From 26d6203d1b7ba3262177f2fc282645f9ce88f62c Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Wed, 11 Nov 2020 11:14:44 +0100
Subject: [PATCH 1/2] Fix #10116: Fix adaptConstant to that it survives Ycheck

---
 .../src/dotty/tools/dotc/typer/Typer.scala     |  2 +-
 tests/pos/i10116.scala                         | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 tests/pos/i10116.scala

diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index 3f8759028542..71dad7958032 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -3425,7 +3425,7 @@ class Typer extends Namer
       // try converting a constant to the target type
       val folded = ConstFold(tree, pt)
       if (folded ne tree)
-        return adaptConstant(folded, folded.tpe.asInstanceOf[ConstantType])
+        return adaptConstant(tree, folded.tpe.asInstanceOf[ConstantType])
 
       val captured = captureWildcards(wtp)
       if (captured `ne` wtp)
diff --git a/tests/pos/i10116.scala b/tests/pos/i10116.scala
new file mode 100644
index 000000000000..f6764b8c6433
--- /dev/null
+++ b/tests/pos/i10116.scala
@@ -0,0 +1,18 @@
+object OverloadedWithLong {
+  def overloaded(x: Long): Any =
+    x
+
+  def overloaded(x: Any): Unit =
+    ???
+}
+
+object Test {
+  def main(args: Array[String]): Unit =
+    import OverloadedWithLong._
+
+    val l: Any = 0 :: Nil
+    val r = overloaded(l match {
+      case x :: xs => 5
+    })
+    assert(r == 5L)
+}
\ No newline at end of file

From 2be0ecaf5496918ba9813c82b312729e644e5a23 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Wed, 11 Nov 2020 13:27:49 +0100
Subject: [PATCH 2/2] Address review comments

---
 compiler/src/dotty/tools/dotc/typer/ConstFold.scala | 9 ---------
 compiler/src/dotty/tools/dotc/typer/Typer.scala     | 9 ++++++---
 2 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/typer/ConstFold.scala b/compiler/src/dotty/tools/dotc/typer/ConstFold.scala
index 954935c0a74e..958aba7eaf9b 100644
--- a/compiler/src/dotty/tools/dotc/typer/ConstFold.scala
+++ b/compiler/src/dotty/tools/dotc/typer/ConstFold.scala
@@ -59,15 +59,6 @@ object ConstFold:
       tree.withFoldedType(Constant(targ.tpe))
     case _ => tree
 
-  /** If tree is a constant value that can be converted to type `pt`, perform
-   *  the conversion.
-   */
-  def apply[T <: Tree](tree: T, pt: Type)(using Context): T =
-    val tree1 = apply(tree)
-    tree.tpe.widenTermRefExpr.normalized match
-      case ConstantType(x) => tree1.withFoldedType(x.convertTo(pt))
-      case _ => tree1
-
   extension [T <: Tree](tree: T)(using Context)
     private def withFoldedType(c: Constant | Null): T =
       if c == null then tree else tree.withType(ConstantType(c)).asInstanceOf[T]
diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index 71dad7958032..75c5dd1dbb70 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -3423,9 +3423,12 @@ class Typer extends Namer
 
     def adaptToSubType(wtp: Type): Tree = {
       // try converting a constant to the target type
-      val folded = ConstFold(tree, pt)
-      if (folded ne tree)
-        return adaptConstant(tree, folded.tpe.asInstanceOf[ConstantType])
+      ConstFold(tree).tpe.widenTermRefExpr.normalized match
+        case ConstantType(x) =>
+          val converted = x.convertTo(pt)
+          if converted != null && (converted ne x) then
+            return adaptConstant(tree, ConstantType(converted))
+        case _ =>
 
       val captured = captureWildcards(wtp)
       if (captured `ne` wtp)