Revert Template.blockParams -> Template.locals change for now

The rename is motivated by:

1. It's confusing for the root node to have "block params"
2. All other AST nodes that has `blockParams` also has a `params`
   field that exposes the source location as `VarHead`s

There is some uncertainty in:

1. Whether there are a lot of existing AST consumers that uses it
   (shouldn't be a big deal in itself, as it's just a deprecation)
2. Whether the direction of using `Template.locals` as the source
   of truth for outside local variables will ultimately prevail

When we have more certainty on those and if this rename is still
desired, it should be possible to revert this commit

Author: chancancode

packages/@glimmer/syntax/lib/parser/handlebars-node-visitors.ts

@@ -35,10 +35,10 @@ export abstract class HandlebarsNodeVisitors extends Parser {
   abstract override beginAttributeValue(quoted: boolean): void;
   abstract override finishAttributeValue(): void;
 
-  parse(program: HBS.Program, locals: string[]): ASTv1.Template {
+  parse(program: HBS.Program, blockParams: string[]): ASTv1.Template {
     let node = b.template({
       body: [],
-      locals,
+      blockParams,
       loc: this.source.spanFor(program.loc),
     });
 

packages/@glimmer/syntax/lib/v1/legacy-interop.ts

@@ -5,35 +5,6 @@ import type * as ASTv1 from './nodes-v1';
 
 import b from './public-builders';
 
-export type TemplateParams = Omit<ASTv1.Template, 'type' | 'blockParams'>;
-
-export function buildLegacyTemplate({ body, locals, loc }: TemplateParams): ASTv1.Template {
-  const node = {
-    type: 'Template',
-    body,
-    locals,
-    loc,
-  };
-
-  Object.defineProperty(node, 'blockParams', {
-    enumerable: false,
-    get(): string[] {
-      deprecate(
-        `Template nodes can never have block params, for in-scope variables, use locals instead`
-      );
-      return this.locals;
-    },
-    set(value: string[]) {
-      deprecate(
-        `Template nodes can never have block params, for in-scope variables, use locals instead`
-      );
-      this.locals = value;
-    },
-  });
-
-  return node as ASTv1.Template;
-}
-
 export type MustacheStatementParams = Omit<ASTv1.MustacheStatement, 'type' | 'escaped'>;
 
 export function buildLegacyMustache({

packages/@glimmer/syntax/lib/v1/nodes-v1.ts

@@ -29,11 +29,6 @@ export type EntityEncodingState = 'transformed' | 'raw';
 
 export interface Template extends CommonProgram {
   type: 'Template';
-  locals: string[];
-
-  /**
-   * @deprecated use locals instead
-   */
   blockParams: string[];
 }
 

packages/@glimmer/syntax/lib/v1/parser-builders.ts

@@ -4,12 +4,7 @@ import { assert } from '@glimmer/util';
 import type * as ASTv1 from './api';
 
 import { SourceSpan } from '../source/span';
-import {
-  buildLegacyLiteral,
-  buildLegacyMustache,
-  buildLegacyPath,
-  buildLegacyTemplate,
-} from './legacy-interop';
+import { buildLegacyLiteral, buildLegacyMustache, buildLegacyPath } from './legacy-interop';
 
 const DEFAULT_STRIP = {
   close: false,
@@ -60,18 +55,19 @@ class Builders {
 
   template({
     body,
-    locals,
+    blockParams,
     loc,
   }: {
     body: ASTv1.Statement[];
-    locals: string[];
+    blockParams: string[];
     loc: SourceSpan;
   }): ASTv1.Template {
-    return buildLegacyTemplate({
+    return {
+      type: 'Template',
       body,
-      locals,
+      blockParams,
       loc,
-    });
+    };
   }
 
   mustache({

packages/@glimmer/syntax/lib/v1/public-builders.ts

@@ -68,7 +68,7 @@ function buildBlock(
   if (_defaultBlock.type === 'Template') {
     deprecate(`b.program is deprecated. Use b.blockItself instead.`);
     defaultBlock = b.blockItself({
-      params: buildBlockParams(_defaultBlock.locals),
+      params: buildBlockParams(_defaultBlock.blockParams),
       body: _defaultBlock.body,
       loc: _defaultBlock.loc,
     });
@@ -78,7 +78,7 @@ function buildBlock(
 
   if (_elseBlock?.type === 'Template') {
     deprecate(`b.program is deprecated. Use b.blockItself instead.`);
-    assert(_elseBlock.locals.length === 0, '{{else}} block cannot have block params');
+    assert(_elseBlock.blockParams.length === 0, '{{else}} block cannot have block params');
 
     elseBlock = b.blockItself({
       params: [],
@@ -422,12 +422,12 @@ function buildBlockItself(
 
 function buildTemplate(
   body: ASTv1.Statement[] = [],
-  locals: string[] = [],
+  blockParams: string[] = [],
   loc?: SourceLocation
 ): ASTv1.Template {
   return b.template({
     body,
-    locals,
+    blockParams,
     loc: buildLoc(loc || null),
   });
 }

packages/@glimmer/syntax/lib/v2/normalize.ts

@@ -41,7 +41,7 @@ export function normalize(
   let normalizeOptions = {
     strictMode: false,
     ...options,
-    locals: ast.locals,
+    locals: ast.blockParams,
   };
 
   let top = SymbolTable.top(