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Fix floattype() for non-concrete types #354

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Merged
kimikage merged 1 commit into from
Oct 12, 2026
+20 −13
Merged

Fix floattype() for non-concrete types #354

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5 changes: 2 additions & 3 deletions src/FixedPointNumbers.jl
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Expand Up @@ -196,9 +196,8 @@ floattype(::Type{T}) where {T <: Integer} = Float64
floattype(::Type{T}) where {T <: LongInts} = BigFloat
floattype(::Type{T}) where {I <: Integer, T <: Rational{I}} = typeof(zero(I)/oneunit(I))

@kimikage kimikage Oct 12, 2026

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While there are doubts regarding the guarantee that this returns an AbstractFloat, that is an issue to be addressed by the package that defined the type.

floattype(::Type{<:AbstractIrrational}) = Float64
floattype(::Type{X}) where {T <: ShortInts, X <: FixedPoint{T}} = Float32
floattype(::Type{X}) where {T <: Integer, X <: FixedPoint{T}} = Float64
floattype(::Type{X}) where {T <: LongInts, X <: FixedPoint{T}} = BigFloat
floattype(::Type{<:FixedPoint}) = BigFloat # fallback for `FixedPoint`
floattype(::Type{<:FixedPoint{T}}) where {T <: Integer} = isconcretetype(T) ? floattype(T) : BigFloat

# Non-Real types
floattype(::Type{Complex{T}}) where T = Complex{floattype(T)}
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8 changes: 0 additions & 8 deletions src/deprecations.jl
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@@ -1,13 +1,5 @@
import Base.@deprecate_binding

function floattype(::Type{T}) where {T <: Real}
Base.depwarn("""
In a future release, the fallback definition of `floattype` will throw a MethodError if it cannot return a type `<:AbstractFloat`.
See the documentation on `floattype` for guidance on whether to define a custom `floattype(::Type{$T})` method.
""", :floattype)
return T
end

function typechar(::Type{X}) where {X}
Base.depwarn("""
`typechar` was deprecated since the prefix may not be a single character in the future.
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1 change: 1 addition & 0 deletions test/fixed.jl
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Expand Up @@ -245,6 +245,7 @@ end
@test float(0.75Q10f53)::BigFloat == big"0.75"

test_floattype(Fixed)
# see test/traits.jl for floattype tests for non-concrete types
end

@testset "conversions from float" begin
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1 change: 1 addition & 0 deletions test/normed.jl
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Expand Up @@ -210,6 +210,7 @@ end
@test float(1N11f53)::BigFloat == big"1.0"

test_floattype(Normed)
# see test/traits.jl for floattype tests for non-concrete types
end

@testset "conversions from float" begin
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18 changes: 16 additions & 2 deletions test/traits.jl
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Expand Up @@ -2,8 +2,21 @@ using FixedPointNumbers, Test
using FixedPointNumbers: bitwidth

struct MyReal <: Real end
struct MyInteger <: Integer end

@testset "floattype for non-concrete/non-FixedPoint types" begin
@test floattype(FixedPoint) === BigFloat
@test floattype(Normed) === BigFloat
@test floattype(Fixed) === BigFloat
@test floattype(FixedPoint{Int8}) === Float32
@test floattype(Normed{UInt32}) === Float64
@test floattype(Fixed{Int64}) === BigFloat
@test floattype(FixedPoint{MyInteger}) === Float64
@test floattype(FixedPoint{Union{},1}) === BigFloat
@test floattype(Normed{Unsigned,2}) === BigFloat
@test floattype(Fixed{T,3} where {T<:Signed}) === BigFloat
@test_throws MethodError floattype(Fixed{T,3} where T) # T is not bounded

@testset "floattype" begin
for T in (UInt8, UInt16, UInt32, UInt64, UInt128, Bool,
Int8, Int16, Int32, Int64, Int128)
@test typemax(T) <= maxintfloat(floattype(T))
Expand All @@ -16,5 +29,6 @@ struct MyReal <: Real end
@test floattype(Base.TwicePrecision{Float64}) === Float64
@test floattype(typeof(π)) === Float64

@test_skip(@test_throws MethodError floattype(MyReal)) # TODO: eliminate `@test_skipped` when depwarn is eliminated. See #177.
@test_throws MethodError floattype(MyReal) # See #177.
@test floattype(MyInteger) === Float64
end
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