New rule S4663: Comments should not be empty

analyzers/its/expected/Ember-MM/EmberAPI-{208AA35E-C6AE-4D2D-A9DD-B6EFD19A4279}-S4663.json

@@ -0,0 +1,17 @@
+{
+"issues":  [
+{
+"id":  "S4663",
+"message":  "Remove this empty comment",
+"location":  {
+"uri":  "sources\Ember-MM\EmberAPI\clsAPICommon.vb",
+"region":  {
+"startLine":  577,
+"startColumn":  19,
+"endLine":  577,
+"endColumn":  21
+}
+}
+}
+]
+}

analyzers/its/expected/Ember-MM/scraper.EmberCore-{EF6A550E-DD76-4F4D-8250-8598140F828B}-S4663.json

@@ -0,0 +1,17 @@
+{
+"issues":  [
+{
+"id":  "S4663",
+"message":  "Remove this empty comment",
+"location":  {
+"uri":  "sources\Ember-MM\Addons\scraper.EmberCore\scraperMovieNativeModule.vb",
+"region":  {
+"startLine":  364,
+"startColumn":  104,
+"endLine":  364,
+"endColumn":  105
+}
+}
+}
+]
+}

analyzers/rspec/cs/S4663_c#.html

@@ -0,0 +1,16 @@
+<p>An empty comment is likely to be a mistake and doesn’t help to improve the readability of the code. For these reasons, it should be removed.</p>
+<h2>Noncompliant Code Example</h2>
+<pre>
+//
+
+///
+
+/**
+
+ */
+
+/*
+
+ */
+</pre>
+

analyzers/rspec/cs/S4663_c#.json

@@ -0,0 +1,15 @@
+{
+  "title": "Comments should not be empty",
+  "type": "CODE_SMELL",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "1min"
+  },
+  "tags": [],
+  "defaultSeverity": "Minor",
+  "ruleSpecification": "RSPEC-4663",
+  "sqKey": "S4663",
+  "scope": "Main",
+  "quickfix": "unknown"
+}

analyzers/rspec/cs/Sonar_way_profile.json

@@ -241,6 +241,7 @@
     "S4583",
     "S4586",
     "S4635",
+    "S4663",
     "S4790",
     "S4792",
     "S4830",

analyzers/rspec/vbnet/S4663_vb.net.html

@@ -0,0 +1,8 @@
+<p>An empty comment is likely to be a mistake and doesn’t help to improve the readability of the code. For these reasons, it should be removed.</p>
+<h2>Noncompliant Code Example</h2>
+<pre>
+'
+
+'''
+</pre>
+

analyzers/rspec/vbnet/S4663_vb.net.json

@@ -0,0 +1,15 @@
+{
+  "title": "Comments should not be empty",
+  "type": "CODE_SMELL",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "1min"
+  },
+  "tags": [],
+  "defaultSeverity": "Minor",
+  "ruleSpecification": "RSPEC-4663",
+  "sqKey": "S4663",
+  "scope": "Main",
+  "quickfix": "unknown"
+}

analyzers/rspec/vbnet/Sonar_way_profile.json

@@ -108,6 +108,7 @@
     "S4581",
     "S4583",
     "S4586",
+    "S4663",
     "S4790",
     "S4792",
     "S4830",

analyzers/src/SonarAnalyzer.CSharp/Facade/CSharpSyntaxFacade.cs

@@ -40,10 +40,14 @@ internal sealed class CSharpSyntaxFacade : SyntaxFacade<SyntaxKind>
 
     public override bool IsKind(SyntaxToken token, SyntaxKind kind) => token.IsKind(kind);
 
+    public override bool IsKind(SyntaxTrivia trivia, SyntaxKind kind) => trivia.IsKind(kind);
+
     public override bool IsAnyKind(SyntaxNode node, ISet<SyntaxKind> syntaxKinds) => node.IsAnyKind(syntaxKinds);
 
     public override bool IsAnyKind(SyntaxNode node, params SyntaxKind[] syntaxKinds) => node.IsAnyKind(syntaxKinds);
 
+    public override bool IsAnyKind(SyntaxTrivia trivia, params SyntaxKind[] syntaxKinds) => trivia.IsAnyKind(syntaxKinds);
+
     public override bool IsNullLiteral(SyntaxNode node) => node.IsNullLiteral();
 
     public override IEnumerable<SyntaxNode> ArgumentExpressions(SyntaxNode node) =>

analyzers/src/SonarAnalyzer.CSharp/Facade/CSharpSyntaxKindFacade.cs

@@ -29,6 +29,13 @@ internal sealed class CSharpSyntaxKindFacade : ISyntaxKindFacade<SyntaxKind>
         SyntaxKindEx.RecordClassDeclaration,
     };
     public SyntaxKind ClassDeclaration => SyntaxKind.ClassDeclaration;
+    public SyntaxKind[] CommentTrivia => new[]
+    {
+        SyntaxKind.SingleLineCommentTrivia,
+        SyntaxKind.MultiLineCommentTrivia,
+        SyntaxKind.SingleLineDocumentationCommentTrivia,
+        SyntaxKind.MultiLineDocumentationCommentTrivia,
+    };
     public SyntaxKind[] ComparisonKinds => new[]
     {
         SyntaxKind.GreaterThanExpression,
@@ -41,19 +48,25 @@ internal sealed class CSharpSyntaxKindFacade : ISyntaxKindFacade<SyntaxKind>
     public SyntaxKind ConstructorDeclaration => SyntaxKind.ConstructorDeclaration;
     public SyntaxKind[] DefaultExpressions => new[] { SyntaxKind.DefaultExpression, SyntaxKindEx.DefaultLiteralExpression };
     public SyntaxKind EnumDeclaration => SyntaxKind.EnumDeclaration;
+    public SyntaxKind EndOfLineTrivia => SyntaxKind.EndOfLineTrivia;
     public SyntaxKind FieldDeclaration => SyntaxKind.FieldDeclaration;
     public SyntaxKind IdentifierName => SyntaxKind.IdentifierName;
     public SyntaxKind IdentifierToken => SyntaxKind.IdentifierToken;
     public SyntaxKind InvocationExpression => SyntaxKind.InvocationExpression;
     public SyntaxKind InterpolatedStringExpression => SyntaxKind.InterpolatedStringExpression;
+    public SyntaxKind LeftShiftAssignmentStatement => SyntaxKind.LeftShiftAssignmentExpression;
+    public SyntaxKind LeftShiftExpression => SyntaxKind.LeftShiftExpression;
     public SyntaxKind LocalDeclaration => SyntaxKind.LocalDeclarationStatement;
     public SyntaxKind[] MethodDeclarations => new[] { SyntaxKind.MethodDeclaration };
     public SyntaxKind[] ObjectCreationExpressions => new[] { SyntaxKind.ObjectCreationExpression, SyntaxKindEx.ImplicitObjectCreationExpression };
     public SyntaxKind Parameter => SyntaxKind.Parameter;
     public SyntaxKind ParameterList => SyntaxKind.ParameterList;
     public SyntaxKind RefKeyword => SyntaxKind.RefKeyword;
     public SyntaxKind ReturnStatement => SyntaxKind.ReturnStatement;
+    public SyntaxKind RightShiftAssignmentStatement => SyntaxKind.RightShiftAssignmentExpression;
+    public SyntaxKind RightShiftExpression => SyntaxKind.RightShiftExpression;
     public SyntaxKind SimpleAssignment => SyntaxKind.SimpleAssignmentExpression;
+    public SyntaxKind SimpleCommentTrivia => SyntaxKind.SingleLineCommentTrivia;
     public SyntaxKind SimpleMemberAccessExpression => SyntaxKind.SimpleMemberAccessExpression;
     public SyntaxKind[] StringLiteralExpressions => new[] { SyntaxKind.StringLiteralExpression, SyntaxKindEx.Utf8StringLiteralExpression };
     public SyntaxKind StructDeclaration => SyntaxKind.StructDeclaration;
@@ -66,8 +79,5 @@ internal sealed class CSharpSyntaxKindFacade : ISyntaxKindFacade<SyntaxKind>
         SyntaxKindEx.RecordClassDeclaration,
         SyntaxKindEx.RecordStructDeclaration,
     };
-    public SyntaxKind LeftShiftExpression => SyntaxKind.LeftShiftExpression;
-    public SyntaxKind RightShiftExpression => SyntaxKind.RightShiftExpression;
-    public SyntaxKind LeftShiftAssignmentStatement => SyntaxKind.LeftShiftAssignmentExpression;
-    public SyntaxKind RightShiftAssignmentStatement => SyntaxKind.RightShiftAssignmentExpression;
+    public SyntaxKind WhitespaceTrivia => SyntaxKind.WhitespaceTrivia;
 }

analyzers/src/SonarAnalyzer.CSharp/Rules/CommentsShouldNotBeEmpty.cs

@@ -0,0 +1,87 @@
+/*
+ * SonarAnalyzer for .NET
+ * Copyright (C) 2015-2023 SonarSource SA
+ * mailto: contact AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+using System.Text;
+
+namespace SonarAnalyzer.Rules.CSharp;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public sealed class CommentsShouldNotBeEmpty : CommentsShouldNotBeEmptyBase<SyntaxKind>
+{
+    protected override ILanguageFacade<SyntaxKind> Language => CSharpFacade.Instance;
+
+    protected override string GetCommentText(SyntaxTrivia trivia) =>
+        trivia.Kind() switch
+        {
+            SyntaxKind.SingleLineCommentTrivia => GetSingleLineText(trivia),
+            SyntaxKind.MultiLineCommentTrivia => GetMultiLineText(trivia),
+            SyntaxKind.SingleLineDocumentationCommentTrivia => GetSingleLineDocumentationText(trivia),
+            SyntaxKind.MultiLineDocumentationCommentTrivia => GetMultiLineDocumentationText(trivia),
+        };
+
+    // //
+    private static string GetSingleLineText(SyntaxTrivia trivia) =>
+        trivia.ToString().Trim().Substring(2);
+
+    // ///
+    private static string GetSingleLineDocumentationText(SyntaxTrivia trivia)
+    {
+        var stringBuilder = new StringBuilder();
+        foreach (var line in trivia.ToFullString().Split(MetricsBase.LineTerminators, StringSplitOptions.None))
+        {
+            var trimmedLine = line.TrimStart(null);
+            trimmedLine = trimmedLine.StartsWith("///")
+                ? trimmedLine.Substring(3).Trim()
+                : trimmedLine.TrimEnd(null);
+            stringBuilder.Append(trimmedLine);
+        }
+        return stringBuilder.ToString();
+    }
+
+    // /* */
+    private static string GetMultiLineText(SyntaxTrivia trivia) =>
+        ParseMultiLine(trivia.ToString(), 2); // Length of "/*"
+
+    // /** */
+    private static string GetMultiLineDocumentationText(SyntaxTrivia trivia) =>
+        ParseMultiLine(trivia.ToFullString(), 3); // Length of "/**"
+
+    private static string ParseMultiLine(string commentText, int initialTrimSize)
+    {
+        commentText = commentText.Trim().Substring(initialTrimSize);
+        if (commentText.EndsWith("*/", StringComparison.Ordinal)) // Might be unclosed, still reported
+        {
+            commentText = commentText.Substring(0, commentText.Length - 2);
+        }
+
+        var stringBuilder = new StringBuilder();
+        foreach (var line in commentText.Split(MetricsBase.LineTerminators, StringSplitOptions.None))
+        {
+            var trimmedLine = line.TrimStart(null);
+            if (trimmedLine.StartsWith("*", StringComparison.Ordinal))
+            {
+                trimmedLine = trimmedLine.TrimStart('*');
+            }
+
+            stringBuilder.Append(trimmedLine.Trim());
+        }
+        return stringBuilder.ToString();
+    }
+}

analyzers/src/SonarAnalyzer.Common/Facade/ISyntaxKindFacade.cs

@@ -26,29 +26,33 @@ public interface ISyntaxKindFacade<out TSyntaxKind>
     abstract TSyntaxKind Attribute { get; }
     abstract TSyntaxKind[] ClassAndRecordDeclaration { get; }
     abstract TSyntaxKind ClassDeclaration { get; }
+    abstract TSyntaxKind[] CommentTrivia { get; }
     abstract TSyntaxKind[] ComparisonKinds { get; }
     abstract TSyntaxKind ConstructorDeclaration { get; }
     abstract TSyntaxKind[] DefaultExpressions { get; }
+    abstract TSyntaxKind EndOfLineTrivia { get; }
     abstract TSyntaxKind EnumDeclaration { get; }
     abstract TSyntaxKind FieldDeclaration { get; }
     abstract TSyntaxKind IdentifierName { get; }
     abstract TSyntaxKind IdentifierToken { get; }
     abstract TSyntaxKind InvocationExpression { get; }
     abstract TSyntaxKind InterpolatedStringExpression { get; }
+    abstract TSyntaxKind LeftShiftAssignmentStatement { get; }
+    abstract TSyntaxKind LeftShiftExpression { get; }
     abstract TSyntaxKind LocalDeclaration { get; }
     abstract TSyntaxKind[] MethodDeclarations { get; }
     abstract TSyntaxKind[] ObjectCreationExpressions { get; }
     abstract TSyntaxKind Parameter { get; }
     abstract TSyntaxKind RefKeyword { get; }
+    abstract TSyntaxKind RightShiftExpression { get; }
+    abstract TSyntaxKind RightShiftAssignmentStatement { get; }
     abstract TSyntaxKind ParameterList { get; }
     abstract TSyntaxKind ReturnStatement { get; }
     abstract TSyntaxKind SimpleAssignment { get; }
+    abstract TSyntaxKind SimpleCommentTrivia { get; }
     abstract TSyntaxKind SimpleMemberAccessExpression { get; }
     abstract TSyntaxKind[] StringLiteralExpressions { get; }
     abstract TSyntaxKind StructDeclaration { get; }
     abstract TSyntaxKind[] TypeDeclaration { get; }
-    abstract TSyntaxKind LeftShiftExpression { get; }
-    abstract TSyntaxKind RightShiftExpression { get; }
-    abstract TSyntaxKind LeftShiftAssignmentStatement { get; }
-    abstract TSyntaxKind RightShiftAssignmentStatement { get; }
+    abstract TSyntaxKind WhitespaceTrivia { get; }
 }

analyzers/src/SonarAnalyzer.Common/Facade/SyntaxFacade.cs

@@ -28,8 +28,10 @@ public abstract class SyntaxFacade<TSyntaxKind>
     public abstract bool IsNullLiteral(SyntaxNode node);
     public abstract bool IsKind(SyntaxNode node, TSyntaxKind kind);
     public abstract bool IsKind(SyntaxToken token, TSyntaxKind kind);
+    public abstract bool IsKind(SyntaxTrivia trivia, TSyntaxKind kind);
     public abstract bool IsAnyKind(SyntaxNode node, ISet<TSyntaxKind> syntaxKinds);
     public abstract bool IsAnyKind(SyntaxNode node, params TSyntaxKind[] syntaxKinds);
+    public abstract bool IsAnyKind(SyntaxTrivia trivia, params TSyntaxKind[] syntaxKinds);
     public abstract IEnumerable<SyntaxNode> ArgumentExpressions(SyntaxNode node);
     public abstract ImmutableArray<SyntaxNode> AssignmentTargets(SyntaxNode assignment);
     public abstract SyntaxNode AssignmentLeft(SyntaxNode assignment);