Add scala.language.experimental.matchWithSubCases

Author: EugeneFlesselle

compiler/src/dotty/tools/dotc/config/Feature.scala

@@ -37,6 +37,7 @@ object Feature:
   val modularity = experimental("modularity")
   val quotedPatternsWithPolymorphicFunctions = experimental("quotedPatternsWithPolymorphicFunctions")
   val packageObjectValues = experimental("packageObjectValues")
+  val matchWithSubCases = experimental("matchWithSubCases")
 
   def experimentalAutoEnableFeatures(using Context): List[TermName] =
     defn.languageExperimentalFeatures

library/src/scala/language.scala

@@ -342,14 +342,19 @@ object language {
      * @see [[https://github.com/scala/improvement-proposals/pull/79]]
      */
     @compileTimeOnly("`betterFors` can only be used at compile time in import statements")
-    @deprecated("The `experimental.betterFors` language import no longer has any effect, the feature is being stablised and can be enabled using `-preview` flag", since = "3.7")
+    @deprecated("The `experimental.betterFors` language import no longer has any effect, the feature is being stabilised and can be enabled using `-preview` flag", since = "3.7")
     object betterFors
 
     /** Experimental support for package object values
      */
     @compileTimeOnly("`packageObjectValues` can only be used at compile time in import statements")
     object packageObjectValues
 
+    /** Experimental support for match expressions with sub-cases.
+     */
+    @compileTimeOnly("`matchWithSubCases` can only be used at compile time in import statements")
+    object matchWithSubCases
+
   }
 
     /** The deprecated object contains features that are no longer officially suypported in Scala.

library/src/scala/runtime/stdLibPatches/language.scala

@@ -147,13 +147,18 @@ object language:
      * @see [[https://github.com/scala/improvement-proposals/pull/79]]
      */
     @compileTimeOnly("`betterFors` can only be used at compile time in import statements")
-    @deprecated("The `experimental.betterFors` language import no longer has any effect, the feature is being stablised and can be enabled using `-preview` flag", since = "3.7")
+    @deprecated("The `experimental.betterFors` language import no longer has any effect, the feature is being stabilised and can be enabled using `-preview` flag", since = "3.7")
     object betterFors
 
     /** Experimental support for package object values
      */
     @compileTimeOnly("`packageObjectValues` can only be used at compile time in import statements")
     object packageObjectValues
+
+    /** Experimental support for match expressions with sub-cases.
+     */
+    @compileTimeOnly("`matchWithSubCases` can only be used at compile time in import statements")
+    object matchWithSubCases
   end experimental
 
   /** The deprecated object contains features that are no longer officially suypported in Scala.