Mangler using wrong variable name in some cases

[loganfsmyth]

Tested out the mangler on our codebase and got the following:

function decodeMessage(message){
    let namespace;
    let name;
    let value = null;

    [, namespace, name, value] = message.split(',') || [];
    console.log(name);
}

converts to

function decodeMessage(a) {
    let b;
    let c;
    let d = null;

    [ , b , d , d ] = a.split(',') || [];
    console.log(c);
}

notice the third item in the destructured array is d instead of c for some reason.

I see there are a few mangler bugs filed, but I don't know if this is one of them. Sorry if it is a duplicate.

[boopathi]

Related #326

[filmic]

Similar issue with broken array destructuring:

function currentData(id) {
	let [alpha, beta, gamma] = id.split('_');
	[alpha, beta, gamma] = _.map([alpha, beta, gamma], idPart => {
		return parseInt(idPart, 10);
	});
}

is converted to:

function currentData(a){let[b,c,d]=a.split('_');[b,d,d]=_.map([b,c,d],e=>{return parseInt(e,10)})}

REPL LINK

[keithamus]

I also have a similar issue, but this is with destructuring in function arguments. Was unsure if I should file a new issue or put it in this one.

Given (repl):

const Main = ({ thing: Thing = 'div' }) => <Thing />;
<Main thing={'span'} />

Actual (formatted)

const Main=({thing:a='div'})=>React.createElement(Thing,null); // ReferenceError Thing is not defined
React.createElement(Main,{thing:'span'});

Expected (formatted)

const Main=({thing:A='div'})=>React.createElement(A,null);
React.createElement(Main,{thing:'span'});

[xtuc]

@keithamus I think this is correct because you shoud write that:

const Main = ({ Thing: ThingInterface = 'div' }) => <Thing />;
<Main thing={'span'} />

The thing variable must be in uppercase. You are 'using' the type insteand of the variable.

[keithamus]

You're right @xtuc, I've updated my expected to reflect that. The salient point, however, is that the name is mangled but this is not reflected into the rest of the function. It either needs to mangle both or mangle neither; currently it mangles one.