#[cfg_attrs(...)]

Provides an alternative syntax to #[cfg_attr(...)] that is easier to use with doc comments.

Syntax
CfgAttrsAttribute :
cfg_attrs ( ConfigurationPredicate , CfgAttrs )

CfgAttrs :
{ Attributes } | Attributes

Attributes :
OuterAttribute* ( , OuterAttribute* )* ,?

Examples

/// This is an example struct.
#[cfg_attrs(
    debug_assertions,
    ///
    /// Hello! These are docs that only appear when
    /// debug assertions are active.
)]
struct Example;

This can also be written as:

/// This is an example struct.
#[cfg_attrs(debug_assertions, {
    ///
    /// Hello! These are docs that only appear when
    /// debug assertions are active.
})]
struct Example;

Either of these will expand to the following usage of #[cfg_attr(...)]:

/// This is an example struct.
#[cfg_attr(
    debug_assertions,
    doc = "",
    doc = " Hello! These are docs that only appear when",
    doc = " debug assertions are active."
)]
struct Example;

Which, if debug assertions are active, would be expanded to:

/// This is an example struct.
///
/// Hello! These are docs that only appear when
/// debug assertions are active.
struct Example;

#[cfg_attrs(...)] may also be used with attributes other than doc comments, though there is little advantage over using #[cfg_attr(...)] in these cases:

#[cfg_attrs(
    feature = "magic",
    #[sparkles]
    #[crackles]
)]
fn bewitched() {}

With that example being equivalent to:

#[cfg_attr(feature = "magic", sparkles, crackles)]
fn bewitched() {}