Fix type inference regression with PIController on Julia 1.10 LTS

lib/OrdinaryDiffEqCore/src/alg_utils.jl

@@ -380,30 +380,26 @@ function default_controller_v7(QT, alg)
 end
 
 function default_controller_v7(QT, alg::OrdinaryDiffEqCompositeAlgorithm)
-    return nothing # This forces a fall-back to the legacy implementation
-    # beta2 = convert(QT, beta2_default(alg.algs[1]))
-    # beta1 = convert(QT, beta1_default(alg.algs[1], beta2))
-    # return PIController(beta1, beta2)
-    # TODO Uncomment this code below to when removing the legacy controllers on OrdinaryDiffEq v7.
-    # return CompositeController(
-    #     __default_controller_v7(QT, alg.algs)
-    # )
-end
-
-# @generated function __default_controller_v7(
-#     QT, algs::T
-# ) where {
-#     T <: Tuple
-# }
-#     return Expr(
-#         :tuple,
-#         map(1:length(T.types)) do i
-#             :(
-#                 default_controller_v7(QT, algs[$i])
-#             )
-#         end...
-#     )
-# end
+    # Use CompositeController for type stability with composite algorithms
+    return CompositeController(
+        _default_controller_v7_tuple(QT, alg.algs)
+    )
+end
+
+@generated function _default_controller_v7_tuple(
+        QT, algs::T
+    ) where {
+        T <: Tuple
+    }
+    return Expr(
+        :tuple,
+        map(1:length(T.types)) do i
+            :(
+                default_controller_v7(QT, algs[$i])
+            )
+        end...
+    )
+end
 
 function legacy_default_controller(alg, cache, qoldinit, _beta1 = nothing, _beta2 = nothing)
     if ispredictive(alg)
@@ -420,6 +416,43 @@ end
 # TODO remove this when done
 default_controller(args...) = legacy_default_controller(args...)
 
+"""
+    new_controller_from_legacy_params(QT, alg, beta1, beta2, qmin, qmax, gamma, qsteady_min, qsteady_max, qoldinit)
+
+Create a new-style controller from legacy parameters. This is used for type stability
+when the user provides legacy controller parameters instead of a controller object.
+"""
+function new_controller_from_legacy_params(QT, alg, beta1, beta2, qmin, qmax, gamma, qsteady_min, qsteady_max, qoldinit)
+    if ispredictive(alg)
+        return NewPredictiveController(QT, alg;
+            qmin = qmin,
+            qmax = qmax,
+            gamma = gamma,
+            qsteady_min = qsteady_min,
+            qsteady_max = qsteady_max
+        )
+    elseif isstandard(alg)
+        return NewIController(QT, alg;
+            qmin = qmin,
+            qmax = qmax,
+            gamma = gamma,
+            qsteady_min = qsteady_min,
+            qsteady_max = qsteady_max
+        )
+    else # Default is PI-controller
+        return NewPIController(QT, alg;
+            beta1 = beta1,
+            beta2 = beta2,
+            qmin = qmin,
+            qmax = qmax,
+            gamma = gamma,
+            qsteady_min = qsteady_min,
+            qsteady_max = qsteady_max,
+            qoldinit = qoldinit
+        )
+    end
+end
+
 function _digest_beta1_beta2(alg, cache, ::Val{QT}, _beta1, _beta2) where {QT}
     if alg isa OrdinaryDiffEqCompositeAlgorithm
         beta2 = _beta2 === nothing ?

lib/OrdinaryDiffEqCore/src/solve.jl

@@ -63,7 +63,7 @@ function SciMLBase.__init(
         isoutofdomain = ODE_DEFAULT_ISOUTOFDOMAIN,
         unstable_check = ODE_DEFAULT_UNSTABLE_CHECK,
         verbose = Standard(),
-        controller = any((gamma, qmin, qmax, qsteady_min, qsteady_max, beta1, beta2, qoldinit) .!== nothing) ? nothing : default_controller_v7(determine_controller_datatype(prob.u0, internalnorm, prob.tspan), alg), # We have to reconstruct the old controller before breaking release.,
+        controller = default_controller_v7(determine_controller_datatype(prob.u0, internalnorm, prob.tspan), alg),
         timeseries_errors = true,
         dense_errors = false,
         advance_to_tstop = false,
@@ -503,7 +503,9 @@ function SciMLBase.__init(
 
     # The following code provides an upgrade path for users by preserving the old behavior.
     legacy_controller_parameters = (gamma, qmin, qmax, qsteady_min, qsteady_max, beta1, beta2, qoldinit)
-    if controller === nothing # We have to reconstruct the old controller before breaking release.
+    if controller === nothing # Fallback for composite algorithms or explicit controller=nothing
+        # Use the new controller constructor with legacy parameters for type stability
+        controller = new_controller_from_legacy_params(QT, _alg, beta1, beta2, qmin, qmax, gamma, qsteady_min, qsteady_max, qoldinit)
         if any(legacy_controller_parameters .== nothing)
             gamma = convert(QT, gamma === nothing ? gamma_default(alg) : gamma)
             qmin = convert(QT, qmin === nothing ? qmin_default(alg) : qmin)
@@ -512,7 +514,6 @@ function SciMLBase.__init(
             qsteady_max = convert(QT, qsteady_max === nothing ? qsteady_max_default(alg) : qsteady_max)
             qoldinit = convert(QT, qoldinit === nothing ? (anyadaptive(alg) ? 1 // 10^4 : 0) : qoldinit)
         end
-        controller = legacy_default_controller(_alg, cache, qoldinit, beta1, beta2)
     else # Controller has been passed
         gamma = hasfield(typeof(controller), :gamma) ? controller.gamma : gamma_default(alg)
         qmin = hasfield(typeof(controller), :qmin) ? controller.qmin : qmin_default(alg)