A well-written question from two years ago hits on essentially the same point as my question, but from a different direction. Unfortunately, the one or two responses to that question and the comments, here, lead to the conclusion that the diagramming of these sorts of sentences can (A) vary dramatically depending upon seemingly minor differences, and (B) require arbitrary decisions on indeterminate matters.
Consider the following sentence:
Tell him to make a sandwich.
This article at the Purdue Writing Lab teaches that the word him should be analyzed as being an "actor" of the infinitive phrase to make a sandwich. The actor is described as being akin to the subject of an independent clause. The cited article explains that him, as the actor, is part of the infinitive phrase.
I question the validity of the actor concept. It seems to me that the pronoun, him, is the indirect object of the verb, tell. Certainly, in the following sentence, him is an indirect object.
Tell him a story.
I find it odd to think that the role of him in the sentence would morph if the direct object, a story, is replaced with the infinitive phrase, to make a sandwich. Following the logic of the cited article, him would cease to be an indirect object, and would become part of the infinitive phrase.
I have not seen the actor concept taught elsewhere. Is the actor a proper element of an infinitive phrase?
[EDIT: I ask this question from the viewpoint of a user who has learned a traditional, schoolbook grammar, not as an academic studying the subject. As @Shoe implies, perhaps the author of the article is writing from a theoretic point of view.]
I, here, add a confounding contra example. One can rewrite the second sentence to replace the indirect object with an adverbial prepositional phrase.
Tell a story to him.
However, the first sentence cannot be rewritten in that fashion.
Tell to make a sandwich to him. [nonsense]
That contrast implies, perhaps, the nature of the word him is altered by the presence of the infinitive phrase.
How would one analyze him in the first two sentences (using traditional grammar)? I believe the answer is that it is an indirect object in both cases, but I'm starting to doubt that conclusion.