Extract rule: template-no-ambiguous-glimmer-paths

README.md

@@ -196,6 +196,7 @@ rules in templates can be disabled with eslint directives with mustache or html
 | :----------------------------------------------------------------------------------------------------- | :-------------------------------------------------------------- | :- | :- | :- |
 | [template-builtin-component-arguments](docs/rules/template-builtin-component-arguments.md)             | disallow setting certain attributes on builtin components       |    |    |    |
 | [template-no-action-modifiers](docs/rules/template-no-action-modifiers.md)                             | disallow usage of {{action}} modifiers                          |    |    |    |
+| [template-no-ambiguous-glimmer-paths](docs/rules/template-no-ambiguous-glimmer-paths.md)               | disallow ambiguous path in templates                            |    |    |    |
 | [template-no-arguments-for-html-elements](docs/rules/template-no-arguments-for-html-elements.md)       | disallow @arguments on HTML elements                            |    |    |    |
 | [template-no-array-prototype-extensions](docs/rules/template-no-array-prototype-extensions.md)         | disallow usage of Ember Array prototype extensions              |    |    |    |
 | [template-no-block-params-for-html-elements](docs/rules/template-no-block-params-for-html-elements.md) | disallow block params on HTML elements                          |    |    |    |

docs/rules/template-no-ambiguous-glimmer-paths.md

@@ -0,0 +1,41 @@
+# ember/template-no-ambiguous-glimmer-paths
+
+> **HBS Only**: This rule applies to classic `.hbs` template files only (loose mode). It is not relevant for `gjs`/`gts` files (strict mode), where these patterns cannot occur.
+
+<!-- end auto-generated rule header -->
+
+Disallow ambiguous path in templates
+
+## Rule Details
+
+This rule requires explicit `this.` or `@` prefix for property access to avoid ambiguity.
+
+## Examples
+
+Examples of **incorrect** code for this rule:
+
+```hbs
+{{user.name}}
+```
+
+```hbs
+{{model.title}}
+```
+
+Examples of **correct** code for this rule:
+
+```hbs
+{{this.user.name}}
+```
+
+```hbs
+{{@model.title}}
+```
+
+```hbs
+{{MyComponent}}
+```
+
+## References
+
+- [eslint-plugin-ember template-no-implicit-this](https://github.com/ember-cli/eslint-plugin-ember/blob/master/docs/rules/template-no-implicit-this.md)

lib/rules/template-no-ambiguous-glimmer-paths.js

@@ -0,0 +1,73 @@
+/** @type {import('eslint').Rule.RuleModule} */
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'disallow ambiguous path in templates',
+      category: 'Best Practices',
+      url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/template-no-ambiguous-glimmer-paths.md',
+      templateMode: 'loose',
+    },
+    schema: [],
+    messages: {
+      ambiguousPath: 'Ambiguous path "{{path}}". Use explicit "this." or "@" prefix.',
+    },
+  },
+
+  create(context) {
+    const BUILTIN_HELPERS = new Set([
+      'if',
+      'unless',
+      'each',
+      'let',
+      'with',
+      'log',
+      'concat',
+      'get',
+      'array',
+      'hash',
+      'fn',
+      'on',
+      'action',
+    ]);
+
+    function isAmbiguous(path) {
+      if (!path || path.type !== 'GlimmerPathExpression') {
+        return false;
+      }
+
+      const pathString = path.original;
+
+      // Not ambiguous if starts with @ or this.
+      if (pathString.startsWith('@') || pathString.startsWith('this.')) {
+        return false;
+      }
+
+      // Not ambiguous if it's a builtin helper
+      if (BUILTIN_HELPERS.has(pathString)) {
+        return false;
+      }
+
+      // Check if it's a simple identifier (no dots)
+      if (!pathString.includes('.')) {
+        return false; // Simple identifiers are component names or helpers
+      }
+
+      return true; // Ambiguous property access
+    }
+
+    return {
+      GlimmerMustacheStatement(node) {
+        if (isAmbiguous(node.path)) {
+          context.report({
+            node,
+            messageId: 'ambiguousPath',
+            data: {
+              path: node.path.original,
+            },
+          });
+        }
+      },
+    };
+  },
+};

tests/lib/rules/template-no-ambiguous-glimmer-paths.js

@@ -0,0 +1,57 @@
+const rule = require('../../../lib/rules/template-no-ambiguous-glimmer-paths');
+const RuleTester = require('eslint').RuleTester;
+
+const ruleTester = new RuleTester({
+  parser: require.resolve('ember-eslint-parser'),
+  parserOptions: { ecmaVersion: 2022, sourceType: 'module' },
+});
+
+ruleTester.run('template-no-ambiguous-glimmer-paths', rule, {
+  valid: [
+    {
+      filename: 'test.gjs',
+      code: '<template>{{this.name}}</template>',
+      output: null,
+    },
+    {
+      filename: 'test.gjs',
+      code: '<template>{{@title}}</template>',
+      output: null,
+    },
+    {
+      filename: 'test.gjs',
+      code: '<template>{{MyComponent}}</template>',
+      output: null,
+    },
+    {
+      filename: 'test.gjs',
+      code: '<template>{{if this.isActive "active" "inactive"}}</template>',
+      output: null,
+    },
+  ],
+
+  invalid: [
+    {
+      filename: 'test.gjs',
+      code: '<template>{{user.name}}</template>',
+      output: null,
+      errors: [
+        {
+          messageId: 'ambiguousPath',
+          data: { path: 'user.name' },
+        },
+      ],
+    },
+    {
+      filename: 'test.gjs',
+      code: '<template>{{model.title}}</template>',
+      output: null,
+      errors: [
+        {
+          messageId: 'ambiguousPath',
+          data: { path: 'model.title' },
+        },
+      ],
+    },
+  ],
+});