Identity operation enforced by compiler?

[emabee]

fn main() {
    println!("> {}",type_code(true));
    println!("> {}",type_code(false));
}

fn type_code(switch: bool) -> u8 {
    // why is the leading "0_u8 + " necessary? Compiler bug?
    0_u8 + if switch { 128 } else { 0 } + base_type_code()
}

fn base_type_code() -> u8 {
    111
}

(Playground)

Output:

> 239
> 111

Shouldn't the above code also compile without the "0_u8 + "?
Note that clippy even complains about this identity operation.

[zackmdavis]

Parentheses work:

fn type_code(switch: bool) -> u8 {
    (if switch { 128 } else { 0 }) + base_type_code()
}

I'm not sure how the parser determines when conditionals-as-expressions need parentheses; I agree that it's very counterintuitive for a leading 0 + to determine whether a subsequent expression even parses (!).

[emabee]

Not yet good, but already much better ;-)
Thanks!

[nagisa]

This is an expected behaviour of semi-colon insertion for semi-statements.

#29071
#49865

At best this is just a diagnostics issue.

[hellow554]

Related: #54186

[nagisa]

I‘m gonna close this as a duplicate of #54186 as that seems to be pretty much exactly the same thing, with a different operator.