Add ConflictCount and conflict_index to ConstraintConflictStatus

src/attributes.jl

@@ -1844,6 +1844,16 @@ struct ConflictStatus <: AbstractModelAttribute end
 
 attribute_value_type(::ConflictStatus) = ConflictStatusCode
 
+"""
+    ConflictCount()
+
+An [`AbstractModelAttribute`](@ref) for the number of conflicts found by the
+solver in the most recent call to [`compute_conflict!`](@ref).
+"""
+struct ConflictCount <: AbstractModelAttribute end
+
+attribute_value_type(::ConflictCount) = Int
+
 """
     ListOfVariableAttributesSet()
 
@@ -2677,8 +2687,24 @@ end
 
 A constraint attribute to query the [`ConflictParticipationStatusCode`](@ref)
 indicating whether the constraint participates in the conflict.
+
+## `conflict_index`
+
+The optimizer may return multiple conflicts. See [`ConflictCount`](@ref)
+for querying the number of conflicts found.
+
+## Implementation
+
+Optimizers should implement the following methods:
+```julia
+MOI.get(::Optimizer, ::MOI.ConstraintConflictStatus, ::MOI.ConstraintIndex)::T
+```
+They should not implement [`set`](@ref) or [`supports`](@ref).
 """
-struct ConstraintConflictStatus <: AbstractConstraintAttribute end
+struct ConstraintConflictStatus <: AbstractConstraintAttribute
+    conflict_index::Int
+    ConstraintConflictStatus(conflict_index = 1) = new(conflict_index)
+end
 
 function attribute_value_type(::ConstraintConflictStatus)
     return ConflictParticipationStatusCode