[BUGFIX LTS] Prevent transformation of block params called attrs

packages/ember-template-compiler/lib/plugins/transform-attrs-into-args.ts

@@ -33,14 +33,27 @@ export default function transformAttrsIntoArgs(env: EmberASTPluginEnvironment):
 
   let stack: string[][] = [[]];
 
+  function updateBlockParamsStack(blockParams: string[]) {
+    let parent = stack[stack.length - 1];
+    stack.push(parent.concat(blockParams));
+  }
+
   return {
     name: 'transform-attrs-into-args',
 
     visitor: {
       Program: {
         enter(node: AST.Program) {
-          let parent = stack[stack.length - 1];
-          stack.push(parent.concat(node.blockParams));
+          updateBlockParamsStack(node.blockParams);
+        },
+        exit() {
+          stack.pop();
+        },
+      },
+
+      ElementNode: {
+        enter(node: AST.ElementNode) {
+          updateBlockParamsStack(node.blockParams);
         },
         exit() {
           stack.pop();

packages/ember-template-compiler/tests/plugins/transform-attrs-into-args-test.js

@@ -0,0 +1,62 @@
+import TransformTestCase from '../utils/transform-test-case';
+import { moduleFor, RenderingTestCase } from 'internal-test-helpers';
+
+moduleFor(
+  'ember-template-compiler: transforming attrs into @args',
+  class extends TransformTestCase {
+    ['@test it transforms attrs into @args']() {
+      expectDeprecation(() => {
+        this.assertTransformed(`{{attrs.foo}}`, `{{@foo}}`);
+      }, /Using {{attrs}} to reference named arguments has been deprecated. {{attrs.foo}} should be updated to {{@foo}}./);
+
+      expectDeprecation(() => {
+        this.assertTransformed(`{{attrs.foo.bar}}`, `{{@foo.bar}}`);
+      }, /Using {{attrs}} to reference named arguments has been deprecated. {{attrs.foo.bar}} should be updated to {{@foo.bar}}./);
+
+      expectDeprecation(() => {
+        this.assertTransformed(`{{if attrs.foo "foo"}}`, `{{if @foo "foo"}}`);
+      }, /Using {{attrs}} to reference named arguments has been deprecated. {{attrs.foo}} should be updated to {{@foo}}./);
+
+      expectDeprecation(() => {
+        this.assertTransformed(`{{#if attrs.foo}}{{/if}}`, `{{#if @foo}}{{/if}}`);
+      }, /Using {{attrs}} to reference named arguments has been deprecated. {{attrs.foo}} should be updated to {{@foo}}./);
+
+      expectDeprecation(() => {
+        this.assertTransformed(`{{deeply (nested attrs.foo.bar)}}`, `{{deeply (nested @foo.bar)}}`);
+      }, /Using {{attrs}} to reference named arguments has been deprecated. {{attrs.foo.bar}} should be updated to {{@foo.bar}}./);
+
+      expectDeprecation(() => {
+        this.assertTransformed(`{{this.attrs.foo}}`, `{{@foo}}`);
+      }, /Using {{attrs}} to reference named arguments has been deprecated. {{attrs.foo}} should be updated to {{@foo}}./);
+    }
+  }
+);
+
+moduleFor(
+  'ember-template-compiler: not transforming block params named "attrs" into @args',
+  class extends RenderingTestCase {
+    ["@test it doesn't transform block params"]() {
+      this.registerComponent('foo', {
+        template: '{{#let "foo" as |attrs|}}{{attrs}}{{/let}}',
+      });
+      this.render('<Foo />');
+      this.assertComponentElement(this.firstChild, { content: 'foo' });
+    }
+
+    ["@test it doesn't transform component block params"]() {
+      this.registerComponent('foo', {
+        template: '{{yield "foo"}}',
+      });
+      this.render('<Foo as |attrs|>{{attrs}}</Foo>');
+      this.assertComponentElement(this.firstChild, { content: 'foo' });
+    }
+
+    ["@test it doesn't transform block params with nested keys"]() {
+      this.registerComponent('foo', {
+        template: '{{yield (hash bar="baz")}}',
+      });
+      this.render('<Foo as |attrs|>{{attrs.bar}}</Foo>');
+      this.assertComponentElement(this.firstChild, { content: 'baz' });
+    }
+  }
+);