783895 - Assertion failure: src->length() > 0 && chars[0] == '(', at js/src/jsfun.cpp:632 reading source of function whose source file has since changed

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect)

Description

[[e-mail]]

I am used to working with the XUL cache disabled. In this configuration, all XUL, DTD and JS files *used* to be reparsed every time they were opened. (Fortunately I don't edit .properties files so often.)

I was trying to fix a bug in SeaMonkey's preferences. This required adding a new string to the XUL and DTD and tweaking the JS code to use it. I edited the code, reopened Preferences... and the bug was still there, but with the new string. Confused, I added in dump()s and alert()s and they never fired. So I opened the Error Console and dumped the source of all the relevant functions to verify that they had in fact changed.

Except JS asserted on me when I tried, because it was actually caching the functions behind my back, together with their source locations. Of course the source no longer existed at those locations because I had edited it. Thus the assertion.

I poked around and found that this bug does also happen when the XUL cache is enabled. Of course in this case my new string would not have shown up so I would never have thought to try to dump the source of the functions...

Comment 1

[:Benjamin Peterson]

Yes, this is certainly a danger of lazily reading sources for |Function.toString| calls.

Comment 2

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

In the process of migrating remaining bugs to the new severity system, the severity for this bug cannot be automatically determined. Please retriage this bug using the new severity system.