Could you look again Jochen? I can't reproduce in Firefox Nightly.

Yes is still an issue...

For example look at https://www.webcomponents.org/element/@polymer/iron-demo-helpers/demo/demo/index.html

Open Developer Tools, go to "Debugger", Expand "No Domain", klick on first file. It has a SOurceUrl comment but it is not used

see https://bugzilla.mozilla.org/show_bug.cgi?id=833744

Here is little test case that uses //# sourceURL in evaluated script (using eval)
http://janodvarko.cz/tests/bugzilla/1470768/

1. Load the page
2. Check that https://www.webcomponents.org/src/lazy-resources.html-5.js file is in the Sources panel
3. See also the (index) file that does the eval

It works just fine.
But, the provided test case is using data: URI, might the issue?

Related MDN page:
https://developer.mozilla.org/en-US/docs/Tools/Debugger/How_to/Debug_eval_sources

Honza

If you have a <script> with a data: URL, //# sourceURL= can still be very useful for setting the location, but we current limit it's effects to things that we see as "eval-like". This means the pragma works for code evalled as a string, e.g. eval, new Function, setTimeout("console.log(42);", 0) and such, including

const s = document.createElement("script"); 
s.text = "code; //# sourceURL=";

but it will not work if you take that same code, encode it as a data: URL, and then put it as the src of a script, e.g.

const s = document.createElement("script"); 
s.src = "data:application/javascript;base64," + encodeBase64("code; //# sourceURL=");

I don't see a reason for us to have this logic be restricted to eval sources when we could instead make this logic essentially source.displayURL || source.url. It appears that one of the only reasons we bother right now is to try to make displayURL relative to a specific URL, but depending on how we deal with https://bugzilla.mozilla.org/show_bug.cgi?id=1192882, we may want to stop doing that anyway? I'll have to do some more research.

https://hg.mozilla.org/mozilla-central/rev/7136265fbb0f

Confirmed with 77.0b2 on Windows 10, macOS 10.15.3, Ubuntu 18.04 based on comment 8.