Rustfmt Unconditionally Indents Code Each Time It's Run

[bheisler]

This is an odd bug I found while running rustfmt on Criterion.rs.

Steps to reproduce:

• cargo init rustfmt-test
• Create a benches directory (this doesn't happen if the code is in src)
• Create a file named test.rs in the benches directory with the following code:

macro_rules! bench {
    ($ty:ident) => {
        criterion_group!(
            name = benches;
            config = ::common_bench::reduced_samples();
            targets = call, map;
        );
    };
}

• Run cargo +nightly fmt. Code now looks like this:

macro_rules! bench {
    ($ty:ident) => {
        criterion_group!(
                    name = benches;
                    config = ::common_bench::reduced_samples();
                    targets = call, map;
                );
    };
}

• Run cargo +nightly fmt again. Code now looks like this:

macro_rules! bench {
    ($ty:ident) => {
        criterion_group!(
                            name = benches;
                            config = ::common_bench::reduced_samples();
                            targets = call, map;
                        );
    };
}

It always adds another 8 spaces before those four lines. I haven't been able to find a workaround for this (though if you find one, please let me know so I can re-enable my rustfmt Travis-CI build).

[topecongiro]

A workaround could be to use {} over () for macro call:

macro_rules! bench {
    ($ty:ident) => {
-        criterion_group!(
+        criterion_group!{
            name = benches;
            config = ::common_bench::reduced_samples();
            targets = call, map;
-        );
+        };
    };
}

[bheisler]

Great, thanks! That works just fine as a workaround.

[Amanieu]

Possible duplicate of #2588?