From fc0ecc9b2f2aa736705bc76eb8dff539ff2f607d Mon Sep 17 00:00:00 2001
From: Corniel Nobel <corniel@gmail.com>
Date: Fri, 18 Oct 2024 13:42:00 +0200
Subject: [PATCH] IDisposables are always disposed after the  foreach
 statement.

---
 .../Valid.CreatedWithinForEach.cs             | 108 ++++++++++++++++++
 .../Helpers/Disposable.Disposes.cs            |   3 +
 2 files changed, 111 insertions(+)
 create mode 100644 IDisposableAnalyzers.Test/IDISP004DoNotIgnoreCreatedTests/Valid.CreatedWithinForEach.cs

diff --git a/IDisposableAnalyzers.Test/IDISP004DoNotIgnoreCreatedTests/Valid.CreatedWithinForEach.cs b/IDisposableAnalyzers.Test/IDISP004DoNotIgnoreCreatedTests/Valid.CreatedWithinForEach.cs
new file mode 100644
index 00000000..5963d82c
--- /dev/null
+++ b/IDisposableAnalyzers.Test/IDISP004DoNotIgnoreCreatedTests/Valid.CreatedWithinForEach.cs
@@ -0,0 +1,108 @@
+namespace IDisposableAnalyzers.Test.IDISP004DoNotIgnoreCreatedTests;
+
+using Gu.Roslyn.Asserts;
+using NUnit.Framework;
+
+public static partial class Valid
+{
+    [Test]
+    public static void StructEnumeratorCreatedWithinForEach()
+    {
+        var code = @"
+using System.Collections;
+using System.Collections.Generic;
+
+namespace N
+{
+    public class C
+    {
+        public void M()
+        {
+            foreach(var n in new Enumerator())
+            {
+            }
+        }
+    }
+
+    public struct Enumerator : IEnumerator<int>, IEnumerable<int>
+    {
+        public int Current => 42;
+        object IEnumerator.Current => 42;
+        public void Dispose() { }
+        public bool MoveNext() => true;
+        public void Reset() { }
+        public IEnumerator<int> GetEnumerator() => this;
+        IEnumerator IEnumerable.GetEnumerator() => this;
+    }
+}";
+        RoslynAssert.Valid(Analyzer, code);
+    }
+
+    [Test]
+    public static void ClassEnumeratorCreatedWithinForEach()
+    {
+        var code = @"
+using System.Collections;
+using System.Collections.Generic;
+
+namespace N
+{
+    public class C
+    {
+        public void M()
+        {
+            foreach(var n in new Enumerator())
+            {
+            }
+        }
+    }
+
+    public class Enumerator : IEnumerator<int>, IEnumerable<int>
+    {
+        public int Current => 42;
+        object IEnumerator.Current => 42;
+        public void Dispose() { }
+        public bool MoveNext() => true;
+        public void Reset() { }
+        public IEnumerator<int> GetEnumerator() => this;
+        IEnumerator IEnumerable.GetEnumerator() => this;
+    }
+}";
+        RoslynAssert.Valid(Analyzer, code);
+    }
+
+    [Test]
+    public static void CreatedEnumerableWithinForEach()
+    {
+        var code = @"
+using System.Collections;
+using System.Collections.Generic;
+
+namespace N
+{
+    public class C
+    {
+        public void M()
+        {
+            foreach(var n in All())
+            {
+            }
+        }
+
+        public IEnumerable<int> All() => new Enumerator();
+    }
+
+    public class Enumerator : IEnumerator<int>, IEnumerable<int>
+    {
+        public int Current => 42;
+        object IEnumerator.Current => 42;
+        public void Dispose() { }
+        public bool MoveNext() => true;
+        public void Reset() { }
+        public IEnumerator<int> GetEnumerator() => this;
+        IEnumerator IEnumerable.GetEnumerator() => this;
+    }
+}";
+        RoslynAssert.Valid(Analyzer, code);
+    }
+}
diff --git a/IDisposableAnalyzers/Helpers/Disposable.Disposes.cs b/IDisposableAnalyzers/Helpers/Disposable.Disposes.cs
index 299c46b5..089f07e2 100644
--- a/IDisposableAnalyzers/Helpers/Disposable.Disposes.cs
+++ b/IDisposableAnalyzers/Helpers/Disposable.Disposes.cs
@@ -90,6 +90,9 @@ private static bool Disposes(ExpressionSyntax candidate, Recursion recursion)
                 when Identity(candidate, recursion) is { } id &&
                      Disposes(id, recursion)
                 => true,
+            { Parent: ForEachStatementSyntax parent }
+                when parent.Expression == candidate
+                => true,
             { Parent: ConditionalAccessExpressionSyntax { WhenNotNull: InvocationExpressionSyntax invocation } }
                 => IsDisposeOrReturnValueDisposed(invocation),
             { Parent: MemberAccessExpressionSyntax { Parent: InvocationExpressionSyntax invocation } }