Simple macro makes rustc use all CPU/memory

[ctz]

I was trying to write a macro which accepts any arguments and compiles to nothing.

My first try was:

macro_rules! warn ( ( $()* ) => () );

fn main() {
    warn!("This will never be printed!");
}

Experienced behaviour: rustc uses up all CPU and memory, then get killed by the kernel OOM killer.

Expected behaviour: either a program with no output, or an error explaining why this macro is invalid.

Versions:

$ rustc --version --verbose
rustc 1.11.0 (9b21dcd6a 2016-08-15)
binary: rustc
commit-hash: 9b21dcd6a89f38e8ceccb2ede8c9027cb409f6e3
commit-date: 2016-08-15
host: x86_64-unknown-linux-gnu
release: 1.11.0

[TimNN]

Duplicate of #5067.

[TimNN]

I'm going to close this, since it's a duplicate.