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REPL reports NPE when partially applied function is called in a semicolon delimited statement

See original GitHub issue

Having a function defined in REPL like in example below:

def bar: Int => Int => Int = a => b => a + b

the following statements are evaluated to NPE:

val b = bar(1);b(2)
java.lang.NullPointerException
	at rs$line$2$.<init>(rs$line$2:1)
	at rs$line$2$.<clinit>(rs$line$2)
	at rs$line$2.res0Show(rs$line$2)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at dotty.tools.repl.Rendering.valueOf(Rendering.scala:58)
	at dotty.tools.repl.Rendering.renderVal(Rendering.scala:79)
	at dotty.tools.repl.ReplDriver.$anonfun$displayDefinitions$8(ReplDriver.scala:269)
	at scala.collection.TraversableLike.$anonfun$map$1(TraversableLike.scala:234)
	at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:59)
	at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:52)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
	at scala.collection.TraversableLike.map(TraversableLike.scala:234)
	at scala.collection.TraversableLike.map$(TraversableLike.scala:227)
	at scala.collection.AbstractTraversable.map(Traversable.scala:104)
	at dotty.tools.repl.ReplDriver.displayMembers$1(ReplDriver.scala:269)
	at dotty.tools.repl.ReplDriver.$anonfun$displayDefinitions$15(ReplDriver.scala:296)
	at scala.Option.map(Option.scala:146)
	at dotty.tools.repl.ReplDriver.$anonfun$displayDefinitions$13(ReplDriver.scala:294)
	at dotty.tools.dotc.core.Periods.atPhase(Periods.scala:26)
	at dotty.tools.dotc.core.Phases.atPhase(Phases.scala:36)
	at dotty.tools.dotc.core.Phases.atPhase$(Phases.scala:35)
	at dotty.tools.dotc.core.Contexts$Context.atPhase(Contexts.scala:57)
	at dotty.tools.repl.ReplDriver.displayDefinitions(ReplDriver.scala:289)
	at dotty.tools.repl.ReplDriver.$anonfun$compile$2(ReplDriver.scala:226)
	at scala.util.Either.fold(Either.scala:188)
	at dotty.tools.repl.ReplDriver.compile(ReplDriver.scala:220)
	at dotty.tools.repl.ReplDriver.interpret(ReplDriver.scala:190)
	at dotty.tools.repl.ReplDriver.runUntilQuit(ReplDriver.scala:143)
	at dotty.tools.repl.Main$.main(Main.scala:6)
	at dotty.tools.repl.Main.main(Main.scala)

java.lang.NoClassDefFoundError: Could not initialize class rs$line$2$
	at rs$line$2.bShow(rs$line$2)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at dotty.tools.repl.Rendering.valueOf(Rendering.scala:58)
	at dotty.tools.repl.Rendering.renderVal(Rendering.scala:79)
	at dotty.tools.repl.ReplDriver.$anonfun$displayDefinitions$8(ReplDriver.scala:269)
	at scala.collection.TraversableLike.$anonfun$map$1(TraversableLike.scala:234)
	at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:59)
	at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:52)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
	at scala.collection.TraversableLike.map(TraversableLike.scala:234)
	at scala.collection.TraversableLike.map$(TraversableLike.scala:227)
	at scala.collection.AbstractTraversable.map(Traversable.scala:104)
	at dotty.tools.repl.ReplDriver.displayMembers$1(ReplDriver.scala:269)
	at dotty.tools.repl.ReplDriver.$anonfun$displayDefinitions$15(ReplDriver.scala:296)
	at scala.Option.map(Option.scala:146)
	at dotty.tools.repl.ReplDriver.$anonfun$displayDefinitions$13(ReplDriver.scala:294)
	at dotty.tools.dotc.core.Periods.atPhase(Periods.scala:26)
	at dotty.tools.dotc.core.Phases.atPhase(Phases.scala:36)
	at dotty.tools.dotc.core.Phases.atPhase$(Phases.scala:35)
	at dotty.tools.dotc.core.Contexts$Context.atPhase(Contexts.scala:57)
	at dotty.tools.repl.ReplDriver.displayDefinitions(ReplDriver.scala:289)
	at dotty.tools.repl.ReplDriver.$anonfun$compile$2(ReplDriver.scala:226)
	at scala.util.Either.fold(Either.scala:188)
	at dotty.tools.repl.ReplDriver.compile(ReplDriver.scala:220)
	at dotty.tools.repl.ReplDriver.interpret(ReplDriver.scala:190)
	at dotty.tools.repl.ReplDriver.runUntilQuit(ReplDriver.scala:143)
	at dotty.tools.repl.Main$.main(Main.scala:6)
	at dotty.tools.repl.Main.main(Main.scala)

Will try to figure it out and fix, any tips from main contributors are very welcome.

Issue Analytics

State:
Created 6 years ago
Comments:5 (5 by maintainers)

Top GitHub Comments

1reaction

allanrenuccicommented, Oct 30, 2017

Methods definitions are not evaluated, they are just pretty printed to the user. Only val definitions are evaluated.

The way I would try to solve this issue, is by looking at the code the REPL generates and see if there is something wrong with it. You should be able to do this by adding some debug code here: https://github.com/lampepfl/dotty/blob/master/compiler/src/dotty/tools/repl/ReplDriver.scala#L221-L226

0reactions

rsoeldnercommented, Oct 30, 2017

@allanrenucci If I understand correct, renderMethod is evaluated before vals

Can you give a hint, how to fix this ?

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