InplaceableThunk

Author: cossio

src/projection.jl

@@ -128,7 +128,7 @@ ProjectTo(::Any) = identity
 ProjectTo(::AbstractZero) = ProjectTo{NoTangent}()  # Any x::Zero in forward pass makes this one projector,
 (::ProjectTo{NoTangent})(dx) = NoTangent()          # but this is the projection only for nonzero gradients,
 (::ProjectTo{NoTangent})(dx::AbstractZero) = dx     # and this one solves an ambiguity.
-(::ProjectTo{NoTangent})(::AbstractThunk) = NoTangent() # solves ambiguity, #685
+(::ProjectTo{NoTangent})(::InplaceableThunk) = NoTangent() # solves ambiguity, #685
 (::ProjectTo{NoTangent})(::Thunk) = NoTangent() # solves ambiguity, #685
 
 # Also, any explicit construction with fields, where all fields project to zero, itself

test/projection.jl

@@ -465,6 +465,10 @@ struct NoSuperType end
     end
 
     @testset "#685" begin
-        @test ProjectTo(BitArray([0]))(@thunk[1.0]) == NoTangent()
+        @test ProjectTo(BitArray([0]))([1.0]) == NoTangent()
+        @test ProjectTo(BitArray([0]))(@thunk [1.0]) == NoTangent()
+
+        it = InplaceableThunk(x -> x + [1], @thunk [1.0])
+        @test ProjectTo(BitArray([0]))(it) == NoTangent()
     end
 end