1571640 - Breakpoints of assigned functions aren't hit

Status: RESOLVED DUPLICATE of bug 1572280

(DevTools :: Debugger, defect)

Description

[Alexandre Poirot [:ochameau]]

When setting a breakpoint on such line:
window.onclick = {document.body.innerHTML+="x";};
we used to only break when clicking on the page.
Now, we do break only on page load and no longer when clicking on the page.
This seems to have changed in a less than 10 days as I think I was having the old behavior I can now see on release builds on a somewhat recent nightly.

Here is a test document:
data:text/html,<script>window.onclick=()=>{document.body.innerHTML+="x";};</script>

Now, we do have to introduce a newline in order to be able to break on the innerHTML code.

Comment 1

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

Thanks for the report Alex.

I can't reproduce the issue. Here is what I am doing:

0. Open DevTools and select the Debugger panel
1. Load data:text/html,<script>window.onclick=()=>{document.body.innerHTML+="x";};</script>
2. Create a breakpoint on line 1
3. Reload the page, the BP should not hit
4. Click on the page, the BP should hit

Steps #3 and #4 are working as described for me (Nightly + Win10).

What am I doing wrong?

Honza

Comment 2

[Alexandre Poirot [:ochameau]]

I do not reproduce your STR from comment 1 and still reproduces mine.
I'm testing against Nightly 70.0a1 (2019-08-05) (64 bits) on Windows.

If I test on a local build, with very lastest m-c changeset, on Linux, I hit bug 1571721 constantly and that doesn't allow me to even try to reproduce this STR.

Comment 3

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

Attachment: image.png

Note that Col BP needs to be properly set

See the attached screenshot:

• If the second col BP is set - the script breaks on click
• If the first col BP is set - the script breaks on reload

Honza

Comment 4

[Alexandre Poirot [:ochameau]]

Ah ok. It works fine if I set the breakpoint on the right column.

But it highlights some randomness in:

• how many column breakpoint are displayed,
• and because of that, the finaly breakpoint being set by default when cliking on the line number.

It looks like there is a race or some random behavior for some reason.
See the two following screenshots from the same firefox instance against the exact same URI, but loaded in two distinct tabs.

Comment 5

[Alexandre Poirot [:ochameau]]

Attachment: First tab, there is 4 breakpoints and the first is selected by default, which isn't the inline function

Comment 6

[Alexandre Poirot [:ochameau]]

Attachment: Second tab, there is only two breakpoints, the first is selected and that is the inline function

Comment 7

[Alexandre Poirot [:ochameau]]

Attachment: First tab, there is 4 breakpoints and the first is selected by default, which isn't the inline function

Comment 8

[Jason Laster [:jlast]]

• 2 vs 4 column breakpoints is related to a GC sensitive api we use (https://bugzilla.mozilla.org/show_bug.cgi?id=1532844)

Comment 9

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

I am marking this as dup since the GC issue will be solved by bug 1572280

Honza