From 38464c27b96e9818257b22c61d2458890957d0fe Mon Sep 17 00:00:00 2001
From: Oscar Dowson <odow@users.noreply.github.com>
Date: Tue, 15 Aug 2023 19:15:10 +1200
Subject: [PATCH] Fix bug modifying a constraint after deletion (#515)

---
 Project.toml                   |  2 +-
 src/MOI_wrapper/MOI_wrapper.jl |  4 +++
 test/MOI/MOI_wrapper.jl        | 46 ++++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index 059d151..a696d4a 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 = "1.0.1"
+version = "1.0.2"
 
 [deps]
 LazyArtifacts = "4af54fe1-eca0-43a8-85a7-787d91b784e3"
diff --git a/src/MOI_wrapper/MOI_wrapper.jl b/src/MOI_wrapper/MOI_wrapper.jl
index ad5dcfc..4fdb053 100644
--- a/src/MOI_wrapper/MOI_wrapper.jl
+++ b/src/MOI_wrapper/MOI_wrapper.jl
@@ -3459,6 +3459,7 @@ function MOI.modify(
     c::MOI.ConstraintIndex{MOI.ScalarAffineFunction{Float64},<:Any},
     chg::MOI.ScalarCoefficientChange{Float64},
 )
+    _update_if_necessary(model)
     ret = GRBchgcoeffs(
         model,
         1,
@@ -3476,6 +3477,7 @@ function MOI.modify(
     cis::Vector{MOI.ConstraintIndex{MOI.ScalarAffineFunction{Float64},S}},
     changes::Vector{MOI.ScalarCoefficientChange{Float64}},
 ) where {S}
+    _update_if_necessary(model)
     nels = length(cis)
     @assert nels == length(changes)
     rows = Vector{Cint}(undef, nels)
@@ -3497,6 +3499,7 @@ function MOI.modify(
     ::MOI.ObjectiveFunction{MOI.ScalarAffineFunction{Float64}},
     chg::MOI.ScalarCoefficientChange{Float64},
 )
+    _update_if_necessary(model)
     ret = GRBsetdblattrelement(
         model,
         "Obj",
@@ -3514,6 +3517,7 @@ function MOI.modify(
     ::MOI.ObjectiveFunction{MOI.ScalarAffineFunction{Float64}},
     changes::Vector{MOI.ScalarCoefficientChange{Float64}},
 )
+    _update_if_necessary(model)
     nels = length(changes)
     cols = Vector{Cint}(undef, nels)
     coefs = Vector{Cdouble}(undef, nels)
diff --git a/test/MOI/MOI_wrapper.jl b/test/MOI/MOI_wrapper.jl
index 321b9db..f254ba9 100644
--- a/test/MOI/MOI_wrapper.jl
+++ b/test/MOI/MOI_wrapper.jl
@@ -811,6 +811,52 @@ function test_dual_qcp_failure()
     return
 end
 
+function test_modify_after_delete()
+    model = Gurobi.Optimizer(GRB_ENV)
+    x = MOI.add_variable(model)
+    c = [MOI.add_constraint(model, i * x, MOI.LessThan(i)) for i in [1.0, 2.0]]
+    MOI.delete(model, c[1])
+    MOI.modify(model, c[2], MOI.ScalarCoefficientChange(x, 4.0))
+    @test MOI.get(model, MOI.ConstraintFunction(), c[2]) ≈ 4.0 * x
+    return
+end
+
+function test_modify_after_delete_plural()
+    model = Gurobi.Optimizer(GRB_ENV)
+    x = MOI.add_variable(model)
+    c = [MOI.add_constraint(model, i * x, MOI.LessThan(i)) for i in [1.0, 2.0]]
+    MOI.delete(model, c[1])
+    MOI.modify(model, [c[2]], [MOI.ScalarCoefficientChange(x, 4.0)])
+    @test MOI.get(model, MOI.ConstraintFunction(), c[2]) ≈ 4.0 * x
+    return
+end
+
+function test_modify_after_delete_objective()
+    model = Gurobi.Optimizer(GRB_ENV)
+    x = MOI.add_variables(model, 2)
+    MOI.set(model, MOI.ObjectiveSense(), MOI.MIN_SENSE)
+    f = 1.0 * x[1] + 2.0 * x[2]
+    attr = MOI.ObjectiveFunction{typeof(f)}()
+    MOI.set(model, attr, f)
+    MOI.delete(model, x[1])
+    MOI.modify(model, attr, MOI.ScalarCoefficientChange(x[2], 3.0))
+    @test MOI.get(model, attr) ≈ 3.0 * x[2]
+    return
+end
+
+function test_modify_after_delete_objective_plural()
+    model = Gurobi.Optimizer(GRB_ENV)
+    x = MOI.add_variables(model, 2)
+    MOI.set(model, MOI.ObjectiveSense(), MOI.MIN_SENSE)
+    f = 1.0 * x[1] + 2.0 * x[2]
+    attr = MOI.ObjectiveFunction{typeof(f)}()
+    MOI.set(model, attr, f)
+    MOI.delete(model, x[1])
+    MOI.modify(model, attr, [MOI.ScalarCoefficientChange(x[2], 3.0)])
+    @test MOI.get(model, attr) ≈ 3.0 * x[2]
+    return
+end
+
 end
 
 TestMOIWrapper.runtests()