[Bridges] fix some getters of ConstraintFunction and add better tests

src/Bridges/Constraint/bridges/all_different.jl

@@ -126,7 +126,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     bridge::AllDifferentToCountDistinctBridge,
 )
-    return bridge.f
+    return copy(bridge.f)
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/all_different_reif.jl

@@ -139,7 +139,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     bridge::ReifiedAllDifferentToCountDistinctBridge,
 )
-    return bridge.f
+    return copy(bridge.f)
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/bin_packing.jl

@@ -117,7 +117,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     bridge::BinPackingToMILPBridge,
 )
-    return bridge.f
+    return copy(bridge.f)
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/circuit.jl

@@ -142,7 +142,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     bridge::CircuitToMILPBridge,
 )
-    return bridge.f
+    return copy(bridge.f)
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/count_at_least.jl

@@ -112,7 +112,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     bridge::CountAtLeastToCountBelongsBridge,
 )
-    return bridge.f
+    return copy(bridge.f)
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/count_belongs.jl

@@ -121,7 +121,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     bridge::CountBelongsToMILPBridge,
 )
-    return bridge.f
+    return copy(bridge.f)
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/count_distinct.jl

@@ -142,7 +142,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     bridge::CountDistinctToMILPBridge,
 )
-    return bridge.f
+    return copy(bridge.f)
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/count_distinct_reif.jl

@@ -154,7 +154,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     bridge::ReifiedCountDistinctToMILPBridge,
 )
-    return bridge.f
+    return copy(bridge.f)
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/count_greater_than.jl

@@ -96,7 +96,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     bridge::CountGreaterThanToMILPBridge,
 )
-    return bridge.f
+    return copy(bridge.f)
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/interval.jl

@@ -429,7 +429,7 @@
     if bridge.upper !== nothing
         return MOI.get(model, attr, bridge.upper)
     end
-    return bridge.func
+    return copy(bridge.func)
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/soc_to_nonconvex_quad.jl

@@ -11,7 +11,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     b::_AbstractSOCtoNonConvexQuadBridge{T},
 ) where {T}
-    return MOI.VectorOfVariables(b.vars)
+    return MOI.VectorOfVariables(copy(b.vars))
 end
 
 function MOI.Bridges.added_constrained_variable_types(

src/Bridges/Constraint/bridges/table.jl

@@ -114,7 +114,7 @@ function MOI.get(
     ::MOI.ConstraintFunction,
     bridge::TableToMILPBridge,
 )
-    return bridge.f
+    return copy(bridge.f)
 end
 
 function MOI.get(

src/Test/test_basic_constraint.jl

@@ -172,6 +172,40 @@ function _set(::Type{T}, ::Type{MOI.HyperRectangle}) where {T}
     return MOI.HyperRectangle(zeros(T, 3), ones(T, 3))
 end
 
+function _test_function_modification(
+    model::MOI.ModelLike,
+    config::Config{T},
+    c::MOI.ConstraintIndex{F},
+    f::F,
+) where {T,F<:Union{MOI.ScalarAffineFunction{T},MOI.ScalarQuadraticFunction{T}}}
+    MOI.Utilities.modify_function!(f, MOI.ScalarConstantChange(f.constant + 1))
+    g = MOI.get(model, MOI.ConstraintFunction(), c)
+    @test !≈(f.constant, g.constant, config)
+    return
+end
+
+function _test_function_modification(
+    model::MOI.ModelLike,
+    config::Config{T},
+    c::MOI.ConstraintIndex{F},
+    f::F,
+) where {T,F<:Union{MOI.VectorAffineFunction{T},MOI.VectorQuadraticFunction{T}}}
+    new_constants = f.constants .+ one(T)
+    MOI.Utilities.modify_function!(f, MOI.VectorConstantChange(new_constants))
+    g = MOI.get(model, MOI.ConstraintFunction(), c)
+    @test !≈(f.constants, g.constants, config)
+    return
+end
+
+function _test_function_modification(
+    ::MOI.ModelLike,
+    ::Config{T},
+    c::MOI.ConstraintIndex{F},
+    ::F,
+) where {T,F<:MOI.AbstractFunction}
+    return
+end
+
 function _basic_constraint_test_helper(
     model::MOI.ModelLike,
     config::Config{T},
@@ -233,6 +267,7 @@ function _basic_constraint_test_helper(
         )
         _test_attribute_value_type(model, MOI.ConstraintFunction(), c)
         _test_attribute_value_type(model, MOI.CanonicalConstraintFunction(), c)
+        _test_function_modification(model, config, c, f)
     end
     ###
     ### Test MOI.ConstraintSet

src/Utilities/vector_of_constraints.jl

@@ -103,7 +103,7 @@ function MOI.get(
 ) where {F,S}
     MOI.throw_if_not_valid(v, ci)
     f, _ = v.constraints[ci]::Tuple{F,S}
-    return f
+    return copy(f)
 end
 
 function MOI.get(

test/Bridges/bridge_optimizer.jl

@@ -732,7 +732,7 @@ function test_recursive_model_constraint(::Type{T} = Int) where {T}
     @test MOI.get(b, MOI.ConstraintFunction(), c) ≈ func
     new_func = T(2) * x
     MOI.set(b, MOI.ConstraintFunction(), c, new_func)
-    @test MOI.get(b, MOI.ConstraintFunction(), c) == new_func
+    @test MOI.get(b, MOI.ConstraintFunction(), c) ≈ new_func
     MOI.modify(b, c, MOI.ScalarCoefficientChange(x, T(3)))
     @test MOI.get(b, MOI.ConstraintFunction(), c) ≈ T(3) * x
     MOI.modify(b, c, MOI.ScalarConstantChange(T(-1)))
@@ -746,6 +746,7 @@ function test_recursive_model_constraint(::Type{T} = Int) where {T}
     @test MOI.is_valid(b, c)
     MOI.delete(b, c)
     @test !MOI.is_valid(b, c)
+    return
 end
 
 function test_recursive_model_objective(::Type{T} = Int) where {T}

test/Utilities/model.jl

@@ -301,7 +301,7 @@ function test_quadratic_functions()
     @test MOI.Utilities.is_canonical(F1)
     F3 = MOI.get(model, MOI.CanonicalConstraintFunction(), c3)
     @test F3 ≈ f3
-    @test F3 === MOI.get(model, MOI.ConstraintFunction(), c3)
+    @test F3 ≈ MOI.get(model, MOI.ConstraintFunction(), c3)
     @test MOI.Utilities.is_canonical(F3)
     @test MOI.get(model, MOI.CanonicalConstraintFunction(), c1) ≈ f3
     @test MOI.Utilities.is_canonical(