Implement getClass

[alexander-myltsev]

Closes #733

[alexander-myltsev]

@DarkDimius @smarter, please check if a test covers expected behaviour.

[DarkDimius]

This PR does not currently have an implementation, only a test that fails due to non-implemented #733. Did you forget to push something?

[alexander-myltsev]

It does not have yet. Is the test correct?

[DarkDimius]

All names but name of the anonymous lambdas (Test$$anonfun$1) are correct.
For lambdas: I guess you would get something like Test$$lambda$1/XXXXX, where XXXX is a number of origin that I am unaware of.

[DarkDimius]

I'd add an empty string to the output here, to have output structured.

[alexander-myltsev]

There are compile-time warnings:

dotty/out$ ../bin/dotc ../tests/run/getclass.scala
warning: encountered F-bounded higher-kinded type parameters for type scala$collection$generic$GenMapFactory$$CC; assuming they are invariant
warning: encountered F-bounded higher-kinded type parameters for type scala$collection$generic$MapFactory$$CC; assuming they are invariant
warning: encountered F-bounded higher-kinded type parameters for type scala$collection$generic$ImmutableMapFactory$$CC; assuming they are invariant
three warnings found

And runtime errors as follows:

dotty/out$ java -cp .:/home/vagrant/.ivy2/cache/org.scala-lang/scala-library/jars/scala-library-2.11.5.jar:/home/vagrant/.ivy2/cache/org.scala-lang/scala-reflect/jars/scala-reflect-2.11.5.jar:/home/vagrant/dotty/target/scala-2.11/dotty_2.11-0.1-SNAPSHOT.jar Test
Exception in thread "main" java.lang.BootstrapMethodError: java.lang.NoClassDefFoundError: scala/compat/java8/JProcedure2
        at Test$.main(getclass.scala:9)
        at Test.main(getclass.scala)
Caused by: java.lang.NoClassDefFoundError: scala/compat/java8/JProcedure2
        ... 2 more
Caused by: java.lang.ClassNotFoundException: scala.compat.java8.JProcedure2
        at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        ... 2 more

What should be fixed?

Everything else passes.

[DarkDimius]

There are compile-time warnings:

Those are known warnings. Ignore them.

NoClassDefFoundError: scala/compat/java8/JProcedure2

That is strange. This is a class defined in dotty/src/scala/compat/java8/JFunction2.java, and it should be(and on my machine is) part of dotty_2.11-0.1-SNAPSHOT.jar

[alexander-myltsev]

Fixed. My CP was wrong.

There is another problem. Seems like Array(List("1")) would have type of Object after erasure. So, Array(List("1")).getClass would be class java.lang.Object instead of class [Lscala.collection.immutable.List;.

[DarkDimius]

Seems like Array(List("1")) would have type of Object after erasure

AFAIK it should not. Though you should not handle arrays at all: classes that extend AnyRef have a runtime .getClass that should be used.

[smarter]

Just import tpd._

[smarter]

There is code in InterceptedMethods to deal with getClass: https://github.com/lampepfl/dotty/blob/cf17b73cc02daf514f6d5499fd7a5562fc93349e/src/dotty/tools/dotc/transform/InterceptedMethods.scala#L116-L125
It'd be good to at least avoid duplication (for example by moving primitiveGetClassMethods inside Definitions.scala and using it in both GetClass and InterceptedMethods) but it might make sense to simply move this code from InterceptedMethods to GetClass, so that all the code that deals with getClass is inside GetClass. @DarkDimius : what do you think?

[DarkDimius]

but it might make sense to simply move this code from InterceptedMethods to GetClass.

This code is left as it tries to cover non-trivial bug. Though I've checked now and the way how this was fixed in scalac does not work in dotty: 5.asInstanceOf[Int with AnyRef].getClass is still erased to 5.getClass.

I believe that we need a different fix. The way I would fix it in dotty is to rewrite

5.asInstanceOf[Int with AnyRef].getClass

to

(5.asInstanceOf[Int with AnyRef]: Object).getClass

This should do the trick.

[DarkDimius]

why not simply tree?

[alexander-myltsev]

Yes, that works.

[DarkDimius]

Did you try to put it in next mini-phase block?

[DarkDimius]

Otherwise LGTM

[alexander-myltsev]

@DarkDimius , well, worked out. Should I squash both commits?

[DarkDimius]

LGTM

[DarkDimius]

@alexander-myltsev, thanks for your contribution!