Extract rule: template-no-dynamic-subexpression-invocations

Author: NullVoxPopuli

README.md

@@ -207,6 +207,7 @@ rules in templates can be disabled with eslint directives with mustache or html
 | [template-no-capital-arguments](docs/rules/template-no-capital-arguments.md)                                 | disallow capital arguments (use lowercase @arg instead of @Arg)         |    |    |    |
 | [template-no-chained-this](docs/rules/template-no-chained-this.md)                                           | disallow redundant `this.this` in templates                             |    | 🔧 |    |
 | [template-no-debugger](docs/rules/template-no-debugger.md)                                                   | disallow {{debugger}} in templates                                      |    |    |    |
+| [template-no-dynamic-subexpression-invocations](docs/rules/template-no-dynamic-subexpression-invocations.md) | disallow dynamic subexpression invocations                              |    |    |    |
 | [template-no-element-event-actions](docs/rules/template-no-element-event-actions.md)                         | disallow element event actions (use {{on}} modifier instead)            |    |    |    |
 | [template-no-implicit-this](docs/rules/template-no-implicit-this.md)                                         | require explicit `this` in property access                              |    |    |    |
 | [template-no-inline-event-handlers](docs/rules/template-no-inline-event-handlers.md)                         | disallow DOM event handler attributes                                   |    |    |    |

docs/rules/template-no-dynamic-subexpression-invocations.md

@@ -0,0 +1,62 @@
+# ember/template-no-dynamic-subexpression-invocations
+
+<!-- end auto-generated rule header -->
+
+Disallow dynamic helper invocations.
+
+Dynamic helper invocations (where the helper name comes from a property or argument) make code harder to understand and can have performance implications. Use explicit helper names instead.
+
+## Rule Details
+
+This rule disallows invoking helpers dynamically using `this` or `@` properties.
+
+## Examples
+
+### Incorrect ❌
+
+```gjs
+<template>
+  {{(this.helper "arg")}}
+</template>
+```
+
+```gjs
+<template>
+  {{(@helperName "value")}}
+</template>
+```
+
+```gjs
+<template>
+  {{this.formatter this.data}}
+</template>
+```
+
+### Correct ✅
+
+```gjs
+<template>
+  {{format-date this.date}}
+</template>
+```
+
+```gjs
+<template>
+  {{(upper-case this.name)}}
+</template>
+```
+
+```gjs
+<template>
+  {{this.formattedData}}
+</template>
+```
+
+## Related Rules
+
+- [template-no-implicit-this](./template-no-implicit-this.md)
+
+## References
+
+- [Ember Guides - Template Helpers](https://guides.emberjs.com/release/components/helper-functions/)
+- [eslint-plugin-ember template-no-dynamic-subexpression-invocations](https://github.com/ember-cli/eslint-plugin-ember/blob/master/docs/rules/template-no-dynamic-subexpression-invocations.md)

lib/rules/template-no-dynamic-subexpression-invocations.js

@@ -0,0 +1,157 @@
+function isInAttrPosition(node) {
+  let p = node.parent;
+  while (p) {
+    if (p.type === 'GlimmerAttrNode') {
+      return true;
+    }
+    if (p.type === 'GlimmerConcatStatement') {
+      p = p.parent;
+      continue;
+    }
+    if (
+      p.type === 'GlimmerElementNode' ||
+      p.type === 'GlimmerTemplate' ||
+      p.type === 'GlimmerBlockStatement' ||
+      p.type === 'GlimmerBlock'
+    ) {
+      return false;
+    }
+    p = p.parent;
+  }
+  return false;
+}
+
+/** @type {import('eslint').Rule.RuleModule} */
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'disallow dynamic subexpression invocations',
+      category: 'Best Practices',
+      url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/template-no-dynamic-subexpression-invocations.md',
+      templateMode: 'both',
+    },
+    fixable: null,
+    schema: [],
+    messages: {
+      noDynamicSubexpressionInvocations:
+        'Do not use dynamic helper invocations. Use explicit helper names instead.',
+    },
+    originallyFrom: {
+      name: 'ember-template-lint',
+      rule: 'lib/rules/no-dynamic-subexpression-invocations.js',
+      docs: 'docs/rule/no-dynamic-subexpression-invocations.md',
+      tests: 'test/unit/rules/no-dynamic-subexpression-invocations-test.js',
+    },
+  },
+
+  create(context) {
+    const localScopes = [];
+
+    function pushLocals(params) {
+      localScopes.push(new Set(params || []));
+    }
+
+    function popLocals() {
+      localScopes.pop();
+    }
+
+    function isLocal(name) {
+      for (const scope of localScopes) {
+        if (scope.has(name)) {
+          return true;
+        }
+      }
+      return false;
+    }
+
+    function isDynamicPath(path) {
+      if (!path || path.type !== 'GlimmerPathExpression') {
+        return false;
+      }
+      if (path.head?.type === 'AtHead') {
+        return true;
+      }
+      if (path.head?.type === 'ThisHead') {
+        return true;
+      }
+      if (path.original && path.original.includes('.')) {
+        return true;
+      }
+      if (path.original && isLocal(path.original)) {
+        return true;
+      }
+      return false;
+    }
+
+    return {
+      GlimmerBlockStatement(node) {
+        if (node.program && node.program.blockParams) {
+          pushLocals(node.program.blockParams);
+        }
+      },
+      'GlimmerBlockStatement:exit'(node) {
+        if (node.program && node.program.blockParams) {
+          popLocals();
+        }
+      },
+
+      GlimmerElementNode(node) {
+        if (node.blockParams && node.blockParams.length > 0) {
+          pushLocals(node.blockParams);
+        }
+      },
+      'GlimmerElementNode:exit'(node) {
+        if (node.blockParams && node.blockParams.length > 0) {
+          popLocals();
+        }
+      },
+
+      GlimmerSubExpression(node) {
+        if (node.path && node.path.type === 'GlimmerPathExpression' && isDynamicPath(node.path)) {
+          context.report({
+            node,
+            messageId: 'noDynamicSubexpressionInvocations',
+          });
+        }
+      },
+
+      GlimmerElementModifierStatement(node) {
+        if (node.path && node.path.type === 'GlimmerPathExpression' && isDynamicPath(node.path)) {
+          context.report({
+            node,
+            messageId: 'noDynamicSubexpressionInvocations',
+          });
+        }
+      },
+
+      GlimmerMustacheStatement(node) {
+        if (node.path && node.path.type === 'GlimmerPathExpression') {
+          const inAttr = isInAttrPosition(node);
+          const hasArgs =
+            (node.params && node.params.length > 0) ||
+            (node.hash && node.hash.pairs && node.hash.pairs.length > 0);
+
+          if (inAttr && isDynamicPath(node.path) && hasArgs) {
+            // In attribute context, flag dynamic paths with arguments
+            context.report({
+              node,
+              messageId: 'noDynamicSubexpressionInvocations',
+            });
+            return;
+          }
+
+          if (!inAttr && hasArgs) {
+            // In body context, only flag this.* paths (not @args)
+            if (node.path.head?.type === 'ThisHead') {
+              context.report({
+                node,
+                messageId: 'noDynamicSubexpressionInvocations',
+              });
+            }
+          }
+        }
+      },
+    };
+  },
+};