Use similar in creation of DiffResults buffer (#95)

* use similar in creation of diffresults buffer
* use the input to make the DiffResults buffer
* remove the logdensity argument from _diffresults_buffer
* removed type-annotation
* patch version bump

Author: torfjelde

Project.toml

@@ -1,7 +1,7 @@
 name = "LogDensityProblems"
 uuid = "6fdf6af0-433a-55f7-b3ed-c6c6e0b8df7c"
 authors = ["Tamas K. Papp <[email protected]>"]
-version = "1.0.2"
+version = "1.0.3"
 
 [deps]
 ArgCheck = "dce04be8-c92d-5529-be00-80e4d2c0e197"

src/AD_ForwardDiff.jl

@@ -45,7 +45,7 @@ end
 
 function logdensity_and_gradient(fℓ::ForwardDiffLogDensity, x::AbstractVector)
     @unpack ℓ, gradientconfig = fℓ
-    buffer = _diffresults_buffer(ℓ, x)
+    buffer = _diffresults_buffer(x)
     result = ForwardDiff.gradient!(buffer, Base.Fix1(logdensity, ℓ), x, gradientconfig)
     _diffresults_extract(result)
 end

src/AD_ReverseDiff.jl

@@ -50,7 +50,7 @@ end
 
 function logdensity_and_gradient(∇ℓ::ReverseDiffLogDensity, x::AbstractVector)
     @unpack ℓ, compiledtape = ∇ℓ
-    buffer = _diffresults_buffer(ℓ, x)
+    buffer = _diffresults_buffer(x)
     if compiledtape === nothing
         result = ReverseDiff.gradient!(buffer, Base.Fix1(logdensity, ℓ), x)
     else

src/DiffResults_helpers.jl

@@ -11,10 +11,10 @@ $(SIGNATURES)
 Allocate a DiffResults buffer for a gradient, taking the element type of `x` into account
 (heuristically).
 """
-function _diffresults_buffer(ℓ, x)
+function _diffresults_buffer(x)
     T = eltype(x)
     S = T <: Real ? float(Real) : Float64 # heuristic
-    DiffResults.MutableDiffResult(zero(S), (Vector{S}(undef, dimension(ℓ)), ))
+    DiffResults.MutableDiffResult(zero(S), (similar(x, S), ))
 end
 
 """
@@ -25,5 +25,5 @@ constructed with [`diffresults_buffer`](@ref). Gradient is not copied as caller
 vector.
 """
 function _diffresults_extract(diffresult::DiffResults.DiffResult)
-    DiffResults.value(diffresult)::Real, DiffResults.gradient(diffresult)
+    DiffResults.value(diffresult), DiffResults.gradient(diffresult)
 end