My belief is that "C for Rust Programmers" should not be "how to write Rust in C" but "How to write C, for people who are Rust Programmers". The expectations for a production quality C library appear to be different than for a production quality Rust library, and I think one of those differences is memory allocation.

While I am certainly ignorant of Rust, my overall issue is that this statement:

"In order to avoid unhelpful segfaults, the program should check for a null pointer and gracefully exit if one is found:"

The following example shows that "gracefully exit" means a perror() and exit() call, which is not appropriate for a C library.

I presumed this is because the author is someone with Rust experience, and who wants to replicate the expected Rust behavior in C. I think the better alternative is to explain that a well-written C library can have different expectations.

I'll add that the essay has a footnote saying "The corresponding Rust function is not idiomatic, and can only correctly handle ASCII text. If I were writing a production version of this function, it would be a single line of code: forward.chars().rev().collect::<String>()."

I see that production version doesn't handle allocation failures either.

My follow-on presumption is that most Rust libraries use this sort of idiomatic production code, where allocation failures simply panic.

I could well be wrong, but this essay certainly doesn't clearly show that I am wrong in my belief.