fix interpolation type stability

Author: oscarddssmith

lib/OrdinaryDiffEqCore/src/dense/generic_dense.jl

@@ -553,7 +553,7 @@ ode_interpolation(tvals,ts,timeseries,ks)
 Get the value at tvals where the solution is known at the
 times ts (sorted), with values timeseries and derivatives ks
 """
-function ode_interpolation(tvals, id::I, idxs, deriv::Type{deriv}, p,
+function ode_interpolation(tvals, id::I, idxs, ::Type{deriv}, p,
         continuity::Symbol = :left) where {I, deriv}
     @unpack ts, timeseries, ks, f, cache, differential_vars = id
     @inbounds tdir = sign(ts[end] - ts[1])

test/interface/inplace_interpolation.jl

@@ -18,23 +18,23 @@ out_VMF = vecarrzero(ntt, size(prob_ode_2Dlinear.u0))   # Vector{Matrix{Float64}
     sol_ODE = solve(prob_ode_linear, alg; kwargs...)
     sol_ODE_2D = solve(prob_ode_2Dlinear, alg; kwargs...)
 
-    sol_ODE_interp = sol_ODE(tt)
-    sol_ODE_2D_interp = sol_ODE_2D(tt)
+    sol_ODE_interp = @inferred sol_ODE(tt)
+    sol_ODE_2D_interp = @inferred sol_ODE_2D(tt)
 
     @testset "1D" begin
         @test_throws MethodError sol_ODE(out_VF, tt; idxs = 1:1)
-        @test sol_ODE(out_VF, tt) isa Vector{Float64}
-        @test sol_ODE(out_VVF_1, tt) isa Vector{Vector{Float64}}
+        @inferred Vector{Float64} sol_ODE(out_VF, tt)
+        @inferred Vector{Vector{Float64}} sol_ODE(out_VVF_1, tt)
         @test sol_ODE_interp.u ≈ out_VF
     end
 
     @testset "2D" begin
         @test_throws MethodError sol_ODE_2D(out_VF, tt; idxs = 3:3)
-        @test sol_ODE_2D(out_VF, tt; idxs = 3) isa Vector{Float64}
-        @test sol_ODE_2D(out_VVF_1, tt; idxs = 3) isa Vector{Vector{Float64}}
-        @test sol_ODE_2D(out_VVF_1, tt; idxs = 3:3) isa Vector{Vector{Float64}}
-        @test sol_ODE_2D(out_VVF_2, tt; idxs = 2:3) isa Vector{Vector{Float64}}
-        @test sol_ODE_2D(out_VMF, tt) isa Vector{Matrix{Float64}}
+        @inferred Vector{Float64} sol_ODE_2D(out_VF, tt; idxs = 3)
+        @inferred Vector{Vector{Float64}} sol_ODE_2D(out_VVF_1, tt; idxs = 3)
+        @inferred Vector{Vector{Float64}}  sol_ODE_2D(out_VVF_1, tt; idxs = 3:3)
+        @inferred Vector{Vector{Float64}}  sol_ODE_2D(out_VVF_2, tt; idxs = 2:3)
+        @inferred Vector{Matrix{Float64}}  sol_ODE_2D(out_VMF, tt)
         @test sol_ODE_2D_interp.u ≈ out_VMF
     end
 end