> It's not operator precedence—that's a separate issue

> It's even mnemonic—when the increment symbol goes before the thing being incremented, the increment happens first; else after—but even if not, it's a fairly basic language feature.

I think you missed the issue.

This is 100% about operator precedence, and has nothing to do with the decrement operator being in front of or behind the variable.

This expression:

    *stack--

means either this:

    (*stack)--

or this:

    *(stack--)

depending on the operator precedence rules.

If this is the layout of memory:

             ~~~~~~
    stack-1: | 52 |
    stack:   | 23 |
    stack+1: | 19 |
             ~~~~~~

(* stack)-- evaluates to 22, while *(stack--) evaluates to 52.

https://godbolt.org/z/P7Ghfc