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use Base.promote_op to infer output container eltype in map #83

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Merged
lkdvos merged 1 commit into from
Aug 16, 2026
+10 −1
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use Base.promote_op to infer output container eltype in map #83

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2 changes: 1 addition & 1 deletion src/mapreduce.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ function Base.map(
@nospecialize(f), a1::StridedView{<:Any, N},
A::Vararg{StridedView{<:Any, N}}
) where {N}
T = Base.promote_eltype(a1, A...)
T = Base.promote_op(f, eltype(a1), eltype.(A)...)
return map!(f, similar(a1, T), a1, A...)
end

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9 changes: 9 additions & 0 deletions test/othertests.jl
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Expand Up @@ -27,6 +27,14 @@ end
A3 = convert(Array{T, N}, B3)
C1 = deepcopy(B1)

# Regression tests for https://github.com/QuantumKitHub/Strided.jl/issues/82:
# `map` must infer its output eltype correctly when the input is a StridedView
@test map(x -> ComplexF64(x), B1) == map(x -> ComplexF64(x), A1)
@test map(x -> ComplexF64(x), B1) isa StridedView
@test eltype(map(x -> ComplexF64(x), B1)) == ComplexF64
@test eltype(map((x, y) -> ComplexF64(x) + im * ComplexF64(y), B1, B2)) ==
ComplexF64

@test rmul!(B1, 1 // 2) ≈ rmul!(A1, 1 // 2)
@test lmul!(1 // 3, B2) ≈ lmul!(1 // 3, A2)
@test axpy!(1 // 3, B1, B2) ≈ axpy!(1 // 3, A1, A2)
Expand All @@ -37,6 +45,7 @@ end
map((x, y, z) -> sin(x) + y / exp(-abs(z)), A1, A2, A3)
@test map((x, y, z) -> sin(x) + y / exp(-abs(z)), B1, B2, B3) isa StridedView
@test map((x, y, z) -> sin(x) + y / exp(-abs(z)), B1, A2, B3) isa Array

@test mul!(B1, 1, B2) ≈ mul!(A1, 1, A2)
@test mul!(B1, B2, 1) ≈ mul!(A1, A2, 1)
end
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