'expected identifier' when 'as' keyword appears after block

[bnoordhuis]

I'm not sure if this qualifies as bug but it's somewhat surprising to me:

fn main() {
    unsafe { 0 as int };  // ok
    unsafe { 0 } as int;  // expected identifier, found keyword `as`
    (unsafe { 0 }) as int;  // ok
}

The same happens with match true { true => 0, false => 0 } as int or if true { 0 } else { 0 } as int unless the expression is wrapped in parentheses.

[steveklabnik]

I feel like this is a dup, but I can't find the issue.

[steveklabnik]

Updated code:

fn main() {
    unsafe { 0 as i32 };  // ok
    unsafe { 0 } as i32;  // expected identifier, found keyword `as`
    (unsafe { 0 }) as i32;  // ok
}

same error.

[steveklabnik]

Triage: no change

[Mark-Simulacrum]

error: expected expression, found `as`
 --> src/main.rs:3:18
  |
3 |     unsafe { 0 } as i32;  // expected identifier, found keyword `as`
  |     ------------ ^^ expected expression
  |     |
  |     help: parentheses are required to parse this as an expression: `(unsafe { 0 })`

error: aborting due to previous error