Broaden promote_rule for Dual to include AbstractIrrational (#687)

* Broaden promote_rule for Dual to include AbstractIrrational

* add IrrationalConstants test dependency

* Add tests for AbstractIrrational promote_rule

* fix pkg and test bugs

Author: ElOceanografo

Project.toml

@@ -21,6 +21,7 @@ CommonSubexpressions = "0.3"
 DiffResults = "0.0.1, 0.0.2, 0.0.3, 0.0.4, 1.0.1"
 DiffRules = "1.4.0"
 DiffTests = "0.0.1, 0.1"
+IrrationalConstants = "0.1, 0.2"
 LogExpFunctions = "0.3"
 NaNMath = "0.2.2, 0.3, 1"
 Preferences = "1"
@@ -35,12 +36,13 @@ ForwardDiffStaticArraysExt = "StaticArrays"
 Calculus = "49dc2e85-a5d0-5ad3-a950-438e2897f1b9"
 DiffTests = "de460e47-3fe3-5279-bb4a-814414816d5d"
 InteractiveUtils = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
+IrrationalConstants = "92d709cd-6900-40b7-9082-c6be49f344b6"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["Calculus", "DiffTests", "SparseArrays", "Test", "InteractiveUtils", "StaticArrays"]
+test = ["Calculus", "DiffTests", "IrrationalConstants", "SparseArrays", "Test", "InteractiveUtils", "StaticArrays"]
 
 [weakdeps]
-StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
+StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"

src/dual.jl

@@ -415,7 +415,7 @@ function Base.promote_rule(::Type{Dual{T,A,N}},
     return Dual{T,promote_type(A, B),N}
 end
 
-for R in (Irrational, Real, BigFloat, Bool)
+for R in (AbstractIrrational, Real, BigFloat, Bool)
     if isconcretetype(R) # issue #322
         @eval begin
             Base.promote_rule(::Type{$R}, ::Type{Dual{T,V,N}}) where {T,V,N} = Dual{T,promote_type($R, V),N}

test/MiscTest.jl

@@ -6,6 +6,7 @@ using Test
 using ForwardDiff
 using DiffTests
 using SparseArrays: sparse
+using IrrationalConstants
 
 include(joinpath(dirname(@__FILE__), "utils.jl"))
 
@@ -141,6 +142,24 @@ let i, j
     end
 end
 
+# AbstractIrrational numbers #
+#----------------------------#
+struct TestTag end
+intrand(V) = V == Int ? rand(2:10) : rand(V)
+
+for N in (0,3), V in (Int, Float32), I in (Irrational, AbstractIrrational)
+    PARTIALS = ForwardDiff.Partials{N,V}(ntuple(n -> intrand(V), N))
+    PRIMAL = intrand(V)
+    FDNUM = ForwardDiff.Dual{TestTag()}(PRIMAL, PARTIALS)
+    
+    @test promote_rule(typeof(FDNUM), I) == promote_rule(I, typeof(FDNUM))
+    # π::Irrational, twoπ::AbstractIrrational
+    for IRR in (π, twoπ)
+        val_dual, val_irr = promote(FDNUM, IRR)
+        @test (val_irr, val_dual) == promote(IRR, FDNUM)
+    end
+end
+
 ########
 # misc #
 ########