Merge branch 'fix-7426' into init-dotty

* fix-7426: Fix #7426: Set correct default source for unpickling

Author: liufengyun

compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala

@@ -750,7 +750,7 @@ class ClassfileParser(
 
  def unpickleTASTY(bytes: Array[Byte]): Some[Embedded] = {
  val unpickler = new tasty.DottyUnpickler(bytes)
- unpickler.enter(roots = Set(classRoot, moduleRoot, moduleRoot.sourceModule))
+ unpickler.enter(roots = Set(classRoot, moduleRoot, moduleRoot.sourceModule))(ctx.withSource(util.NoSource))
  Some(unpickler)
  }
 

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -63,6 +63,7 @@ class CompilationTests extends ParallelTesting {
  compileDir("tests/pos-special/adhoc-extension", defaultOptions.and("-strict", "-feature", "-Xfatal-warnings")),
  compileFile("tests/pos-special/i7575.scala", defaultOptions.and("-language:dynamics")),
  compileFile("tests/pos-special/kind-projector.scala", defaultOptions.and("-Ykind-projector")),
+ compileFile("tests/run/i5606.scala", defaultOptions.and("-Yretain-trees")),
  ).checkCompile()
  }