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make length(StepRange()) type stable #45236

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Merged
KristofferC merged 2 commits into from
May 11, 2022
Merged

make length(StepRange()) type stable #45236

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6379ab8
make `length(StepRange())` type stable
Moelf May 8, 2022
937a25c
add checked_length
Moelf May 9, 2022
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10 changes: 5 additions & 5 deletions base/range.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -767,13 +767,13 @@ let bigints = Union{Int, UInt, Int64, UInt64, Int128, UInt128}
# therefore still be valid (if the result is representable at all)
# n.b. !(s isa T)
if s isa Unsigned || -1 <= s <= 1 || s == -s
a = div(diff, s)
a = div(diff, s) % T
elseif s < 0
a = div(unsigned(-diff), -s) % typeof(diff)
a = div(unsigned(-diff), -s) % T
else
a = div(unsigned(diff), s) % typeof(diff)
a = div(unsigned(diff), s) % T
end
return Integer(a) + oneunit(a)
return a + oneunit(T)
end
function checked_length(r::OrdinalRange{T}) where T<:bigints
s = step(r)
Expand All @@ -791,7 +791,7 @@ let bigints = Union{Int, UInt, Int64, UInt64, Int128, UInt128}
else
a = div(checked_sub(start, stop), -s)
end
return checked_add(a, oneunit(a))
return checked_add(convert(T, a), oneunit(T))
end
end

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5 changes: 5 additions & 0 deletions test/ranges.jl
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Expand Up @@ -2031,6 +2031,11 @@ end
@test typeof(step(r)) === Int8
end

@testset "length(StepRange()) type stability" begin
typeof(length(StepRange(1,Int128(1),1))) == typeof(length(StepRange(1,Int128(1),0)))
typeof(checked_length(StepRange(1,Int128(1),1))) == typeof(checked_length(StepRange(1,Int128(1),0)))
end

@testset "LinRange eltype for element types that wrap integers" begin
struct RealWrapper{T <: Real} <: Real
x :: T
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