Replace EvalSol [1:end] .= broadcasts with copyto! across MIRK/FIRK/MIRKN

The `EvalSol.u[1:end] .= x` and `EvalSol.cache.k_discrete[1:end] .=`
patterns create unnecessary SubArray views under @views. Using copyto!
avoids the view allocation entirely.

Applied to MIRK, FIRK, and MIRKN loss functions.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ChrisRackauckas

lib/BoundaryValueDiffEqFIRK/src/firk.jl

@@ -1337,7 +1337,7 @@ end
     y_ = recursive_unflatten!(y, u)
     resids = [get_tmp(r, u) for r in residual]
     Φ!(resids[2:end], cache, y_, u, trait, constraint)
-    eval_sol.u[1:end] .= y_
+    copyto!(eval_sol.u, y_)
     eval_bc_residual!(resids[1], pt, bc!, eval_sol, p, mesh)
     recursive_flatten!(resid, resids)
     return nothing
@@ -1350,7 +1350,7 @@ end
     y_ = recursive_unflatten!(y, u)
     resids = [r for r in residual]
     Φ!(resids[2:end], cache, y_, u, trait, constraint)
-    eval_sol.u[1:end] .= y_
+    copyto!(eval_sol.u, y_)
     eval_bc_residual!(resids[1], pt, bc!, eval_sol, p, mesh)
     recursive_flatten!(resid, resids)
     return nothing
@@ -1410,7 +1410,7 @@ end
         u, p, y, pt::StandardBVProblem, bc::BC, mesh, cache, eval_sol, trait
     ) where {BC}
     y_ = recursive_unflatten!(y, u)
-    eval_sol.u[1:end] .= y_
+    copyto!(eval_sol.u, y_)
     resid_bc = eval_bc_residual(pt, bc, eval_sol, p, mesh)
     resid_co = Φ(cache, y_, u, trait)
     return vcat(resid_bc, mapreduce(vec, vcat, resid_co))

lib/BoundaryValueDiffEqMIRK/src/mirk.jl

@@ -441,8 +441,8 @@ end
     ) where {BC}
     y_ = recursive_unflatten!(y, u)
     Φ!(residual[2:end], cache, y_, u, trait, constraint)
-    EvalSol.u[1:end] .= __restructure_sol(y_, cache.in_size)
-    EvalSol.cache.k_discrete[1:end] .= cache.k_discrete
+    copyto!(EvalSol.u, __restructure_sol(y_, cache.in_size))
+    copyto!(EvalSol.cache.k_discrete, cache.k_discrete)
     eval_bc_residual!(get_tmp(residual[1], u), pt, bc!, EvalSol, p, mesh)
     recursive_flatten!(resid, residual, u)
     return nothing
@@ -454,8 +454,8 @@ end
     ) where {BC}
     y_ = recursive_unflatten!(y, u)
     Φ!(residual[2:end], cache, y_, u, trait, constraint)
-    EvalSol.u[1:end] .= __restructure_sol(y_, cache.in_size)
-    EvalSol.cache.k_discrete[1:end] .= cache.k_discrete
+    copyto!(EvalSol.u, __restructure_sol(y_, cache.in_size))
+    copyto!(EvalSol.cache.k_discrete, cache.k_discrete)
     eval_bc_residual!(residual[1], pt, bc!, EvalSol, p, mesh)
     recursive_flatten!(resid, residual)
     return nothing
@@ -515,8 +515,8 @@ end
     ) where {BC}
     y_ = recursive_unflatten!(y, u)
     resid_co = Φ(cache, y_, u, trait)
-    EvalSol.u[1:end] .= __restructure_sol(y_, cache.in_size)
-    EvalSol.cache.k_discrete[1:end] .= cache.k_discrete
+    copyto!(EvalSol.u, __restructure_sol(y_, cache.in_size))
+    copyto!(EvalSol.cache.k_discrete, cache.k_discrete)
     resid_bc = eval_bc_residual(pt, bc, EvalSol, p, mesh)
     return vcat(resid_bc, mapreduce(vec, vcat, resid_co))
 end

lib/BoundaryValueDiffEqMIRKN/src/mirkn.jl

@@ -385,10 +385,10 @@ end
     y_ = recursive_unflatten!(y, u)
     resids = [get_tmp(r, u) for r in residual]
     Φ!(resids[3:end], cache, y_, u, p)
-    EvalSol.u[1:end] .= __restructure_sol(y_[1:length(cache.mesh)], cache.in_size)
-    EvalSol.cache.k_discrete[1:end] .= cache.k_discrete
-    EvalDSol.u[1:end] .= __restructure_sol(y_[(length(cache.mesh) + 1):end], cache.in_size)
-    EvalDSol.cache.k_discrete[1:end] .= cache.k_discrete
+    copyto!(EvalSol.u, __restructure_sol(y_[1:length(cache.mesh)], cache.in_size))
+    copyto!(EvalSol.cache.k_discrete, cache.k_discrete)
+    copyto!(EvalDSol.u, __restructure_sol(y_[(length(cache.mesh) + 1):end], cache.in_size))
+    copyto!(EvalDSol.cache.k_discrete, cache.k_discrete)
     eval_bc_residual!(resids[1:2], pt, bc, EvalSol, EvalDSol, p, mesh)
     recursive_flatten!(resid, resids)
     return nothing
@@ -400,10 +400,10 @@ end
     ) where {BC}
     y_ = recursive_unflatten!(y, u)
     resid_co = Φ(cache, y_, u, p)
-    EvalSol.u[1:end] .= __restructure_sol(y_[1:length(cache.mesh)], cache.in_size)
-    EvalSol.cache.k_discrete[1:end] .= cache.k_discrete
-    EvalDSol.u[1:end] .= __restructure_sol(y_[(length(cache.mesh) + 1):end], cache.in_size)
-    EvalDSol.cache.k_discrete[1:end] .= cache.k_discrete
+    copyto!(EvalSol.u, __restructure_sol(y_[1:length(cache.mesh)], cache.in_size))
+    copyto!(EvalSol.cache.k_discrete, cache.k_discrete)
+    copyto!(EvalDSol.u, __restructure_sol(y_[(length(cache.mesh) + 1):end], cache.in_size))
+    copyto!(EvalDSol.cache.k_discrete, cache.k_discrete)
     resid_bc = eval_bc_residual(pt, bc, EvalSol, EvalDSol, p, mesh)
     return vcat(resid_bc, mapreduce(vec, vcat, resid_co))
 end