Macro find_attr

macro_rules! find_attr {
    ($attributes_list:expr, $pattern:pat $(if $guard:expr)?) => { ... };
    ($attributes_list:expr, $pattern:pat $(if $guard:expr)? => $e:expr) => { ... };
}

Finds attributes in sequences of attributes by pattern matching.

A little like matches but for attributes.

// finds the repr attribute
if let Some(r) = find_attr!(attrs, AttributeKind::Repr(r) => r) {

}

// checks if one has matched
if find_attr!(attrs, AttributeKind::Repr(_)) {

}

Often this requires you to first end up with a list of attributes. A common way to get those is through tcx.get_all_attrs(did)