fix #23261 Handle ConstantType comparison for floating-point 0.0 with sign sensitivity #23265
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… with sign sensitivity - Ensure match types distinguish between 0.0 and -0.0 in pattern matching. - This enables accurate reduction in match types involving Double constants.
kijuky
commented
May 25, 2025
| @@ -401,7 +401,13 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling | |||
| compareErasedValueType | |||
| case ConstantType(v2) => | |||
| tp1 match { | |||
| case ConstantType(v1) => v1.value == v2.value && recur(v1.tpe, v2.tpe) | |||
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MEMO
I tried to modify the Constants.scala below to change the processing of the == method, but it didn't work.
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The line should use equals, which is already correct, see equalHashValue comment.
case ConstantType(v1) => v1.value.equals(v2.value) && recur(v1.tpe, v2.tpe)
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sorry, second look says
v1 == v2 && recur(v1.tpe, v2.tpe)
Do not unwrap Constant to underlying value, use equals on Constant.
kijuky
commented
May 25, 2025
| case ConstantType(v1) => | ||
| (v1.value, v2.value) match { | ||
| // To distinguish 0.0 and -0.0, floating-point numbers use the equals method of their boxing type. | ||
| case (d1: Double, d2: Double) => java.lang.Double.valueOf(d1).equals(java.lang.Double.valueOf(d2)) && recur(v1.tpe, v2.tpe) |
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MEMO
The equals method of a wrapper type is useful for distinguishing between 0.0 and -0.0.
som-snytt
reviewed
May 25, 2025
tests/neg/i23261.scala
Outdated
| @@ -0,0 +1,7 @@ | |||
| @main def main(): Unit = | |||
| summon[0.0 =:= -0.0] | |||
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summon[0.0 =:= -0.0] // error
to annotate an expected error on that line
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Fixes #23261