feat: overlay eltype conversion

src/Overlay.jl

@@ -115,3 +115,16 @@ for randfun in (:rand, :randn, :randexp)
         # end
     end
 end
+
+# Type Conversions
+## We don't define it outside our interpreter since it is inconsistent with how it is
+## defined in Base for other types like Complex
+@reactant_overlay @noinline function (::Type{T})(x::TracedRNumber) where {T<:Number}
+    return TracedUtils.promote_to(TracedRNumber{T}, x)
+end
+
+@reactant_overlay @noinline function Base.convert(
+    ::Type{T}, x::TracedRNumber
+) where {T<:Number}
+    return TracedUtils.promote_to(TracedRNumber{T}, x)
+end

src/TracedRNumber.jl

@@ -22,7 +22,7 @@ function Base.eps(::Type{TracedRNumber{T}}) where {T}
     return TracedUtils.promote_to(TracedRNumber{T}, eps(T))
 end
 
-function Base.convert(::Type{<:TracedRNumber{T}}, x::Number) where {T}
+function Base.convert(::Type{TracedRNumber{T}}, x::Number) where {T}
     return TracedUtils.promote_to(TracedRNumber{T}, T(x))
 end
 
@@ -49,10 +49,6 @@ function Base.promote_rule(::Type{T}, ::Type{TracedRNumber{S}}) where {T,S}
     return TracedRNumber{Base.promote_type(T, S)}
 end
 
-function Base.convert(::Type{TracedRNumber{T}}, x::Number) where {T}
-    return TracedUtils.promote_to(TracedRNumber{T}, x)
-end
-
 TracedRNumber{T}(x::TracedRNumber{T}) where {T} = x
 
 function TracedRNumber{T}(x::Number) where {T}

test/basic.jl

@@ -676,3 +676,15 @@ end
     fill!(z, 1.0)
     @test all(==(1.0), Array(z))
 end
+
+@testset "eltype conversion inside interpreter" begin
+    function test_convert(x::AbstractArray{T}, eta) where {T}
+        eta = T(eta)
+        return x .* eta, eta
+    end
+
+    res = @jit test_convert(ConcreteRArray(rand(4, 2)), ConcreteRNumber(3.0f0))
+
+    @test res[1] isa ConcreteRArray{Float64,2}
+    @test res[2] isa ConcreteRNumber{Float64}
+end