Better error message for invalid octal digit

[jruderman]

fn main() {
    0o19;
}

Gives me:

error: expected one of `;`, `}` but found `9`

It would be better to say something like:

error: `9` is not a valid octal digit

[SiegeLord]

Fixing this will break some (arguably dodgy) code:

#![feature(macro_rules)]

macro_rules! test
{
    ($a: expr $b: expr) =>
    {
        $a as u32 + $b as u32
    }
}

fn main()
{
    println!("{}", test!(0o19));
}

[lilyball]

@SiegeLord Egad, that code deserves to be broken.

[steveklabnik]

Same error today.

[bombless]

I think this has been fixed by #23872
The example code give us error: invalid digit for a base 8 literal for Beta.

[fhahn]

It is indeed fixed in master and there is also a testcase src/test/parse-fail/lex-bad-octal-literal.rs, so I think this issue can be closed.