From ad8f2ce35deb8f3cd805fbf1dc86c658f8e5af09 Mon Sep 17 00:00:00 2001
From: Oscar Dowson <o.dowson@gmail.com>
Date: Mon, 7 Sep 2026 13:41:43 +1200
Subject: [PATCH] [Bridges] fix modifying SplitIntervaBridge with
 Interval(-Inf, Inf)

---
 .../Constraint/bridges/SplitIntervalBridge.jl        |  6 ++++++
 test/Bridges/Constraint/test_SplitIntervalBridge.jl  | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/src/Bridges/Constraint/bridges/SplitIntervalBridge.jl b/src/Bridges/Constraint/bridges/SplitIntervalBridge.jl
index a0c789f932..af393a1863 100644
--- a/src/Bridges/Constraint/bridges/SplitIntervalBridge.jl
+++ b/src/Bridges/Constraint/bridges/SplitIntervalBridge.jl
@@ -354,6 +354,9 @@ function MOI.modify(
     if bridge.upper !== nothing
         MOI.modify(model, bridge.upper, change)
     end
+    if bridge.lower === bridge.upper === nothing
+        bridge.func = MOI.Utilities.modify_function(bridge.func, change)
+    end
     return
 end
 
@@ -369,6 +372,9 @@ function MOI.set(
     if bridge.upper !== nothing
         MOI.set(model, MOI.ConstraintFunction(), bridge.upper, func)
     end
+    if bridge.lower === bridge.upper === nothing
+        bridge.func = func
+    end
     return
 end
 
diff --git a/test/Bridges/Constraint/test_SplitIntervalBridge.jl b/test/Bridges/Constraint/test_SplitIntervalBridge.jl
index 488a8a490a..1e6a56bde6 100644
--- a/test/Bridges/Constraint/test_SplitIntervalBridge.jl
+++ b/test/Bridges/Constraint/test_SplitIntervalBridge.jl
@@ -523,6 +523,18 @@ function test_modify_set()
     return
 end
 
+function test_split_interval_free_modify()
+    inner = MOI.Utilities.Model{Float64}()
+    model = MOI.Bridges.Constraint.SplitInterval{Float64}(inner)
+    x, y = MOI.add_variable(model), MOI.add_variable(model)
+    ci = MOI.add_constraint(model, 1.0 * x, MOI.Interval(-Inf, Inf))
+    MOI.modify(model, ci, MOI.ScalarCoefficientChange(y, 2.0))
+    @test ≈(MOI.get(model, MOI.ConstraintFunction(), ci), 1.0 * x + 2.0 * y)
+    MOI.set(model, MOI.ConstraintFunction(), ci, 3.0 * x + 4.0 * y)
+    @test ≈(MOI.get(model, MOI.ConstraintFunction(), ci), 3.0 * x + 4.0 * y)
+    return
+end
+
 end  # module
 
 TestConstraintSplitInterval.runtests()