@cfleming decided to try out that exception debugging fancyness, and got some unexpected behaviour. function locals seem to be null?

https://www.dropbox.com/s/ixot5psra2uyjzs/Screenshot%202017-01-03%2012.35.16.png?dl=0

come on slack you can't inline a dropbox screenshot? https://www.dropbox.com/s/ixot5psra2uyjzs/Screenshot%202017-01-03%2012.35.16.png

guess not

@bfabry It’s probably locals clearing doing that, which can be tricky. Are you AOTing your code?

nope

it's running in debug mode with the little thingy at the top saying "locals will not be cleared"

nope as in no aot sorry, that was unclear

One sec

If you enter *compiler-options* in your REPL, what does it show?

*compiler-options*
=> {:disable-locals-clearing true}

Seems pretty conclusive 🙂

haha

So the tricky thing is that that option takes effect when Clojure is compiling code, not when the code is executed.

If you reload the namespace which has the problem and then try again, does that help?

interesting. it was a fresh repl and loaded namespace, it's the first time I've started the repl in debug mode

but

reloading it did fix it

HMMM

lemme check something

Sure. Do you have code loading in your REPL using injections, or something?

I don't think so...

I’ve seen this myself sometimes, but I haven’t investigated because I AOT code and I thought that was the issue. I’ll have to check that again.

Back in a moment

I'm guessing it's getting required in by my custom user.clj, which is compiled prior to that option being set

yup, that's it

god dammit, the whole clojure core loading user.clj early has screwed me over like 3 times in the last few months

now I've gotta try and remember the jira issue for that thing again

ARGH and now I'm mad at ME because I found the commit where I last encountered this and it just says "work around clojure bug" without a link to the friggen bug!

Hehe

I hate that - I just spent a bunch of time tracking down a bug which I had solved previously, but the commit message didn’t help at all.

HA there it is, TADA https://github.com/technomancy/leiningen/issues/1787

user.clj is loaded prior to anything else

last time my issue was that it's loaded prior to javac running, meaning if your project includes java code it blows up with class not found exception

new issue is that it gets loaded prior to your locals clearing var being set

aight, well, I don't know why I bothered tracking that down because it seems basically unsolvable. no doubt changing the load time of user.clj would break so many things. I just need to remember not to require things in there

I’ll check to see if I can inject before that point somehow.

kind of frustrating. it's useful to require things in there. seems like that namespace/file is serving double purposes

Assuming user.clj is only used for dev, you could actually set the compile flag in there.

(alter-var-root #'*compiler-options* assoc :disable-locals-clearing true)

You’ll get occasional OOMs if you hold onto seqs, but during dev that’s not an issue.

IIRC you can also set those flags via system properties which might be an option, but I’d have to look at the code again to be sure.

And also to ensure that they get set before user.clj is loaded.

@cfleming my fix: https://clojurians.slack.com/archives/clojure/p1483481654009051

Nice