Generic isfinite method (#36380)

* Add generic isfinite method

* Test isfinite for Period instances

* Add isfinite method for Period

* Generic isfinite only for Number subtypes

Author: omus

base/float.jl

@@ -537,20 +537,6 @@ isnan(x::AbstractFloat) = (x != x)::Bool
 isnan(x::Float16) = reinterpret(UInt16,x)&0x7fff > 0x7c00
 isnan(x::Real) = false
 
-"""
-    isfinite(f) -> Bool
-
-Test whether a number is finite.
-
-# Examples
-```jldoctest
-julia> isfinite(5)
-true
-
-julia> isfinite(NaN32)
-false
-```
-"""
 isfinite(x::AbstractFloat) = x - x == 0
 isfinite(x::Float16) = reinterpret(UInt16,x)&0x7c00 != 0x7c00
 isfinite(x::Real) = decompose(x)[3] != 0

base/number.jl

@@ -59,6 +59,22 @@ true
 """
 isone(x) = x == one(x) # fallback method
 
+"""
+    isfinite(f) -> Bool
+
+Test whether a number is finite.
+
+# Examples
+```jldoctest
+julia> isfinite(5)
+true
+
+julia> isfinite(NaN32)
+false
+```
+"""
+isfinite(x::Number) = iszero(x - x)
+
 size(x::Number) = ()
 size(x::Number, d::Integer) = d < 1 ? throw(BoundsError()) : 1
 axes(x::Number) = ()

stdlib/Dates/src/periods.jl

@@ -54,6 +54,7 @@ Base.zero(::Union{Type{P},P}) where {P<:Period} = P(0)
 Base.one(::Union{Type{P},P}) where {P<:Period} = 1  # see #16116
 Base.typemin(::Type{P}) where {P<:Period} = P(typemin(Int64))
 Base.typemax(::Type{P}) where {P<:Period} = P(typemax(Int64))
+Base.isfinite(::Union{Type{P}, P}) where {P<:Period} = true
 
 # Default values (as used by TimeTypes)
 """

stdlib/Dates/test/periods.jl

@@ -226,6 +226,8 @@ end
     @test Dates.string(Dates.Year(1)) == "1 year"
     @test Dates.string(Dates.Year(-1)) == "-1 year"
     @test Dates.string(Dates.Year(2)) == "2 years"
+    @test isfinite(Dates.Year)
+    @test isfinite(Dates.Year(0))
     @test zero(Dates.Year) == Dates.Year(0)
     @test zero(Dates.Year(10)) == Dates.Year(0)
     @test zero(Dates.Month) == Dates.Month(0)

test/numbers.jl

@@ -2704,3 +2704,9 @@ end
     @test all(m -> m.file == Symbol("deprecated.jl"),
         collect(methods(T))[findall(R -> !(R<:T), Base.return_types(T))])
 end
+
+@testset "generic isfinite" begin
+    @test invoke(isfinite, Tuple{Number}, 0.0) == true
+    @test invoke(isfinite, Tuple{Number}, NaN) == false
+    @test invoke(isfinite, Tuple{Number}, Inf) == false
+end