* ``--hashes`` option for hashing the distributions used in a solution.
* ``--urls`` option to dump the URL of the distribution downloaded for the solution into a comment.
* ``--multiline`` and ``--no-multiline`` options to change how the solution is printed. When not provided the mode is automatically selected.
* ``--no-explanations`` option to omit the constraint explanations from the comment following the pin in a solution.
* ``req-candidates`` now starts printing candidates at matching versions
to give a better view of what is available on the index.
* ``--only-binary <project>`` option to force selecting wheels for the provided projects. Passing ``:all:`` will force ``req-compile`` to only use wheels.
* ``--extra-index-url`` option to allow using the system index as the primary with extra indexes as supplements.
* Allow requirements files to use ``--index-url`` and ``--extra-index-url`` directives.
* ``--index-url`` and ``--extra-index-url`` are now emitted to the output if they differ from system default.
* Download setup requirements to a provided wheel directory, even though they aren't necessarily in the solution. This allows for fully offline source distribution installs via ``pip install <project> --no-index --find-links .wheeldir`` when all dependent projects correctly declare their setup requirements.
* Improved errors when passing invalid requirements files.