Merge pull request #8200 from dotty-staging/fix-#8198

Fix #8198: Handle trees with TypedSplice

Author: liufengyun

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

@@ -948,8 +948,9 @@ trait Applications extends Compatibility {
      *     { val xs = es; e' = e' + args }
      */
     def typedOpAssign(implicit ctx: Context): Tree = {
-      val Apply(Select(lhs, name), rhss) = tree
-      val lhs1 = typedExpr(lhs)
+      val (lhs1, name, rhss) = tree match
+        case Apply(Select(lhs, name), rhss) => (typedExpr(lhs), name, rhss)
+        case Apply(untpd.TypedSplice(Select(lhs1, name)), rhss) => (lhs1, name, rhss)
       val liftedDefs = new mutable.ListBuffer[Tree]
       val lhs2 = untpd.TypedSplice(LiftComplex.liftAssigned(liftedDefs, lhs1))
       val assign = untpd.Assign(lhs2,

tests/pos/i8198.scala

@@ -0,0 +1,10 @@
+trait Eq[A] {
+  def (x: A) === (y: A): Boolean
+  def (x: A) /== (y: A): Boolean = !(x === y)
+}
+
+case class Id[T](id: T)
+
+given idEq[A](given eqA: Eq[A]): Eq[Id[A]] = new {
+  def (i1: Id[A]) === (i2: Id[A]) = !(i1.id /== i2.id)
+}