Put i13864 in the blacklist of best-effort test.

[Cherry-picked fe0bdad][modified]

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -2048,14 +2048,16 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
       untpd.Block(makeCanThrow(capabilityProof), expr)
 
   def typedTry(tree: untpd.Try, pt: Type)(using Context): Try = {
-    // We want to type check tree.expr first to comput NotNullInfo, but `addCanThrowCapabilities`
-    // uses the types of patterns in `tree.cases` to determine the capabilities.
-    // Hence, we create a copy of cases with empty body and type check that first, then type check
-    // the rest of the tree in order.
-    val casesEmptyBody1 = tree.cases.mapconserve(cpy.CaseDef(_)(body = EmptyTree))
-    val casesEmptyBody2 = typedCases(casesEmptyBody1, EmptyTree, defn.ThrowableType, WildcardType)
-
     val expr2 :: cases2x = harmonic(harmonize, pt) {
+      // We want to type check tree.expr first to comput NotNullInfo, but `addCanThrowCapabilities`
+      // uses the types of patterns in `tree.cases` to determine the capabilities.
+      // Hence, we create a copy of cases with empty body and type check that first, then type check
+      // the rest of the tree in order.
+      // It may seem that invalid references can be created if the type of the pattern contains
+      // type binds, but this is not a valid `CanThrow` capability (checked by `addCanThrowCapabilities`),
+      // so it is not a problem.
+      val casesEmptyBody1 = tree.cases.mapconserve(cpy.CaseDef(_)(body = EmptyTree))
+      val casesEmptyBody2 = typedCases(casesEmptyBody1, EmptyTree, defn.ThrowableType, WildcardType)
       val expr1 = typed(addCanThrowCapabilities(tree.expr, casesEmptyBody2), pt.dropIfProto)
       val casesCtx = ctx.addNotNullInfo(expr1.notNullInfo.retractedInfo)
       val cases1 = typedCases(tree.cases, EmptyTree, defn.ThrowableType, pt.dropIfProto)(using casesCtx)

tests/explicit-nulls/neg/i21380b.scala

@@ -3,19 +3,19 @@ def test1 =
   x = ""
   1 match
     case 1 => x = null
-    case _ => x = x.trim() // ok
+    case _ => x = x.trim() // error // LTS specific
   x.replace("", "") // error
 
 def test2(i: Int) =
   var x: String | Null = null
   i match
     case 1 => x = "1"
     case _ => x = " "
-  x.replace("", "") // ok
+  x.replace("", "") // error // LTS specific
 
 def test3(i: Int) =
   var x: String | Null = null
   i match
     case 1 if x != null => ()
     case _ => x = " "
-  x.trim() // ok
+  x.trim() // error // LTS specific

tests/explicit-nulls/neg/i21380c.scala

@@ -3,7 +3,7 @@ def test1(i: Int): Int =
   if i == 0 then x = ""
   else x = ""
   try
-    x = x.replace(" ", "") // ok
+    x = x.replace(" ", "") // error // LTS specific
     throw new Exception()
   catch
     case e: Exception =>
@@ -15,7 +15,7 @@ def test2: Int =
   var x: String | Null = null
   try throw new Exception()
   finally x = ""
-  x.length // ok
+  x.length // error // LTS specific
 
 def test3 =
   var x: String | Null = ""