Syntax error while casting implicitly returned match block within a nested scope without extra parentheses

[vthriller]

Sounds cryptic, I know, sorry for that. Here's what's going on:

fn main() {
        let foo = 1;

        // works as expected
        let bar = match foo {
                1 => 2,
                _ => 3,
        } as u8;
        
        // error: expected expression, found keyword `as`
        let bar = {
                match foo {
                        1 => 2,
                        _ => 3,
                } as u8
        };
        
        // but this works
        let bar = {
                (match foo {
                        1 => 2,
                        _ => 3,
                }) as u8
        };
        
        // and also this
        let bar = {
                1 as u8
        };
}

Meta

rustc --version --verbose:

This is present since at least stable-1.19, but here I rustup updated just to be sure:

rustc 1.21.0 (3b72af97e 2017-10-09)
binary: rustc
commit-hash: 3b72af97e42989b2fe104d8edbaee123cdf7c58f
commit-date: 2017-10-09
host: x86_64-unknown-linux-gnu
release: 1.21.0
LLVM version: 4.0

rustc 1.23.0-nightly (bd0e45a32 2017-11-06)
binary: rustc
commit-hash: bd0e45a323f85a1940d997ac237023c00670da67
commit-date: 2017-11-06
host: x86_64-unknown-linux-gnu
release: 1.23.0-nightly
LLVM version: 4.0

[vthriller]

(Moving as u8 outside the scope also works.)

[durka]

This is known and can't be fixed due to the type of parser we use. Duplicate of #13012.

[vthriller]

Aight, closing this as dup then.