From d296dd4cd5b7072d9b53a46d338bc9d68ee23300 Mon Sep 17 00:00:00 2001
From: noti0na1 <noti0na1@users.noreply.github.com>
Date: Mon, 31 Jan 2022 13:26:43 -0500
Subject: [PATCH] Remove StickyKey

---
 .../src/dotty/tools/dotc/transform/PatternMatcher.scala    | 7 +------
 compiler/src/dotty/tools/dotc/typer/Nullables.scala        | 7 -------
 compiler/src/dotty/tools/dotc/typer/Typer.scala            | 5 +----
 3 files changed, 2 insertions(+), 17 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala b/compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala
index fb4657f9d01a..5ba43253e8b3 100644
--- a/compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala
+++ b/compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala
@@ -13,7 +13,6 @@ import SymUtils._
 import Flags._, Constants._
 import Decorators._
 import NameKinds.{PatMatStdBinderName, PatMatAltsName, PatMatResultName}
-import typer.Nullables
 import config.Printers.patmatch
 import reporting._
 import dotty.tools.dotc.ast._
@@ -44,12 +43,8 @@ class PatternMatcher extends MiniPhase {
         case rt => tree.tpe
       val translated = new Translator(matchType, this).translateMatch(tree)
 
-      val engineCtx =
-        if tree.hasAttachment(Nullables.UnsafeNullsMatch)
-        then ctx.retractMode(Mode.SafeNulls) else ctx
-
       // check exhaustivity and unreachability
-      val engine = new patmat.SpaceEngine()(using engineCtx)
+      val engine = new patmat.SpaceEngine
       engine.checkExhaustivity(tree)
       engine.checkRedundancy(tree)
 
diff --git a/compiler/src/dotty/tools/dotc/typer/Nullables.scala b/compiler/src/dotty/tools/dotc/typer/Nullables.scala
index dc3957e78510..0ea7207c7b2b 100644
--- a/compiler/src/dotty/tools/dotc/typer/Nullables.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Nullables.scala
@@ -20,13 +20,6 @@ import ast.Trees.mods
 object Nullables:
   import ast.tpd._
 
-  /** An attachment that represents a match tree is created under Unsafe Nulls.
-   *  This is used to pass Unsafe Nulls information to PatternMatcher Phase,
-   *  so we don't get Match case Unreachable Warning when using `case null => ???`
-   *  on non-nullable type.
-   */
-  val UnsafeNullsMatch = Property.StickyKey[Unit]
-
   inline def unsafeNullsEnabled(using Context): Boolean =
     ctx.explicitNulls && !ctx.mode.is(Mode.SafeNulls)
 
diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index 112a5dd7fd18..02f3f6b4f164 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -1499,7 +1499,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
   }
 
   def typedMatch(tree: untpd.Match, pt: Type)(using Context): Tree =
-    val tree1 = tree.selector match {
+    tree.selector match {
       case EmptyTree =>
         if (tree.isInline) {
           checkInInlineContext("summonFrom", tree.srcPos)
@@ -1601,9 +1601,6 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
             result
         }
     }
-    if Nullables.unsafeNullsEnabled && ctx.phase == Phases.typerPhase then
-      tree1.putAttachment(Nullables.UnsafeNullsMatch, ())
-    tree1
 
   /** Special typing of Match tree when the expected type is a MatchType,
    *  and the patterns of the Match tree and the MatchType correspond.