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Instantiating a generic value class results in a class cast exception when given a primitive array #7521

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scabug opened this issue May 27, 2013 · 7 comments
Closed

Instantiating a generic value class results in a class cast exception when given a primitive array #7521

scabug opened this issue May 27, 2013 · 7 comments
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@retronym
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valueclass
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2.12.0-M1

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@scabug
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scabug commented May 27, 2013 

scala> class Wrapper[Repr](val xs: Repr) extends AnyVal
defined class Wrapper

scala> new Wrapper(new Array[Int](1))
java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.Integer;
	at .<init>(<console>:9)
	at .<clinit>(<console>)
	at .<init>(<console>:7)
	at .<clinit>(<console>)
	at $print(<console>)

Similarly:

scala> class Wrap[Repr](val xs: Repr) extends AnyVal
defined class Wrap

scala> implicit class ops[Repr](val xs: Repr) extends AnyVal { def toWrap = new Wrap(xs) }
defined class ops

scala> (new Array[Int](1)).toWrap
java.lang.ClassCastException: [I cannot be cast to [Ljava.lang.Integer;
	at .<init>(<console>:9)
	at .<clinit>(<console>)
	at .<init>(<console>:7)
	at .<clinit>(<console>)
	at $print(<console>)

Note the primitive array being cast in the second example.
@scabug
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scabug commented May 27, 2013

Imported From: https://issues.scala-lang.org/browse/SI-7521?orig=1
Reporter: @axel22
Affected Versions: 2.10.1
See #5353

@scabug
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scabug commented May 27, 2013

@retronym said:

scala> class C { new Wrapper(new Array[Int](0)) }
defined class C

scala> :javap -v C
...
{
public C();
  Code:
   Stack=2, Locals=1, Args_size=1
   0:	aload_0
   1:	invokespecial	#9; //Method java/lang/Object."<init>":()V
   4:	getstatic	#15; //Field scala/runtime/ScalaRunTime$.MODULE$:Lscala/runtime/ScalaRunTime$;
   7:	iconst_0
   8:	newarray int
   10:	invokevirtual	#19; //Method scala/runtime/ScalaRunTime$.toObjectArray:(Ljava/lang/Object;)[Ljava/lang/Object;
   13:	checkcast	#21; //class "[Ljava/lang/Integer;"
   16:	pop
   17:	return
  LocalVariableTable:
   Start  Length  Slot  Name   Signature
   0      18      0    this       LC;

  LineNumberTable:
   line 8: 0


}

@scabug
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scabug commented May 27, 2013

@retronym said:
Culpable code:

scala/scala@39fc4aa84#L1R740
scala/scala@39fc4aa84#L6R283
scala/scala@39fc4aa84#L6R89

erasedValueClassArg(<<Wrapper[Array[Int]]>>) = Array[Integer]

@scabug
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scabug commented May 27, 2013

@paulp said:
This is fixed in my patch for #5353.

@scabug
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scabug commented Aug 5, 2014

@gkossakowski said:
The 2.11.2 is out so I'm rescheduling the issue for 2.11.3.

@scabug
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scabug commented Nov 4, 2014

@retronym said:
Updating fix-by version to 2.11.5.

@scabug
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scabug commented Nov 10, 2014

@retronym said:
scala/scala#4124

@scabug scabug closed this as completed Nov 21, 2014
@scabug scabug added this to the 2.12.0-M1 milestone Apr 7, 2017
bsloane1650 pushed a commit to bsloane1650/incubator-daffodil that referenced this issue Dec 17, 2019
Add work around for 2.11 bug with DataValue
37b60a5 
Scala 2.11 requires a special implementation of DataValue to work around scala/bug#7521
bsloane1650 pushed a commit to bsloane1650/incubator-daffodil that referenced this issue Dec 17, 2019
Add work around for 2.11 bug with DataValue
8c8a9ac 
Scala 2.11 requires a special implementation of DataValue to work around scala/bug#7521
bsloane1650 pushed a commit to bsloane1650/incubator-daffodil that referenced this issue Dec 17, 2019
Add work around for 2.11 bug with DataValue
69fd4e0 
Scala 2.11 requires a special implementation of DataValue to work around scala/bug#7521
bsloane1650 added a commit to bsloane1650/incubator-daffodil that referenced this issue Dec 18, 2019
@bsloane1650
Add typesafty to our handling of infoset data values.
ca70be7 
For performance reasons, we have been making extensive use of
AnyRef to store data values in our infoset, and throughout the runtime.
This allows us to avoid boxing, but prevents the type system from validating
that unexepected types to not infect our values.

This commit introduces a value type, DataValue, which provides a 0 overhead (eg. no boxing)
wrapper around AnyRef, while only allowing a limited number of types to populate it.

In doing so, an unrelated bug of mixing Java and Scala BigInts was uncovered and corrected.
Such a bug should be much less likely to occur in the future.

Due to a bug in Scala 2.11 (scala/bug#7521), we have 2 implementations
of DataValue. The 2.11 version automatically boxes/unboxes all instances of Array[Byte]

DAFFODIL-2169
bsloane1650 added a commit to apache/daffodil that referenced this issue Dec 18, 2019
@bsloane1650
Add typesafty to our handling of infoset data values.
eb7e040 
For performance reasons, we have been making extensive use of
AnyRef to store data values in our infoset, and throughout the runtime.
This allows us to avoid boxing, but prevents the type system from validating
that unexepected types to not infect our values.

This commit introduces a value type, DataValue, which provides a 0 overhead (eg. no boxing)
wrapper around AnyRef, while only allowing a limited number of types to populate it.

In doing so, an unrelated bug of mixing Java and Scala BigInts was uncovered and corrected.
Such a bug should be much less likely to occur in the future.

Due to a bug in Scala 2.11 (scala/bug#7521), we have 2 implementations
of DataValue. The 2.11 version automatically boxes/unboxes all instances of Array[Byte]

DAFFODIL-2169
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