handle abstract fields right in mutable tangents outside of zero tangent

Author: oxinabox

src/tangent_types/structural_tangent.jl

@@ -73,10 +73,6 @@ It itself is also mutable.
 struct MutableTangent{P,F} <: StructuralTangent{P}
     backing::F
 
-    function MutableTangent{P}(fieldvals) where P
-        backing = map(Ref, fieldvals)
-        return new{P, typeof(backing)}(backing)
-    end
     function MutableTangent{P}(
         any_mask::NamedTuple{names, <:NTuple{<:Any, Bool}}, fvals::NamedTuple{names}
     ) where {names, P}
@@ -91,8 +87,14 @@ struct MutableTangent{P,F} <: StructuralTangent{P}
         end
         return new{P, typeof(backing)}(backing)
     end
+
+    function MutableTangent{P}(fvals) where P
+        any_mask = NamedTuple{fieldnames(P)}((!isconcretetype).(fieldtypes(P)))
+        return MutableTangent{P}(any_mask, fvals)
+    end
 end
 
+
 ####################################################################
 # StructuralTangent Common
 

test/tangent_types/structural_tangent.jl

@@ -4,6 +4,11 @@ struct Foo
     y::Float64
 end
 
+mutable struct MFoo
+    x::Float64
+    y
+end
+
 # For testing Primal + Tangent performance
 struct Bar
     x::Float64
@@ -452,14 +457,40 @@ end
     end
 
     @testset "== and hash" begin
-        @test MutableTangent{Any}(; x=1.0) == MutableTangent{MDemo}(; x=1.0)
-        @test MutableTangent{MDemo}(; x=1.0) == MutableTangent{Any}(; x=1.0)
-        @test MutableTangent{Any}(; x=2.0) != MutableTangent{MDemo}(; x=1.0)
-        @test MutableTangent{MDemo}(; x=1.0) != MutableTangent{Any}(; x=2.0)
+        @test MutableTangent{MDemo}(; x=1f0) == MutableTangent{MDemo}(; x=1.0)
+        @test MutableTangent{MDemo}(; x=1.0) == MutableTangent{MDemo}(; x=1f0)
+        @test MutableTangent{MDemo}(; x=2.0) != MutableTangent{MDemo}(; x=1.0)
+        @test MutableTangent{MDemo}(; x=1.0) != MutableTangent{MDemo}(; x=2.0)
 
         nt = (; x=1.0)
         @test MutableTangent{typeof(nt)}(nt) != MutableTangent{MDemo}(; x=1.0)
 
-        @test hash(MutableTangent{Any}(; x=1.0)) == hash(MutableTangent{MDemo}(; x=1.0))
+        @test hash(MutableTangent{MDemo}(; x=1f0)) == hash(MutableTangent{MDemo}(; x=1.0))
+    end
+
+    @testset "Mutation" begin
+        v = MutableTangent{MFoo}(x=1.5, y=2.4)
+        v.x = 1.6
+        @test v == MutableTangent{MFoo}(x=1.6, y=2.4)
+        v.y = [1.0, 2.0]  # change type, because primal can change type
+        @test v == MutableTangent{MFoo}(x=1.6, y=[1.0, 2.0])
+    end
+end
+
+@testset "map" begin
+    @testset "Tangent" begin
+        ∂foo = Tangent{Foo}(x=1.5, y=2.4)
+        @test map(v->2*v, ∂foo) == Tangent{Foo}(x=3.0, y=4.8)
+
+        ∂foo = Tangent{Foo}(x=1.5)
+        @test map(v->2*v, ∂foo) == Tangent{Foo}(x=3.0)
+    end
+    @testset "MutableTangent" begin
+        ∂foo = MutableTangent{MFoo}(x=1.5, y=2.4)
+        ∂foo2 = map(v->2*v, ∂foo)
+        @test ∂foo2 == MutableTangent{MFoo}(x=3.0, y=4.8)
+        # Check can still be mutated to new typ
+        ∂foo2.y=[1.0, 2.0]
+        @test ∂foo2 == MutableTangent{MFoo}(x=3.0, y=[1.0, 2.0])
     end
 end