Add promotion rule for generic numbers

Author: MilesCranmer

src/utils.jl

@@ -27,6 +27,7 @@ end
 end
 
 Base.float(q::AbstractUnionQuantity) = new_quantity(typeof(q), float(ustrip(q)), dimension(q))
+Base.convert(::Type{Number}, q::AbstractQuantity) = q
 function Base.convert(::Type{T}, q::AbstractUnionQuantity) where {T<:Number}
     @assert iszero(dimension(q)) "$(typeof(q)): $(q) has dimensions! Use `ustrip` instead."
     return convert(T, ustrip(q))
@@ -43,6 +44,9 @@ end
 function Base.promote_rule(::Type{<:Quantity{T1,D1}}, ::Type{<:Quantity{T2,D2}}) where {T1,T2,D1,D2}
     return Quantity{promote_type(T1,T2),promote_type(D1,D2)}
 end
+function Base.promote_rule(::Type{<:AbstractQuantity}, ::Type{<:Number})
+    return Number
+end
 
 Base.keys(d::AbstractDimensions) = static_fieldnames(typeof(d))
 Base.getindex(d::AbstractDimensions, k::Symbol) = getfield(d, k)

test/unittests.jl

@@ -440,6 +440,9 @@ end
     q1 = Quantity(1.0, length=1)
     q2 = Quantity(2, mass=1)
     @test typeof(promote(q1, q2)) == typeof((q1, q1))
+
+    x = [0.5, 0.5u"km/s"]
+    @test x isa Vector{Number}
 end
 
 struct MyDimensions{R} <: AbstractDimensions{R}