Non-inlined recursive function produced different value when optimised

[mayanksharma3]

I'm in the (fairly early) process of building a Rust fuzzer (here) and whilst running it, it came across this discrepancy between optimization levels on the latest released Rust version (1.61.0). It generated a huge file, but this is a reduced code snippet exhibiting the same behaviour.

I tried this code:

#[inline(never)]
fn fun27(var1374: &Box<i32>) -> ! {
    fun27(var1374)
}

fn main() {
    let var1040 = Box::from(1745183449i32);
    fun27(&var1040);
}

I expected to see this happen: Run forever (or stack overflow)

Instead, this happened: Crashes with a trace trap (shown below) while running, when run on any optimization level. Running on optimization level 0 does throw a stack overflow error (as expected)

Some changes that would stop the runtime error:

• Removing the argument from fun27
• Changing the argument from a heap value to something on the stack (like a plain i32 for example)
• Removing the #[inline(never)] from fun27

Also, changing the return type of fun27 from ! to () doesn't throw a compilation error (should it?) but when run, the program gracefully exits with a 0 error code.

Meta

rustc --version --verbose:

rustc 1.61.0 (fe5b13d68 2022-05-18)
binary: rustc
commit-hash: fe5b13d681f25ee6474be29d748c65adcd91f69e
commit-date: 2022-05-18
host: aarch64-apple-darwin
release: 1.61.0
LLVM version: 14.0.0

Backtrace

[1]    61641 trace trap  ./test

[nikic]

This is likely a duplicate of #97428. Does it work on nightly?

[mayanksharma3]

Ah yes, it does work on nightly. Thank you for linking me to the original issue