Move adjoint plan construction logic from AdjointPlan constructor to Base.adjoint

Author: Gaurav Arya

src/definitions.jl

@@ -597,14 +597,12 @@ mutable struct AdjointPlan{T,P} <: Plan{T}
     p::P
     pinv::Plan
     AdjointPlan{T,P}(p) where {T,P} = new(p)
-    # always have adjoint inside scaled
-    AdjointPlan{T,P}(p::P) where {T,P<:ScaledPlan{T}} = ScaledPlan{T}(AdjointPlan{T}(p.p), p.scale)
-    AdjointPlan{T,P}(p::AdjointPlan{T}) where {T,P} = new(p.p)
 end
 
-AdjointPlan{T}(p::P) where {T,P} = AdjointPlan{T,P}(p)
-AdjointPlan(p::Plan{T}) where {T} = AdjointPlan{T}(p)
-Base.adjoint(p::Plan{T}) where {T} = AdjointPlan{T}(p)
+Base.adjoint(p::Plan{T}) where {T} = AdjointPlan{T, typeof(p)}(p)
+Base.adjoint(p::AdjointPlan{T}) where {T} = p.p
+# always have AdjointPlan inside ScaledPlan.
+Base.adjoint(p::ScaledPlan{T}) where {T} = ScaledPlan{T}(p.p', p.scale)
 
 size(p::AdjointPlan) = output_size(p)
 output_size(p::AdjointPlan) = size(p)