Add support for three-arg div to FixedDecimals in Julia 1.4+.

This commit simply implements `div(x,y,::RoundingMode)` for
FixedDecimals by delegating to `div` of the fields.

Author: NHDaly

src/FixedPointDecimals.jl

@@ -305,6 +305,9 @@ for divfn in [:div, :fld, :fld1]
     # We don't need any widening logic, since we won't be multiplying by the coefficient.
     @eval $divfn(x::T, y::T) where {T <: FD} = T($divfn(x.i, y.i))
 end
+if VERSION >= v"1.4.0-"
+    Base.div(x::T, y::T, r::RoundingMode) where {T <: FD} = T(div(x.i, y.i, r))
+end
 
 convert(::Type{AbstractFloat}, x::FD) = convert(floattype(typeof(x)), x)
 function convert(::Type{TF}, x::FD{T, f}) where {TF <: AbstractFloat, T, f}

test/runtests.jl

@@ -536,6 +536,16 @@ end
 
         @test one(FD{Int32, 2}) ÷ one(FD{Int64, 6}) isa FD{Int64, 6}
     end
+
+    @testset "div with rounding modes" begin
+        if VERSION >= v"1.4.0-"
+            @testset for x in keyvalues[FD2]
+                for R in (RoundUp, RoundDown, RoundNearest, RoundNearestTiesAway)
+                    @test div(x, 2one(x), R) === div(x, 2, R) === FD2(div(x.i, FD2(2).i, R))
+                end
+            end
+        end
+    end
 end
 
 @testset "abs, sign" begin