From 8587e0d202826e0cc1823ddfd7fb6190dd0058ad Mon Sep 17 00:00:00 2001
From: Adrian Hill <adrian.hill@mailbox.org>
Date: Wed, 14 Aug 2024 18:28:40 +0200
Subject: [PATCH] Fix `convert` on `Dual` (#166)

---
 src/overloads/conversion.jl |  2 +-
 test/test_gradient.jl       | 10 ++++++++++
 test/test_hessian.jl        | 14 ++++++++++++++
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/src/overloads/conversion.jl b/src/overloads/conversion.jl
index 56529c35..91f4dd31 100644
--- a/src/overloads/conversion.jl
+++ b/src/overloads/conversion.jl
@@ -44,7 +44,7 @@ Base.float(::Type{D}) where {P,T,D<:Dual{P,T}} = Dual{float(P),T}
 
 Base.convert(::Type{D}, x::Real) where {P,T,D<:Dual{P,T}}           = Dual(x, myempty(T))
 Base.convert(::Type{D}, d::D)    where {P,T,D<:Dual{P,T}}           = d
-Base.convert(::Type{N}, d::D)    where {N<:Real,P,T,D<:Dual{P,T}}   = Dual(convert(T, primal(d)), tracer(d))
+Base.convert(::Type{N}, d::D)    where {N<:Real,P,T,D<:Dual{P,T}}   = Dual(convert(N, primal(d)), tracer(d))
 
 function Base.convert(::Type{Dual{P1,T}}, d::Dual{P2,T}) where {P1,P2,T} 
     return Dual(convert(P1, primal(d)), tracer(d))
diff --git a/test/test_gradient.jl b/test/test_gradient.jl
index 310f7c24..0b4abc32 100644
--- a/test/test_gradient.jl
+++ b/test/test_gradient.jl
@@ -73,6 +73,11 @@ REAL_TYPES = (Float64, Int, Bool, UInt8, Float16, Rational{Int})
         @test J(x -> zero(x)^ℯ, 1) ≈ [0;;]
         @test J(x -> ℯ^zero(x), 1) ≈ [0;;]
 
+        # Conversions
+        @testset "Conversion to $T" for T in REAL_TYPES
+            @test J(x -> convert(T, x), 1.0) ≈ [1;;]
+        end
+
         # Round
         @test J(round, 1.1) ≈ [0;;]
         @test J(x -> round(Int, x), 1.1) ≈ [0;;]
@@ -217,6 +222,11 @@ end
         @test J(x -> ℯ^x, 1) ≈ [1;;]
         @test J(x -> 0, 1) ≈ [0;;]
 
+        # Conversions
+        @testset "Conversion to $T" for T in REAL_TYPES
+            @test J(x -> convert(T, x), 1.0) ≈ [1;;]
+        end
+
         # Round
         @test J(round, 1.1) ≈ [0;;]
         @test J(x -> round(Int, x), 1.1) ≈ [0;;]
diff --git a/test/test_hessian.jl b/test/test_hessian.jl
index 7fbfda71..24665718 100644
--- a/test/test_hessian.jl
+++ b/test/test_hessian.jl
@@ -36,6 +36,13 @@ H(f, x) = hessian_sparsity(f, x, method)
         @test H(x -> ℯ^x, 1) ≈ [1;;]
         @test H(x -> 0, 1) ≈ [0;;]
 
+        # Conversions
+        @testset "Conversion to $T" for T in REAL_TYPES
+            @test H(x -> convert(T, x), 1.0) ≈ [0;;]
+            @test H(x -> convert(T, x^2), 1.0) ≈ [1;;]
+            @test H(x -> convert(T, x)^2, 1.0) ≈ [1;;]
+        end
+
         # Round
         @test H(round, 1.1) ≈ [0;;]
         @test H(x -> round(Int, x), 1.1) ≈ [0;;]
@@ -337,6 +344,13 @@ end
         @test H(x -> ℯ^x, 1) ≈ [1;;]
         @test H(x -> 0, 1) ≈ [0;;]
 
+        # Conversions
+        @testset "Conversion to $T" for T in REAL_TYPES
+            @test H(x -> convert(T, x), 1.0) ≈ [0;;]
+            @test H(x -> convert(T, x^2), 1.0) ≈ [1;;]
+            @test H(x -> convert(T, x)^2, 1.0) ≈ [1;;]
+        end
+
         # Round
         @test H(round, 1.1) ≈ [0;;]
         @test H(x -> round(Int, x), 1.1) ≈ [0;;]