Fix save_end overriding behavior

Fixes #1842

src/integrators/integrator_utils.jl

@@ -79,6 +79,10 @@ function _savevalues!(integrator, force_save, reduce_size)::Tuple{Bool, Bool}
                     integrator.cache.current)
             end
         else # ==t, just save
+            if curt == integrator.sol.prob.tspan[2] && !integrator.opts.save_end
+                integrator.saveiter -= 1
+                continue
+            end
             savedexactly = true
             copyat_or_push!(integrator.sol.t, integrator.saveiter, integrator.t)
             if integrator.opts.save_idxs === nothing
@@ -145,6 +149,7 @@ postamble!(integrator::ODEIntegrator) = _postamble!(integrator)
 function _postamble!(integrator)
     DiffEqBase.finalize!(integrator.opts.callback, integrator.u, integrator.t, integrator)
     solution_endpoint_match_cur_integrator!(integrator)
+    save
     resize!(integrator.sol.t, integrator.saveiter)
     resize!(integrator.sol.u, integrator.saveiter)
     if !(integrator.sol isa DAESolution)

src/solve.jl

@@ -293,9 +293,16 @@ function DiffEqBase.__init(prob::Union{DiffEqBase.AbstractODEProblem,
         sizehint!(ts, 50)
         sizehint!(ks, 50)
     elseif !isempty(saveat_internal)
-        sizehint!(timeseries, length(saveat_internal) + 1)
-        sizehint!(ts, length(saveat_internal) + 1)
-        sizehint!(ks, length(saveat_internal) + 1)
+        savelength = length(saveat_internal) + 1
+        if save_start == false
+            savelength -= 1
+        end
+        if save_end == false && prob.tspan[2] in saveat_internal.valtree
+            savelength -= 1
+        end
+        sizehint!(timeseries, savelength)
+        sizehint!(ts, savelength)
+        sizehint!(ks, savelength)
     else
         sizehint!(timeseries, 2)
         sizehint!(ts, 2)

test/interface/ode_saveat_tests.jl

@@ -187,3 +187,28 @@ prob = ODEProblem(SIR!, [0.99, 0.01, 0.0], (t_obs[1], t_obs[end]), [0.20, 0.15])
 sol = solve(prob, DP5(), reltol = 1e-6, abstol = 1e-6, saveat = t_obs)
 @test maximum(sol) <= 1
 @test minimum(sol) >= 0
+
+@testset "Proper save_start and save_end behavior" begin
+    function f2(du, u, p, t)
+        du[1] = -cos(u[1]) * u[1]
+    end
+    prob = ODEProblem(f2, [10], (0.0, 0.4))
+
+    @test solve(prob, Tsit5(); saveat = 0:.1:.4).t == [0.0; 0.1; 0.2; 0.3; 0.4]
+    @test solve(prob, Tsit5(); saveat = 0:.1:.4, save_start = true, save_end = true).t == [0.0; 0.1; 0.2; 0.3; 0.4]
+    @test solve(prob, Tsit5(); saveat = 0:.1:.4, save_start = false, save_end = false).t == [0.1; 0.2; 0.3]
+
+    ts = solve(prob, Tsit5()).t
+    @test 0.0 in ts
+    @test 0.4 in ts
+    ts = solve(prob, Tsit5(); save_start = true, save_end = true).t
+    @test 0.0 in ts
+    @test 0.4 in ts
+    ts = solve(prob, Tsit5(); save_start = false, save_end = false).t
+    @test 0.0 ∉ ts
+    @test 0.4 ∉ ts
+
+    @test solve(prob, Tsit5(); saveat = [.2]).t == [0.2]
+    @test solve(prob, Tsit5(); saveat = [.2], save_start = true, save_end = true).t == [0.0; 0.2; 0.4]
+    @test solve(prob, Tsit5(); saveat = [.2], save_start = false, save_end = false).t == [0.2]
+end