From d92bf6e18816a825c0ff3b7bf5e16d69b22d7e89 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Wed, 8 Apr 2020 13:28:30 +0200
Subject: [PATCH] =?UTF-8?q?Improve=20type=20inference=C2=A0of=20quote=20pa?=
 =?UTF-8?q?ttern=20splices?=
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Infer higher bound for type splices. This means that when type information is not given
the pattern should match all term that could fit in this hole.
---
 .../dotty/tools/dotc/typer/QuotesAndSplices.scala |  2 +-
 .../quote-matcher-inference/Macro_1.scala         | 15 +++++++++++++++
 .../quote-matcher-inference/Test_2.scala          | 10 ++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 tests/run-macros/quote-matcher-inference/Macro_1.scala
 create mode 100644 tests/run-macros/quote-matcher-inference/Test_2.scala

diff --git a/compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala b/compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala
index 7a57b67d7f6a..007d49116757 100644
--- a/compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala
+++ b/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))(
diff --git a/tests/run-macros/quote-matcher-inference/Macro_1.scala b/tests/run-macros/quote-matcher-inference/Macro_1.scala
new file mode 100644
index 000000000000..743e6b9cd452
--- /dev/null
+++ b/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
diff --git a/tests/run-macros/quote-matcher-inference/Test_2.scala b/tests/run-macros/quote-matcher-inference/Test_2.scala
new file mode 100644
index 000000000000..327112a64868
--- /dev/null
+++ b/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))))
+  }
+
+}