On Wednesday, 6 January 2021 at 06:50:34 UTC, Walter Bright wrote:
As far as I can tell, the only algorithms that are incorrect with extended precision intermediate values are ones specifically designed to tease out the roundoff to the reduced precision.
It becomes impossible to write good unit-tests for floating point if you don't know what the exact results should be.
Anyway, it is ok if this is up to the compiler vendor if you can test a flag for it.
Just get rid of implicit conversion for floating point. Nobody interested in numerics would want that.