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typeTag fails when non-root scala package in scope #9397

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scabug opened this issue Jul 14, 2015 · 2 comments
Closed

typeTag fails when non-root scala package in scope #9397

scabug opened this issue Jul 14, 2015 · 2 comments
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reflection
Milestone
2.12.0-M5

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@scabug
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scabug commented Jul 14, 2015

If a package named scala that is not the root scala package is in scope, root.scala.reflect.runtime.universe.typeTag fail with a "No TypeTag available for T" exception, where T is the type argument. An example of T is String. I suspect that other reflection methods have the same problem.

The attached project demonstrates the problem.
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scabug commented Jul 14, 2015

Imported From: https://issues.scala-lang.org/browse/SI-9397?orig=1
Reporter: Jeff Shaw (shawjef3)
Affected Versions: 2.10.5, 2.11.7
Attachments:

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scabug commented Jul 21, 2015

@retronym said (edited on Jul 21, 2015 12:32:39 AM UTC):

% cat sandbox/test.scala

class C {
  type scala
  object scala
  def test {
    implicitly[reflect.runtime.universe.TypeTag[String]]
  }

}

%scalac -Ydebug -Ymacro-debug-verbose sandbox/test.scala
[running phase parser on test.scala]
[running phase namer on test.scala]
[running phase packageobjects on test.scala]
[running phase typer on test.scala]
macroExpand: expander = scala.tools.nsc.typechecker.Macros$DefMacroExpander@68be2bc2, expandee = Apply[1](TypeApply[2](Select[3](This[4](typeNames.PACKAGE), TermName("materializeTypeTag")#9691), List(TypeTree[5]())), List(Select[6](Select[7](Select[8](Select[9](This[10](TypeName("scala")), scala.reflect#2775), scala.reflect.runtime#2961), scala.reflect.runtime.package#14945), TermName("universe")#15044)))
[1] TypeRef(SingleType(SingleType(SingleType(SingleType(ThisType(scala#27), scala.reflect#2775), scala.reflect.runtime#2961), scala.reflect.runtime.package#14945), TermName("universe")#15044), TypeName("TypeTag")#11505, List(TypeRef(SingleType(ThisType(scala#27), scala.Predef#1781), TypeName("String")#7839, List())))
[2] MethodType(List(TermName("u")#9692), TypeRef(SingleType(NoPrefix, TermName("u")#9692), TypeName("TypeTag")#11505, List(TypeRef(SingleType(ThisType(scala#27), scala.Predef#1781), TypeName("String")#7839, List()))))
[3] PolyType(List(TypeName("T")#9693), MethodType(List(TermName("u")#9692), TypeRef(SingleType(NoPrefix, TermName("u")#9692), TypeName("TypeTag")#11505, List(TypeRef(NoPrefix, TypeName("T")#9693, List())))))
[4] ThisType(scala.reflect.api.package#9545)
[5] TypeRef(SingleType(ThisType(scala#27), scala.Predef#1781), TypeName("String")#7839, List())
[6] SingleType(SingleType(SingleType(SingleType(ThisType(scala#27), scala.reflect#2775), scala.reflect.runtime#2961), scala.reflect.runtime.package#14945), TermName("universe")#15044)
[7] SingleType(SingleType(SingleType(ThisType(scala#27), scala.reflect#2775), scala.reflect.runtime#2961), scala.reflect.runtime.package#14945)
[8] SingleType(SingleType(ThisType(scala#27), scala.reflect#2775), scala.reflect.runtime#2961)
[9] SingleType(ThisType(scala#27), scala.reflect#2775)
[10] ThisType(scala#27), desugared = ()
looking for macro implementation: term macro materializeTypeTag
macro expansion is serviced by a fast track
calculateUndetparams: Set()
performing macro expansion `package`.this.materializeTypeTag[String](scala.this.reflect.runtime.`package`.universe) at source-/Users/jason/code/scala3/sandbox/test.scala,line-6,offset=66
context: MacroContext(materializeTypeTag@source-/Users/jason/code/scala3/sandbox/test.scala,line-6,offset=66 +0)
prefix: `package`.this
targs: List(String)
argss: List(List(scala.this.reflect.runtime.`package`.universe))
paramss: List(List(value u))
macroImplArgs: List(scala.this.reflect.runtime.`package`.universe)
inferring implicit value of type api.this.Universe#TypeTag[String], macros = false
typechecking {
  val $u: scala.this.reflect.runtime.`package`.universe.type = scala.this.reflect.runtime.`package`.universe;
  val $m: $u.Mirror = scala.this.reflect.runtime.`package`.universe.runtimeMirror(Predef.this.classOf[<empty>.this.C].getClassLoader);
  $u.TypeTag.apply[String]($m, {
    final class $typecreator1 extends TypeCreator {
      def <init>() = {
        super.<init>();
        ()
      };
      def apply[U >: Nothing <: Universe with Singleton]($m$untyped: Mirror[U]): U#Type = {
        val $u: U = $m$untyped.universe;
        val $m: $u.Mirror = $m$untyped.asInstanceOf[$u.Mirror];
        $u.internal.reificationSupport.TypeRef($u.internal.reificationSupport.SingleType($u.internal.reificationSupport.ThisType($m.staticPackage("scala").asModule.moduleClass), $m.staticModule("scala.Predef")), $u.internal.reificationSupport.selectType($m.staticModule("scala.Predef").asModule.moduleClass, "String"), scala.collection.immutable.List.apply())
      }
    };
    new $typecreator1.<init>()
  })
} with expected type ?, implicit views = true, macros = true
value collection is not a member of object C.this.scala
macro expansion has been aborted
macro expansion has failed: No TypeTag available for String
macroExpand: expander = scala.tools.nsc.typechecker.Macros$DefMacroExpander@6a396c1e, expandee = Apply[1](TypeApply[2](Select[3](This[4](typeNames.PACKAGE), TermName("materializeTypeTag")#9691), List(TypeTree[5]())), List(Select[6](Select[7](Select[8](Select[9](This[10](TypeName("scala")), scala.reflect#2775), scala.reflect.runtime#2961), scala.reflect.runtime.package#14945), TermName("universe")#15044)))
[1] TypeRef(SingleType(SingleType(SingleType(SingleType(ThisType(scala#27), scala.reflect#2775), scala.reflect.runtime#2961), scala.reflect.runtime.package#14945), TermName("universe")#15044), TypeName("TypeTag")#11505, List(TypeRef(SingleType(ThisType(scala#27), scala.Predef#1781), TypeName("String")#7839, List())))
[2] MethodType(List(TermName("u")#9692), TypeRef(SingleType(NoPrefix, TermName("u")#9692), TypeName("TypeTag")#11505, List(TypeRef(SingleType(ThisType(scala#27), scala.Predef#1781), TypeName("String")#7839, List()))))
[3] PolyType(List(TypeName("T")#9693), MethodType(List(TermName("u")#9692), TypeRef(SingleType(NoPrefix, TermName("u")#9692), TypeName("TypeTag")#11505, List(TypeRef(NoPrefix, TypeName("T")#9693, List())))))
[4] ThisType(scala.reflect.api.package#9545)
[5] TypeRef(SingleType(ThisType(scala#27), scala.Predef#1781), TypeName("String")#7839, List())
[6] SingleType(SingleType(SingleType(SingleType(ThisType(scala#27), scala.reflect#2775), scala.reflect.runtime#2961), scala.reflect.runtime.package#14945), TermName("universe")#15044)
[7] SingleType(SingleType(SingleType(ThisType(scala#27), scala.reflect#2775), scala.reflect.runtime#2961), scala.reflect.runtime.package#14945)
[8] SingleType(SingleType(ThisType(scala#27), scala.reflect#2775), scala.reflect.runtime#2961)
[9] SingleType(ThisType(scala#27), scala.reflect#2775)
[10] ThisType(scala#27), desugared = ()
looking for macro implementation: term macro materializeTypeTag
macro expansion is serviced by a fast track
calculateUndetparams: Set()
performing macro expansion `package`.this.materializeTypeTag[String](scala.this.reflect.runtime.`package`.universe) at source-/Users/jason/code/scala3/sandbox/test.scala,line-6,offset=66
context: MacroContext(materializeTypeTag@source-/Users/jason/code/scala3/sandbox/test.scala,line-6,offset=66 +0)
prefix: `package`.this
targs: List(String)
argss: List(List(scala.this.reflect.runtime.`package`.universe))
paramss: List(List(value u))
macroImplArgs: List(scala.this.reflect.runtime.`package`.universe)
inferring implicit value of type api.this.Universe#TypeTag[String], macros = false
typechecking {
  val $u: scala.this.reflect.runtime.`package`.universe.type = scala.this.reflect.runtime.`package`.universe;
  val $m: $u.Mirror = scala.this.reflect.runtime.`package`.universe.runtimeMirror(Predef.this.classOf[<empty>.this.C].getClassLoader);
  $u.TypeTag.apply[String]($m, {
    final class $typecreator2 extends TypeCreator {
      def <init>() = {
        super.<init>();
        ()
      };
      def apply[U >: Nothing <: Universe with Singleton]($m$untyped: Mirror[U]): U#Type = {
        val $u: U = $m$untyped.universe;
        val $m: $u.Mirror = $m$untyped.asInstanceOf[$u.Mirror];
        $u.internal.reificationSupport.TypeRef($u.internal.reificationSupport.SingleType($u.internal.reificationSupport.ThisType($m.staticPackage("scala").asModule.moduleClass), $m.staticModule("scala.Predef")), $u.internal.reificationSupport.selectType($m.staticModule("scala.Predef").asModule.moduleClass, "String"), scala.collection.immutable.List.apply())
      }
    };
    new $typecreator2.<init>()
  })
} with expected type ?, implicit views = true, macros = true
value collection is not a member of object C.this.scala
macro expansion has been aborted
macro expansion has failed: No TypeTag available for String
sandbox/test.scala:6: error: No TypeTag available for String
    implicitly[reflect.runtime.universe.TypeTag[String]]
              ^
sandbox/test.scala:6: error: [ suppressed ] not enough arguments for method implicitly: (implicit <param> e: scala.this.reflect.runtime.universe.TypeTag[String])scala.this.reflect.runtime.universe.TypeTag[String].
Unspecified value parameter e.
    implicitly[reflect.runtime.universe.TypeTag[String]]
              ^
two errors found

I suspect this is the first culprit:

git diff head -- src/compiler/scala/reflect/
diff --git a/src/compiler/scala/reflect/reify/codegen/GenUtils.scala b/src/compiler/scala/reflect/reify/codegen/GenUtils.scala
index b5b0f93..242e5d6 100644
--- a/src/compiler/scala/reflect/reify/codegen/GenUtils.scala
+++ b/src/compiler/scala/reflect/reify/codegen/GenUtils.scala
@@ -55,7 +55,7 @@ trait GenUtils {
     mirrorCall(TermName("" + prefix), args: _*)

   def scalaFactoryCall(name: TermName, args: Tree*): Tree =
-    call(s"scala.$name.apply", args: _*)
+    call(s"_root_.scala.$name.apply", args: _*)

   def scalaFactoryCall(name: String, args: Tree*): Tree =
     scalaFactoryCall(TermName(name), args: _*)

@scabug scabug closed this as completed May 11, 2016
@scabug scabug added this to the 2.12.0-M5 milestone Apr 7, 2017
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