Avoid extra copies of functions in copy_to

docs/src/submodules/Utilities/reference.md

@@ -180,6 +180,8 @@ The following functions can be used to canonicalize a function:
 Utilities.is_canonical
 Utilities.canonical
 Utilities.copy_if_modifiable
+Utilities.UnsafeConstraintFunction
+Utilities.UnsafeObjectiveFunction
 Utilities.canonicalize!
 ```
 

src/Bridges/Constraint/bridges/AbstractFunctionConversionBridge.jl

@@ -18,6 +18,36 @@ function MOI.get(
     model::MOI.ModelLike,
     attr::MOI.AbstractConstraintAttribute,
     bridge::AbstractFunctionConversionBridge,
+)
+    return _get_invariant(model, attr, bridge)
+end
+
+# Needed to avoid an ambiguity with the getter for
+# MOI.AbstractConstraintAttribute and the fallback in `bridge.jl`. Subtypes have
+# to implement `MOI.ConstraintFunction` as it is not invariant under function
+# conversion.
+function MOI.get(
+    model::MOI.ModelLike,
+    attr::MOI.ConstraintFunction,
+    bridge::AbstractFunctionConversionBridge,
+)
+    return _get_invariant(model, attr, bridge)
+end
+
+# Needed to avoid an ambiguity with the getter for
+# MOI.AbstractConstraintAttribute and the fallback in `bridge.jl`.
+function MOI.get(
+    ::MOI.ModelLike,
+    ::MOI.Utilities.UnsafeConstraintFunction,
+    bridge::AbstractFunctionConversionBridge,
+)
+    return MOI.Bridges._throw_constraint_function_not_allowed(bridge)
+end
+
+function _get_invariant(
+    model::MOI.ModelLike,
+    attr::MOI.AbstractConstraintAttribute,
+    bridge::AbstractFunctionConversionBridge,
 )
     if !invariant_under_function_conversion(attr)
         throw(

src/Bridges/Constraint/bridges/AllDifferentToCountDistinctBridge.jl

@@ -123,10 +123,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::AllDifferentToCountDistinctBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/BinPackingToMILPBridge.jl

@@ -114,10 +114,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::BinPackingToMILPBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/CircuitToMILPBridge.jl

@@ -138,10 +138,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::CircuitToMILPBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/CountAtLeastToCountBelongsBridge.jl

@@ -109,10 +109,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::CountAtLeastToCountBelongsBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/CountBelongsToMILPBridge.jl

@@ -118,10 +118,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::CountBelongsToMILPBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/CountDistinctToMILPBridge.jl

@@ -157,10 +157,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::CountDistinctToMILPBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/CountGreaterThanToMILPBridge.jl

@@ -93,10 +93,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::CountGreaterThanToMILPBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/ExponentialConeToScalarNonlinearFunctionBridge.jl

@@ -92,10 +92,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::ExponentialConeToScalarNonlinearFunctionBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/IndicatorToMILPBridge.jl

@@ -108,10 +108,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::IndicatorToMILPBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/ReifiedAllDifferentToCountDistinctBridge.jl

@@ -136,10 +136,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::ReifiedAllDifferentToCountDistinctBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/ReifiedCountDistinctToMILPBridge.jl

@@ -151,10 +151,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::ReifiedCountDistinctToMILPBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/SOS1ToMILPBridge.jl

@@ -120,10 +120,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::SOS1ToMILPBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(::MOI.ModelLike, ::MOI.ConstraintSet, bridge::SOS1ToMILPBridge)

src/Bridges/Constraint/bridges/SOS2ToMILPBridge.jl

@@ -111,10 +111,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::SOS2ToMILPBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(::MOI.ModelLike, ::MOI.ConstraintSet, bridge::SOS2ToMILPBridge)

src/Bridges/Constraint/bridges/SplitIntervalBridge.jl

@@ -421,7 +421,7 @@ end
 
 function MOI.get(
     model::MOI.ModelLike,
-    attr::MOI.ConstraintFunction,
+    attr::MOI.Utilities.UnsafeConstraintFunction,
     bridge::SplitIntervalBridge,
 )
     if bridge.lower !== nothing
@@ -430,7 +430,7 @@ function MOI.get(
     if bridge.upper !== nothing
         return MOI.get(model, attr, bridge.upper)
     end
-    return MOI.Utilities.copy_if_modifiable(bridge.func)
+    return bridge.func
 end
 
 function MOI.get(

src/Bridges/Constraint/bridges/TableToMILPBridge.jl

@@ -115,10 +115,10 @@ end
 
 function MOI.get(
     ::MOI.ModelLike,
-    ::MOI.ConstraintFunction,
+    ::MOI.Utilities.UnsafeConstraintFunction,
     bridge::TableToMILPBridge,
 )
-    return MOI.Utilities.copy_if_modifiable(bridge.f)
+    return bridge.f
 end
 
 function MOI.get(

src/Bridges/Variable/set_map.jl

@@ -77,11 +77,24 @@ end
 
 function MOI.get(
     model::MOI.ModelLike,
-    attr::Union{
-        MOI.ConstraintFunction,
-        MOI.ConstraintPrimal,
-        MOI.ConstraintPrimalStart,
-    },
+    attr::Union{MOI.ConstraintPrimal,MOI.ConstraintPrimalStart},
+    bridge::SetMapBridge,
+)
+    return _get_mapped(model, attr, bridge)
+end
+
+# Separate method to avoid an ambiguity with the fallback in `bridge.jl`.
+function MOI.get(
+    model::MOI.ModelLike,
+    attr::MOI.ConstraintFunction,
+    bridge::SetMapBridge,
+)
+    return _get_mapped(model, attr, bridge)
+end
+
+function _get_mapped(
+    model::MOI.ModelLike,
+    attr::MOI.AbstractConstraintAttribute,
     bridge::SetMapBridge,
 )
     value = MOI.get(model, attr, bridge.constraint)

src/Bridges/bridge.jl

@@ -149,6 +149,53 @@ function MOI.get(
     return throw(MOI.GetAttributeNotAllowed(attr, message))
 end
 
+"""
+    MOI.get(
+        model::MOI.ModelLike,
+        ::MOI.ConstraintFunction,
+        bridge::AbstractBridge,
+    )
+
+Return a copy of the function of the constraint bridged by `bridge` if it can
+be modified, see [`MOI.Utilities.copy_if_modifiable`](@ref).
+
+A bridge that stores the function of the constraint it bridges only needs to
+implement [`MOI.Utilities.UnsafeConstraintFunction`](@ref) and return the
+stored function. A bridge that builds a new function should implement
+`MOI.ConstraintFunction` instead.
+
+There is no fallback of `MOI.Utilities.UnsafeConstraintFunction` to
+`MOI.ConstraintFunction` for bridges as it would create an infinite recursion
+for bridges implementing neither of them. The bridge optimizer therefore always
+gets `MOI.ConstraintFunction` from the bridges.
+"""
+function MOI.get(
+    model::MOI.ModelLike,
+    ::MOI.ConstraintFunction,
+    bridge::AbstractBridge,
+)
+    return MOI.Utilities.copy_if_modifiable(
+        MOI.get(model, MOI.Utilities.UnsafeConstraintFunction(), bridge),
+    )
+end
+
+# A bridge that implements neither `MOI.ConstraintFunction` nor
+# `MOI.Utilities.UnsafeConstraintFunction` should throw the same error as before
+# `MOI.Utilities.UnsafeConstraintFunction` was introduced.
+function MOI.get(
+    ::MOI.ModelLike,
+    ::MOI.Utilities.UnsafeConstraintFunction,
+    bridge::AbstractBridge,
+)
+    return _throw_constraint_function_not_allowed(bridge)
+end
+
+function _throw_constraint_function_not_allowed(bridge::AbstractBridge)
+    attr = MOI.ConstraintFunction()
+    message = _attribute_error_message(attr, typeof(bridge), "accessing")
+    return throw(MOI.GetAttributeNotAllowed(attr, message))
+end
+
 function MOI.get(
     model::MOI.ModelLike,
     ::MOI.CanonicalConstraintFunction,

src/Bridges/bridge_optimizer.jl

@@ -1264,6 +1264,15 @@ function MOI.get(b::AbstractBridgeOptimizer, attr::MOI.ObjectiveFunction)
     return unbridged_function(b, _bridged_function(b, attr))
 end
 
+# The objective function of `b.model` may be bridged so we cannot forward
+# `UnsafeObjectiveFunction` to `b.model`.
+function MOI.get(
+    b::AbstractBridgeOptimizer,
+    ::MOI.Utilities.UnsafeObjectiveFunction{F},
+) where {F}
+    return MOI.get(b, MOI.ObjectiveFunction{F}())
+end
+
 function MOI.set(
     b::AbstractBridgeOptimizer,
     attr::MOI.ObjectiveSense,
@@ -1515,7 +1524,7 @@ end
 
 function MOI.get(
     b::AbstractBridgeOptimizer,
-    attr::MOI.ConstraintFunction,
+    attr::Union{MOI.ConstraintFunction,MOI.Utilities.UnsafeConstraintFunction},
     ci::MOI.ConstraintIndex,
 )
     if is_bridged(b, ci)
@@ -1526,8 +1535,9 @@ function MOI.get(
             return Variable.function_for(Variable.bridges(b)::Variable.Map, ci)
         else
             # Otherwise, we need to query ConstraintFunction in the context of
-            # the bridge...
-            func = call_in_context(MOI.get, b, ci, attr)
+            # the bridge. We don't forward `UnsafeConstraintFunction` as bridges
+            # building a new function only implement `ConstraintFunction`...
+            func = call_in_context(MOI.get, b, ci, MOI.ConstraintFunction())
             # and then unbridge this function (because it may contain variables
             # that are themselves bridged).
             return unbridged_constraint_function(b, func)