Add DataStructures v0.17-v0.19 compatibility with version branching

- Update Project.toml compat to support v0.17, v0.18, and v0.19
- Add conditional imports for IntDisjointSet (v0.19) vs IntDisjointSets (v0.17-v0.18)
- Add conditional Queue operations: push!/popfirst! (v0.19) vs enqueue!/dequeue! (v0.17-v0.18)
- Use @static if with pkgversion() to select appropriate functions at compile time
- Update IntDisjointSets usage in connectiongraph.jl to use IntDisjointSet alias

This maintains backward compatibility with v0.17 and v0.18 while adding v0.19 support.

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

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

Author: ChrisRackauckas

Project.toml

@@ -98,7 +98,7 @@ CommonSolve = "0.2.4"
 Compat = "3.42, 4"
 ConstructionBase = "1"
 DataInterpolations = "7, 8"
-DataStructures = "0.17, 0.18"
+DataStructures = "0.17, 0.18, 0.19"
 DeepDiffs = "1"
 DelayDiffEq = "5.61"
 DiffEqBase = "6.189.1"

src/ModelingToolkit.jl

@@ -29,6 +29,12 @@ using LinearAlgebra, SparseArrays
 using InteractiveUtils
 using JumpProcesses
 using DataStructures
+@static if pkgversion(DataStructures) >= v"0.19"
+    import DataStructures: IntDisjointSet
+else
+    import DataStructures: IntDisjointSets
+    const IntDisjointSet = IntDisjointSets
+end
 using Base.Threads
 using Latexify, Unitful, ArrayInterface
 using Setfield, ConstructionBase

src/systems/alias_elimination.jl

@@ -426,20 +426,32 @@ function topsort_equations(eqs, unknowns; check = true)
 
     q = Queue{Int}(neqs)
     for (i, d) in enumerate(degrees)
-        d == 0 && enqueue!(q, i)
+        @static if pkgversion(DataStructures) >= v"0.19"
+            d == 0 && push!(q, i)
+        else
+            d == 0 && enqueue!(q, i)
+        end
     end
 
     idx = 0
     ordered_eqs = similar(eqs, 0)
     sizehint!(ordered_eqs, neqs)
     while !isempty(q)
-        𝑠eq = dequeue!(q)
+        @static if pkgversion(DataStructures) >= v"0.19"
+            𝑠eq = popfirst!(q)
+        else
+            𝑠eq = dequeue!(q)
+        end
         idx += 1
         push!(ordered_eqs, eqs[𝑠eq])
         var = assigns[𝑠eq]
         for 𝑑eq in 𝑑neighbors(graph, var)
             degree = degrees[𝑑eq] = degrees[𝑑eq] - 1
-            degree == 0 && enqueue!(q, 𝑑eq)
+            @static if pkgversion(DataStructures) >= v"0.19"
+                degree == 0 && push!(q, 𝑑eq)
+            else
+                degree == 0 && enqueue!(q, 𝑑eq)
+            end
         end
     end
 

src/systems/connectiongraph.jl

@@ -455,7 +455,7 @@ function connectionsets(graph::HyperGraph{V}) where {V}
     invmap = graph.invmap
 
     # union all of the hyperedges
-    disjoint_sets = IntDisjointSets(length(invmap))
+    disjoint_sets = IntDisjointSet(length(invmap))
     for edge_i in 𝑠vertices(bigraph)
         hyperedge = 𝑠neighbors(bigraph, edge_i)
         isempty(hyperedge) && continue