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-Ywarn-numeric-widen gets triggered on case class with a Short #8340

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scabug opened this issue Feb 26, 2014 · 5 comments
Closed

-Ywarn-numeric-widen gets triggered on case class with a Short #8340

scabug opened this issue Feb 26, 2014 · 5 comments
Milestone
2.11.0

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@scabug
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scabug commented Feb 26, 2014

The following is preventing me from turning on fatal warnings, which is something I really want to do:

$ scala -Ywarn-numeric-widen
Welcome to Scala version 2.10.3 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_45).
Type in expressions to have them evaluated.
Type :help for more information.

scala> case class A(b: Short)
<console>:7: warning: implicit numeric widening
       case class A(b: Short)
                  ^
defined class A

scala>
@scabug
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scabug commented Feb 26, 2014

Imported From: https://issues.scala-lang.org/browse/SI-8340?orig=1
Reporter: @puffnfresh
Affected Versions: 2.10.3

@scabug
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scabug commented Feb 26, 2014

@puffnfresh said:
It's to do with the hashCode:

$ scala -Ywarn-numeric-widen
Welcome to Scala version 2.10.3 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_45).
Type in expressions to have them evaluated.
Type :help for more information.

scala> case class A(b: Short) { override def hashCode: Int = 0 }
defined class A

scala>

The default hashCode doesn't seem to be bad, though:

override <synthetic> def hashCode(): Int = {
  <synthetic> var acc: Int = -889275714;
  acc = Statics.this.mix(acc, b.toInt);
  Statics.this.finalizeHash(acc, 1)
};

@scabug
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scabug commented Feb 26, 2014

@puffnfresh said:
Fixed in master.

@scabug scabug closed this as completed May 16, 2014
@scabug
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scabug commented Apr 30, 2015

Guillaume Massé (masgui) said (edited on Apr 30, 2015 5:35:20 PM UTC):
Similar bug with multiple parameters and double
scala 2.10.4

implicit numeric widening
case class A(c: Int, v: Double)
           ^

@scabug
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scabug commented Feb 18, 2017

Nicolas Rinaudo (nrinaudo) said:
This still happens to me with scala 2.10.6

This generates an implicit numeric warning:

case class A(a: Char, b: Char)

This does not:

case class A(a: Char, b: Char) {
  override def hashCode: Int = 0
}

@scabug scabug added this to the 2.11.0 milestone Apr 7, 2017
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