Fix template-no-at-ember-render-modifiers: detect GJS/GTS imports

In GJS/GTS, @ember/render-modifiers is consumed via per-modifier default
imports (e.g. 'import didInsert from "@ember/render-modifiers/modifiers/did-insert"').
The local name is user-chosen, so the rule can't match on a hardcoded
kebab-case list. Track ImportDeclaration nodes in strict-mode files and
flag modifier usages based on the local import name.

HBS behavior is unchanged: the canonical kebab-case names (did-insert,
did-update, will-destroy) are still flagged via resolver-style matching,
matching upstream ember-template-lint.

Author: johanrd

lib/rules/template-no-at-ember-render-modifiers.js

@@ -1,3 +1,13 @@
+// Map of `@ember/render-modifiers` sub-path → canonical kebab-case modifier name.
+// Default-imported names are user-chosen, so we track local names to canonical.
+const RENDER_MODIFIER_IMPORT_PATHS = {
+  '@ember/render-modifiers/modifiers/did-insert': 'did-insert',
+  '@ember/render-modifiers/modifiers/did-update': 'did-update',
+  '@ember/render-modifiers/modifiers/will-destroy': 'will-destroy',
+};
+
+const KEBAB_NAMES = new Set(['did-insert', 'did-update', 'will-destroy']);
+
 /** @type {import('eslint').Rule.RuleModule} */
 module.exports = {
   meta: {
@@ -23,24 +33,56 @@ module.exports = {
   },
 
   create(context) {
+    const filename = context.filename;
+    const isStrictMode = filename.endsWith('.gjs') || filename.endsWith('.gts');
+
+    // local import name → canonical kebab name. Only populated in GJS/GTS.
+    const importedModifiers = new Map();
+
+    function isRenderModifier(name) {
+      if (isStrictMode) {
+        return importedModifiers.has(name);
+      }
+      // HBS: resolver-resolved by canonical kebab name
+      return KEBAB_NAMES.has(name);
+    }
+
+    function canonicalName(name) {
+      return importedModifiers.get(name) || name;
+    }
+
     return {
+      ImportDeclaration(node) {
+        if (!isStrictMode) {
+          return;
+        }
+        const canonical = RENDER_MODIFIER_IMPORT_PATHS[node.source.value];
+        if (!canonical) {
+          return;
+        }
+        // Default import (`import didInsert from '...'`) is the supported form
+        for (const specifier of node.specifiers) {
+          if (specifier.type === 'ImportDefaultSpecifier') {
+            importedModifiers.set(specifier.local.name, canonical);
+          }
+        }
+      },
+
       GlimmerElementNode(node) {
         if (!node.modifiers) {
           return;
         }
 
         for (const modifier of node.modifiers) {
-          if (
-            modifier.path &&
-            modifier.path.type === 'GlimmerPathExpression' &&
-            (modifier.path.original === 'did-insert' ||
-              modifier.path.original === 'did-update' ||
-              modifier.path.original === 'will-destroy')
-          ) {
+          if (modifier.path?.type !== 'GlimmerPathExpression') {
+            continue;
+          }
+          const name = modifier.path.original;
+          if (isRenderModifier(name)) {
             context.report({
               node: modifier,
               messageId: 'noRenderModifier',
-              data: { modifier: modifier.path.original },
+              data: { modifier: canonicalName(name) },
             });
           }
         }

tests/lib/rules/template-no-at-ember-render-modifiers.js

@@ -32,6 +32,19 @@ ruleTester.run('template-no-at-ember-render-modifiers', rule, {
     '<template>{{did-insert}}</template>',
     '<template>{{did-update}}</template>',
     '<template>{{will-destroy}}</template>',
+
+    // In GJS/GTS, kebab identifiers cannot be imports; these are bare paths
+    // that happen to share the canonical name but are not the render modifier.
+    {
+      filename: 'test.gjs',
+      code: '<template><div {{did-insert this.setup}}></div></template>',
+    },
+    // Unrelated imports with matching local names should not match
+    {
+      filename: 'test.gjs',
+      code: `import didInsert from './my-lib';
+        <template><div {{didInsert this.setup}}></div></template>`,
+    },
   ],
 
   invalid: [
@@ -87,6 +100,37 @@ ruleTester.run('template-no-at-ember-render-modifiers', rule, {
       output: null,
       errors: [{ messageId: 'noRenderModifier' }],
     },
+
+    // GJS/GTS import-based forms — local name is user-chosen
+    {
+      filename: 'test.gjs',
+      code: `import didInsert from '@ember/render-modifiers/modifiers/did-insert';
+        <template><div {{didInsert this.setup}}></div></template>`,
+      output: null,
+      errors: [{ messageId: 'noRenderModifier' }],
+    },
+    {
+      filename: 'test.gjs',
+      code: `import didUpdate from '@ember/render-modifiers/modifiers/did-update';
+        <template><div {{didUpdate this.update}}></div></template>`,
+      output: null,
+      errors: [{ messageId: 'noRenderModifier' }],
+    },
+    {
+      filename: 'test.gjs',
+      code: `import willDestroy from '@ember/render-modifiers/modifiers/will-destroy';
+        <template><div {{willDestroy this.cleanup}}></div></template>`,
+      output: null,
+      errors: [{ messageId: 'noRenderModifier' }],
+    },
+    // Renamed default import still flags
+    {
+      filename: 'test.gjs',
+      code: `import myInsert from '@ember/render-modifiers/modifiers/did-insert';
+        <template><div {{myInsert this.setup}}></div></template>`,
+      output: null,
+      errors: [{ messageId: 'noRenderModifier' }],
+    },
   ],
 });