Fix #5536: Add regression test

Author: nicolasstucki

tests/run-separate-compilation/i5536/Macro_1.scala

@@ -0,0 +1,29 @@
+import scala.quoted._
+import scala.tasty._
+
+object scalatest {
+  inline def assert(condition: => Boolean): Unit = ~assertImpl('(condition))
+
+  def assertImpl(condition: Expr[Boolean])(implicit refl: Reflection): Expr[Unit] = {
+    import refl._
+    import quoted.Toolbox.Default._
+
+    val tree = condition.unseal
+    def exprStr: String = condition.show
+
+    tree.underlyingArgument match {
+      case Term.Apply(Term.Select(lhs, op, _), rhs :: Nil) =>
+        val left = lhs.seal[Any]
+        val right = rhs.seal[Any]
+        op match {
+          case "===" =>
+            '{
+              val _left   = ~left
+              val _right  = ~right
+              val _result = _left == _right
+              scala.Predef.assert(_result)
+            }
+        }
+    }
+  }
+}

tests/run-separate-compilation/i5536/Test_2.scala

@@ -0,0 +1,22 @@
+
+class Equalizer[L](val leftSide: L) {
+  def ===(literalNull: Null): Boolean = leftSide == null
+}
+
+object Equality {
+  implicit def toEqualizer[T](x: T): Equalizer[T] = new Equalizer(x)
+}
+
+
+object Test {
+  import scalatest._
+  import Equality._
+
+  def main(args: Array[String]): Unit = {
+    val x = "String"
+    try assert(x === null)
+    catch {
+      case _: AssertionError => // OK
+    }
+  }
+}