Merge pull request #2682 from jClugstor/sparsity_detection_fix

AutoSparse Detection Fix for BDF etc.

Author: ChrisRackauckas

lib/OrdinaryDiffEqNonlinearSolve/src/utils.jl

@@ -181,7 +181,6 @@ function build_nlsolver(
 
     if nlalg isa Union{NLNewton, NonlinearSolveAlg}
         nf = nlsolve_f(f, alg)
-        J, W = build_J_W(alg, u, uprev, p, t, dt, f, nothing, uEltypeNoUnits, Val(true))
 
         # TODO: check if the solver is iterative
         weight = zero(u)
@@ -199,6 +198,7 @@ function build_nlsolver(
             end
             jac_config = build_jac_config(alg, nf, uf, du1, uprev, u, ztmp, dz)
         end
+        J, W = build_J_W(alg, u, uprev, p, t, dt, f, jac_config, uEltypeNoUnits, Val(true))
         linprob = LinearProblem(W, _vec(k); u0 = _vec(dz))
         Pl, Pr = wrapprecs(
             alg.precs(W, nothing, u, p, t, nothing, nothing, nothing,

test/interface/autosparse_detection_tests.jl

@@ -11,6 +11,8 @@ prob = prob_ode_2Dlinear
 
 @test_nowarn solve(prob, Rodas5P(autodiff = ad, linsolve = LinearSolve.KrylovJL_GMRES()))
 
+@test_nowarn solve(prob, FBDF(autodiff = ad))
+
 # Test that no dense matrices are made sparse
 diag_prob = ODEProblem((du, u, p, t) -> du .= -1.0 .* u, rand(Int(1e7)), (0, 1.0))