Fix for setting breakpoints in async code.

[sannysanoff]

this fixes long standing issues with stepping through and setting breakpoints in the scala/async async code.

bug happens because NamePattern.forElement(elem) returns nothing for async psi elements, and as a result method returns zero candidate classes for given SourcePosition.

nothing in NamePattern.forElement(elem) is returned because it doesn't know that async methods generate classes (in our case, classes generated are named Basename$statemachine$...). I think the logic that filters out our case in NamePattern.forElement(elem) should be improved but I don't know how.

but creating NamePattern directly helps. Although filter is more loose and may falsely accept more cases, hasLocations(refType: ReferenceType, position: SourcePosition) seems to be strict enough to filter out the only one correct class from generated statemachine. I wonder what could be the cases that are falsely accepted.

Environment for which it fixes bug:

scala-async_2.11 0.9.6-RC2
idea162.x branch as of today
scala 2.11.7

maybe fix for scala/scala-async#136
and for https://youtrack.jetbrains.com/issue/SCL-4935

best regards.

[sannysanoff]

The example code is this:

  def handleSystemConfigurationRequest(req: Boolean): Future[DatabaseResponse] = async {
/*[BP here]*/    val config = await(singleSelect(q"""         select ...          from ....           """))
    new DatabaseResponse(
      result = REQUEST_PROCESSED,
      systemConfigurationResponse = Some(SystemConfigurationResponse( ...)))
  }

In fact, the only case where this example worked (once) is when I set breakpoint and THEN launch application. The notification from java debugger (causing processClassPrepare() and friends inside IDEA) results in setting correct breakpoint. But after class is loaded, clearing and setting breakpoint DID NOT work, because execution in IDEA goes to different branch in createOrWaitPrepare() function, which did not work (before this patch).

[niktrop]

Thanks for pointing to this issue and a suggested solution. But I think that we need to compute an appropriate NamePattern in the first place. Please try if this fix works in your case:
b0875be

If you'll have any problems with it please let me know.

[sannysanoff]

If idea caught up my new zip correctly, your patch seems to work!

thanks!