constprop in jacobi derivative

Author: jishnub

src/Spaces/Jacobi/JacobiOperators.jl

@@ -1,14 +1,19 @@
 ## Derivative
 
-function Derivative(J::Jacobi,k::Number)
+@inline function _Derivative(J::Jacobi, k::Number)
     assert_integer(k)
     k==1 ? ConcreteDerivative(J,1) :
         DerivativeWrapper(
             TimesOperator(
                 Derivative(Jacobi(J.b+1,J.a+1,J.domain),k-1),ConcreteDerivative(J,1)),
         J, k)
 end
-
+@static if VERSION >= v"1.8"
+    Base.@constprop :aggressive Derivative(J::Jacobi, k::Number) =
+        _Derivative(J, k)
+else
+    Derivative(J::Jacobi, k::Number) = _Derivative(J, k)
+end
 
 
 rangespace(D::ConcreteDerivative{J}) where {J<:Jacobi}=Jacobi(D.space.b+D.order,D.space.a+D.order,domain(D))

test/JacobiTest.jl

@@ -110,15 +110,19 @@ using StaticArrays: SVector
     end
 
     @testset "Derivative" begin
-        D=Derivative(Jacobi(0.,1.,Segment(1.,0.)))
+        D = if VERSION >= v"1.8"
+            @inferred Derivative(Jacobi(0.,1.,Segment(1.,0.)))
+        else
+            Derivative(Jacobi(0.,1.,Segment(1.,0.)))
+        end
         @time testbandedoperator(D)
         # only one band should be populated
         @test bandwidths(D, 1) == -bandwidths(D, 2)
 
         @testset for d in [-1..1, 0..1]
             f = Fun(x->x^2, Chebyshev(d))
             C = space(f)
-            for J = Any[Jacobi(-0.5, -0.5, d), Legendre(d)]
+            for J = (Jacobi(-0.5, -0.5, d), Legendre(d))
                 g = (Derivative(J) * Conversion(C, J)) * f
                 h = Derivative(C) * f
                 @test g ≈ h
@@ -128,9 +132,9 @@ using StaticArrays: SVector
                 @test g ≈ h
             end
         end
-        @testset for S1 in Any[Jacobi(0,0),
-            Jacobi(0,0,1..2), Jacobi(2,2,1..2), Jacobi(0.5,2.5,1..2)],
-                S in Any[S1, NormalizedPolynomialSpace(S1)]
+        @testset for S1 in (Jacobi(0,0), Jacobi(0,0,1..2),
+                            Jacobi(2,2,1..2), Jacobi(0.5,2.5,1..2)),
+                S in (S1, NormalizedPolynomialSpace(S1))
             f = Fun(x->x^3 + 4x^2 + 2x + 6, S)
             @test Derivative(S) * f ≈ Fun(x->3x^2 + 8x + 2, S)
             @test Derivative(S)^2 * f ≈ Fun(x->6x+8, S)