Closed
Description
openedon Dec 2, 2021
It appears 1.7.0 fails to correctly preserve bitstypeness of parameterised types in some situations. Here's a reproducible, original failing case was using UnsafeArrays.jl. In real world code, this leads to allocations and performance regressions.
Reproducible
struct UnsafeArray{T,N}
pointer::Ptr{T}
size::NTuple{N,Int}
end
struct X{T}
x::T
end
struct Y{T}
x::UnsafeArray{X{T}, 1}
end
struct Y2
x::UnsafeArray{X{Int}, 1}
end
@show isbitstype(Y{Int})
@show isbitstype(UnsafeArray{Int, 1})
@show isbitstype(Y2)
Julia 1.7.0 output
isbitstype(Y{Int}) = false
isbitstype(UnsafeArray{Int, 1}) = true
isbitstype(Y2) = true
Julia 1.6.4 output
isbitstype(Y{Int}) = true
isbitstype(UnsafeArray{Int, 1}) = true
isbitstype(Y2) = true
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