The definitions the function fn makes in the frame of its caller (assign("x", v, envir = parent.frame())) for the call call within another function: the reads of that frame may see them, which the frame does not know of when it is processed, as it learns of the callee later (the top level runs them in instantiateEnvOps).
The definitions the function
fnmakes in the frame of its caller (assign("x", v, envir = parent.frame())) for the callcallwithin another function: the reads of that frame may see them, which the frame does not know of when it is processed, as it learns of the callee later (the top level runs them in instantiateEnvOps).