Option to Exclude Built-in Objects from Mangle Process

[kyaido]

Bug report or Feature request?

Feature request

Version (complete output of terser -V or specific git commit)

https://try.terser.org/

I would like to inquire if there's a possibility to exclude built-in objects from the mangling process.
Currently, when declaring a variable with the same name as a built-in object, such as Symbol, and then using that built-in object, both the user-defined variable and the usage of the built-in object get mangled.

Here's a snippet that reproduces the issue, which you can also replicate using the Terser REPL:

terser input

console.log(Symbol);
const Symbol = 'Symbol';
console.log(Symbol);

terser output or error

console.log(o);const o="Symbol";console.log(o); // => o is not defined

However, the desired outcome is to keep the built-in object Symbol intact while only mangling the user-defined variable name:

Expected result

console.log(Symbol);const o="Symbol";console.log(o);

Is there an existing option or workaround to achieve this behavior? If not, could this be considered for a future enhancement?

[fabiosantoscode]

With const I don't think this reproduces a problem, because Terser's output is going to crash the same way as the input:

ReferenceError: can't access lexical declaration 'Symbol' before initialization

Maybe your example was a bit more contrived before you made it a minimal repro?

edit: I had an example with var that I thought was a reproduction, but it was a false alarm. I made a mistake while using the browser console

[fabiosantoscode]

What's the source issue you're trying to solve? Is this related to concatenating files?