Simplify the termination code

Author: avik-pal

.JuliaFormatter.toml

@@ -1 +1,2 @@
-style = "sciml"
+style = "sciml"
+annotate_untyped_fields_with_any = false

.github/workflows/Downstream.yml

@@ -83,6 +83,9 @@ jobs:
             @info "Not compatible with this release. No problem." exception=err
             exit(0)  # Exit immediately, as a success
           end
+        env:
+          RETESTITEMS_NWORKERS: 4
+          RETESTITEMS_NWORKER_THREADS: 2
       - uses: julia-actions/julia-processcoverage@v1
       - uses: codecov/codecov-action@v4
         with:

Project.toml

@@ -5,11 +5,13 @@ version = "6.148.0"
 
 [deps]
 ArrayInterface = "4fba245c-0d91-5ea0-9b3e-6abc04ee57a9"
+ConcreteStructs = "2569d6c7-a4a2-43d3-a901-331e8e4be471"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 DocStringExtensions = "ffbed154-4ef7-542d-bbb7-c09d3a79fcae"
 EnumX = "4e289a0a-7415-4d19-859d-a7e5c4648b56"
 EnzymeCore = "f151be2c-9106-41f4-ab19-57ee4f262869"
 FastBroadcast = "7034ab61-46d4-4ed7-9d0f-46aef9175898"
+FastClosures = "9aa1b823-49e4-5ca5-8b0f-3971ec8bab6a"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 FunctionWrappers = "069b7b12-0de2-55c6-9aab-29f3d0a68a2e"
 FunctionWrappersWrappers = "77dc65aa-8811-40c2-897b-53d922fa7daf"
@@ -60,12 +62,14 @@ DiffEqBaseUnitfulExt = "Unitful"
 [compat]
 ArrayInterface = "7.8"
 ChainRulesCore = "1"
+ConcreteStructs = "0.2.3"
 DataStructures = "0.18"
 Distributions = "0.25"
 DocStringExtensions = "0.9"
 EnumX = "1"
 EnzymeCore = "0.5, 0.6, 0.7"
 FastBroadcast = "0.2"
+FastClosures = "0.3.2"
 ForwardDiff = "0.10"
 FunctionWrappers = "1.0"
 FunctionWrappersWrappers = "0.1"

src/DiffEqBase.jl

@@ -37,6 +37,9 @@ PrecompileTools.@recompile_invalidations begin
 
     using Markdown
 
+    using ConcreteStructs: @concrete
+    using FastClosures: @closure
+
     # Could be made optional/glue
     import PreallocationTools
 
@@ -138,6 +141,7 @@ include("common_defaults.jl")
 include("solve.jl")
 include("internal_euler.jl")
 include("forwarddiff.jl")
+include("termination_conditions_deprecated.jl")  # TODO: remove in the next major release
 include("termination_conditions.jl")
 include("norecompile.jl")