[Bug]: visitors.merge removes noScope

[j4k0xb]

💻

• Would you like to work on a fix?

How are you using Babel?

Programmatic API (babel.transform, babel.parse)

Input code

const parse = require('@babel/parser').parse;
const traverse = require('@babel/traverse').default;
const generate = require('@babel/generator').default;
const visitors = require('@babel/traverse/lib/visitors');

const ast = parse('const a = 1; { const b = 2 };');

const visitor = visitors.merge([
  {
    Program(path) {
      console.log(!!path.scope);
    },
    noScope: true,
  },
  {
    BlockStatement(path) {
      console.log(!!path.scope);
    },
    noScope: true,
  },
]);

traverse(ast, visitor); // should log false

traverse(ast, {}); // some visitor that initializes scope

traverse(ast, visitor); // should log true

Configuration file name

No response

Configuration

No response

Current and expected behavior

Current behaviour (since #15702): noScope of merged visitors gets removed and causes the scope to be crawled anyways and overwrites the old scope.
Expected behaviour (v7.22.6): keep noScope in the merged visitor

I have to use multiple traversals, most use noScope: true to achieve better performance while still accessing the scope/references of a previous traversal.
Another reason is that the AST is sometimes temporarily in a broken state or I manually update references, and don't want the scope to be overwritten.

Environment

System:
OS: Linux 5.15 Manjaro Linux
Binaries:
Node: 18.12.0 - ~/.nvm/versions/node/v18.12.0/bin/node
Yarn: 1.22.19 - /usr/bin/yarn
npm: 8.19.2 - ~/.nvm/versions/node/v18.12.0/bin/npm
npmPackages:
@babel/generator: ^7.22.7 => 7.22.7
@babel/helper-validator-identifier: ^7.22.5 => 7.22.5
@babel/parser: ^7.22.7 => 7.22.7
@babel/template: ^7.22.5 => 7.22.5
@babel/traverse: ^7.22.8 => 7.22.8
@babel/types: ^7.22.5 => 7.22.5
eslint: ^8.44.0 => 8.44.0

Possible solution

Set noScope of the merged visitor if all visitors have it.
Or v7.22.6 behaviour: if at least one has it?

Additional context

No response

[babel-bot]

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[JLHwung]

The noScope, alongside with some other options:

babel/packages/babel-traverse/src/index.ts

Lines 23 to 28 in 30ff3ac

	export type TraverseOptions<S = t.Node> = {
	scope?: Scope;
	noScope?: boolean;
	denylist?: string[];
	shouldSkip?: (node: NodePath) => boolean;
	} & Visitor<S>;

are ignored in shouldIgnoreKey. We should merge such options in

babel/packages/babel-traverse/src/visitors.ts

Line 52 in 30ff3ac

if (shouldIgnoreKey(nodeType)) continue;

@j4k0xb I have assigned this issue to you since you voiced your intent to work on this issue. Feel free to ask any questions if there are bumps when working on a fix.