1592782 - Line numbers for `Function("throw new Error()")()` eval are wrong

Status: NEW

(Core :: JavaScript Engine, defect, P3)

Description

[Dayan]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:70.0) Gecko/20100101 Firefox/70.0

Steps to reproduce:

1. Execute the code below in console:
   Function(console.log('test'); throw new Error('error'); //# sourceURL=test.js)();
2. Click in error link

Actual results:

The line is not correct.
Breakingpoints also don't work correct

Expected results:

Select right line

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 2

[Jan Honza Odvarko [:Honza] (always need-info? me)]

Attachment: image.png

Thanks for the report!

I am attaching a screenshot of what I am seeing on my machine. Is that what you see?

• The error location says line 3 -> BUG
• The source shows all on line 1 and there is no way to add BP -> BUG

Honza

Comment 3

[Logan Smyth [:loganfsmyth]]

This is because Function() internally creates a function with the source text

function anonymous(
) {
  console.log('test'); throw new Error('error'); //# sourceURL=test.js
}

so in fact the code passed to Function is line 3 of the function.

Comment 4

[André Bargull [:anba]]

The formatting for functions created through Function is required per spec, cf. CreateDynamicFunction, where line endings are added before and after the bodyArg (step 16).

Comment 5

[Logan Smyth [:loganfsmyth]]

@anba That's true, but the string there is used exclusively to populate F.[[SourceText]] for .toString(). I think users would entirely expect that line numbers for errors would correspond directly with the string passed to Function(), rather than relative to the overall function source text.

Comment 6

[Logan Smyth [:loganfsmyth]]

Oh, I realize I was speaking relative to the overall text, not the 2 wrapping newlines you mentioned, but I think the point stands.

Comment 7

[André Bargull [:anba]]

I just wanted to clarify why we have that funny formatting. :-)