This release fixes a bug that was introduced in 0.5.14 (the previous release). You are only affected if you manually enabled the Yul optimizer (not the regular optimizer) and either used Yul stand-alone or via ABIEncoderV2. For more details, please see buglist.json.
Bugfixes:
- Yul Optimizer: Fix incorrect redundant load optimization crossing user-defined functions that contain for-loops with memory / storage writes.
If you want to perform a source build, please only use solidity_0.5.15.tar.gz and not the zip provided by github directly.