Add GetAttributeNotAllowed error

src/Utilities/cachingoptimizer.jl

@@ -939,11 +939,11 @@ function MOI.get(
             model.model_to_optimizer_map[index],
         )
     catch err
-        if err isa ArgumentError  # Thrown if .optimizer doesn't support attr
-            return get_fallback(model, attr, index)
-        else
+        # Thrown if .optimizer doesn't support attr
+        if !(err isa MOI.GetAttributeNotAllowed)
             rethrow(err)
         end
+        return get_fallback(model, attr, index)
     end
 end
 
@@ -965,11 +965,11 @@ function MOI.get(
             [model.model_to_optimizer_map[i] for i in indices],
         )
     catch err
-        if err isa ArgumentError  # Thrown if .optimizer doesn't support attr
-            return [get_fallback(model, attr, i) for i in indices]
-        else
+        # Thrown if .optimizer doesn't support attr
+        if !(err isa MOI.GetAttributeNotAllowed)
             rethrow(err)
         end
+        return [get_fallback(model, attr, i) for i in indices]
     end
 end
 

src/attributes.jl

@@ -100,6 +100,28 @@ SetAttributeNotAllowed(attr::AnyAttribute) = SetAttributeNotAllowed(attr, "")
 operation_name(err::SetAttributeNotAllowed) = "Setting attribute $(err.attr)"
 message(err::SetAttributeNotAllowed) = err.message
 
+"""
+    struct GetAttributeNotAllowed{AttrType} <: NotAllowedError
+        attr::AttrType
+        message::String
+    end
+
+An error indicating that the attribute `attr` cannot be got for some reason (see
+the error string).
+"""
+struct GetAttributeNotAllowed{AttrType<:AnyAttribute} <: NotAllowedError
+    attr::AttrType
+    message::String
+
+    function GetAttributeNotAllowed(attr::AnyAttribute, message::String = "")
+        return new{typeof(attr)}(attr, message)
+    end
+end
+
+operation_name(err::GetAttributeNotAllowed) = "Getting attribute $(err.attr)"
+
+message(err::GetAttributeNotAllowed) = err.message
+
 """
     AbstractSubmittable
 
@@ -341,7 +363,8 @@ function get_fallback(
     attr::Union{AbstractModelAttribute,AbstractOptimizerAttribute},
 )
     return throw(
-        ArgumentError(
+        GetAttributeNotAllowed(
+            attr,
             "$(typeof(model)) does not support getting the attribute $(attr).",
         ),
     )
@@ -353,7 +376,8 @@ function get_fallback(
     ::VariableIndex,
 )
     return throw(
-        ArgumentError(
+        GetAttributeNotAllowed(
+            attr,
             "$(typeof(model)) does not support getting the attribute $(attr).",
         ),
     )
@@ -365,15 +389,17 @@ function get_fallback(
     ::ConstraintIndex,
 )
     return throw(
-        ArgumentError(
+        GetAttributeNotAllowed(
+            attr,
             "$(typeof(model)) does not support getting the attribute $(attr).",
         ),
     )
 end
 
 function get_fallback(::ModelLike, attr::AnyAttribute, args...)
     return throw(
-        ArgumentError(
+        GetAttributeNotAllowed(
+            attr,
             "Unable to get attribute $(attr): invalid arguments $(args).",
         ),
     )

test/attributes.jl

@@ -150,30 +150,48 @@ function test_get_fallback()
     model = DummyModelWithAdd()
     x = MOI.add_variable(model)
     c = MOI.add_constraint(model, x, MOI.EqualTo(0.0))
-    err = ArgumentError(
-        "$(typeof(model)) does not support getting the attribute " *
-        "$(MOI.SolveTimeSec()).",
+    @test_throws(
+        MOI.GetAttributeNotAllowed(
+            MOI.SolveTimeSec(),
+            "$(typeof(model)) does not support getting the attribute " *
+            "$(MOI.SolveTimeSec()).",
+        ),
+        MOI.get(model, MOI.SolveTimeSec()),
     )
-    @test_throws(err, MOI.get(model, MOI.SolveTimeSec()))
     output = Ref{Cdouble}()
-    @test_throws(err, MOI.get!(output, model, MOI.SolveTimeSec()))
-    errv = ArgumentError(
-        "$(typeof(model)) does not support getting the attribute " *
-        "$(MOI.VariablePrimal()).",
+    @test_throws(
+        MOI.GetAttributeNotAllowed(
+            MOI.SolveTimeSec(),
+            "$(typeof(model)) does not support getting the attribute " *
+            "$(MOI.SolveTimeSec()).",
+        ),
+        MOI.get!(output, model, MOI.SolveTimeSec()),
     )
-    @test_throws(errv, MOI.get(model, MOI.VariablePrimal(), x))
-    errc = ArgumentError(
-        "$(typeof(model)) does not support getting the attribute " *
-        "$(MOI.ConstraintPrimal()).",
+    @test_throws(
+        MOI.GetAttributeNotAllowed(
+            MOI.VariablePrimal(),
+            "$(typeof(model)) does not support getting the attribute " *
+            "$(MOI.VariablePrimal()).",
+        ),
+        MOI.get(model, MOI.VariablePrimal(), x),
+    )
+    @test_throws(
+        MOI.GetAttributeNotAllowed(
+            MOI.ConstraintPrimal(),
+            "$(typeof(model)) does not support getting the attribute " *
+            "$(MOI.ConstraintPrimal()).",
+        ),
+        MOI.get(model, MOI.ConstraintPrimal(), c),
     )
-    @test_throws(errc, MOI.get(model, MOI.ConstraintPrimal(), c))
     @test_throws(
-        ArgumentError(
+        MOI.GetAttributeNotAllowed(
+            MOI.VariablePrimal(),
             "Unable to get attribute $(MOI.VariablePrimal()): invalid " *
             "arguments $((c,)).",
         ),
         MOI.get(model, MOI.VariablePrimal(), c),
     )
+    return
 end
 
 function test_ConstraintBasisStatus_fallback()
@@ -215,6 +233,57 @@ function test_attribute_value_type()
           Float64
 end
 
+MOI.Utilities.@model(
+    _Model1777,
+    (),
+    (MOI.LessThan,),
+    (MOI.Nonnegatives,),
+    (),
+    (),
+    (MOI.ScalarAffineFunction,),
+    (MOI.VectorOfVariables,),
+    ()
+)
+
+function MOI.supports_constraint(
+    ::_Model1777,
+    ::Type{MOI.VectorOfVariables},
+    ::Type{MOI.Reals},
+)
+    return false
+end
+
+function MOI.supports_add_constrained_variables(
+    ::_Model1777,
+    ::Type{MOI.Nonnegatives},
+)
+    return true
+end
+
+MOI.supports_add_constrained_variables(::_Model1777, ::Type{MOI.Reals}) = false
+
+function MOI.get(
+    model::_Model1777,
+    attr::MOI.ConstraintFunction,
+    ci::MOI.ConstraintIndex,
+)
+    return MOI.get_fallback(model, attr, ci)
+end
+
+function test_issue_1777()
+    model = MOI.Utilities.CachingOptimizer(
+        MOI.Utilities.UniversalFallback(MOI.Utilities.Model{Float64}()),
+        MOI.Bridges.full_bridge_optimizer(_Model1777{Float64}(), Float64),
+    )
+    x = MOI.add_variable(model)
+    c = MOI.add_constraint(model, 1.0 * x, MOI.LessThan(1.0))
+    MOI.Utilities.attach_optimizer(model)
+    MOI.set(model, MOI.ConstraintSet(), c, MOI.LessThan(2.0))
+    @test MOI.get(model, MOI.ConstraintSet(), c) == MOI.LessThan(2.0)
+    @test MOI.Utilities.state(model) == MOI.Utilities.EMPTY_OPTIMIZER
+    return
+end
+
 function runtests()
     for name in names(@__MODULE__; all = true)
         if startswith("$name", "test_")

test/errors.jl

@@ -334,6 +334,21 @@ function test_compute_conflict_fallback()
     return
 end
 
+function test_get_fallback_error()
+    model = MOI.Utilities.Model{Float64}()
+    @test_throws(
+        MOI.GetAttributeNotAllowed,
+        MOI.get(model, MOI.SolveTimeSec()),
+    )
+    err = MOI.GetAttributeNotAllowed(MOI.SolveTimeSec(), "")
+    @test sprint(showerror, err) ==
+          "$(typeof(err)): Getting attribute $(MOI.SolveTimeSec()) cannot be " *
+          "performed. You may want to use a `CachingOptimizer` in " *
+          "`AUTOMATIC` mode or you may need to call `reset_optimizer` before " *
+          "doing this operation if the `CachingOptimizer` is in `MANUAL` mode."
+    return
+end
+
 function runtests()
     for name in names(@__MODULE__; all = true)
         if startswith("$name", "test_")