If statement optimization causes assignments to be executed out of order

[simonlampen]

Bug report or feature request?

Bug

bisected version
Bisected and GOOD at 3.4.8 and BROKEN at 3.4.9

JavaScript input
input.js:

function string2buf(str) {  
    var i=0,
        buf = new Array(2),
        c = str.charCodeAt(0);
    if (c < 0x800) {
        /* two byte char */
        buf[i++] = 0xC0 | (c >>> 6);
        buf[i++] = 0x80 | (c & 0x3f);
    } else {
        /* three byte char */
        buf[i++] = 0xE0 | (c >>> 12);
        buf[i++] = 0x80 | (c >>> 6 & 0x3f);
        buf[i++] = 0x80 | (c & 0x3f);
    }
    return buf;
};
console.log(string2buf("é"));

Command line:
cls&&uglifyjs --mangle --compress -- input.js > output.js&&echo expected:&&node input.js&&echo actual:&&node output.js

expectation and failure
expected:
[ 195, 169 ]
actual:
[ 169, 195 ]

The if statements are optimised into conditional clauses but the assignments within the if clauses are caused to run out of order. In this example it causes elements to be added to an array out of order.

[fabiosantoscode]

Bug does not occur in terser

[nylen]

Releasing a new version and then disappearing is bad form. Please follow up with your community after the release.

If you don't have time to do that, better not to do the release in the first place.

[nylen]

@fabiosantoscode do you have a test case for this issue? Might help you improve coverage a bit.

[fabiosantoscode]

Nice suggestion @nylen, I've added a test now.

[nylen]

Thanks - this is not the first time I've seen incredibly poor software development and community management practices on this repository, so I'm going to look into switching current and future projects to terser.

Please keep improving the test coverage, that is really important for critical web infrastructure like a JS minifier, and really nice to see!