Backport "Only check seen for LazyRef for TypeSizeAccumulator" to 3.3 LTS

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -6587,23 +6587,24 @@ object Types extends TypeUtils {
   class TypeSizeAccumulator(using Context) extends TypeAccumulator[Int] {
     var seen = util.HashSet[Type](initialCapacity = 8)
     def apply(n: Int, tp: Type): Int =
-      if seen.contains(tp) then n
-      else {
-        seen += tp
-        tp match {
-          case tp: AppliedType =>
-            val tpNorm = tp.tryNormalize
-            if tpNorm.exists then apply(n, tpNorm)
-            else foldOver(n + 1, tp)
-          case tp: RefinedType =>
-            foldOver(n + 1, tp)
-          case tp: TypeRef if tp.info.isTypeAlias =>
-            apply(n, tp.superType)
-          case tp: TypeParamRef =>
-            apply(n, TypeComparer.bounds(tp))
-          case _ =>
+      tp match {
+        case tp: AppliedType =>
+          val tpNorm = tp.tryNormalize
+          if tpNorm.exists then apply(n, tpNorm)
+          else foldOver(n + 1, tp)
+        case tp: RefinedType =>
+          foldOver(n + 1, tp)
+        case tp: TypeRef if tp.info.isTypeAlias =>
+          apply(n, tp.superType)
+        case tp: TypeParamRef =>
+          apply(n, TypeComparer.bounds(tp))
+        case tp: LazyRef =>
+          if seen.contains(tp) then n
+          else
+            seen += tp
             foldOver(n, tp)
-        }
+        case _ =>
+          foldOver(n, tp)
       }
   }
 

project/Build.scala

@@ -597,6 +597,17 @@ object Build {
     recur(lines, false)
   }
 
+  // Hotfix for JDK 8
+  def replaceJDK11APIs(lines: List[String], file: File): List[String] = {
+    if (file.getName == "InlayHints.scala") {
+      lines.map{
+        _.replace(".repeat(naiveIndent)", " * naiveIndent")
+      }
+    } else {
+      lines
+    }
+  }
+
   /** replace imports of `com.google.protobuf.*` with compiler implemented version */
   def replaceProtobuf(lines: List[String]): List[String] = {
     def recur(ls: List[String]): List[String] = ls match {
@@ -1271,7 +1282,7 @@ object Build {
           val mtagsSharedSources = (targetDir ** "*.scala").get.toSet
           mtagsSharedSources.foreach(f => {
             val lines = IO.readLines(f)
-            val substitutions = (replaceProtobuf(_)) andThen (insertUnsafeNullsImport(_))
+            val substitutions = (replaceProtobuf(_)) andThen (insertUnsafeNullsImport(_)) andThen (replaceJDK11APIs(_, f))
             IO.writeLines(f, substitutions(lines))
           })
           mtagsSharedSources

tests/neg/i15692.scala

@@ -0,0 +1,5 @@
+trait TC[X]
+object TC {
+  given [T, S <: TC[S]](using TC[S]): TC[T] = ???
+  summon[TC[Int]] // error
+}

tests/pos/i15692.scala

@@ -0,0 +1,24 @@
+sealed trait Nat
+sealed trait Succ[Prev <: Nat] extends Nat
+sealed trait Zero extends Nat
+
+class Sum[M <: Nat, N <: Nat] {
+  type Out <: Nat
+}
+
+object Sum {
+  type Aux[M <: Nat, N <: Nat, R <: Nat] = Sum[M, N] { type Out = R }
+
+  implicit def sum0[N <: Nat]: Sum.Aux[Zero, N, N] = new Sum[Zero, N] { type Out = N }
+  implicit def sum1[M <: Nat, N <: Nat, R <: Nat](implicit sum: Sum.Aux[M, Succ[N], R]): Sum.Aux[Succ[M], N, R] =
+    new Sum[Succ[M], N] { type Out = R }
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    type _3 = Succ[Succ[Succ[Zero]]]
+    type _5 = Succ[Succ[_3]]
+
+    implicitly[Sum[_3, _5]]
+  }
+}