Fix OptimizationFunction{iip} to respect explicit iip parameter

Remove isinplace call from OptimizationFunction{iip} constructor when
iip is explicitly provided. This matches the behavior of ODEFunction
and fixes issue #1103 where functions that fail isinplace checks
(like compiled Reactant functions) cannot be used even when the user
explicitly specifies the iip parameter.

The isinplace check is kept for the non-parameterized
OptimizationFunction constructor where it's needed to infer the iip value.

Fixes #1103

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: ChrisRackauckas

src/scimlfunctions.jl

@@ -4279,7 +4279,6 @@ function OptimizationFunction{iip}(f, adtype::AbstractADType = NoAD();
         lag_hess_colorvec = nothing,
         initialization_data = __has_initialization_data(f) ? f.initialization_data :
                               nothing) where {iip}
-    isinplace(f, 2; has_two_dispatches = false, isoptimization = true)
     sys = sys_or_symbolcache(sys, syms, paramsyms)
     OptimizationFunction{
         iip, typeof(adtype), typeof(f), typeof(grad), typeof(fg), typeof(hess),

test/function_building_error_messages.jl

@@ -507,6 +507,14 @@ optf(u, p) = 1.0
 OptimizationFunction(optf)
 OptimizationProblem(optf, 1.0)
 
+# Test OptimizationFunction{iip} respects explicit iip parameter
+# This function would fail isinplace check due to method ambiguity
+struct ProblematicOptFunction end
+(::ProblematicOptFunction)(x, p) = sum(x.^2)
+# But when iip is explicitly provided, it should work without calling isinplace
+@test_nowarn OptimizationFunction{false}(ProblematicOptFunction())
+@test_nowarn OptimizationFunction{true}(ProblematicOptFunction())
+
 # BVPFunction
 
 bfoop(u, p, t) = u