From c0972b23b79dafe3d635af1058da76a9f045f147 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?G=C3=A9rald=20Barr=C3=A9?= <git@meziantou.net>
Date: Sat, 24 Feb 2024 18:39:32 -0500
Subject: [PATCH] Add code fixer for MA0154

---
 .../Rules/UseLangwordInXmlCommentFixer.cs     | 54 +++++++++++++++++++
 .../Rules/UseLangwordInXmlCommentAnalyzer.cs  |  3 +-
 .../UseLangwordInXmlCommentAnalyzerTests.cs   | 24 +++++++--
 3 files changed, 76 insertions(+), 5 deletions(-)
 create mode 100644 src/Meziantou.Analyzer.CodeFixers/Rules/UseLangwordInXmlCommentFixer.cs

diff --git a/src/Meziantou.Analyzer.CodeFixers/Rules/UseLangwordInXmlCommentFixer.cs b/src/Meziantou.Analyzer.CodeFixers/Rules/UseLangwordInXmlCommentFixer.cs
new file mode 100644
index 000000000..496506a19
--- /dev/null
+++ b/src/Meziantou.Analyzer.CodeFixers/Rules/UseLangwordInXmlCommentFixer.cs
@@ -0,0 +1,54 @@
+using System.Collections.Immutable;
+using System.Composition;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CodeActions;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.Editing;
+using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
+
+namespace Meziantou.Analyzer.Rules;
+
+[ExportCodeFixProvider(LanguageNames.CSharp), Shared]
+public sealed class UseLangwordInXmlCommentFixer : CodeFixProvider
+{
+    public override ImmutableArray<string> FixableDiagnosticIds => ImmutableArray.Create(RuleIdentifiers.UseLangwordInXmlComment);
+
+    public override FixAllProvider GetFixAllProvider() => WellKnownFixAllProviders.BatchFixer;
+
+    public override async Task RegisterCodeFixesAsync(CodeFixContext context)
+    {
+        var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+        var nodeToFix = root?.FindNode(context.Span, getInnermostNodeForTie: true, findInsideTrivia: true);
+        if (nodeToFix is null)
+            return;
+
+        if (!context.Diagnostics[0].Properties.TryGetValue("keyword", out var keyword) || keyword is null)
+            return;
+
+        var title = $"Use <see langword=\"{keyword}\" />";
+        var codeAction = CodeAction.Create(
+            title,
+            cancellationToken => Fix(context.Document, nodeToFix, keyword, cancellationToken),
+            equivalenceKey: title);
+
+        context.RegisterCodeFix(codeAction, context.Diagnostics);
+    }
+
+    private static async Task<Document> Fix(Document document, SyntaxNode nodeToFix, string keyword, CancellationToken cancellationToken)
+    {
+        var editor = await DocumentEditor.CreateAsync(document, cancellationToken).ConfigureAwait(false);
+
+        var newNode = XmlNullKeywordElement()
+                .WithLessThanToken(Token(SyntaxKind.LessThanToken))
+                .WithAttributes(
+                    SingletonList<XmlAttributeSyntax>(
+                        XmlTextAttribute("langword", keyword)));
+
+        editor.ReplaceNode(nodeToFix, newNode);
+        return editor.GetChangedDocument();
+    }
+}
diff --git a/src/Meziantou.Analyzer/Rules/UseLangwordInXmlCommentAnalyzer.cs b/src/Meziantou.Analyzer/Rules/UseLangwordInXmlCommentAnalyzer.cs
index 15147b4db..998e9b0e9 100644
--- a/src/Meziantou.Analyzer/Rules/UseLangwordInXmlCommentAnalyzer.cs
+++ b/src/Meziantou.Analyzer/Rules/UseLangwordInXmlCommentAnalyzer.cs
@@ -159,7 +159,8 @@ private static void AnalyzeSymbol(SymbolAnalysisContext context)
                             var item = elementSyntax.Content.SingleOrDefaultIfMultiple();
                             if (item is XmlTextSyntax { TextTokens: [var codeText] } && CSharpKeywords.Contains(codeText.Text))
                             {
-                                context.ReportDiagnostic(Rule, elementSyntax);
+                                var properties = ImmutableDictionary<string, string?>.Empty.Add("keyword", codeText.Text);
+                                context.ReportDiagnostic(Rule, properties, elementSyntax);
                             }
                         }
                         else
diff --git a/tests/Meziantou.Analyzer.Test/Rules/UseLangwordInXmlCommentAnalyzerTests.cs b/tests/Meziantou.Analyzer.Test/Rules/UseLangwordInXmlCommentAnalyzerTests.cs
index e5ee34e8d..cfcf9bbfd 100644
--- a/tests/Meziantou.Analyzer.Test/Rules/UseLangwordInXmlCommentAnalyzerTests.cs
+++ b/tests/Meziantou.Analyzer.Test/Rules/UseLangwordInXmlCommentAnalyzerTests.cs
@@ -10,17 +10,33 @@ private static ProjectBuilder CreateProjectBuilder()
     {
         return new ProjectBuilder()
             .WithAnalyzer<UseLangwordInXmlCommentAnalyzer>()
+            .WithCodeFixProvider<UseLangwordInXmlCommentFixer>()
             .WithTargetFramework(TargetFramework.NetLatest);
     }
 
     [Theory]
-    [InlineData("[|<c>void</c>|]")]
-    [InlineData("[|<code>void</code>|]")]
-    [InlineData("[|<code>null</code>|]")]
+    [InlineData("[|<c>void</c>|]", "<see langword=\"void\"/>")]
+    [InlineData("[|<code>void</code>|]", "<see langword=\"void\"/>")]
+    [InlineData("[|<code>null</code>|]", "<see langword=\"null\"/>")]
+    public async Task ValidateSummary_Invalid(string comment, string fix)
+    {
+        await CreateProjectBuilder()
+              .WithSourceCode($$"""
+/// <summary>{{comment}}</summary>
+class Sample { }
+""")
+              .ShouldFixCodeWith($$"""
+/// <summary>{{fix}}</summary>
+class Sample { }
+""")
+              .ValidateAsync();
+    }
+
+    [Theory]
     [InlineData("<i>in</i>")]
     [InlineData("null")]
     [InlineData("this is null")]
-    public async Task ValidateSummary(string comment)
+    public async Task ValidateSummary_Valid(string comment)
     {
         await CreateProjectBuilder()
               .WithSourceCode($$"""