# PEP 517: Debug vs. Release Builds

**URL:** <https://discuss.python.org/t/pep-517-debug-vs-release-builds/1924>\
**Category:** Packaging\
**Created:** [June 30, 2019, 10:09pm UTC](https://discuss.python.org/t/pep-517-debug-vs-release-builds/1924 "2019-06-30T22:09:38Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![konstin](https://sea2.discourse-cdn.com/flex002/user_avatar/discuss.python.org/konstin/32/20207_2.png) [@konstin](https://discuss.python.org/u/konstin)\
**Post date:** [June 30, 2019, 10:09pm UTC](https://discuss.python.org/t/pep-517-debug-vs-release-builds/1924/1 "2019-06-30T22:09:38Z")

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When building a wheel with native code, a PEP 517 backend can either build in debug mode or in release mode. For cases where the package is installed as a dependency, a user most likely wants a release build, but e.g. when testing with tox and build isolation, a much faster debug build is better. It would be ideal if the build frontend could decide which kind of build it wants.

PEP 517 introduces `config_settings` for passing configuration from the frontend to the backend without specifying the semantics. Would it be possible to extend PEP 517 or to introduce a convention how to communicate the prefered build mode between frontend and the backend, e.g. using `config_settings["build_mode"]` with either `"release"` or `"debug"` as value? If so, what would be the steps required to introduce such a field?