Class literals for JsTypes in superdevmode

[Chris DiGiano]

I'm having trouble referencing a JsType interface when running under superdevmode. I'm trying to pass the JsType as a class reference to a method that uses the class to coerce the results into the expected type:

    myelement.getCustomStampedElement("dialog", PolymerDialog.class).open();

Unfortunately, in superdevmode (and only in SDM) I get this error:

    Uncaught ReferenceError: Lcom_google_ccc_groups_rosters_frontend_polymer_jstype_PolymerDialog_2_classLit_0_g$ is not defined

PolymerDialog is declared like this:

@JsType

public interface PolymerDialog {

  void open();

}

and getCustomStampedElement is defined like this:

    /**

     * Returns the element specified in this custom element's template that matches the given id

     * with the result coerced to a non-vanilla element type. Equivalent to Polymer's $ function.

     *

     * @see

     *     <a href="https://www.polymer-project.org/1.0/docs/devguide/local-dom.html#node-finding">

     *     Polymer automatic node finding</a>

     */

    <T> T getCustomStampedElement(String id, Class<T> type);

It appears that the PolymerDialog JsType is being left out of the list of class literals available in superdevmode. Is this a bug? Any ideas for workarounds?

Chris DiGiano

[Ray Cromwell]

Try rolling back this CL and see if it fixes it (https://critique.corp.google.com/#review/92873682/depot/google3/third_party/java_src/gwt/svn/trunk/dev/core/src/com/google/gwt/dev/jjs/impl/GenerateJavaScriptAST.java)

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[Ray Cromwell]

Ooops, wrong pointer (for external users) This one https://gwt-review.googlesource.com/#/c/12311/

[Roberto Lublinerman]

This might be due to the way we handle class literals. Class literals for interfaces if not referenced during the initial compile might cause that error. The error should go aways if you restart SDM.

The offending sequence is 

0) Suppose initially you have (interface A, class B and class C) and start SDM.

1) Now edit class B to add a reference to A.class and recompile with SDM (do not touch A at this time nor anything that makes it recompile) . This should work fine because the literals that are referenced but whose classes where not part of this compile will be generated in the epilogue.

2) Now edit class C in any way that does not make B or A recompile. Here you will have an error like the one you described.

If you restart SDM at this point it should work.

I'll get a fix for this tomorrow.

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[Chris DiGiano]

@Ray, rolling back your change indeed fixed the problem (https://gwt-review.googlesource.com/#/c/12311/). How do you recommend we proceed? Anything I can do to help?

@Roberto, thanks for your suggestion, but I had already tried restarting the code server and clearing the cache. This did not fix things.

Chris

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[Ray Cromwell]

Chris, 

  My change actually fixed a bug which may have obscured a problem. There were duplicate class literals being generated. So you'd get InterfaceFoo.class twice in the output, and it may be in SDM you'd be covered, but in regular compiled mode you'd get the duplicates which were causing closure compiler issues.

 Roberto,  Maybe this is an issue with ControlFlowRecorder/RapidTypeAnalyzer and interface literals?

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[Chris DiGiano]

Roberto, if it's any hint to the underlying problem: you're right that that the class is not reference anywhere else—it is used solely for the purpose of type coercion.

Chris

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[Roberto Lublinerman]

I have uploaded the real fix for review at https://gwt-review.googlesource.com/#/c/12920.

It should fix your situation but  could you verify?

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[Roberto Lublinerman]

SDM expects that classes/interfaces get generated as a whole either all of it or none. As you know, class literals are not really part of the class but they are field in a separate synthetic class). Even SDM (with all optimizations off, no pruning at UnifyAST) if a reference to the class literal is not seen when generating the JS for the class then its class literal field wont be part of the JS for the class. 

For SDM it could only happen for interfaces (and maybe primitive types) because GwtAstBuilder will synthezise a getClass for each class containing reference to its class literals. 

The problem is further obscured because we (re)generate an epilogue each time and it contains all the class literals that are referenced from the code that is being recompiled whose classes where not part of the current compile. This serves a purpose in NON SDM where if only the class literal for a class is referenced, the class can be pruned.

The only glitch remaining is that in SDM there might be duplicated class literals (but it should not affect the correctness). Is this an issue for Closure?

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[Ray Cromwell]

I don't think it's an issue that blocks since people are most likely to use SDM in uncompiled mode, and the 'error' can always be suppressed and turned into a warning. At best, it might inhibit a const optimization in Closure where it sees the same variable declared/assigned twice I think.

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[Roberto Lublinerman]

I tweaked the code a bit and now it should never output duplicated class literals. @Ray, Could you review the patch?

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[Ray Cromwell]

ok, taking a look

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