StackOverflowError from @fastmath

[ChrisRackauckas]

SIUnits.jl is incompatible with @fastmath. Here's a small example showing how to get the StackOverflowError (requires that you have optimized Julia to your system, like re-built the system image, and I can only get this error on Linux but not Windows)

using SIUnits, SIUnits.ShortUnits
u = 1.5N
halfΔt = 0.03125s
tmp2 = .25N/s
u+halfΔt*tmp2
@fastmath u+halfΔt*tmp2