Using macro with literal patterns in other macro fails

[waucka]

Code

fn foo1(x: &str) {
        println!("foo1({})", x);
}

fn foo2(x: &str) {
        println!("foo2({})", x);
}

macro_rules! wtf {
        (1) => (foo1);
        (2) => (foo2);
}

macro_rules! wtf_foo {
        ($x:expr, $num:expr) => {
                wtf!($num)($x);
        }
}

fn main() {
        //Fails
        wtf_foo!("one", 1);
        //Works
        wtf!(1)("one");
}

Output

$ rustc foo.rs 
foo.rs:16:8: 17:12 error: no rules expected the token `1`
foo.rs:16               wtf!($num)($x);
                             ^~~~

Expected Output

$ rustc foo.rs 
foo.rs:5:1: 7:2 warning: function is never used: `foo2`, #[warn(dead_code)] on by default
foo.rs:5 fn foo2(x: &str) {
foo.rs:6        println!("foo2({})", x);
foo.rs:7 }
$ ./foo
foo1(one)
foo1(one)

Other

This works fine, so the problem appears to be limited to literal patterns (not sure if that's the right term):

macro_rules! print_stuff_for_real {
        ($x:expr) => (println!("Printing stuff: {}", $x));
}

macro_rules! print_stuff {
        ($x:expr) => (print_stuff_for_real!($x));
}

fn main() {
        print_stuff!("stuff");
}

Meta

I used two versions of rustc; they behaved identically.

rustc 1.0.0 (a59de37e9 2015-05-13) (built 2015-05-14)
binary: rustc
commit-hash: a59de37e99060162a2674e3ff45409ac73595c0e
commit-date: 2015-05-13
build-date: 2015-05-14
host: x86_64-unknown-linux-gnu
release: 1.0.0

rustc 1.2.0-nightly (f76d9bcfc 2015-05-28) (built 2015-05-28)
binary: rustc
commit-hash: f76d9bcfc2c269452522fbbe19f66fe653325646
commit-date: 2015-05-28
build-date: 2015-05-28
host: x86_64-unknown-linux-gnu
release: 1.2.0-nightly

[oli-obk]

so basically we need a lit bound for macro arguments...

[steveklabnik]

Triage: yes, it seems like we need a new feature for macros for this, though I'm not good at macros, so I very much could be wrong.

[nayato]

is there a workaround for this?..

[dtolnay]

Closing as a duplicate of #41472 which is newer but has a more accurate and general title.