[blegat]

The problem with deletion is that we have 219 possible function/set VectorOfConstraints containers and even thought they are empty we still need to compile the methods for them to delete variables in their functions.

Julia	Original first deletion	With workaround
1.10.12	0.56 s	0.13 s
1.13.3	18.35 s	0.72 s
1.14.0-alpha2	16.66 s	0.33 s
1.15.0-DEV.244	16.49 s	0.34 s

There is a runtime tradeoff: with three tiny constraints, warmed deletion increased from 0.19 to 0.97 μs, allocating 432 additional bytes per deletion.

Closes #3124

[odow]

The other option is

diff --git a/src/Utilities/struct_of_constraints.jl b/src/Utilities/struct_of_constraints.jl
index a376e2438..9f28b9d7b 100644
--- a/src/Utilities/struct_of_constraints.jl
+++ b/src/Utilities/struct_of_constraints.jl
@@ -33,12 +33,11 @@ function final_touch(model::StructOfConstraints, index_map)
 end
 
 function _throw_if_cannot_delete(model::StructOfConstraints, vis, fast_in_vis)
-    broadcastcall(model) do constrs
-        if constrs !== nothing
-            _throw_if_cannot_delete(constrs, vis, fast_in_vis)
-        end
-        return
+    function inner(@nospecialize constrs)
+        return _throw_if_cannot_delete(constrs, vis, fast_in_vis)
     end
+    inner(::Nothing) = nothing
+    broadcastcall(inner, model)
     return
 end
 
@@ -47,12 +46,11 @@ function _deleted_constraints(
     model::StructOfConstraints,
     vi,
 )
-    broadcastcall(model) do constrs
-        if constrs !== nothing
-            _deleted_constraints(callback, constrs, vi)
-        end
-        return
+    function inner(@nospecialize constrs)
+        return _deleted_constraints(callback, constrs, vi)
     end
+    inner(::Nothing) = nothing
+    broadcastcall(inner, model)
     return
 end