JUCE's SIMDRegister/CheckTruncate Unit Test sporadically fails

On an M1 MBP, when running the JUCE unit tests on an Apple Silicon build, the tests would fail about 50% of the time, with:

In Rosetta builds it runs just fine.

This is on commit 087cda7e1f359855 using Xcode 12.5.1 on macOS 11.4

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Thanks for reporting. I think this assertion might be unnecessary, given that the test passes after hitting the assertion. It looks like this fallback implementation is used for SIMD operations on doubles on ARM. An x86_64 machine won’t use the fallback implementation (it will be able to use equivalent SSE/AVX intrinsics), which is why we don’t see the assertion firing on most desktop machines.