In REPL after typing "let a=a", variable a is locked and cannot be assigned

[zhanzhenzhen]

• Version: 14
• Platform: Darwin
• Subsystem: maybe the underlying V8

What steps will reproduce the bug?

In REPL, first type let a=a then type a=1

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior?

The first statement causes an error. The second statement doesn't cause an error.

What do you see instead?

Both the first statement and the second statement cause errors.

> let a=a
Uncaught ReferenceError: Cannot access 'a' before initialization
> a=1
Uncaught ReferenceError: Cannot access 'a' before initialization

Additional information

[kaizhu256]

this seems to be v8 issue, as its reproducible in chrome, and differs in behavior wrt to firefox:

// chrome:
let a=a;
// Uncaught ReferenceError: a is not defined
a=1;
// Uncaught ReferenceError: Cannot access 'a' before initialization

// firefox:
let a=a;
// Uncaught ReferenceError: can't access lexical declaration 'a' before initialization
a=1;
1

i don't understand the es-specs @ https://tc39.es/ecma262/#sec-let-and-const-declarations, but maybe someone else could determine whether:

1. nodejs and chrome violate specs
2. firefox violate specs
3. both violate specs
4. neither violate specs because behavior is undefined

[Slayer95]

This is dupe of #8309

[devsnek]

Duplicate of #8309