Idea: Locally scoped variable can have the same mangled name

Expected Behavior

Obfuscated code can have multiple locally scoped variable name identical. I know this could be difficult to implement, it is an idea, if someone have the skills to implement this.

It would make de obfuscation much harder

Example:

var a = 2 // can't use 'a' anymore as it is in the top scope
function(b, c) {
  return window[b] = c
}
for(var b = 0; b < c; b++) { // notice 'b', 'c' is also in the function, they where in local scope in the previous function
    var d = 5+b
}

This would be harder to de obfuscate as a variable name can have multiple purposes.

Current Behavior

Raw code

var myvalue = 2
function(key, value) {
  return window[key] = value
}
for(var i = 0; i < myvalue; i++) {
    var mycounter = 5+i
}

Obfuscated code

var a = 2
function(b, c) {
  return window[b] = c
}
for(var d = 0; d < e; d++) {
    var e = 5+d
}

[sanex3339]

In this branch, I added the new preparing transformer, called ScopeTransformer, that added scope property to all nodes.

Then, in MangledIdentifierNamesGenerator identifiers for each scope are tried to generate.

[sanex3339]

Much smallest minimal example with bug

 let obfuscatedCode: string = JavaScriptObfuscator.obfuscate(
        `
        (function () {
            let a = 0;
            
            function param1 (param1, param2) {
               
            }
        })();
        `,
        {
            ...NO_ADDITIONAL_NODES_PRESET,
            compact: false,
            stringArray: false,
            stringArrayThreshold: 1,
            transformObjectKeys: true,
            identifierNamesGenerator: IdentifierNamesGenerator.MangledIdentifierNamesGenerator,
            seed: 1
        }
    ).getObfuscatedCode();

Obfuscated code with error:

(function () {
    let c = 0x0;
    function d(d, d) {
    }
}());