'yield' not supported here
+"""