bugfix: Fix issues after backports

Author: tgodzik

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionExtensionSuite.scala

@@ -473,7 +473,6 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
          |ensuring(cond: Boolean, msg: => Any): Bar
          |ensuring(cond: Bar => Boolean, msg: => Any): Bar
          |nn: `?1`.type
-         |runtimeChecked: `?2`.type
          |formatted(fmtstr: String): String
          |→[B](y: B): (Bar, B)
          | """.stripMargin

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionSuite.scala

@@ -126,7 +126,6 @@ class CompletionSuite extends BaseCompletionSuite:
          |ensuring(cond: Boolean, msg: => Any): List.type
          |ensuring(cond: List.type => Boolean, msg: => Any): List.type
          |nn: List.type
-         |runtimeChecked scala.collection.immutable
          |formatted(fmtstr: String): String
          |→[B](y: B): (List.type, B)
          |""".stripMargin

tests/warn/i17762.scala

@@ -1,4 +1,4 @@
-//> using options -Werror -Wunused:all
+//> using options -Xfatal-warnings -Wunused:all
 
 class SomeType
 
@@ -17,4 +17,4 @@ object UsesCanEqual:
 object UsesCanEqual2:
   import HasCanEqual.f
   def testIt(st1: SomeType, st2: SomeType): Boolean =
-    st1 != st2
+    st1 == st2