From 1256b1f5acc12c13e80e8408c66894d4348c625b Mon Sep 17 00:00:00 2001
From: Dale Wijnand <dale.wijnand@gmail.com>
Date: Thu, 23 Jul 2020 18:38:40 +0100
Subject: [PATCH] Avoid exhaustive warnings in try/catch

---
 .../nsc/transform/patmat/MatchTranslation.scala    |  5 ++++-
 test/files/neg/t5365c.scala                        | 14 ++++++++++++++
 test/files/run/sd187.check                         |  2 +-
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala
index b31c76136768..36756299f7c1 100644
--- a/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala
+++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala
@@ -262,12 +262,15 @@ trait MatchTranslation {
 
           val exSym = freshSym(pos, pureType(ThrowableTpe), "ex")
 
+          val unchecked = AnnotationInfo(UncheckedClass.tpe, Nil, Nil)
+          val scrut = atPos(pos)(Typed(REF(exSym), TypeTree(pureType(ThrowableTpe).withAnnotation(unchecked))))
+
           List(
               atPos(pos) {
                 CaseDef(
                   Bind(exSym, Ident(nme.WILDCARD)), // TODO: does this need fixing upping?
                   EmptyTree,
-                  combineCasesNoSubstOnly(REF(exSym), scrutSym, casesNoSubstOnly, pt, selectorPos, matchOwner, Some(scrut => Throw(REF(exSym))))
+                  combineCasesNoSubstOnly(scrut, scrutSym, casesNoSubstOnly, pt, selectorPos, matchOwner, Some(scrut => Throw(REF(exSym))))
                 )
               })
         }
diff --git a/test/files/neg/t5365c.scala b/test/files/neg/t5365c.scala
index 7db29f004848..c09dd40cfcb3 100644
--- a/test/files/neg/t5365c.scala
+++ b/test/files/neg/t5365c.scala
@@ -14,4 +14,18 @@ object C {
   def uncheckedUnsealedTrait(z: Z) = (z: @unchecked) match {
     case Q(_) =>
   }
+
+  def catchBlock() = {
+    try { 42 } catch { case MyException(_) => 43 } // Throwable isn't sealed, but don't warn here
+  }
+
+  def catchBlockWithTypePattern() = {
+    try { 42 } catch { case _: MyException => 43 } // See?  Just behave like Java.
+  }
+
+  def partialFunction(): PartialFunction[Throwable, Int] = { // Or like PartialFunction behaves.
+    case MyException(_) => 67
+  }
 }
+
+case class MyException(x: String) extends Exception
diff --git a/test/files/run/sd187.check b/test/files/run/sd187.check
index 2257aa0f0ccd..1b0643b0f1ad 100644
--- a/test/files/run/sd187.check
+++ b/test/files/run/sd187.check
@@ -74,7 +74,7 @@
       [1607][1607][1607]C.this.toString()
     } catch {
       [1505]case [1505](ex6 @ [1505]_) => [1505]{
-        [1812]<synthetic> val x4: [1812]Throwable = [1812]ex6;
+        [1812]<synthetic> val x4: [1812]Throwable = [1505]([1505]ex6: [1505]Throwable @unchecked);
         [1505]case9(){
           [1812]if ([1812][1812]x4.ne([1812]null))
             [1812]{