Some subtlety of GWT compilation - "gwt module may need to be (re)compiled."

Question

I'm deploying an app to GAE. I have a single project setup in Eclipse, with three separate GWT modules, each with its own HTML page, entry point, etc. They share a lot of code.

When I deploy the app to appengine, TWO of the modules work fine. I can access their HTML pages perfectly. The third gives me the error that "gwt module 'xyz' may need to be (re)compiled." I have tried recompiling and redeploying twice, to no avail, and have no ideas about moving forward.

Other threads about this problem point to the gwt.codeserver argument, and indeed, if I add that argument, the bad module runs... but it seems to be running in dev mode! If this is true, I'm a little bit apalled, since I don't want to serve dev mode code to anyone.

Any suggestions would be welcome - my work is basically entirely stalled on this issue.

Answer 1

I've found my own answer: in my case, the error was not being caused by a missing gwt.codesvr argument (as in all other cases I found referenced online). Instead, a module rename-to attribute I added in my module definition gwt.xml file caused a mixup. I'll recount the whole story in case it helps others understand more.

I created a new module and a new HTML page. The module's name was com.reallylong.and.unwieldy, and my HTML page pulled in the javascript from com.reallylong.and.unwieldy/com.reallylong.and.unwieldy.nocache.js. Later, I got smart and used the rename-to attribute to rename com.reallylong.and.unwieldy to "short," not changing my HTML code. I forgot.

This didn't affect me for several days, since I guess eclipse is smart enough to recompile both files, or something. Who knows. I suspect the gwt.codesvr argument was actually enabling this obscuring behavior, loading the code from dev mode instead of from the js file.

Ultimately, the fix was simple: I changed my HTML file so that the js was being pulled from short/short.nocache.js. And it worked! Woohoo!