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Should report error when invoking method on package visible class via super #4626

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scabug opened this issue May 20, 2011 · 6 comments
Open

Should report error when invoking method on package visible class via super #4626

scabug opened this issue May 20, 2011 · 6 comments
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@scabug
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scabug commented May 20, 2011 •
edited by retronym

Suppose we have class "A" implemented in Java in the package "a" defined with the default visibility and implementing public method foo:

// a/A.java}
package a;

class A {
    public void foo() {}
}

And public class "SuperA" in the same package that extends class "a.A" (it doesn't matter if this class is implemented in java or scala):

//a/SuperA.scala
package a

class SuperA extends A

The third class "B" in the package "b" extends "SuperA" and invokes "super.foo()":

// b/B.scala
package b

class B extends a.SuperA {
  super.foo()
}

On an attempt to compile class "b.B" scala compiler crashes throwing the following exception:

$ ./runme.sh 
error: java.lang.Error: Unexpected tree in genLoad: B.super/class scala.reflect.generic.Trees$Super at: source-src/b/B.scala,line-4,offset=40
	at scala.tools.nsc.symtab.SymbolTable.abort(SymbolTable.scala:35)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.scala$tools$nsc$backend$icode$GenICode$ICodePhase$$genLoad(GenICode.scala:1126)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.genLoadQualifier(GenICode.scala:1175)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.scala$tools$nsc$backend$icode$GenICode$ICodePhase$$genLoad(GenICode.scala:738)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.genLoadQualifier(GenICode.scala:1175)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.scala$tools$nsc$backend$icode$GenICode$ICodePhase$$genLoad(GenICode.scala:921)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.scala$tools$nsc$backend$icode$GenICode$ICodePhase$$genStat(GenICode.scala:174)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase$$anonfun$genStat$1.apply(GenICode.scala:143)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase$$anonfun$genStat$1.apply(GenICode.scala:143)
	at scala.collection.LinearSeqOptimized$class.foldLeft(LinearSeqOptimized.scala:111)
	at scala.collection.immutable.List.foldLeft(List.scala:45)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.genStat(GenICode.scala:143)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.scala$tools$nsc$backend$icode$GenICode$ICodePhase$$genLoad(GenICode.scala:1052)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.gen(GenICode.scala:114)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase$$anonfun$gen$1.apply(GenICode.scala:69)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase$$anonfun$gen$1.apply(GenICode.scala:69)
	at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:59)
	at scala.collection.immutable.List.foreach(List.scala:45)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.gen(GenICode.scala:69)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.gen(GenICode.scala:136)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.gen(GenICode.scala:88)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase$$anonfun$gen$1.apply(GenICode.scala:69)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase$$anonfun$gen$1.apply(GenICode.scala:69)
	at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:59)
	at scala.collection.immutable.List.foreach(List.scala:45)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.gen(GenICode.scala:69)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.gen(GenICode.scala:79)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.gen(GenICode.scala:65)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.apply(GenICode.scala:61)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$applyPhase$1.apply(Global.scala:326)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$applyPhase$1.apply(Global.scala:326)
	at scala.tools.nsc.reporters.Reporter.withSource(Reporter.scala:47)
	at scala.tools.nsc.Global$GlobalPhase.applyPhase(Global.scala:326)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$run$1.apply(Global.scala:294)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$run$1.apply(Global.scala:294)
	at scala.collection.Iterator$class.foreach(Iterator.scala:652)
	at scala.collection.mutable.ListBuffer$$anon$1.foreach(ListBuffer.scala:311)
	at scala.tools.nsc.Global$GlobalPhase.run(Global.scala:294)
	at scala.tools.nsc.backend.icode.GenICode$ICodePhase.run(GenICode.scala:54)
	at scala.tools.nsc.Global$Run.compileSources(Global.scala:949)
	at scala.tools.nsc.Global$Run.compile(Global.scala:1034)
	at scala.tools.nsc.Main$.process(Main.scala:106)
	at scala.tools.nsc.Main$.main(Main.scala:123)
	at scala.tools.nsc.Main.main(Main.scala)

To reproduce this issue unpack attached archive and execute runme.sh script with scala 2.9.0
@scabug
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scabug commented May 20, 2011

Imported From: https://issues.scala-lang.org/browse/SI-4626?orig=1
Reporter: Alexei Krainiouk (akrainiouk)
Affected Versions: 2.9.0
Attachments:

@scabug
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scabug commented Jul 5, 2011

@paulp said (edited on Jul 5, 2011 5:24:23 AM UTC):
Well this is an interesting one. We're missing an entire category of superaccessor. Watch what java does with these classes:

// A.java
package a;

class A {
  public void foo1() { }
  public void foo2() { }
  public void foo3() { }
}
// A2.java
package a;

public class A2 extends A { }

Now look at A2. It gets accessor methods for every method in A even though it can access them just fine since it's in the same package. But its subclasses won't be able to, and thanks to separate compilation it has to assume the worst and put in forwarders for everything. Nice.

public class a.A2 extends a.A{
public a.A2();
  Code:
   0:	aload_0
   1:	invokespecial	#1; //Method a/A."<init>":()V
   4:	return

public void foo3();
  Code:
   0:	aload_0
   1:	invokespecial	#2; //Method a/A.foo3:()V
   4:	return

public void foo2();
  Code:
   0:	aload_0
   1:	invokespecial	#3; //Method a/A.foo2:()V
   4:	return

public void foo1();
  Code:
   0:	aload_0
   1:	invokespecial	#4; //Method a/A.foo1:()V
   4:	return

}

Of course if you make A public, A2 gets nothing.

@scabug
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scabug commented Jul 5, 2011

@paulp said:
Looks like "implementation restriction" will be our man.

@scabug
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scabug commented May 4, 2012

@paulp said:
See also duplicate #5650, where there is a related issue mentioned in comments.

@scabug
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scabug commented Mar 15, 2013

@adriaanm said:
Un-assigning to foster work stealing, as announced in https://groups.google.com/forum/?fromgroups=#!topic/scala-internals/o8WG4plpNkw

@scabug scabug added the access label Apr 7, 2017
@scabug scabug added this to the Backlog milestone Apr 7, 2017
This was referenced Apr 7, 2017
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@som-snytt
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Not a crasher, but surprisingly:

$ ~/scala-2.11.12/bin/scalac b/B.scala 
b/B.scala:5: error: Unable to access method f in class A with a super reference.
  def g = super.f
                ^
one error found

but 2.12 and 2.13 have no problem with it.

@scala scala deleted a comment from scabug Feb 11, 2020
@scala scala deleted a comment from scabug Feb 11, 2020
@scala scala deleted a comment from scabug Feb 11, 2020
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