From 2ebab07b99a2cf1b2c9deb42a7ca52f41f5fb16e Mon Sep 17 00:00:00 2001
From: Nathan Mytelka <Forgind@users.noreply.github.com>
Date: Wed, 2 Dec 2020 09:58:10 -0800
Subject: [PATCH 1/2] Optimization neglected to include condition

Fixes #5766
---
 src/Build/Evaluation/LazyItemEvaluator.RemoveOperation.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Build/Evaluation/LazyItemEvaluator.RemoveOperation.cs b/src/Build/Evaluation/LazyItemEvaluator.RemoveOperation.cs
index 546ef225a4e..bcfe47d6c84 100644
--- a/src/Build/Evaluation/LazyItemEvaluator.RemoveOperation.cs
+++ b/src/Build/Evaluation/LazyItemEvaluator.RemoveOperation.cs
@@ -38,7 +38,7 @@ protected override void ApplyImpl(ImmutableList<ItemData>.Builder listBuilder, I
                     new BuildEventFileInfo(string.Empty),
                     "OM_MatchOnMetadataIsRestrictedToOnlyOneReferencedItem");
 
-                if (_matchOnMetadata.IsEmpty && ItemspecContainsASingleBareItemReference(_itemSpec, _itemElement.ItemType))
+                if (_matchOnMetadata.IsEmpty && ItemspecContainsASingleBareItemReference(_itemSpec, _itemElement.ItemType) && _conditionResult)
                 {
                     // Perf optimization: If the Remove operation references itself (e.g. <I Remove="@(I)"/>)
                     // then all items are removed and matching is not necessary

From 247318e8aedd8cc62ffc21ec9c28b44cdbec003b Mon Sep 17 00:00:00 2001
From: Nathan Mytelka <Forgind@users.noreply.github.com>
Date: Wed, 2 Dec 2020 11:20:47 -0800
Subject: [PATCH 2/2] Test Remove optimization still respects condition

---
 .../Definition/ProjectItem_Tests.cs                   | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/Build.OM.UnitTests/Definition/ProjectItem_Tests.cs b/src/Build.OM.UnitTests/Definition/ProjectItem_Tests.cs
index 9299381c7ca..d94e4ab56e0 100644
--- a/src/Build.OM.UnitTests/Definition/ProjectItem_Tests.cs
+++ b/src/Build.OM.UnitTests/Definition/ProjectItem_Tests.cs
@@ -2774,6 +2774,17 @@ public void UpdateShouldImportMetadataFromReferencedItem()
             ObjectModelHelpers.AssertItemHasMetadata(expectedMetadataC, items[4]);
         }
 
+        [Fact]
+        public void OptimizedRemoveOperationRespectsCondition()
+        {
+            string content = @"<TheItem Include=""InitialValue"" />
+                               <TheItem Remove=""@(TheItem)"" Condition=""false"" />
+                               <TheItem Include=""ReplacedValue"" Condition=""false"" /> ";
+            IList<ProjectItem> items = ObjectModelHelpers.GetItemsFromFragment(content, true);
+
+            items[0].EvaluatedInclude.ShouldBe("InitialValue");
+        }
+
         [Theory]
         [InlineData(true)]
         [InlineData(false)]