Bug 221548 – comment blocks cause incorrect reporting of column numbers in stack traces

• Component: JavaScriptCore
• Status: RESOLVED FIXED

Consider this JavaScript executing on a webpage, imported as an external script file:

window.onload = () => {
  console.log('something unrelated');const e = new Error("new error");console.log(e.stack);console.log('something unrelated');
}

The output of `console.log(e.stack)` in the Safari console is: http://127.0.0.1:8081/build/main.js:2:57

Note the column number. 57 is between the "r" and the "(" in new Error("new error"). This looks good.

Now consider this:

window.onload = () => {/*
  something about this comment means the line number gets reported incorrectly in the stack
  */console.log('something unrelated');const e = new Error("new error");console.log(e.stack);console.log('something unrelated');
}

The relevant output is then: http://127.0.0.1:8081/build/main.js:3:161

Now the stack trace is reporting the error occurred at column 161, which does not exist.

[Radar WebKit Bug Importer]

<rdar://problem/74347565>

[Andrew Swan]

In addition to the original report, this also happens with multi-line strings:

window.onload = () => {
    let s = `
multi
line
string
`;console.log('something unrelated');const e = new Error("new error");console.log(e.stack);console.log('something unrelated');
}

This is creating problems for us as we use source maps to translate the locations of javascript errors, but the incorrect column numbers are causing this translation to break.

[Andrew Swan]

And fwiw, I think https://bugs.webkit.org/show_bug.cgi?id=213873 is probably due to the same underlying issue.

[Yusuke Suzuki]

Thanks! This is fixed in bug 235607 :)
Let us add some more test cases to ensure this.

*** This bug has been marked as a duplicate of bug 235607 ***

[Yusuke Suzuki]

Reopening to attach new patch.

[Yusuke Suzuki]

Created attachment 455712 [details]
Patch

[EWS]

Committed r291847 (248859@main): <https://commits.webkit.org/248859@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 455712 [details].