Add autofix for empty-tag-not-self-closed rule

Introduces an auto-fix action for the 'empty-tag-not-self-closed' rule, converting void HTML elements to self-closing format. Updates documentation and changelog, enables the rule in test config, and adds comprehensive test cases for void elements.

Author: coliff

htmlhint-server/src/server.ts

@@ -2230,6 +2230,142 @@ function createFormMethodRequireFix(
   };
 }
 
+/**
+ * Create auto-fix action for empty-tag-not-self-closed rule
+ *
+ * This fixes void HTML elements by converting them to proper self-closing format.
+ * Void elements should be self-closing and never have closing tags.
+ * Only applies to void HTML elements (br, img, hr, input, etc.).
+ *
+ * Example transformations:
+ * - <br> → <br/>
+ * - <img src="test.jpg"> → <img src="test.jpg"/>
+ * - <hr> → <hr/>
+ */
+function createEmptyTagNotSelfClosedFix(
+  document: TextDocument,
+  diagnostic: Diagnostic,
+): CodeAction | null {
+  trace(
+    `[DEBUG] createEmptyTagNotSelfClosedFix called with diagnostic: ${JSON.stringify(diagnostic)}`,
+  );
+
+  if (
+    !diagnostic.data ||
+    diagnostic.data.ruleId !== "empty-tag-not-self-closed"
+  ) {
+    trace(
+      `[DEBUG] createEmptyTagNotSelfClosedFix: Invalid diagnostic data or ruleId: ${JSON.stringify(diagnostic.data)}`,
+    );
+    return null;
+  }
+
+  const text = document.getText();
+  const diagnosticOffset = document.offsetAt(diagnostic.range.start);
+
+  // List of void elements that should be self-closing
+  const voidElements = [
+    "area",
+    "base",
+    "br",
+    "col",
+    "embed",
+    "hr",
+    "img",
+    "input",
+    "link",
+    "meta",
+    "source",
+    "track",
+    "wbr",
+  ];
+
+  // Find the tag boundaries around the diagnostic position
+  const tagBoundaries = findTagBoundaries(text, diagnosticOffset);
+  if (!tagBoundaries) {
+    trace(
+      `[DEBUG] createEmptyTagNotSelfClosedFix: Could not find tag boundaries`,
+    );
+    return null;
+  }
+
+  const { tagStart, tagEnd } = tagBoundaries;
+
+  // Extract the content around the diagnostic position to find void elements
+  const searchStart = Math.max(0, tagStart - 50);
+  const searchEnd = Math.min(text.length, tagEnd + 50);
+  const searchText = text.substring(searchStart, searchEnd);
+
+  // Pattern to match void elements that are not self-closing: <tagname> or <tagname attributes>
+  const voidElementPattern = /<(\w+)(\s[^>]*?)?\s*>/gi;
+  let match;
+
+  while ((match = voidElementPattern.exec(searchText)) !== null) {
+    const matchStart = searchStart + match.index;
+    const matchEnd = matchStart + match[0].length;
+    const tagName = match[1].toLowerCase();
+    const attributes = match[2] || "";
+    const fullMatch = match[0];
+
+    // Skip if already self-closing
+    if (fullMatch.endsWith("/>")) {
+      continue;
+    }
+
+    // Check if this match contains our diagnostic position
+    if (matchStart <= diagnosticOffset && diagnosticOffset <= matchEnd) {
+      // Verify this is a void element
+      if (!voidElements.includes(tagName)) {
+        trace(
+          `[DEBUG] createEmptyTagNotSelfClosedFix: ${tagName} is not a void element`,
+        );
+        return null;
+      }
+
+      trace(
+        `[DEBUG] createEmptyTagNotSelfClosedFix: Found non-self-closing ${tagName} tag at position ${matchStart}-${matchEnd}`,
+      );
+
+      // Create the self-closing replacement
+      const selfClosingTag = attributes.trim()
+        ? `<${tagName}${attributes} />`
+        : `<${tagName} />`;
+
+      const edit: TextEdit = {
+        range: {
+          start: document.positionAt(matchStart),
+          end: document.positionAt(matchEnd),
+        },
+        newText: selfClosingTag,
+      };
+
+      trace(
+        `[DEBUG] createEmptyTagNotSelfClosedFix: Will replace "${fullMatch}" with "${selfClosingTag}"`,
+      );
+
+      const action = CodeAction.create(
+        `Convert ${tagName} tag to self-closing`,
+        {
+          changes: {
+            [document.uri]: [edit],
+          },
+        },
+        CodeActionKind.QuickFix,
+      );
+
+      action.diagnostics = [diagnostic];
+      action.isPreferred = true;
+
+      return action;
+    }
+  }
+
+  trace(
+    `[DEBUG] createEmptyTagNotSelfClosedFix: No matching empty tag pair found`,
+  );
+  return null;
+}
+
 /**
  * Create auto-fix actions for supported rules
  */
@@ -2336,6 +2472,10 @@ async function createAutoFixes(
           trace(`[DEBUG] Calling createFormMethodRequireFix`);
           fix = createFormMethodRequireFix(document, diagnostic);
           break;
+        case "empty-tag-not-self-closed":
+          trace(`[DEBUG] Calling createEmptyTagNotSelfClosedFix`);
+          fix = createEmptyTagNotSelfClosedFix(document, diagnostic);
+          break;
         default:
           trace(`[DEBUG] No autofix function found for rule: ${ruleId}`);
           break;

htmlhint/CHANGELOG.md

@@ -4,7 +4,8 @@ All notable changes to the "vscode-htmlhint" extension will be documented in thi
 
 ### v1.15.0 (2025-11-27)
 
-- Smarter autofix for rules which accommodates for `tag-self-close` rule.
+- Add autofix for the `empty-tag-not-self-closed` rule
+- Smarter autofix for rules which accommodates for `tag-self-close` rule
 
 ### v1.14.0 (2025-11-26)
 

htmlhint/README.md

@@ -36,6 +36,7 @@ The extension provides automatic fixes for many common HTML issues. Currently su
 - **`button-type-require`** - Adds type attribute to buttons
 - **`doctype-first`** - Adds DOCTYPE declaration at the beginning
 - **`doctype-html5`** - Updates DOCTYPE to HTML5
+- **`empty-tag-not-self-closed`** - Converts void elements to self-closing format (e.g., `<br>` → `<br/>`)
 - **`form-method-require`** - Adds empty method attribute to forms
 - **`html-lang-require`** - Adds `lang` attribute to `<html>` tag
 - **`meta-charset-require`** - Adds charset meta tag

test/autofix/.htmlhintrc

@@ -9,6 +9,7 @@
   "button-type-require": true,
   "doctype-first": true,
   "doctype-html5": true,
+  "empty-tag-not-self-closed": true,
   "html-lang-require": true,
   "id-unique": true,
   "meta-charset-require": true,

test/autofix/empty-tag-not-self-closed-test.html

@@ -0,0 +1,62 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <meta name="description" content="Empty Tag Not Self-Closed Test" />
+    <title>Empty Tag Not Self-Closed Test</title>
+  </head>
+  <body>
+    <!-- Test case 1: br tag (should be converted to self-closing) -->
+    <br>
+
+    <!-- Test case 2: img tag (should be converted to self-closing) -->
+    <img src="test.jpg" alt="Test">
+
+    <!-- Test case 3: hr tag (should be converted to self-closing) -->
+    <hr>
+
+    <!-- Test case 4: input tag (should be converted to self-closing) -->
+    <input type="text">
+
+    <!-- Test case 5: meta tag (should be converted to self-closing) -->
+    <meta name="test" content="test">
+
+    <!-- Test case 6: link tag (should be converted to self-closing) -->
+    <link rel="stylesheet" href="style.css">
+
+    <!-- Test case 7: area tag (should be converted to self-closing) -->
+    <area shape="rect" coords="0,0,100,100" href="#">
+
+    <!-- Test case 8: base tag (should be converted to self-closing) -->
+    <base href="https://example.com">
+
+    <!-- Test case 9: col tag (should be converted to self-closing) -->
+    <col span="2">
+
+    <!-- Test case 10: embed tag (should be converted to self-closing) -->
+    <embed src="test.swf" type="application/x-shockwave-flash">
+
+    <!-- Test case 11: source tag (should be converted to self-closing) -->
+    <source src="test.mp4" type="video/mp4">
+
+    <!-- Test case 12: track tag (should be converted to self-closing) -->
+    <track src="subtitles.vtt" kind="subtitles" srclang="en">
+
+    <!-- Test case 13: wbr tag (should be converted to self-closing) -->
+    <wbr>
+
+    <!-- Test case 14: Already self-closing tags - should not trigger -->
+    <br />
+    <img src="test2.jpg" alt="Test 2" />
+    <hr />
+
+    <!-- Test case 15: Non-void elements with content - should not trigger -->
+    <div>Content</div>
+    <p>Paragraph content</p>
+
+    <!-- Test case 16: Empty non-void elements - should not trigger -->
+    <div></div>
+    <p></p>
+  </body>
+</html>