Implement SIP-67: strictEquality pattern matching (Github issue #22732)

Author: mberndt123

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -5052,11 +5052,12 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
 
         Linter.warnOnImplausiblePattern(tree, pt)
 
-        val cmp =
-          untpd.Apply(
-            untpd.Select(untpd.TypedSplice(tree), nme.EQ),
-            untpd.TypedSplice(dummyTreeOfType(pt)))
-        typedExpr(cmp, defn.BooleanType)
+        if ! (tree.tpe <:< pt && (tree.symbol.flags.isAllOf(Flags.EnumValue) || (tree.symbol.flags.isAllOf(Flags.Module | Flags.Case)))) then
+          val cmp =
+            untpd.Apply(
+              untpd.Select(untpd.TypedSplice(tree), nme.EQ),
+              untpd.TypedSplice(dummyTreeOfType(pt)))
+          typedExpr(cmp, defn.BooleanType)
       case _ =>
 
   private def checkStatementPurity(tree: tpd.Tree)(original: untpd.Tree, exprOwner: Symbol, isUnitExpr: Boolean = false)(using Context): Unit =

compiler/test/dotty/tools/dotc/typer/SIP67Tests.scala

@@ -0,0 +1,52 @@
+// filepath: /home/mberndt/scala3/compiler/test/dotty/tools/dotc/typer/SIP67Tests.scala
+package dotty.tools.dotc.typer
+
+import dotty.tools.DottyTest
+import dotty.tools.dotc.core.Contexts.*
+
+import org.junit.Test
+import org.junit.Assert.fail
+
+class SIP67Tests extends DottyTest {
+
+
+  @Test
+  def sip67test1: Unit = {
+    val source = """
+    import scala.language.strictEquality
+    enum Foo {
+      case Bar
+    }
+
+    val _ =
+      (??? : Foo) match {
+        case Foo.Bar =>
+      }
+    """
+    val ctx = checkCompile("typer", source) { (_, ctx) => }
+    if ctx.reporter.hasErrors then
+      fail("Unexpected compilation errors were reported")
+  }
+
+  @Test
+  def sip67test2: Unit = {
+    val source = """
+    import scala.language.strictEquality
+
+    sealed trait Foo
+
+    object Foo {
+      case object Bar extends Foo
+    }
+
+    val _ =
+      (??? : Foo) match {
+        case Foo.Bar =>
+      }
+    """
+    val ctx = checkCompile("typer", source) { (_, ctx) => }
+    if ctx.reporter.hasErrors then
+      fail("Unexpected compilation errors were reported")
+  }
+
+}