New rule S6609: "Min/Max" properties of "Set" types should be used in…

…stead of the "Enumerable" extension methods (#7202)

analyzers/its/expected/Net7/Net7--net7.0-S1144.json

@@ -54,6 +54,19 @@
 },
 {
 "id":  "S1144",
+"message":  "Remove the unused private method 'Method'.",
+"location":  {
+"uri":  "sources\Net7\Net7\features\SetPropertiesInsteadOfLinqMethods.cs",
+"region":  {
+"startLine":  8,
+"startColumn":  20,
+"endLine":  8,
+"endColumn":  26
+}
+}
+},
+{
+"id":  "S1144",
 "message":  "Remove the unused internal class 'lowercasename'.",
 "location":  {
 "uri":  "sources\Net7\Net7\features\WarningWave7.cs",

analyzers/its/expected/Net7/Net7--net7.0-S1451.json

@@ -186,6 +186,19 @@
 "id":  "S1451",
 "message":  "Add or update the header of this file.",
 "location":  {
+"uri":  "sources\Net7\Net7\features\SetPropertiesInsteadOfLinqMethods.cs",
+"region":  {
+"startLine":  1,
+"startColumn":  1,
+"endLine":  1,
+"endColumn":  1
+}
+}
+},
+{
+"id":  "S1451",
+"message":  "Add or update the header of this file.",
+"location":  {
 "uri":  "sources\Net7\Net7\features\StaticVirtualMembersInInterfaces.cs",
 "region":  {
 "startLine":  1,

analyzers/its/expected/Net7/Net7--net7.0-S6609.json

@@ -0,0 +1,17 @@
+{
+"issues":  [
+{
+"id":  "S6609",
+"message":  ""Min" property of Set type should be used instead of the "Min()" extension method.",
+"location":  {
+"uri":  "sources\Net7\Net7\features\SetPropertiesInsteadOfLinqMethods.cs",
+"region":  {
+"startLine":  11,
+"startColumn":  24,
+"endLine":  11,
+"endColumn":  27
+}
+}
+}
+]
+}

analyzers/its/sources/Net7/Net7/features/OrderByBeforeWhere.cs

@@ -1,8 +1,8 @@
 namespace Net7.features
 {
-    public static class Foo
+    public static class OrderByBeforeWhere
     {
-        public static List<int> Bar()
+        public static List<int> Method()
         {
             var list = new List<int>();
             return list.OrderBy(x => x).Where(x => true).ToList();

analyzers/its/sources/Net7/Net7/features/SetPropertiesInsteadOfLinqMethods.cs

@@ -0,0 +1,14 @@
+using System.Linq;
+using System.Collections.Generic;
+
+namespace Net7.features
+{
+    public static class SetPropertiesInsteadOfLinqMethods
+    {
+        static int Method()
+        {
+            var set = new SortedSet<int>();
+            return set.Min();
+        }
+    }
+}

analyzers/rspec/cs/S6609.html

@@ -0,0 +1,150 @@
+<h2>Why is this an issue?</h2>
+<p>Both the <code>Enumerable.Max</code> extension method and the <code>SortedSet&lt;T&gt;.Max</code> property can be used to find the maximum value in
+a <code>SortedSet&lt;T&gt;</code>. However, <code>SortedSet&lt;T&gt;.Max</code> is much faster than <code>Enumerable.Max</code>. For small
+collections, the performance difference may be minor, but for large collections, it can be noticeable. The same applies for the <code>Min</code>
+property as well.</p>
+<p><code>Max</code> and <code>Min</code> in <code>SortedSet&lt;T&gt;</code> exploit the fact that the set is implemented via a <code>Red-Black
+tree</code>. The algorithm to find the <code>Max</code>/<code>Min</code> is "go left/right whenever possible". The operation has the time complexity
+of <code>O(h)</code> which becomes <code>O(ln(n))</code> due to the fact that the tree is balanced. This is much better than the <code>O(n)</code>
+time complexity of extension methods.</p>
+<p><code>Max</code> and <code>Min</code> in <code>ImmutableSortedSet&lt;T&gt;</code> exploits a tree augmentation technique, storing the
+<code>Min</code>, <code>Max</code> and <code>Count</code> values on each node of the data structure. The time complexity in this case is
+<code>O(1)</code> that is significantly better than <code>O(n)</code> of extension methods.</p>
+<p><strong>Applies to:</strong></p>
+<ul>
+  <li> <a href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.sortedset-1.max">SortedSet&lt;T&gt;.Max</a> </li>
+  <li> <a href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.sortedset-1.min">SortedSet&lt;T&gt;.Min</a> </li>
+  <li> <a
+  href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.immutable.immutablesortedset-1.max">ImmutableSortedSet&lt;T&gt;.Max</a> </li>
+  <li> <a
+  href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.immutable.immutablesortedset-1.min">ImmutableSortedSet&lt;T&gt;.Min</a> </li>
+  <li> <a
+  href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.immutable.immutablesortedset-1.builder.max">ImmutableSortedSet&lt;T&gt;.Builder.Max</a> </li>
+  <li> <a
+  href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.immutable.immutablesortedset-1.builder.min">ImmutableSortedSet&lt;T&gt;.Builder.Min</a> </li>
+</ul>
+<h3>What is the potential impact?</h3>
+<p>We measured a significant improvement both in execution time and memory allocation. For more details see the <code>Benchmarks</code> section from
+the <code>More info</code> tab.</p>
+<h2>How to fix it</h2>
+<p>The <code>Min</code> and <code>Max</code> properties are defined on the following classes, and the extension method call can be replaced by calling
+the propery instead:</p>
+<ul>
+  <li> <code>SortedSet&lt;T&gt;</code> </li>
+  <li> <code>ImmutableSortedSet&lt;T&gt;</code> </li>
+  <li> <code>ImmutableSortedSet&lt;T&gt;.Builder</code> </li>
+</ul>
+<h3>Code examples</h3>
+<h4>Noncompliant code example</h4>
+<pre data-diff-id="1" data-diff-type="noncompliant">
+int GetMax(SortedSet&lt;int&gt; data) =&gt;
+    data.Max();
+</pre>
+<pre data-diff-id="2" data-diff-type="noncompliant">
+int GetMin(SortedSet&lt;int&gt; data) =&gt;
+    data.Min();
+</pre>
+<h4>Compliant solution</h4>
+<pre data-diff-id="1" data-diff-type="compliant">
+int GetMax(SortedSet&lt;int&gt; data) =&gt;
+    data.Max;
+</pre>
+<pre data-diff-id="2" data-diff-type="compliant">
+int GetMin(SortedSet&lt;int&gt; data) =&gt;
+    data.Min;
+</pre>
+<h2>Resources</h2>
+<h3>Documentation</h3>
+<ul>
+  <li> <a href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.sortedset-1">SortedSet&lt;T&gt;</a> </li>
+  <li> <a href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.immutable.immutablesortedset-1">ImmutableSortedSet&lt;T&gt;</a> </li>
+  <li> <a
+  href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.immutable.immutablesortedset-1.builder">ImmutableSortedSet&lt;T&gt;.Builder</a> </li>
+</ul>
+<h3>Benchmarks</h3>
+<table>
+  <colgroup>
+    <col style="width: 20%;">
+    <col style="width: 20%;">
+    <col style="width: 20%;">
+    <col style="width: 20%;">
+    <col style="width: 20%;">
+  </colgroup>
+  <thead>
+    <tr>
+      <th>Method</th>
+      <th>Runtime</th>
+      <th>Mean</th>
+      <th>StdDev</th>
+      <th>Allocated</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <td><p>MaxMethod</p></td>
+      <td><p>.NET 7.0</p></td>
+      <td><p>68,961.483 us</p></td>
+      <td><p>499.6623 us</p></td>
+      <td><p>248063 B</p></td>
+    </tr>
+    <tr>
+      <td><p>MaxProperty</p></td>
+      <td><p>.NET 7.0</p></td>
+      <td><p>4.638 us</p></td>
+      <td><p>0.0634 us</p></td>
+      <td><p>-</p></td>
+    </tr>
+    <tr>
+      <td><p>MaxMethod</p></td>
+      <td><p>.NET Framework 4.6.2</p></td>
+      <td><p>85,827.359 us</p></td>
+      <td><p>1,531.1611 us</p></td>
+      <td><p>281259 B</p></td>
+    </tr>
+    <tr>
+      <td><p>MaxProperty</p></td>
+      <td><p>.NET Framework 4.6.2</p></td>
+      <td><p>67.682 us</p></td>
+      <td><p>0.3757 us</p></td>
+      <td><p>312919 B</p></td>
+    </tr>
+  </tbody>
+</table>
+<p>The results were generated by running the following snippet with <a href="https://github.com/dotnet/BenchmarkDotNet">BenchmarkDotNet</a>:</p>
+<pre>
+private SortedSet&lt;string&gt; data;
+
+[Params(1_000)]
+public int Iterations;
+
+[GlobalSetup]
+public void Setup() =&gt;
+    data = new SortedSet&lt;string&gt;(Enumerable.Range(0, Iterations).Select(x =&gt; Guid.NewGuid().ToString()));
+
+[Benchmark(Baseline = true)]
+public void MaxMethod()
+{
+    for (var i = 0; i &lt; Iterations; i++)
+    {
+        _ = data.Max();     // Max() extension method
+    }
+}
+
+[Benchmark]
+public void MaxProperty()
+{
+    for (var i = 0; i &lt; Iterations; i++)
+    {
+        _ = data.Max;       // Max property
+    }
+}
+</pre>
+<p>Hardware configuration:</p>
+<pre>
+BenchmarkDotNet=v0.13.5, OS=Windows 10 (10.0.19045.2846/22H2/2022Update)
+11th Gen Intel Core i7-11850H 2.50GHz, 1 CPU, 16 logical and 8 physical cores
+  [Host]               : .NET Framework 4.8 (4.8.4614.0), X64 RyuJIT VectorSize=256
+  .NET 7.0             : .NET 7.0.5 (7.0.523.17405), X64 RyuJIT AVX2
+  .NET Framework 4.6.2 : .NET Framework 4.8 (4.8.4614.0), X64 RyuJIT VectorSize=256
+</pre>
+

analyzers/rspec/cs/S6609.json

@@ -0,0 +1,17 @@
+{
+  "title": "\"Min\/Max\" properties of \"Set\" types should be used instead of the \"Enumerable\" extension methods",
+  "type": "CODE_SMELL",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "5min"
+  },
+  "tags": [
+    "performance"
+  ],
+  "defaultSeverity": "Minor",
+  "ruleSpecification": "RSPEC-6609",
+  "sqKey": "S6609",
+  "scope": "All",
+  "quickfix": "targeted"
+}

analyzers/rspec/cs/Sonar_way_profile.json

@@ -276,6 +276,7 @@
     "S6605",
     "S6607",
     "S6608",
+    "S6609",
     "S6610",
     "S6613"
   ]