Fix static arrays

Project.toml

@@ -1,7 +1,7 @@
 name = "NonlinearSolve"
 uuid = "8913a72c-1f9b-4ce2-8d82-65094dcecaec"
 authors = ["SciML"]
-version = "3.5.4"
+version = "3.5.5"
 
 [deps]
 ADTypes = "47edcb42-4c32-4615-8424-f2b9edc5f35b"

src/internal/linear_solve.jl

@@ -49,15 +49,32 @@ function reinit_cache!(cache::LinearSolverCache, args...; kwargs...)
     cache.nfactors = 0
 end
 
+@inline __fix_strange_type_combination(A, b, u) = u
+@inline function __fix_strange_type_combination(A, b, u::SArray)
+    A isa SArray && b isa SArray && return u
+    @warn "Solving Linear System A::$(typeof(A)) x::$(typeof(u)) = b::$(typeof(u)) is not \
+           properly supported. Converting `x` to a mutable array. Check the return type \
+           of the nonlinear function provided for optimal performance." maxlog=1
+    return MArray(u)
+end
+
+@inline __set_lincache_u!(cache, u) = (cache.lincache.u = u)
+@inline function __set_lincache_u!(cache, u::SArray)
+    cache.lincache.u isa MArray && return __set_lincache_u!(cache, MArray(u))
+    cache.lincache.u = u
+end
+
 function LinearSolverCache(alg, linsolve, A, b, u; kwargs...)
+    u_fixed = __fix_strange_type_combination(A, b, u)
+
     if (A isa Number && b isa Number) || (linsolve === nothing && A isa SMatrix) ||
        (A isa Diagonal) || (linsolve isa typeof(\))
         return LinearSolverCache(nothing, nothing, A, b, nothing, 0, 0)
     end
-    @bb u_ = copy(u)
+    @bb u_ = copy(u_fixed)
     linprob = LinearProblem(A, b; u0 = u_, kwargs...)
 
-    weight = __init_ones(u)
+    weight = __init_ones(u_fixed)
     if __hasfield(alg, Val(:precs))
         precs = alg.precs
         Pl_, Pr_ = precs(A, nothing, u, nothing, nothing, nothing, nothing, nothing,
@@ -97,7 +114,7 @@ function (cache::LinearSolverCache)(; A = nothing, b = nothing, linu = nothing,
 
     __update_A!(cache, A, reuse_A_if_factorization)
     b !== nothing && (cache.lincache.b = b)
-    linu !== nothing && (cache.lincache.u = linu)
+    linu !== nothing && __set_lincache_u!(cache, linu)
 
     Plprev = cache.lincache.Pl isa ComposePreconditioner ? cache.lincache.Pl.outer :
              cache.lincache.Pl

test/misc/polyalg_tests.jl

@@ -178,7 +178,7 @@ end
 end
 
 @testitem "[OOP] Infeasible" setup=[InfeasibleFunction] begin
-    using StaticArrays
+    using LinearAlgebra, StaticArrays
 
     u0 = [0.0, 0.0, 0.0]
     prob = NonlinearProblem(f1_infeasible, u0)
@@ -189,8 +189,12 @@ end
 
     u0 = @SVector [0.0, 0.0, 0.0]
     prob = NonlinearProblem(f1_infeasible, u0)
-    sol = solve(prob)
 
-    @test all(!isnan, sol.u)
-    @test !SciMLBase.successful_retcode(sol.retcode)
+    try
+        sol = solve(prob)
+        @test all(!isnan, sol.u)
+        @test !SciMLBase.successful_retcode(sol.retcode)
+    catch err
+        @test err isa LinearAlgebra.SingularException
+    end
 end