Unsafe blocks fail to parse as expressions in comparisons #95410
Description
Example gist: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=01dfdf28913f8fe69d419dfd7472dc49
In short, take these three functions:
fn test_one() -> u32 {
unsafe { 2 }
}
fn test_two() -> bool {
let x: u32 = unsafe { 2 };
let y: u32 = unsafe { 2 };
x == y
}
fn test_three() -> bool {
unsafe { 2 } == unsafe { 2 }
}The first two of these functions parse correctly, but the last one does not. The parser complains about seeing == after an unsafe block, and in its recovery, assumes that the unsafe block has type () instead of {integer}.
Exact output:
Compiling playground v0.0.1 (/playground)
error: expected expression, found `==`
--> src/lib.rs:12:18
|
12 | unsafe { 2 } == unsafe { 2 }
| ^^ expected expression
error[[E0308]](https://doc.rust-lang.org/nightly/error-index.html#E0308): mismatched types
|
12 | unsafe { 2 } == unsafe { 2 }
| ^ expected `()`, found integer
For more information about this error, try `rustc --explain E0308`.
error: could not compile `playground` due to 2 previous errors
This fails on the current stable compiler and nightly, those being 1.59.0 and 2022-03-27, respectively.
I found this code when using unions:
union Test {
raw: u8,
// other stuff that doesn't matter
}
impl PartialEq for Test {
fn eq(&self, rhs: &Test) -> bool {
unsafe { self.raw } == unsafe { rhs.raw }
}
}