From 812ffd313a6152681a8813481de7008faf3bddd3 Mon Sep 17 00:00:00 2001
From: Oscar Dowson <odow@users.noreply.github.com>
Date: Sun, 7 Feb 2021 16:42:02 +1300
Subject: [PATCH] Fix handling of solution statuses for multiple results (#393)

---
 Project.toml            |  2 +-
 src/MOI_wrapper.jl      | 13 ++++++++-----
 test/MOI/MOI_wrapper.jl |  4 ++++
 3 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/Project.toml b/Project.toml
index 33694f41..be213bbe 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "Gurobi"
 uuid = "2e9cd046-0924-5485-92f1-d5272153d98b"
 repo = "https://github.com/jump-dev/Gurobi.jl"
-version = "0.9.8"
+version = "0.9.9"
 
 [deps]
 CEnum = "fa961155-64e5-5f13-b03f-caf6b980ea82"
diff --git a/src/MOI_wrapper.jl b/src/MOI_wrapper.jl
index e7cc4d9b..9e6d81d1 100644
--- a/src/MOI_wrapper.jl
+++ b/src/MOI_wrapper.jl
@@ -2474,21 +2474,22 @@ end
 
 function MOI.get(model::Optimizer, attr::MOI.PrimalStatus)
     _throw_if_optimize_in_progress(model, attr)
-    if attr.N != 1
-        return MOI.NO_SOLUTION
-    end
     term = MOI.get(model, MOI.TerminationStatus())
     if term == MOI.DUAL_INFEASIBLE || term == MOI.INFEASIBLE_OR_UNBOUNDED
-        if _has_primal_ray(model)
+        if attr.N != 1
+            return MOI.NO_SOLUTION
+        elseif _has_primal_ray(model)
             return MOI.INFEASIBILITY_CERTIFICATE
         else
             return MOI.NO_SOLUTION
         end
     end
+    # Check SolCount explicitly instead of ResultCount to avoid returning 1 when
+    # there is a certiticate.
     valueP = Ref{Cint}()
     ret = GRBgetintattr(model, "SolCount", valueP)
     _check_ret(model, ret)
-    return valueP[] > 0 ? MOI.FEASIBLE_POINT : MOI.NO_SOLUTION
+    return 1 <= attr.N <= valueP[] ? MOI.FEASIBLE_POINT : MOI.NO_SOLUTION
 end
 
 function _has_dual_ray(model::Optimizer)
@@ -2519,6 +2520,8 @@ function MOI.get(model::Optimizer, attr::MOI.DualStatus)
             return MOI.NO_SOLUTION
         end
     end
+    # Check SolCount explicitly instead of ResultCount to avoid returning 1 when
+    # there is a certiticate.
     valueP = Ref{Cint}()
     ret = GRBgetintattr(model, "SolCount", valueP)
     _check_ret(model, ret)
diff --git a/test/MOI/MOI_wrapper.jl b/test/MOI/MOI_wrapper.jl
index 9961df1b..bdc56136 100644
--- a/test/MOI/MOI_wrapper.jl
+++ b/test/MOI/MOI_wrapper.jl
@@ -1572,6 +1572,8 @@ function test_multiple_solutions()
             MOI.ResultIndexBoundsError,
             MOI.get(model, MOI.ObjectiveValue(n)),
         )
+        @test MOI.get(model, MOI.PrimalStatus(n)) == MOI.NO_SOLUTION
+        @test MOI.get(model, MOI.DualStatus(n)) == MOI.NO_SOLUTION
     end
     for n = 1:RC
         xn = MOI.get(model, MOI.VariablePrimal(n), x)
@@ -1581,6 +1583,8 @@ function test_multiple_solutions()
             item_values' * xn,
             atol=1e-6,
         )
+        @test MOI.get(model, MOI.PrimalStatus(n)) == MOI.FEASIBLE_POINT
+        @test MOI.get(model, MOI.DualStatus(n)) == MOI.NO_SOLUTION
     end
 end