Parsing inconsistencies with semi-statements in expressions

[nagisa]

    x = if true {
        10u32
    } else {
        20u32
    } as ()

parses as

    x = (if true {
        10u32
    } else {
        20u32
    } as ())

but

    if true {
        10u32
    } else {
        20u32
    } as ()

parses as

    if true {
        10u32
    } else {
        20u32
    }; 
    as ()

[nagisa]

This might showcase it better:

    x&if true {
        10u32
    } else {
        20u32
    }&x

parsed as

    (x & if true {
        10u32
    } else {
        20u32
    } & x)

but

    if true {
        10u32
    } else {
        20u32
    }&x

is parsed as

    if true {
        10u32
    } else {
        20u32
    };
    &x

which is completely different thing.

[nagisa]

Fixing this, would be a breaking change, but we at least need to ensure we have a test for this.

[arielb1]

@nagisa

This looks like a consequence of "semicolon insertion" (the stmt: block_expr rule) being eager.