[Bridges] error on set(_, ::ConstraintSet with variable and constraint bridges (#2472)

Author: odow

src/Bridges/bridge_optimizer.jl

@@ -1444,6 +1444,10 @@ function MOI.set(
     # mapped through the bridge substitution. This includes moving constants
     # into the set.
     if Variable.has_bridges(Variable.bridges(b))
+        if is_bridged(b, ci)
+            # If `ci` is also ConstraintBridged, then we give up as the current code path is known to contain unresolved issues, see https://github.com/jump-dev/MathOptInterface.jl/issues/2452
+            throw(MOI.SetAttributeNotAllowed(attr))
+        end
         func = MOI.get(b, MOI.ConstraintFunction(), ci)
         # Updating the set will not modify the function, so we don't care about
         # the first argument. We only care about the new set.

test/Bridges/bridge_optimizer.jl

@@ -1232,28 +1232,34 @@ function test_issue_2452_multiple_variable_bridges()
     index_map = MOI.copy_to(dest, src)
     set = MOI.get(dest, MOI.ConstraintSet(), index_map[c])
     @test set == MOI.EqualTo(3.0)
-    MOI.set(dest, MOI.ConstraintSet(), index_map[c], set)
-    @test MOI.get(dest, MOI.ConstraintSet(), index_map[c]) == set
-    new_set = MOI.EqualTo(2.0)
-    MOI.set(dest, MOI.ConstraintSet(), index_map[c], new_set)
-    @test MOI.get(dest, MOI.ConstraintSet(), index_map[c]) == new_set
+    @test_throws(
+        MOI.SetAttributeNotAllowed,
+        MOI.set(dest, MOI.ConstraintSet(), index_map[c], set),
+    )
     return
 end
 
-function test_issue_2452()
+function test_2452()
+    F, S = MOI.VectorAffineFunction{Float64}, MOI.Zeros
     src = MOI.Utilities.UniversalFallback(MOI.Utilities.Model{Float64}())
     x = MOI.add_variable(src)
     MOI.add_constraint(src, x, MOI.GreaterThan(1.0))
-    c = MOI.add_constraint(src, 2.0 * x, MOI.EqualTo(3.0))
+    set = MOI.EqualTo(3.0)
+    c = MOI.add_constraint(src, 2.0 * x, set)
     dest = MOI.instantiate(Model2452{Float64}; with_bridge_type = Float64)
     index_map = MOI.copy_to(dest, src)
-    set = MOI.get(dest, MOI.ConstraintSet(), index_map[c])
-    @test set == MOI.EqualTo(3.0)
-    MOI.set(dest, MOI.ConstraintSet(), index_map[c], set)
+    y = only(MOI.get(dest.model, MOI.ListOfVariableIndices()))
+    ci = only(MOI.get(dest.model, MOI.ListOfConstraintIndices{F,S}()))
     @test MOI.get(dest, MOI.ConstraintSet(), index_map[c]) == set
-    new_set = MOI.EqualTo(2.0)
-    MOI.set(dest, MOI.ConstraintSet(), index_map[c], new_set)
-    @test MOI.get(dest, MOI.ConstraintSet(), index_map[c]) == new_set
+    @test ≈(
+        MOI.get(dest.model, MOI.ConstraintFunction(), ci),
+        MOI.Utilities.operate(vcat, Float64, -1.0 + 2.0 * y),
+    )
+    @test MOI.get(dest.model, MOI.ConstraintSet(), ci) == MOI.Zeros(1)
+    @test_throws(
+        MOI.SetAttributeNotAllowed,
+        MOI.set(dest, MOI.ConstraintSet(), index_map[c], set),
+    )
     return
 end