Merge pull request #6787 from dotty-staging/fix-#6679

Fix #6679: Handle wildcards in PCP check

Author: nicolasstucki

compiler/src/dotty/tools/dotc/transform/PCPCheckAndHeal.scala

@@ -98,10 +98,14 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
       case _: This =>
         assert(checkSymLevel(tree.symbol, tree.tpe, tree.sourcePos).isEmpty)
         tree
-      case _: Ident =>
-        checkSymLevel(tree.symbol, tree.tpe, tree.sourcePos) match {
-          case Some(tpRef) => tpRef
-          case _ => tree
+      case Ident(name) =>
+        if (name == nme.WILDCARD) {
+          untpd.Ident(name).withType(checkType(tree.sourcePos).apply(tree.tpe)).withSpan(tree.span)
+        } else {
+          checkSymLevel(tree.symbol, tree.tpe, tree.sourcePos) match {
+            case Some(tpRef) => tpRef
+            case _ => tree
+          }
         }
       case _: TypeTree | _: AppliedTypeTree | _: Apply | _: TypeApply | _: UnApply | Select(_, OuterSelectName(_, _)) =>
         tree.withType(checkTp(tree.tpe))

tests/run-macros/i6679.check

@@ -0,0 +1 @@
+Ok

tests/run-macros/i6679/Macro_1.scala

@@ -0,0 +1,14 @@
+import scala.quoted._
+
+def makeMatch[A: Type](head : Expr[A]) given (qctx : QuoteContext) : Expr[Unit] = {
+  import qctx.tasty._
+
+  val sacrifice = '{ $head match { case _ => ??? } }
+  sacrifice.unseal
+
+  '{ println("Ok") }
+}
+
+def mm(implicit qctx : QuoteContext) = makeMatch('{42})
+
+inline def f = ${ mm }

tests/run-macros/i6679/Test_2.scala

@@ -0,0 +1,8 @@
+import scala.quoted._
+
+object Test {
+
+  def main(args: Array[String]): Unit = {
+    f
+  }
+}