question_mark suggestion changes code semantics

[divagant-martian]

Summary

If let expression that produces a result is suggested to change to ?, changing the semantics of the code

Lint Name

question_mark

Reproducer

I tried this code:

fn do_stuff() -> Result<(), ()> {
    let result = if let Err(e) = op1() { Err(e) } else { Ok(()) };

    do_something_with_result(&result);

    result
}

fn op1() -> Result<(), ()> {
    Err(())
}

fn do_something_with_result(arg: &Result<(), ()>) {
    println!("doing something with the result {arg:?}");
}

fn main() {
    do_stuff().unwrap();
}

}

I saw this happen:

warning: this block may be rewritten with the `?` operator
 --> src/main.rs:2:18
  |
2 |     let result = if let Err(e) = op1() { Err(e) } else { Ok(()) };
  |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `op1()?`
  |
  = note: `#[warn(clippy::question_mark)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#question_mark

I expected to see this happen:
There should be no warning. Changing the code for what clippy suggests would prevent calling do_something_with_result when the result is an error

Version

rustc 1.64.0 (a55dd71d5 2022-09-19)
binary: rustc
commit-hash: a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52
commit-date: 2022-09-19
host: x86_64-unknown-linux-gnu
release: 1.64.0
LLVM version: 14.0.6

Additional Labels

No response

[kraktus]

@rustbot claim

[ebobrow]

If I'm not mistaken, it looks like there are two issues here. Clippy's suggested code wouldn't even compile because the question mark returns the inner value of the Result while the original code returns a new Result (I think related to #8281 (comment)). Do you have a reproduction where Clippy's suggestion is valid code, but we still get this semantics error? Or is this issue fixed by fixing the other false positive?