specialize Derivative

Author: jishnub

src/Spaces/Jacobi/JacobiOperators.jl

@@ -1,5 +1,7 @@
 ## Derivative
 
+# specialize Derivative so that this is type-inferred even without constant propagation
+Derivative(J::Jacobi) = ConcreteDerivative(J,1)
 @inline function _Derivative(J::Jacobi, k::Number)
     assert_integer(k)
     k==1 ? ConcreteDerivative(J,1) :

test/JacobiTest.jl

@@ -110,10 +110,10 @@ using StaticArrays: SVector
     end
 
     @testset "Derivative" begin
-        D = if VERSION >= v"1.8"
-            @inferred Derivative(Jacobi(0.,1.,Segment(1.,0.)))
-        else
-            Derivative(Jacobi(0.,1.,Segment(1.,0.)))
+        D = @inferred Derivative(Jacobi(0.,1.,Segment(1.,0.)))
+        if VERSION >= v"1.8"
+            D2 = @inferred (() -> Derivative(Jacobi(0.,1.,Segment(1.,0.)), 1))()
+            @test D2 == D
         end
         @time testbandedoperator(D)
         # only one band should be populated