MOI infeasibility analysis

Author: joaquimg

src/ModelAnalyzer.jl

@@ -216,6 +216,6 @@ end
 
 include("numerical.jl")
 include("feasibility.jl")
-# include("infeasibility.jl")
+include("infeasibility.jl")
 
 end # module ModelAnalyzer

src/_eval_variables.jl

@@ -0,0 +1,31 @@
+# Copyright (c) 2025: Joaquim Garcia, Oscar Dowson and contributors
+#
+# Use of this source code is governed by an MIT-style license that can be found
+# in the LICENSE.md file or at https://opensource.org/licenses/MIT.
+
+function _eval_variables end
+
+function _eval_variables(value_fn::Function, t::MOI.ScalarAffineTerm)
+    return t.coefficient * value_fn(t.variable)
+end
+
+function _eval_variables(value_fn::Function, t::MOI.ScalarQuadraticTerm)
+    out = t.coefficient * value_fn(t.variable_1) * value_fn(t.variable_2)
+    return t.variable_1 == t.variable_2 ? out / 2 : out
+end
+
+_eval_variables(value_fn::Function, f::MOI.VariableIndex) = value_fn(f)
+
+function _eval_variables(
+    value_fn::Function,
+    f::MOI.ScalarAffineFunction{T},
+) where {T}
+    # TODO: this conversion exists in JuMP, but not in MOI
+    S = Base.promote_op(value_fn, MOI.VariableIndex)
+    U = Base.promote_op(*, T, S)
+    out = convert(U, f.constant)
+    for t in f.terms
+        out += _eval_variables(value_fn, t)
+    end
+    return out
+end