Pickling issue with CC library

[nicolasstucki]

Minimization of tests/run/i4523.scala

class C:
  def foo = Seq(5).map { i => i }

sbt> set ThisBuild/Build.scala2Library := Build.Scala2LibraryCCTasty
sbt> scala3-bootstrapped/scalac Test.scala -Ytest-pickler

  exception occurred while compiling List(tests/run/i4523.scala)

  An unhandled exception was thrown in the compiler.
  Please file a crash report here:
  https://github.com/lampepfl/dotty/issues/new/choose
  For non-enriched exceptions, compile with -Yno-enrich-error-messages.

     while compiling: <no file>
        during phase: parser
                mode: Mode(ImplicitsEnabled)
     library version: version 2.13.12
    compiler version: version 3.4.1-RC1-bin-SNAPSHOT-git-7bcfce2
            settings: -Ytest-pickler true -classpath /Users/nicolasstucki/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.12/scala-library-2.13.12.jar:/Users/nicolasstucki/Github/dotty/library/../out/bootstrap/scala3-library-bootstrapped/scala-3.4.1-RC1-bin-SNAPSHOT-nonbootstrapped/scala3-library_3-3.4.1-RC1-bin-SNAPSHOT.jar:/Users/nicolasstucki/Github/dotty/scala2-library-cc-tasty/../out/bootstrap/scala2-library-cc-tasty/scala-3.4.1-RC1-bin-SNAPSHOT-nonbootstrapped/scala2-library-cc-tasty_3-3.4.1-RC1-bin-SNAPSHOT.jar -d /

Exception in thread "main" scala.MatchError: AppliedType(TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class collection)),object immutable),Seq),List(TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Int))) (of class dotty.tools.dotc.core.Types$CachedAppliedType)
        at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readPathTree$1(TreeUnpickler.scala:1239)
        at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readSimpleTree$1(TreeUnpickler.scala:1309)
        at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readTree(TreeUnpickler.scala:1556)
        at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.$anonfun$33(TreeUnpickler.scala:1474)
        at dotty.tools.tasty.TastyReader.until(TastyReader.scala:135)
        at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readLengthTree$1(TreeUnpickler.scala:1474)
        at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readTree(TreeUnpickler.scala:1556)
        ...

sbt> set ThisBuild/Build.scala2Library := Build.Scala2LibraryCCTasty
sbt> scala3-bootstrapped/scalac Test.scala -Yprint-tasty

-Yprint-tasty output

**** pickled info of class C
Header:
  version: 28.5.1
  tooling: Scala 3.4.1-RC1-bin-SNAPSHOT-git-7bcfce2
     UUID: 00f7ab37-0348-1ec0-00f7-e5d0d668eb32

Names (399 bytes, starting from 64):
     0: ASTs
     1: <empty>
     2: C
     3: <init>
     4: java
     5: lang
     6: java[Qualified . lang]
     7: Object
     8: java[Qualified . lang][Qualified . Object]
     9: <init>[Signed Signature(List(),java.lang.Object) @<init>]
    10: Unit
    11: scala
    12: foo
    13: Seq
    14: collection
    15: scala[Qualified . collection]
    16: immutable
    17: scala[Qualified . collection][Qualified . immutable]
    18: Int
    19: annotation
    20: scala[Qualified . annotation]
    21: retains
    22: scala[Qualified . annotation][Qualified . retains]
    23: scala[Qualified . collection][Qualified . immutable][Qualified . Seq]
    24: <init>[Signed Signature(List(scala.collection.immutable.Seq),scala.annotation.retains) @<init>]
    25: _root_
    26: Any
    27: f
    28: Function1
    29: <repeated>
    30: map
    31: scala[Qualified . Function1]
    32: map[Signed Signature(List(1, scala.Function1),java.lang.Object) @map]
    33: apply
    34: SeqOps
    35: scala[Qualified . collection][Qualified . SeqOps]
    36: apply[Signed Signature(List(1, scala.collection.immutable.Seq),scala.collection.SeqOps) @apply]
    37: package
    38: Delegate
    39: SeqFactory
    40: SeqFactory[ModuleClass]
    41: IterableOps
    42: $anonfun
    43: i
    44: SourceFile
    45: internal
    46: scala[Qualified . annotation][Qualified . internal]
    47: scala[Qualified . annotation][Qualified . internal][Qualified . SourceFile]
    48: String
    49: java[Qualified . lang][Qualified . String]
    50: <init>[Signed Signature(List(java.lang.String),scala.annotation.internal.SourceFile) @<init>]
    51: tests/run/i4523.scala
    52: Positions
    53: Comments
    54: Attributes


Trees (194 bytes, starting from 466):
     0: PACKAGE(191)
     3:   TERMREFpkg 1 [<empty>]
     5:   TYPEDEF(186) 2 [C]
     9:     TEMPLATE(162)
    12:       APPLY(10)
    14:         SELECTin(8) 9 [<init>[Signed Signature(List(),java.lang.Object) @<init>]]
    17:           NEW
    18:             TYPEREF 7 [Object]
    20:               TERMREFpkg 6 [java[Qualified . lang]]
    22:           SHAREDtype 18
    24:       DEFDEF(7) 3 [<init>]
    27:         EMPTYCLAUSE
    28:         TYPEREF 10 [Unit]
    30:           TERMREFpkg 11 [scala]
    32:         STABLE
    33:       DEFDEF(138) 12 [foo]
    37:         ANNOTATEDtype(58)
    39:           APPLIEDtype(8)
    41:             TYPEREF 13 [Seq]
    43:               TERMREFpkg 17 [scala[Qualified . collection][Qualified . immutable]]
    45:             TYPEREF 18 [Int]
    47:               SHAREDtype 30
    49:           APPLY(46)
    51:             SELECTin(14) 24 [<init>[Signed Signature(List(scala.collection.immutable.Seq),scala.annotation.retains) @<init>]]
    54:               NEW
    55:                 SELECTtpt 21 [retains]
    57:                   SELECT 19 [annotation]
    59:                     SELECT 11 [scala]
    61:                       TERMREFpkg 25 [_root_]
    63:               TYPEREF 21 [retains]
    65:                 TERMREFpkg 20 [scala[Qualified . annotation]]
    67:             TYPED(28)
    69:               REPEATED(18)
    71:                 TYPEREF 26 [Any]
    73:                   TERMREFpkg 11 [scala]
    75:                 SHAREDtype 39
    77:                 IDENT 27 [f]
    79:                   APPLIEDtype(8)
    81:                     TYPEREF 28 [Function1]
    83:                       SHAREDtype 30
    85:                     SHAREDtype 45
    87:                     SHAREDtype 45
    89:               APPLIEDtype(6)
    91:                 TYPEREF 29 [<repeated>]
    93:                   SHAREDtype 73
    95:                 SHAREDtype 71
    97:         APPLY(75)
    99:           TYPEAPPLY(47)
   101:             SELECTin(43) 32 [map[Signed Signature(List(1, scala.Function1),java.lang.Object) @map]]
   104:               APPLY(36)
   106:                 TYPEAPPLY(18)
   108:                   SELECTin(14) 36 [apply[Signed Signature(List(1, scala.collection.immutable.Seq),scala.collection.SeqOps) @apply]]
   111:                     TERMREF 13 [Seq]
   113:                       TERMREF 37 [package]
   115:                         SHAREDtype 30
   117:                     TYPEREF 38 [Delegate]
   119:                       THIS
   120:                         TYPEREF 40 [SeqFactory[ModuleClass]]
   122:                           TERMREFpkg 15 [scala[Qualified . collection]]
   124:                   SHAREDtype 45
   126:                 TYPED(14)
   128:                   REPEATED(4)
   130:                     SHAREDtype 45
   132:                     INTconst 5
   134:                   APPLIEDtype(6)
   136:                     TYPEREF 29 [<repeated>]
   138:                       SHAREDtype 30
   140:                     SHAREDtype 45
   142:               TYPEREF 41 [IterableOps]
   144:                 SHAREDtype 122
   146:             SHAREDtype 45
   148:           BLOCK(24)
   150:             BLOCK(22)
   152:               LAMBDA(3)
   154:                 TERMREFdirect 157
   157:               DEFDEF(15) 42 [$anonfun]
   160:                 PARAM(3) 43 [i]
   163:                   SHAREDtype 45
   165:                 SHAREDtype 45
   167:                 BLOCK(3)
   169:                   TERMREFdirect 160
   172:                 SYNTHETIC
   173:                 ARTIFACT
   174:     ANNOTATION(18)
   176:       TYPEREF 44 [SourceFile]
   178:         TERMREFpkg 46 [scala[Qualified . annotation][Qualified . internal]]
   180:       APPLY(12)
   182:         SELECTin(8) 50 [<init>[Signed Signature(List(java.lang.String),scala.annotation.internal.SourceFile) @<init>]]
   185:           NEW
   186:             SHAREDtype 176
   189:           SHAREDtype 176
   192:         STRINGconst 51 [tests/run/i4523.scala]
   194:

Positions (86 bytes, starting from 662):
  lines: 4
  line sizes:
     0, 8, 33, 0
  positions:
     0: 1 .. 43
     5: 1 .. 43
     9: 12 .. 43
    18: 7 .. 7
    24: 12 .. 12
    28: 12 .. 12
    33: 12 .. 43
    37: 19 .. 19
   101: 22 .. 32
   104: 22 .. 28
   111: 22 .. 25
   124: 22 .. 25
   130: 27 .. 27
   132: 26 .. 27
   134: 27 .. 27
   146: 22 .. 32
   148: 33 .. 43
   154: 41 .. 41
   157: 35 .. 41
   160: 35 .. 36
   163: 36 .. 36
   165: 36 .. 36
   169: 40 .. 41
   180: 1 .. 43
   186: 1 .. 1
   192: 1 .. 1

  source paths:
     0: 51 [tests/run/i4523.scala]


Attributes (2 bytes, starting from 752):
  SOURCEFILEattr 51 [tests/run/i4523.scala]

**** end of pickled info of class C

Originally posted by @nicolasstucki in #19652 (comment)