Add plan_mul to capture partial interface implementation

Author: dlfivefifty

ext/AbstractFFTsForwardDiffExt.jl

@@ -7,8 +7,8 @@ import AbstractFFTs: Plan
 
 for P in (:Plan, :ScaledPlan)  # need ScaledPlan to avoid ambiguities
     @eval begin
-        Base.:*(p::AbstractFFTs.$P, x::AbstractArray{DT}) where DT<:Dual = array2dual(DT, p * dual2array(x))
-        Base.:*(p::AbstractFFTs.$P, x::AbstractArray{Complex{DT}}) where DT<:Dual = array2dual(DT, p * dual2array(x))
+        AbstractFFTs.plan_mul(p::AbstractFFTs.$P, x::AbstractArray{DT}) where DT<:Dual = array2dual(DT, p * dual2array(x))
+        AbstractFFTs.plan_mul(p::AbstractFFTs.$P, x::AbstractArray{Complex{DT}}) where DT<:Dual = array2dual(DT, p * dual2array(x))
     end
 end
 

src/definitions.jl

@@ -221,7 +221,9 @@ rfft(x::AbstractArray{<:Union{Integer,Rational}}, region=1:ndims(x)) = rfft(real
 plan_rfft(x::AbstractArray, region; kws...) = plan_rfft(realfloat(x), region; kws...)
 
 # only require implementation to provide *(::Plan{T}, ::Array{T})
-*(p::Plan{T}, x::AbstractArray) where {T} = p * copy1(T, x)
+plan_mul(p::Plan{T}, x::AbstractArray) where {T} = p * copy1(T, x)
+plan_mul(p::Plan{T}, x::AbstractArray{T}) where {T} = error("The plan interface requires overloading *(::MyPlan{T}, ::AbstractArray{T}) where T")
+*(p::Plan, x::AbstractArray) = plan_mul(p, x)
 
 # Implementations should also implement mul!(Y, plan, X) so as to support
 # pre-allocated output arrays.  We don't define * in terms of mul!