// This is a call to C.xxx; set goname to "xxx".
	// It may have already been mangled by rewriteName.
	var goname string
	switch fun := call.Call.Fun.(type) {
	case *ast.SelectorExpr:
		goname = fun.Sel.Name
	case *ast.Ident:
		goname = strings.TrimPrefix(fun.Name, "_C2func_")
		goname = strings.TrimPrefix(goname, "_Cfunc_")
	}
	if goname == "" || goname == "malloc" {
		return "", false
	}

		}
	case *ast.TypeAssertExpr:
		f.walk(&n.X, ctxExpr, visit)
		f.walk(&n.Type, ctxType, visit)
	case *ast.CallExpr:
		if context == ctxAssign2 {
			f.walk(&n.Fun, ctxCall2, visit)
		} else {
			f.walk(&n.Fun, ctxCall, visit)
		}
		f.walk(n.Args, ctxExpr, visit)
	case *ast.StarExpr:
		f.walk(&n.X, context, visit)
	case *ast.UnaryExpr:
		f.walk(&n.X, ctxExpr, visit)
	case *ast.BinaryExpr: