Merge pull request #8695 from dotty-staging/improve-type-inference-of-quote-pattern-splices

Improve type inference of quote pattern splices

Author: nicolasstucki

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

@@ -73,7 +73,7 @@ trait QuotesAndSplices {
       case _ =>
     }
     if (ctx.mode.is(Mode.QuotedPattern))
-      if (isFullyDefined(pt, ForceDegree.all)) {
+      if (isFullyDefined(pt, ForceDegree.flipBottom)) {
         def spliceOwner(ctx: Context): Symbol =
           if (ctx.mode.is(Mode.QuotedPattern)) spliceOwner(ctx.outer) else ctx.owner
         val pat = typedPattern(tree.expr, defn.QuotedExprClass.typeRef.appliedTo(pt))(

tests/run-macros/quote-matcher-inference/Macro_1.scala

@@ -0,0 +1,15 @@
+import scala.quoted._
+
+
+object Macros {
+
+  inline def g(inline x: Unit): Unit = ${impl('x)}
+
+  private def impl(x: Expr[Any])(using QuoteContext): Expr[Any] = {
+    x match
+      case '{ println(f($y)) } => y
+  }
+
+}
+
+def f[T](x: T): T = x

tests/run-macros/quote-matcher-inference/Test_2.scala

@@ -0,0 +1,10 @@
+import Macros._
+
+
+object Test {
+
+  def main(args: Array[String]): Unit = {
+    g(println(f((5))))
+  }
+
+}