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Constant fold results of nonempty tests in pattern matching #11617

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Merged
merged 1 commit into from
Mar 5, 2021
Merged

Constant fold results of nonempty tests in pattern matching #11617

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7 changes: 4 additions & 3 deletions compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -692,9 +692,10 @@ object PatternMatcher {
val scrutinee = plan.scrutinee
(plan.test: @unchecked) match {
case NonEmptyTest =>
scrutinee
.select(nme.isEmpty, _.info.isParameterless)
.select(nme.UNARY_!, _.info.isParameterless)
constToLiteral(
scrutinee
.select(nme.isEmpty, _.info.isParameterless)
.select(nme.UNARY_!, _.info.isParameterless))
case NonNullTest =>
scrutinee.testNotNull
case GuardTest =>
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14 changes: 14 additions & 0 deletions tests/pos/i11605.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
package example

class Extractor[A](val get: A) extends AnyVal {
// https://github.com/scala/scala/pull/9343
def isEmpty: false = false
}

object Foo {
def unapply(x: String): Extractor[String] = new Extractor(x)
}

object Main {
val Foo(a) = "a"
}