Short version for non-lawyers:
The combine-proc-macro crate is dual-licensed under Apache 2.0 and MIT terms.
Longer version:
Copyrights in this library are retained by their contributors. No copyright
assignment is required to contribute to the library.
Except as otherwise noted (below and/or in individual files), the library is
licensed under the Apache License, Version 2.0 <LICENSE-APACHE> or
<http://www.apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT>
or <http://opensource.org/licenses/MIT>, at your option.
This library may include packages written by third parties which carry their
own copyright notices and license terms.