# Macro rustfmt_nightly::is_nightly_channel

source ·

    macro_rules! is_nightly_channel {
        () => { ... };
    }

Expand description

Checks if we’re in a nightly build.

The environment variable `CFG_RELEASE_CHANNEL` is set during the rustc bootstrap to “stable”, “beta”, or “nightly” depending on what toolchain is being built. If we are being built as part of the stable or beta toolchains, we want to disable unstable configuration options.

If we’re being built by cargo (e.g., `cargo +nightly install rustfmt-nightly`), `CFG_RELEASE_CHANNEL` is not set. As we only support being built against the nightly compiler when installed from crates.io, default to nightly mode.