From 37c563a39f5524b86cafb022810e0547ee426f56 Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Sat, 7 Oct 2023 03:41:50 +0330
Subject: [PATCH 01/12] simplify `:alg` extraction

---
 src/solve.jl | 111 ++++++++++++++++++++-------------------------------
 1 file changed, 43 insertions(+), 68 deletions(-)

diff --git a/src/solve.jl b/src/solve.jl
index b530ba38f..f78793c83 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -501,36 +501,19 @@ function init(prob::AbstractJumpProblem, args...; kwargs...)
 end
 
 function init_up(prob::DEProblem, sensealg, u0, p, args...; kwargs...)
-    if haskey(kwargs, :alg) && (isempty(args) || args[1] === nothing)
-        alg = kwargs[:alg]
+    alg = extract_alg(args, kwargs, prob.kwargs)
+    if isnothing(alg) # Default algorithm handling
+        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); kwargs...)
+        init_call(_prob, args...; kwargs...)
+    else
         _prob = get_concrete_problem(prob, isadaptive(alg); kwargs...)
         _alg = prepare_alg(alg, _prob.u0, _prob.p, _prob)
         check_prob_alg_pairing(_prob, alg) # alg for improved inference
-
-        if length(args) <= 1
-            init_call(_prob, _alg; kwargs...)
-        else
+        if length(args) > 1
             init_call(_prob, _alg, Base.tail(args)...; kwargs...)
-        end
-    elseif haskey(prob.kwargs, :alg) && (isempty(args) || args[1] === nothing)
-        alg = prob.kwargs[:alg]
-        _prob = get_concrete_problem(prob, isadaptive(alg); kwargs...)
-        _alg = prepare_alg(alg, _prob.u0, _prob.p, _prob)
-        check_prob_alg_pairing(_prob, alg) # alg for improved inference
-        if length(args) <= 1
-            init_call(_prob, _alg; kwargs...)
         else
-            init_call(_prob, _alg, Base.tail(args)...; kwargs...)
+            init_call(_prob, _alg; kwargs...)
         end
-    elseif !isempty(args) && typeof(args[1]) <: DEAlgorithm
-        alg = args[1]
-        _prob = get_concrete_problem(prob, isadaptive(alg); kwargs...)
-        check_prob_alg_pairing(_prob, alg)
-        _alg = prepare_alg(alg, _prob.u0, _prob.p, _prob)
-        init_call(_prob, _alg, Base.tail(args)...; kwargs...)
-    else # Default algorithm handling
-        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); kwargs...)
-        init_call(_prob, args...; kwargs...)
     end
 end
 
@@ -1005,36 +988,20 @@ end
 
 function solve_up(prob::Union{DEProblem, NonlinearProblem}, sensealg, u0, p, args...;
     kwargs...)
-    if haskey(kwargs, :alg) && (isempty(args) || args[1] === nothing)
-        alg = kwargs[:alg]
+    alg = extract_alg(args, kwargs, prob.kwargs)
+    if isnothing(alg) # Default algorithm handling
+        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
+            p = p, kwargs...)
+        solve_call(_prob, args...; kwargs...)
+    else
         _prob = get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
         _alg = prepare_alg(alg, _prob.u0, _prob.p, _prob)
         check_prob_alg_pairing(_prob, alg) # use alg for improved inference
-        if length(args) <= 1
-            solve_call(_prob, _alg; kwargs...)
-        else
+        if length(args) > 1
             solve_call(_prob, _alg, Base.tail(args)...; kwargs...)
-        end
-    elseif haskey(prob.kwargs, :alg) && (isempty(args) || args[1] === nothing)
-        alg = prob.kwargs[:alg]
-        _prob = get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
-        _alg = prepare_alg(alg, _prob.u0, _prob.p, _prob)
-        check_prob_alg_pairing(_prob, alg) # use alg for improved inference
-        if length(args) <= 1
-            solve_call(_prob, _alg; kwargs...)
         else
-            solve_call(_prob, _alg, Base.tail(args)...; kwargs...)
+            solve_call(_prob, _alg; kwargs...)
         end
-    elseif !isempty(args) && typeof(args[1]) <: DEAlgorithm
-        alg = args[1]
-        _prob = get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
-        _alg = prepare_alg(alg, _prob.u0, _prob.p, _prob)
-        check_prob_alg_pairing(_prob, alg) # use alg for improved inference
-        solve_call(_prob, _alg, Base.tail(args)...; kwargs...)
-    else # Default algorithm handling
-        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
-            p = p, kwargs...)
-        solve_call(_prob, args...; kwargs...)
     end
 end
 
@@ -1424,16 +1391,12 @@ end
 
 function _solve_adjoint(prob, sensealg, u0, p, originator, args...; merge_callbacks = true,
     kwargs...)
-    alg, _prob = if haskey(kwargs, :alg) && (isempty(args) || args[1] === nothing)
-        alg = kwargs[:alg]
-        alg, get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
-    elseif !isempty(args) && typeof(args[1]) <: DEAlgorithm
-        alg = args[1]
-        alg, get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
-    else # Default algorithm handling
-        alg = isempty(args) ? nothing : args[1]
-        alg, get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0, p = p,
-            kwargs...)
+    alg = extract_alg(args, kwargs, prob.kwargs)
+    if isnothing(alg) # Default algorithm handling
+        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
+            p = p, kwargs...)
+    else
+        _prob = get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
     end
 
     if has_kwargs(_prob)
@@ -1458,16 +1421,12 @@ end
 
 function _solve_forward(prob, sensealg, u0, p, originator, args...; merge_callbacks = true,
     kwargs...)
-    alg, _prob = if haskey(kwargs, :alg) && (isempty(args) || args[1] === nothing)
-        alg = kwargs[:alg]
-        alg, get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
-    elseif !isempty(args) && typeof(args[1]) <: DEAlgorithm
-        alg = args[1]
-        alg, get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
-    else # Default algorithm handling
-        alg = isempty(args) ? nothing : args[1]
-        alg, get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0, p = p,
-            kwargs...)
+    alg = extract_alg(args, kwargs, prob.kwargs)
+    if isnothing(alg) # Default algorithm handling
+        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
+            p = p, kwargs...)
+    else
+        _prob = get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
     end
 
     if has_kwargs(_prob)
@@ -1490,6 +1449,22 @@ function _solve_forward(prob, sensealg, u0, p, originator, args...; merge_callba
     end
 end
 
+@inline function extract_alg(solve_args, solve_kwargs, prob_kwargs)
+    if isempty(solve_args) || isnothing(solve_args[1])
+        if haskey(solve_kwargs, :alg)
+            solve_kwargs[:alg]
+        elseif haskey(prob_kwargs, :alg)
+            prob_kwargs[:alg]
+        else
+            nothing
+        end
+    elseif solve_args[1] isa DEAlgorithm
+        solve_args[1]
+    else
+        nothing
+    end
+end
+
 ####
 # Catch undefined AD overload cases
 

From e2183d9afbeeb302154b77bf949bdad8a345697f Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Sat, 7 Oct 2023 03:52:01 +0330
Subject: [PATCH 02/12] pass `u0` & `p`

---
 src/solve.jl | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/solve.jl b/src/solve.jl
index f78793c83..76454839c 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -503,10 +503,11 @@ end
 function init_up(prob::DEProblem, sensealg, u0, p, args...; kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
     if isnothing(alg) # Default algorithm handling
-        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); kwargs...)
+        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
+            p = p, kwargs...)
         init_call(_prob, args...; kwargs...)
     else
-        _prob = get_concrete_problem(prob, isadaptive(alg); kwargs...)
+        _prob = get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
         _alg = prepare_alg(alg, _prob.u0, _prob.p, _prob)
         check_prob_alg_pairing(_prob, alg) # alg for improved inference
         if length(args) > 1

From 70f5d22f0d9b7d84daacbf920b313c39957054c4 Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Sat, 7 Oct 2023 17:52:28 +0330
Subject: [PATCH 03/12] replace deprecated types

---
 ext/DiffEqBaseReverseDiffExt.jl | 12 ++++----
 ext/DiffEqBaseTrackerExt.jl     |  6 ++--
 src/DiffEqBase.jl               |  6 ++--
 src/solve.jl                    | 50 ++++++++++++++++-----------------
 4 files changed, 37 insertions(+), 37 deletions(-)

diff --git a/ext/DiffEqBaseReverseDiffExt.jl b/ext/DiffEqBaseReverseDiffExt.jl
index 96e2d4301..cc0371c5e 100644
--- a/ext/DiffEqBaseReverseDiffExt.jl
+++ b/ext/DiffEqBaseReverseDiffExt.jl
@@ -76,7 +76,7 @@ end
 end
 
 # `ReverseDiff.TrackedArray`
-function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
+function DiffEqBase.solve_up(prob::DiffEqBase.AbstractDEProblem,
     sensealg::Union{
         SciMLBase.AbstractOverloadingSensitivityAlgorithm,
         Nothing}, u0::ReverseDiff.TrackedArray,
@@ -84,7 +84,7 @@ function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
     ReverseDiff.track(DiffEqBase.solve_up, prob, sensealg, u0, p, args...; kwargs...)
 end
 
-function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
+function DiffEqBase.solve_up(prob::DiffEqBase.AbstractDEProblem,
     sensealg::Union{
         SciMLBase.AbstractOverloadingSensitivityAlgorithm,
         Nothing}, u0, p::ReverseDiff.TrackedArray,
@@ -92,7 +92,7 @@ function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
     ReverseDiff.track(DiffEqBase.solve_up, prob, sensealg, u0, p, args...; kwargs...)
 end
 
-function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
+function DiffEqBase.solve_up(prob::DiffEqBase.AbstractDEProblem,
     sensealg::Union{
         SciMLBase.AbstractOverloadingSensitivityAlgorithm,
         Nothing}, u0::ReverseDiff.TrackedArray, p,
@@ -101,7 +101,7 @@ function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
 end
 
 # `AbstractArray{<:ReverseDiff.TrackedReal}`
-function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
+function DiffEqBase.solve_up(prob::DiffEqBase.AbstractDEProblem,
     sensealg::Union{
         SciMLBase.AbstractOverloadingSensitivityAlgorithm,
         Nothing},
@@ -112,7 +112,7 @@ function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
         kwargs...)
 end
 
-function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
+function DiffEqBase.solve_up(prob::DiffEqBase.AbstractDEProblem,
     sensealg::Union{
         SciMLBase.AbstractOverloadingSensitivityAlgorithm,
         Nothing}, u0,
@@ -121,7 +121,7 @@ function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
     DiffEqBase.solve_up(prob, sensealg, u0, reduce(vcat, p), args...; kwargs...)
 end
 
-function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
+function DiffEqBase.solve_up(prob::DiffEqBase.AbstractDEProblem,
     sensealg::Union{
         SciMLBase.AbstractOverloadingSensitivityAlgorithm,
         Nothing},
diff --git a/ext/DiffEqBaseTrackerExt.jl b/ext/DiffEqBaseTrackerExt.jl
index 362537f60..618d2d017 100644
--- a/ext/DiffEqBaseTrackerExt.jl
+++ b/ext/DiffEqBaseTrackerExt.jl
@@ -67,7 +67,7 @@ end
 end
 @inline DiffEqBase.ODE_DEFAULT_NORM(u::Tracker.TrackedReal, t::Tracker.TrackedReal) = abs(u)
 
-function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
+function DiffEqBase.solve_up(prob::DiffEqBase.AbstractDEProblem,
     sensealg::Union{
         SciMLBase.AbstractOverloadingSensitivityAlgorithm,
         Nothing}, u0::Tracker.TrackedArray,
@@ -75,7 +75,7 @@ function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
     Tracker.track(DiffEqBase.solve_up, prob, sensealg, u0, p, args...; kwargs...)
 end
 
-function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
+function DiffEqBase.solve_up(prob::DiffEqBase.AbstractDEProblem,
     sensealg::Union{
         SciMLBase.AbstractOverloadingSensitivityAlgorithm,
         Nothing}, u0::Tracker.TrackedArray, p, args...;
@@ -83,7 +83,7 @@ function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
     Tracker.track(DiffEqBase.solve_up, prob, sensealg, u0, p, args...; kwargs...)
 end
 
-function DiffEqBase.solve_up(prob::DiffEqBase.DEProblem,
+function DiffEqBase.solve_up(prob::DiffEqBase.AbstractDEProblem,
     sensealg::Union{
         SciMLBase.AbstractOverloadingSensitivityAlgorithm,
         Nothing}, u0, p::Tracker.TrackedArray, args...;
diff --git a/src/DiffEqBase.jl b/src/DiffEqBase.jl
index 0053aae55..0ece946cb 100644
--- a/src/DiffEqBase.jl
+++ b/src/DiffEqBase.jl
@@ -48,19 +48,19 @@ PrecompileTools.@recompile_invalidations begin
     import PreallocationTools
 
     import FunctionWrappersWrappers
-    
+
     using SciMLBase
 
     using SciMLOperators: AbstractSciMLOperator, AbstractSciMLScalarOperator
 
-    using SciMLBase: @def, DEIntegrator, DEProblem,
+    using SciMLBase: @def, DEIntegrator, AbstractDEProblem,
         AbstractDiffEqInterpolation,
         DECallback, AbstractDEOptions, DECache, AbstractContinuousCallback,
         AbstractDiscreteCallback, AbstractLinearProblem, AbstractNonlinearProblem,
         AbstractOptimizationProblem, AbstractSteadyStateProblem,
         AbstractJumpProblem,
         AbstractNoiseProblem, AbstractEnsembleProblem, AbstractDynamicalODEProblem,
-        DEAlgorithm, StandardODEProblem, AbstractIntegralProblem,
+        AbstractDEAlgorithm, StandardODEProblem, AbstractIntegralProblem,
         AbstractSensitivityAlgorithm, AbstractODEAlgorithm,
         AbstractSDEAlgorithm, AbstractDDEAlgorithm, AbstractDAEAlgorithm,
         AbstractSDDEAlgorithm, AbstractRODEAlgorithm, DAEInitializationAlgorithm,
diff --git a/src/solve.jl b/src/solve.jl
index 76454839c..9db213086 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -7,7 +7,7 @@ NO_TSPAN_PROBS = Union{AbstractLinearProblem, AbstractNonlinearProblem,
     AbstractIntegralProblem, AbstractSteadyStateProblem,
     AbstractJumpProblem}
 
-has_kwargs(_prob::DEProblem) = has_kwargs(typeof(_prob))
+has_kwargs(_prob::AbstractDEProblem) = has_kwargs(typeof(_prob))
 Base.@pure __has_kwargs(::Type{T}) where {T} = :kwargs ∈ fieldnames(T)
 has_kwargs(::Type{T}) where {T} = __has_kwargs(T)
 
@@ -196,7 +196,7 @@ end
 const NON_SOLVER_MESSAGE = """
                            The arguments to solve are incorrect.
                            The second argument must be a solver choice, `solve(prob,alg)`
-                           where `alg` is a `<: DEAlgorithm`, e.g. `Tsit5()`.
+                           where `alg` is a `<: AbstractDEAlgorithm`, e.g. `Tsit5()`.
 
                            Please double check the arguments being sent to the solver.
 
@@ -484,7 +484,7 @@ function init_call(_prob, args...; merge_callbacks = true, kwargshandle = nothin
     end
 end
 
-function init(prob::Union{DEProblem, NonlinearProblem}, args...; sensealg = nothing,
+function init(prob::Union{AbstractDEProblem, NonlinearProblem}, args...; sensealg = nothing,
     u0 = nothing, p = nothing, kwargs...)
     if sensealg === nothing && haskey(prob.kwargs, :sensealg)
         sensealg = prob.kwargs[:sensealg]
@@ -500,7 +500,7 @@ function init(prob::AbstractJumpProblem, args...; kwargs...)
     init_call(prob, args...; kwargs...)
 end
 
-function init_up(prob::DEProblem, sensealg, u0, p, args...; kwargs...)
+function init_up(prob::AbstractDEProblem, sensealg, u0, p, args...; kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
     if isnothing(alg) # Default algorithm handling
         _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
@@ -566,7 +566,7 @@ mutable struct NullODEIntegrator{IIP, ProbType, T, SolType, F, P} <:
     f::F
     p::P
 end
-function build_null_integrator(prob::DEProblem, args...;
+function build_null_integrator(prob::AbstractDEProblem, args...;
     kwargs...)
     sol = solve(prob, args...; kwargs...)
     return NullODEIntegrator{isinplace(prob), typeof(prob), eltype(prob.tspan), typeof(sol),
@@ -592,7 +592,7 @@ function step!(integ::NullODEIntegrator, dt = nothing, stop_at_tdt = false)
     return nothing
 end
 
-function build_null_solution(prob::DEProblem, args...;
+function build_null_solution(prob::AbstractDEProblem, args...;
     saveat = (),
     save_everystep = true,
     save_on = true,
@@ -635,7 +635,7 @@ end
 
 """
 ```julia
-solve(prob::DEProblem, alg::Union{DEAlgorithm,Nothing}; kwargs...)
+solve(prob::AbstractDEProblem, alg::Union{AbstractDEAlgorithm,Nothing}; kwargs...)
 ```
 
 ## Arguments
@@ -914,7 +914,7 @@ the extension to other types is straightforward.
   to save size or because the user does not care about the others. Finally, with
   `progress = true` you are enabling the progress bar.
 """
-function solve(prob::DEProblem, args...; sensealg = nothing,
+function solve(prob::AbstractDEProblem, args...; sensealg = nothing,
     u0 = nothing, p = nothing, wrap = Val(true), kwargs...)
     if sensealg === nothing && haskey(prob.kwargs, :sensealg)
         sensealg = prob.kwargs[:sensealg]
@@ -987,8 +987,8 @@ function solve(prob::NonlinearProblem, args...; sensealg = nothing,
     end
 end
 
-function solve_up(prob::Union{DEProblem, NonlinearProblem}, sensealg, u0, p, args...;
-    kwargs...)
+function solve_up(prob::Union{AbstractDEProblem, NonlinearProblem}, sensealg, u0, p,
+    args...; kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
     if isnothing(alg) # Default algorithm handling
         _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
@@ -1070,12 +1070,12 @@ function get_concrete_problem(prob::AbstractEnsembleProblem, isadapt; kwargs...)
     prob
 end
 
-function solve(prob::PDEProblem, alg::DiffEqBase.DEAlgorithm, args...;
+function solve(prob::PDEProblem, alg::AbstractDEAlgorithm, args...;
     kwargs...)
     solve(prob.prob, alg, args...; kwargs...)
 end
 
-function init(prob::PDEProblem, alg::DiffEqBase.DEAlgorithm, args...;
+function init(prob::PDEProblem, alg::AbstractDEAlgorithm, args...;
     kwargs...)
     init(prob.prob, alg, args...; kwargs...)
 end
@@ -1266,27 +1266,27 @@ handle_distribution_u0(_u0) = _u0
 eval_u0(u0::Function) = true
 eval_u0(u0) = false
 
-function __solve(prob::DEProblem, args...; default_set = false, second_time = false,
+function __solve(prob::AbstractDEProblem, args...; default_set = false, second_time = false,
     kwargs...)
     if second_time
         throw(NoDefaultAlgorithmError())
-    elseif length(args) > 0 && !(typeof(args[1]) <: Union{Nothing, DEAlgorithm})
+    elseif length(args) > 0 && !(typeof(args[1]) <: Union{Nothing, AbstractDEAlgorithm})
         throw(NonSolverError())
     else
-        __solve(prob::DEProblem, nothing, args...; default_set = false, second_time = true,
-            kwargs...)
+        __solve(prob::AbstractDEProblem, nothing, args...; default_set = false,
+            second_time = true, kwargs...)
     end
 end
 
-function __init(prob::DEProblem, args...; default_set = false, second_time = false,
+function __init(prob::AbstractDEProblem, args...; default_set = false, second_time = false,
     kwargs...)
     if second_time
         throw(NoDefaultAlgorithmError())
-    elseif length(args) > 0 && !(typeof(args[1]) <: Union{Nothing, DEAlgorithm})
+    elseif length(args) > 0 && !(typeof(args[1]) <: Union{Nothing, AbstractDEAlgorithm})
         throw(NonSolverError())
     else
-        __init(prob::DEProblem, nothing, args...; default_set = false, second_time = true,
-            kwargs...)
+        __init(prob::AbstractDEProblem, nothing, args...; default_set = false,
+            second_time = true, kwargs...)
     end
 end
 
@@ -1360,7 +1360,7 @@ Ignores all adjoint definitions (i.e. `sensealg`) and proceeds to do standard
 AD through the `solve` functions. Generally only used internally for implementing
 discrete sensitivity algorithms.
 """
-struct SensitivityADPassThrough <: SciMLBase.DEAlgorithm end
+struct SensitivityADPassThrough <: AbstractDEAlgorithm end
 
 function ChainRulesCore.frule(::typeof(solve_up), prob,
     sensealg::Union{Nothing, AbstractSensitivityAlgorithm},
@@ -1370,7 +1370,7 @@ function ChainRulesCore.frule(::typeof(solve_up), prob,
         kwargs...)
 end
 
-function ChainRulesCore.rrule(::typeof(solve_up), prob::SciMLBase.DEProblem,
+function ChainRulesCore.rrule(::typeof(solve_up), prob::AbstractDEProblem,
     sensealg::Union{Nothing, AbstractSensitivityAlgorithm},
     u0, p, args...;
     kwargs...)
@@ -1382,8 +1382,8 @@ end
 ### Legacy Dispatches to be Non-Breaking
 ###
 
-@deprecate concrete_solve(prob::SciMLBase.DEProblem,
-    alg::Union{SciMLBase.DEAlgorithm, Nothing},
+@deprecate concrete_solve(prob::AbstractDEProblem,
+    alg::Union{AbstractDEAlgorithm, Nothing},
     u0 = prob.u0, p = prob.p, args...; kwargs...) solve(prob, alg,
     args...;
     u0 = u0,
@@ -1459,7 +1459,7 @@ end
         else
             nothing
         end
-    elseif solve_args[1] isa DEAlgorithm
+    elseif solve_args[1] isa AbstractDEAlgorithm
         solve_args[1]
     else
         nothing

From dc0e5c1a05ea63e4627e424fa492c8f391fcded4 Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Sat, 7 Oct 2023 17:56:39 +0330
Subject: [PATCH 04/12] fix unnecessary type check

---
 src/solve.jl | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/solve.jl b/src/solve.jl
index 9db213086..76201a01c 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -1273,8 +1273,7 @@ function __solve(prob::AbstractDEProblem, args...; default_set = false, second_t
     elseif length(args) > 0 && !(typeof(args[1]) <: Union{Nothing, AbstractDEAlgorithm})
         throw(NonSolverError())
     else
-        __solve(prob::AbstractDEProblem, nothing, args...; default_set = false,
-            second_time = true, kwargs...)
+        __solve(prob, nothing, args...; default_set = false, second_time = true, kwargs...)
     end
 end
 
@@ -1285,8 +1284,7 @@ function __init(prob::AbstractDEProblem, args...; default_set = false, second_ti
     elseif length(args) > 0 && !(typeof(args[1]) <: Union{Nothing, AbstractDEAlgorithm})
         throw(NonSolverError())
     else
-        __init(prob::AbstractDEProblem, nothing, args...; default_set = false,
-            second_time = true, kwargs...)
+        __init(prob, nothing, args...; default_set = false, second_time = true, kwargs...)
     end
 end
 

From bbe7e8581d94bb235133c3d63a5e89be6bb8b7d4 Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Thu, 19 Oct 2023 01:09:09 +0330
Subject: [PATCH 05/12] use `AbstractSciMLAlgorithm`

---
 src/solve.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/solve.jl b/src/solve.jl
index 76201a01c..98ce33924 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -1457,7 +1457,7 @@ end
         else
             nothing
         end
-    elseif solve_args[1] isa AbstractDEAlgorithm
+    elseif solve_args[1] isa SciMLBase.AbstractSciMLAlgorithm
         solve_args[1]
     else
         nothing

From a390882248d3dfec8f06da19cab9bbb6941f5810 Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Thu, 19 Oct 2023 01:09:37 +0330
Subject: [PATCH 06/12] use `first` instead of `[1]`

---
 src/solve.jl | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/solve.jl b/src/solve.jl
index 98ce33924..046613aaa 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -573,7 +573,7 @@ function build_null_integrator(prob::AbstractDEProblem, args...;
         typeof(prob.f), typeof(prob.p),
     }(Float64[],
         Float64[],
-        first(prob.tspan),
+        prob.tspan[1],
         prob,
         sol,
         prob.f,
@@ -1015,7 +1015,7 @@ function solve_call(prob::SteadyStateProblem,
 end
 
 function solve(prob::EnsembleProblem, args...; kwargs...)
-    if isempty(args) || length(args) == 1 && typeof(args[1]) <: EnsembleAlgorithm
+    if isempty(args) || length(args) == 1 && typeof(first(args)) <: EnsembleAlgorithm
         __solve(prob, nothing, args...; kwargs...)
     else
         __solve(prob, args...; kwargs...)
@@ -1270,7 +1270,7 @@ function __solve(prob::AbstractDEProblem, args...; default_set = false, second_t
     kwargs...)
     if second_time
         throw(NoDefaultAlgorithmError())
-    elseif length(args) > 0 && !(typeof(args[1]) <: Union{Nothing, AbstractDEAlgorithm})
+    elseif length(args) > 0 && !(typeof(first(args)) <: Union{Nothing, AbstractDEAlgorithm})
         throw(NonSolverError())
     else
         __solve(prob, nothing, args...; default_set = false, second_time = true, kwargs...)
@@ -1281,7 +1281,7 @@ function __init(prob::AbstractDEProblem, args...; default_set = false, second_ti
     kwargs...)
     if second_time
         throw(NoDefaultAlgorithmError())
-    elseif length(args) > 0 && !(typeof(args[1]) <: Union{Nothing, AbstractDEAlgorithm})
+    elseif length(args) > 0 && !(typeof(first(args)) <: Union{Nothing, AbstractDEAlgorithm})
         throw(NonSolverError())
     else
         __init(prob, nothing, args...; default_set = false, second_time = true, kwargs...)
@@ -1449,7 +1449,7 @@ function _solve_forward(prob, sensealg, u0, p, originator, args...; merge_callba
 end
 
 @inline function extract_alg(solve_args, solve_kwargs, prob_kwargs)
-    if isempty(solve_args) || isnothing(solve_args[1])
+    if isempty(solve_args) || isnothing(first(solve_args))
         if haskey(solve_kwargs, :alg)
             solve_kwargs[:alg]
         elseif haskey(prob_kwargs, :alg)
@@ -1457,8 +1457,8 @@ end
         else
             nothing
         end
-    elseif solve_args[1] isa SciMLBase.AbstractSciMLAlgorithm
-        solve_args[1]
+    elseif first(solve_args) isa SciMLBase.AbstractSciMLAlgorithm
+        first(solve_args)
     else
         nothing
     end

From bf1eeb78b35e13a0a39afdfd31b4441f75b88e61 Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Thu, 19 Oct 2023 01:20:17 +0330
Subject: [PATCH 07/12] update `solve(prob::EnsembleProblem`

---
 src/solve.jl | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/solve.jl b/src/solve.jl
index 046613aaa..7fb9feb54 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -1015,10 +1015,11 @@ function solve_call(prob::SteadyStateProblem,
 end
 
 function solve(prob::EnsembleProblem, args...; kwargs...)
-    if isempty(args) || length(args) == 1 && typeof(first(args)) <: EnsembleAlgorithm
-        __solve(prob, nothing, args...; kwargs...)
+    alg = extract_alg(args, kwargs, prob.kwargs)
+    if length(args) > 1
+        __solve(prob, alg, Base.tail(args)...; kwargs...)
     else
-        __solve(prob, args...; kwargs...)
+        __solve(prob, alg; kwargs...)
     end
 end
 function solve(prob::SciMLBase.WeightedEnsembleProblem, args...; kwargs...)

From 93045ea62cee4dc8d21a8a5f907d5e6f7748b7c6 Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Thu, 19 Oct 2023 01:21:30 +0330
Subject: [PATCH 08/12] move `extract_alg` to a better place

---
 src/solve.jl | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/src/solve.jl b/src/solve.jl
index 7fb9feb54..4c71fc554 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -1352,6 +1352,22 @@ function check_prob_alg_pairing(prob, alg)
     end
 end
 
+@inline function extract_alg(solve_args, solve_kwargs, prob_kwargs)
+    if isempty(solve_args) || isnothing(first(solve_args))
+        if haskey(solve_kwargs, :alg)
+            solve_kwargs[:alg]
+        elseif haskey(prob_kwargs, :alg)
+            prob_kwargs[:alg]
+        else
+            nothing
+        end
+    elseif first(solve_args) isa SciMLBase.AbstractSciMLAlgorithm
+        first(solve_args)
+    else
+        nothing
+    end
+end
+
 ################### Differentiation
 
 """
@@ -1449,22 +1465,6 @@ function _solve_forward(prob, sensealg, u0, p, originator, args...; merge_callba
     end
 end
 
-@inline function extract_alg(solve_args, solve_kwargs, prob_kwargs)
-    if isempty(solve_args) || isnothing(first(solve_args))
-        if haskey(solve_kwargs, :alg)
-            solve_kwargs[:alg]
-        elseif haskey(prob_kwargs, :alg)
-            prob_kwargs[:alg]
-        else
-            nothing
-        end
-    elseif first(solve_args) isa SciMLBase.AbstractSciMLAlgorithm
-        first(solve_args)
-    else
-        nothing
-    end
-end
-
 ####
 # Catch undefined AD overload cases
 

From 820758cd0cb53154d40155299e45792366758aa6 Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Thu, 19 Oct 2023 01:32:07 +0330
Subject: [PATCH 09/12] fix: `alg` shouldn't be repeated

---
 src/solve.jl | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/solve.jl b/src/solve.jl
index 4c71fc554..525fa4e3b 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -1427,11 +1427,11 @@ function _solve_adjoint(prob, sensealg, u0, p, originator, args...; merge_callba
         kwargs = isempty(_prob.kwargs) ? kwargs : merge(values(_prob.kwargs), kwargs)
     end
 
-    if isempty(args)
-        _concrete_solve_adjoint(_prob, alg, sensealg, u0, p, originator; kwargs...)
-    else
+    if length(args) > 1
         _concrete_solve_adjoint(_prob, alg, sensealg, u0, p, originator,
             Base.tail(args)...; kwargs...)
+    else
+        _concrete_solve_adjoint(_prob, alg, sensealg, u0, p, originator; kwargs...)
     end
 end
 
@@ -1457,11 +1457,11 @@ function _solve_forward(prob, sensealg, u0, p, originator, args...; merge_callba
         kwargs = isempty(_prob.kwargs) ? kwargs : merge(values(_prob.kwargs), kwargs)
     end
 
-    if isempty(args)
-        _concrete_solve_forward(_prob, alg, sensealg, u0, p, originator; kwargs...)
-    else
+    if length(args) > 1
         _concrete_solve_forward(_prob, alg, sensealg, u0, p, originator,
             Base.tail(args)...; kwargs...)
+    else
+        _concrete_solve_forward(_prob, alg, sensealg, u0, p, originator; kwargs...)
     end
 end
 

From 1574722d7cf36b533fc70d99e37007a6548a83f4 Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Thu, 19 Oct 2023 03:19:06 +0330
Subject: [PATCH 10/12] fix: `isadaptive` error

---
 src/solve.jl | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/solve.jl b/src/solve.jl
index 525fa4e3b..8ea6fa391 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -502,7 +502,7 @@ end
 
 function init_up(prob::AbstractDEProblem, sensealg, u0, p, args...; kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
-    if isnothing(alg) # Default algorithm handling
+    if isnothing(alg) || !(alg isa AbstractDEAlgorithm) # Default algorithm handling
         _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
             p = p, kwargs...)
         init_call(_prob, args...; kwargs...)
@@ -990,7 +990,7 @@ end
 function solve_up(prob::Union{AbstractDEProblem, NonlinearProblem}, sensealg, u0, p,
     args...; kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
-    if isnothing(alg) # Default algorithm handling
+    if isnothing(alg) || !(alg isa AbstractDEAlgorithm) # Default algorithm handling
         _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
             p = p, kwargs...)
         solve_call(_prob, args...; kwargs...)
@@ -1408,7 +1408,7 @@ end
 function _solve_adjoint(prob, sensealg, u0, p, originator, args...; merge_callbacks = true,
     kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
-    if isnothing(alg) # Default algorithm handling
+    if isnothing(alg) || !(alg isa AbstractDEAlgorithm) # Default algorithm handling
         _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
             p = p, kwargs...)
     else
@@ -1438,7 +1438,7 @@ end
 function _solve_forward(prob, sensealg, u0, p, originator, args...; merge_callbacks = true,
     kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
-    if isnothing(alg) # Default algorithm handling
+    if isnothing(alg) || !(alg isa AbstractDEAlgorithm) # Default algorithm handling
         _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
             p = p, kwargs...)
     else

From c1b95fce8e1bb3535054950a13ffe106b4dc7a7b Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Thu, 19 Oct 2023 03:28:43 +0330
Subject: [PATCH 11/12] replace `typeof(...) <:` by `isa`

---
 src/solve.jl | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/solve.jl b/src/solve.jl
index 8ea6fa391..6ec3c8d66 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -477,7 +477,7 @@ function init_call(_prob, args...; merge_callbacks = true, kwargshandle = nothin
     if _prob isa Union{ODEProblem, DAEProblem} && isnothing(_prob.u0)
         build_null_integrator(_prob, args...; kwargs...)
     elseif hasfield(typeof(_prob), :f) && hasfield(typeof(_prob.f), :f) &&
-           typeof(_prob.f.f) <: EvalFunc
+           _prob.f.f isa EvalFunc
         Base.invokelatest(__init, _prob, args...; kwargs...)#::T
     else
         __init(_prob, args...; kwargs...)#::T
@@ -503,7 +503,7 @@ end
 function init_up(prob::AbstractDEProblem, sensealg, u0, p, args...; kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
     if isnothing(alg) || !(alg isa AbstractDEAlgorithm) # Default algorithm handling
-        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
+        _prob = get_concrete_problem(prob, !(prob isa DiscreteProblem); u0 = u0,
             p = p, kwargs...)
         init_call(_prob, args...; kwargs...)
     else
@@ -549,7 +549,7 @@ function solve_call(_prob, args...; merge_callbacks = true, kwargshandle = nothi
     end
 
     if hasfield(typeof(_prob), :f) && hasfield(typeof(_prob.f), :f) &&
-       typeof(_prob.f.f) <: EvalFunc
+       _prob.f.f isa EvalFunc
         Base.invokelatest(__solve, _prob, args...; kwargs...)#::T
     else
         __solve(_prob, args...; kwargs...)#::T
@@ -991,7 +991,7 @@ function solve_up(prob::Union{AbstractDEProblem, NonlinearProblem}, sensealg, u0
     args...; kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
     if isnothing(alg) || !(alg isa AbstractDEAlgorithm) # Default algorithm handling
-        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
+        _prob = get_concrete_problem(prob, !(prob isa DiscreteProblem); u0 = u0,
             p = p, kwargs...)
         solve_call(_prob, args...; kwargs...)
     else
@@ -1271,7 +1271,7 @@ function __solve(prob::AbstractDEProblem, args...; default_set = false, second_t
     kwargs...)
     if second_time
         throw(NoDefaultAlgorithmError())
-    elseif length(args) > 0 && !(typeof(first(args)) <: Union{Nothing, AbstractDEAlgorithm})
+    elseif length(args) > 0 && !(first(args) isa Union{Nothing, AbstractDEAlgorithm})
         throw(NonSolverError())
     else
         __solve(prob, nothing, args...; default_set = false, second_time = true, kwargs...)
@@ -1282,7 +1282,7 @@ function __init(prob::AbstractDEProblem, args...; default_set = false, second_ti
     kwargs...)
     if second_time
         throw(NoDefaultAlgorithmError())
-    elseif length(args) > 0 && !(typeof(first(args)) <: Union{Nothing, AbstractDEAlgorithm})
+    elseif length(args) > 0 && !(first(args) isa Union{Nothing, AbstractDEAlgorithm})
         throw(NonSolverError())
     else
         __init(prob, nothing, args...; default_set = false, second_time = true, kwargs...)
@@ -1409,7 +1409,7 @@ function _solve_adjoint(prob, sensealg, u0, p, originator, args...; merge_callba
     kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
     if isnothing(alg) || !(alg isa AbstractDEAlgorithm) # Default algorithm handling
-        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
+        _prob = get_concrete_problem(prob, !(prob isa DiscreteProblem); u0 = u0,
             p = p, kwargs...)
     else
         _prob = get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)
@@ -1439,7 +1439,7 @@ function _solve_forward(prob, sensealg, u0, p, originator, args...; merge_callba
     kwargs...)
     alg = extract_alg(args, kwargs, prob.kwargs)
     if isnothing(alg) || !(alg isa AbstractDEAlgorithm) # Default algorithm handling
-        _prob = get_concrete_problem(prob, !(typeof(prob) <: DiscreteProblem); u0 = u0,
+        _prob = get_concrete_problem(prob, !(prob isa DiscreteProblem); u0 = u0,
             p = p, kwargs...)
     else
         _prob = get_concrete_problem(prob, isadaptive(alg); u0 = u0, p = p, kwargs...)

From 319fd6250f0d1acc0256912ae4982898e577b14b Mon Sep 17 00:00:00 2001
From: Hossein Pourbozorg <prbzrg@gmail.com>
Date: Thu, 19 Oct 2023 11:58:56 +0330
Subject: [PATCH 12/12] fix : "type EnsembleProblem has no field kwargs"

---
 src/solve.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/solve.jl b/src/solve.jl
index 6ec3c8d66..2c96f72a6 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -1015,7 +1015,7 @@ function solve_call(prob::SteadyStateProblem,
 end
 
 function solve(prob::EnsembleProblem, args...; kwargs...)
-    alg = extract_alg(args, kwargs, prob.kwargs)
+    alg = extract_alg(args, kwargs, kwargs)
     if length(args) > 1
         __solve(prob, alg, Base.tail(args)...; kwargs...)
     else