Private fields, in and precedence (?)

[jakubledl]

Bug report

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

terser 5.30.3

Complete CLI command or minify() options used

terser input.js --compress --mangle

terser input

class Test {
    #test;

    test(num, obj) {
        return num === 2 && #test in obj;
    }
}

const t = new Test();
console.log(t.test(2, {}));

terser output or error

Parse error at input.js:5,28
        return num === 2 && #test in obj;
                            ^
ERROR: Unexpected token: privatename (test)
    at ...

Expected result

class Test{#t;test(t,s){return 2===t&&#t in s}}const t=new Test;console.log(t.test(2,{}));

Version 5.30.2 works and gives the expected output, 5.30.3 gives the error. The input is valid code, works in browsers and node.

Changing the offending line to

return (num === 2) && (#test in obj);

makes the error goes away, so maybe the problem is with operator precedence and 0e04a22 might be to blame? Both in and === have higher precedence than &&, so the two return statements should be entirely equivalent.

[fabiosantoscode]

I've fixed it. Since a lone #privateprop is not a valid expression, the detection for #private in needs to happen in more places.