Weird DivideError: materialize and rational matmul

[Voltobene]

I came across some strange behaviour which I was able to break down to the following:

julia> using LazyArrays
julia> A = zeros(Rational{Int64}, 2, 2);
julia> B = zeros(Rational{Int64}, 2, 25);
julia> materialize(@~ A * B)

throws (even on a clean julia 1.6.3, LazyArrays V 0.22.1)

julia> materialize(@~ A * B)
ERROR: DivideError: integer division error
Stacktrace:
  [1] div
    @ ./int.jl:261 [inlined]
  [2] divgcd
    @ ./rational.jl:45 [inlined]
  [3] *(y::Bool, x::Rational{Int64})
    @ Base ./rational.jl:319
...

Interestingly enough, the following (invoking A * B upfront) works:

julia> A * B;
julia> materialize(@~ A * B)
2×25 Matrix{Rational{Int64}}:
 0//1  0//1  0//1  0//1  0//1  0//1  …  0//1  0//1  0//1  0//1  0//1  0//1
 0//1  0//1  0//1  0//1  0//1  0//1     0//1  0//1  0//1  0//1  0//1  0//1

Maybe some not yet compiled code is the culprit?

[dlfivefifty]

@tkf I think you wrote the macro? I'm not familiar enough to understand what could be happening here.

[dlfivefifty]

@Voltobene always include the full stacktrace in an issue as it makes it more obvious what the problem might be:

julia> materialize(@~ A * B)
ERROR: DivideError: integer division error
Stacktrace:
  [1] div
    @ ./int.jl:261 [inlined]
  [2] divgcd
    @ ./rational.jl:45 [inlined]
  [3] *(y::Bool, x::Rational{Int64})
    @ Base ./rational.jl:319
  [4] macro expansion
    @ ~/Projects/julia-1.6/usr/share/julia/stdlib/v1.6/LinearAlgebra/src/generic.jl:221 [inlined]
  [5] macro expansion
    @ ./simdloop.jl:77 [inlined]
  [6] lmul!
    @ ~/Projects/julia-1.6/usr/share/julia/stdlib/v1.6/LinearAlgebra/src/generic.jl:220 [inlined]
  [7] materialize!
    @ ~/.julia/packages/ArrayLayouts/NI7mz/src/lmul.jl:73 [inlined]
  [8] lmul!
    @ ~/.julia/packages/ArrayLayouts/NI7mz/src/lmul.jl:47 [inlined]
  [9] tiled_blasmul!(tile_size::Int64, α::Rational{Int64}, A::Matrix{Rational{Int64}}, B::Matrix{Rational{Int64}}, β::Bool, C::Matrix{Rational{Int64}})
    @ ArrayLayouts ~/.julia/packages/ArrayLayouts/NI7mz/src/muladd.jl:131
 [10] materialize!(M::ArrayLayouts.MulAdd{ArrayLayouts.DenseColumnMajor, ArrayLayouts.DenseColumnMajor, ArrayLayouts.DenseColumnMajor, Rational{Int64}, Matrix{Rational{Int64}}, Matrix{Rational{Int64}}, Matrix{Rational{Int64}}})
    @ ArrayLayouts ~/.julia/packages/ArrayLayouts/NI7mz/src/muladd.jl:241
 [11] muladd!
    @ ~/.julia/packages/ArrayLayouts/NI7mz/src/muladd.jl:70 [inlined]
 [12] copyto!
    @ ~/.julia/packages/ArrayLayouts/NI7mz/src/muladd.jl:77 [inlined]
 [13] copy(M::ArrayLayouts.MulAdd{ArrayLayouts.DenseColumnMajor, ArrayLayouts.DenseColumnMajor, ArrayLayouts.ZerosLayout, Rational{Int64}, Matrix{Rational{Int64}}, Matrix{Rational{Int64}}, FillArrays.Zeros{Rational{Int64}, 2, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}}}})
    @ ArrayLayouts ~/.julia/packages/ArrayLayouts/NI7mz/src/muladd.jl:72
 [14] copy
    @ ~/.julia/packages/ArrayLayouts/NI7mz/src/mul.jl:108 [inlined]
 [15] materialize
    @ ~/.julia/packages/ArrayLayouts/NI7mz/src/mul.jl:105 [inlined]
 [16] mul
    @ ~/.julia/packages/ArrayLayouts/NI7mz/src/mul.jl:106 [inlined]
 [17] copy
    @ ~/.julia/packages/LazyArrays/zulEl/src/linalg/mul.jl:13 [inlined]
 [18] materialize(A::Applied{LazyArrays.MulStyle, typeof(*), Tuple{Matrix{Rational{Int64}}, Matrix{Rational{Int64}}}})
    @ LazyArrays ~/.julia/packages/LazyArrays/zulEl/src/lazyapplying.jl:82
 [19] top-level scope
    @ REPL[4]:1

Nevermind @tkf looks unrelated to the macro.