fix: avoid task checkbox for setext heading text

src/Tokenizer.ts

@@ -415,16 +415,19 @@ export class _Tokenizer<ParserOutput = string, RendererOutput = string> {
         this.lexer.state.top = false;
         item.tokens = this.lexer.blockTokens(item.text, []);
         if (item.task) {
+          if (item.tokens[0]?.type !== 'text' && item.tokens[0]?.type !== 'paragraph') {
+            item.task = false;
+            continue;
+          }
+
           // Remove checkbox markdown from item tokens
           item.text = item.text.replace(this.rules.other.listReplaceTask, '');
-          if (item.tokens[0]?.type === 'text' || item.tokens[0]?.type === 'paragraph') {
-            item.tokens[0].raw = item.tokens[0].raw.replace(this.rules.other.listReplaceTask, '');
-            item.tokens[0].text = item.tokens[0].text.replace(this.rules.other.listReplaceTask, '');
-            for (let i = this.lexer.inlineQueue.length - 1; i >= 0; i--) {
-              if (this.rules.other.listIsTask.test(this.lexer.inlineQueue[i].src)) {
-                this.lexer.inlineQueue[i].src = this.lexer.inlineQueue[i].src.replace(this.rules.other.listReplaceTask, '');
-                break;
-              }
+          item.tokens[0].raw = item.tokens[0].raw.replace(this.rules.other.listReplaceTask, '');
+          item.tokens[0].text = item.tokens[0].text.replace(this.rules.other.listReplaceTask, '');
+          for (let i = this.lexer.inlineQueue.length - 1; i >= 0; i--) {
+            if (this.rules.other.listIsTask.test(this.lexer.inlineQueue[i].src)) {
+              this.lexer.inlineQueue[i].src = this.lexer.inlineQueue[i].src.replace(this.rules.other.listReplaceTask, '');
+              break;
             }
           }
 

test/unit/Lexer.test.js

@@ -1297,6 +1297,45 @@ paragraph
       });
     });
 
+    it('does not parse setext heading text as a task checkbox', () => {
+      expectTokens({
+        md: '- [x] title\n  ---',
+        tokens: [
+          {
+            type: 'list',
+            raw: '- [x] title\n  ---',
+            ordered: false,
+            start: '',
+            loose: false,
+            items: [
+              {
+                type: 'list_item',
+                raw: '- [x] title\n  ---',
+                task: false,
+                loose: false,
+                text: '[x] title\n---',
+                tokens: [
+                  {
+                    type: 'heading',
+                    raw: '[x] title\n---',
+                    depth: 2,
+                    text: '[x] title',
+                    tokens: [
+                      {
+                        type: 'text',
+                        raw: '[x] title',
+                        text: '[x] title',
+                      },
+                    ],
+                  },
+                ],
+              },
+            ],
+          },
+        ],
+      });
+    });
+
     it('multiline', () => {
       expectTokens({
         md: `

test/unit/marked.test.js

@@ -54,6 +54,12 @@ describe('marked unit', () => {
 
       assert.strictEqual(html, '<ul>\n<li><p><input disabled="" type="checkbox"> item 1</p>\n</li>\n<li><p><input disabled="" type="checkbox"> item 2</p>\n</li>\n</ul>\n');
     });
+
+    it('does not parse setext heading text as a task checkbox', () => {
+      const html = marked.parse('- [x] title\n  ---');
+
+      assert.strictEqual(html, '<ul>\n<li><h2>[x] title</h2>\n</li>\n</ul>\n');
+    });
   });
 
   describe('parseInline', () => {