Add unapplySeq tests

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/init/Objects.scala

@@ -1201,6 +1201,7 @@ object Objects:
      *  Currently, we assume all cases are reachable, thus all patterns are assumed to match.
      */
     def evalPattern(scrutinee: Value, pat: Tree): Value = log("match " + scrutinee.show + " against " + pat.show, printer, (_: Value).show):
+      val trace2 = Trace.trace.add(pat)
       pat match
       case Alternative(pats) =>
         for pat <- pats do evalPattern(scrutinee, pat)
@@ -1211,11 +1212,9 @@ object Objects:
         initLocal(bind.symbol, value)
         scrutinee
 
-      case SeqLiteral(pats, _) =>
-        // TODO: handle unapplySeq
-        Bottom
-
       case UnApply(fun, implicits, pats) =>
+        given Trace = trace2
+
         val fun1 = funPart(fun)
         val funRef = fun1.tpe.asInstanceOf[TermRef]
         val unapplyResTp = funRef.widen.finalResultType
@@ -1300,7 +1299,7 @@ object Objects:
         end if
         scrutinee
 
-      case Ident(nme.WILDCARD) =>
+      case Ident(nme.WILDCARD) | Ident(nme.WILDCARD_STAR) =>
         scrutinee
 
       case Typed(pat, _) =>
@@ -1315,7 +1314,7 @@ object Objects:
     /**
      * Evaluate a sequence value against sequence patterns.
      */
-    def evalSeqPatterns(scrutinee: Value, scrutineeType: Type, elemType: Type, pats: List[Tree]): Unit =
+    def evalSeqPatterns(scrutinee: Value, scrutineeType: Type, elemType: Type, pats: List[Tree])(using Trace): Unit =
       // call .lengthCompare or .length
       val lengthCompareDenot = getMemberMethod(scrutineeType, nme.lengthCompare, lengthCompareType)
       if lengthCompareDenot.exists then

tests/init-global/neg/patmat-unapplySeq.check

@@ -0,0 +1,11 @@
+-- Error: tests/init-global/neg/patmat-unapplySeq.scala:8:32 -----------------------------------------------------------
+8 |  def apply(i: Int): Box = array(i)             // error
+  |                           ^^^^^^^^
+  |Reading mutable state of object A during initialization of object B.
+  |Reading mutable state of other static objects is forbidden as it breaks initialization-time irrelevance. Calling trace: 
+  |-> object B:	[ patmat-unapplySeq.scala:15 ]
+  |   ^
+  |-> case A(b) =>	[ patmat-unapplySeq.scala:17 ]
+  |        ^^^^
+  |-> def apply(i: Int): Box = array(i)             // error	[ patmat-unapplySeq.scala:8 ]
+  |                            ^^^^^^^^

tests/init-global/neg/patmat-unapplySeq.scala

@@ -0,0 +1,17 @@
+object A:
+  class Box(var x: Int)
+
+  val array: Array[Box] = new Array(1)
+  array(0) = new Box(10)
+
+  def length: Int = array.length
+  def apply(i: Int): Box = array(i)             // error
+  def drop(n: Int): Seq[Box] = array.toSeq
+  def toSeq: Seq[Box] = array.toSeq
+
+  def unapplySeq(array: Array[Box]): A.type = this
+
+
+object B:
+  A.array match
+  case A(b) =>

tests/init-global/neg/patmat-unapplySeq2.scala

@@ -0,0 +1,17 @@
+object A:
+  class Box(var x: Int)
+
+  val array: Array[Box] = new Array(1)
+  array(0) = new Box(10)
+
+  def length: Int = array.length
+  def apply(i: Int): Box = array(i)             // error
+  def drop(n: Int): Seq[Box] = array.toSeq
+  def toSeq: Seq[Box] = array.toSeq
+
+  def unapplySeq(array: Array[Box]): A.type = this
+
+
+object B:
+  A.array match
+  case A(b*) =>