Move Mode to core

Mode is used from a lot of low-level code, does not just reflect Typer info.
So it makes more sense top to place it in the core package.

13 files changed, 87 insertions, 13 deletions

diff --git a/src/dotty/tools/dotc/core/Annotations.scala b/src/dotty/tools/dotc/core/Annotations.scala
index 2b27b5e01..dc4897233 100644
--- a/src/dotty/tools/dotc/core/Annotations.scala
+++ b/src/dotty/tools/dotc/core/Annotations.scala
@@ -5,7 +5,6 @@ import Symbols._, Types._, util.Positions._, Contexts._, Constants._, ast.tpd._
 import config.ScalaVersion
 import StdNames._
 import dotty.tools.dotc.ast.{tpd, untpd}
-import dotty.tools.dotc.typer.ProtoTypes.FunProtoTyped
 
 object Annotations {
 
diff --git a/src/dotty/tools/dotc/core/Contexts.scala b/src/dotty/tools/dotc/core/Contexts.scala
index fd0cff94e..a0bb03e50 100644
--- a/src/dotty/tools/dotc/core/Contexts.scala
+++ b/src/dotty/tools/dotc/core/Contexts.scala
@@ -18,7 +18,7 @@ import util.Positions._
 import ast.Trees._
 import ast.untpd
 import util.{FreshNameCreator, SimpleMap, SourceFile, NoSource}
-import typer._
+import typer.{Implicits, ImplicitRunInfo, ImportInfo, NamerContextOps, SearchHistory, TypeAssigner, Typer}
 import Implicits.ContextualImplicits
 import config.Settings._
 import config.Config
diff --git a/src/dotty/tools/dotc/core/Decorators.scala b/src/dotty/tools/dotc/core/Decorators.scala
index 60c019bce..7d108a459 100644
--- a/src/dotty/tools/dotc/core/Decorators.scala
+++ b/src/dotty/tools/dotc/core/Decorators.scala
@@ -7,7 +7,6 @@ import Contexts._, Names._, Phases._, printing.Texts._, printing.Printer, printi
 import util.Positions.Position, util.SourcePosition
 import collection.mutable.ListBuffer
 import dotty.tools.dotc.transform.TreeTransforms._
-import typer.Mode
 import scala.language.implicitConversions
 
 /** This object provides useful implicit decorators for types defined elsewhere */
diff --git a/src/dotty/tools/dotc/core/Denotations.scala b/src/dotty/tools/dotc/core/Denotations.scala
index b52c11201..218fb8561 100644
--- a/src/dotty/tools/dotc/core/Denotations.scala
+++ b/src/dotty/tools/dotc/core/Denotations.scala
@@ -18,7 +18,6 @@ import printing.Texts._
 import printing.Printer
 import io.AbstractFile
 import config.Config
-import typer.Mode
 import util.common._
 import collection.mutable.ListBuffer
 import Decorators.SymbolIteratorDecorator
diff --git a/src/dotty/tools/dotc/core/Mode.scala b/src/dotty/tools/dotc/core/Mode.scala
new file mode 100644
index 000000000..5b3dbc872
--- /dev/null
+++ b/src/dotty/tools/dotc/core/Mode.scala
@@ -0,0 +1,85 @@
+package dotty.tools.dotc.core
+
+/** A collection of mode bits that are part of a context */
+case class Mode(val bits: Int) extends AnyVal {
+  import Mode._
+  def | (that: Mode) = Mode(bits | that.bits)
+  def & (that: Mode) = Mode(bits & that.bits)
+  def &~ (that: Mode) = Mode(bits & ~that.bits)
+  def is (that: Mode) = (bits & that.bits) == that.bits
+
+  def isExpr = (this & PatternOrType) == None
+
+  override def toString =
+    (0 until 31).filter(i => (bits & (1 << i)) != 0).map(modeName).mkString("Mode(", ",", ")")
+}
+
+object Mode {
+  val None = Mode(0)
+
+  private val modeName = new Array[String](32)
+
+  def newMode(bit: Int, name: String): Mode = {
+    modeName(bit) = name
+    Mode(1 << bit)
+  }
+
+  val Pattern = newMode(0, "Pattern")
+  val Type = newMode(1, "Type")
+
+  val ImplicitsEnabled = newMode(2, "ImplicitsEnabled")
+  val InferringReturnType = newMode(3, "InferringReturnType")
+
+  /** This mode bit is set if we collect information without reference to a valid
+   *  context with typerstate and constraint. This is typically done when we
+   *  cache the eligibility of implicits. Caching needs to be done across different constraints.
+   *  Therefore, if TypevarsMissContext is set, subtyping becomes looser, and assumes
+   *  that PolyParams can be sub- and supertypes of anything. See TypeComparer.
+   */
+  val TypevarsMissContext = newMode(4, "TypevarsMissContext")
+  val CheckCyclic = newMode(5, "CheckCyclic")
+
+  val InSuperCall = newMode(6, "InSuperCall")
+
+  /** This mode bit is set if we want to allow accessing a symbol's denotation
+   *  at a period before that symbol is first valid. An example where this is
+   *  the case is if we want to examine the environment where an access is made.
+   *  The computation might take place at an earlier phase (e.g. it is part of
+   *  some completion such as unpickling), but the environment might contain
+   *  synbols that are not yet defined in that phase.
+   *  If the mode bit is set, getting the denotation of a symbol at a phase
+   *  before the symbol is defined will return the symbol's denotation at the
+   *  first phase where it is valid, instead of throwing a NotDefinedHere error.
+   */
+  val FutureDefsOK = newMode(7, "FutureDefsOK")
+
+  /** Allow GADTFlexType labelled types to have their bounds adjusted */
+  val GADTflexible = newMode(8, "GADTflexible")
+
+  /** Allow dependent functions. This is currently necessary for unpickling, because
+   *  some dependent functions are passed through from the front end(s?), even though they
+   *  are technically speaking illegal.
+   */
+  val AllowDependentFunctions = newMode(9, "AllowDependentFunctions")
+
+  /** We are currently printing something: avoid to produce more logs about
+   *  the printing
+   */
+  val Printing = newMode(10, "Printing")
+
+  /** We are currently typechecking an ident to determine whether some implicit
+   *  is shadowed - don't do any other shadowing tests.
+   */
+  val ImplicitShadowing = newMode(11, "ImplicitShadowing")
+
+  /** We are currently in a `viewExists` check. In that case, ambiguous
+   *  implicits checks are disabled and we succeed with the first implicit
+   *  found.
+   */
+  val ImplicitExploration = newMode(12, "ImplicitExploration")
+
+  /** We are currently unpickling Scala2 info */
+  val Scala2Unpickling = newMode(13, "Scala2Unpickling")
+
+  val PatternOrType = Pattern | Type
+}
diff --git a/src/dotty/tools/dotc/core/SymDenotations.scala b/src/dotty/tools/dotc/core/SymDenotations.scala
index a83e7726a..28932b691 100644
--- a/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -13,7 +13,6 @@ import Decorators.SymbolIteratorDecorator
 import ast._
 import annotation.tailrec
 import CheckRealizable._
-import typer.Mode
 import util.SimpleMap
 import util.Stats
 import config.Config
diff --git a/src/dotty/tools/dotc/core/TypeApplications.scala b/src/dotty/tools/dotc/core/TypeApplications.scala
index 8f8a7dbdd..26ffefec4 100644
--- a/src/dotty/tools/dotc/core/TypeApplications.scala
+++ b/src/dotty/tools/dotc/core/TypeApplications.scala
@@ -12,7 +12,6 @@ import Names._
 import NameOps._
 import Flags._
 import StdNames.tpnme
-import typer.Mode
 import util.Positions.Position
 import config.Printers._
 import collection.mutable
diff --git a/src/dotty/tools/dotc/core/TypeComparer.scala b/src/dotty/tools/dotc/core/TypeComparer.scala
index 4e7a4a75d..c846737b6 100644
--- a/src/dotty/tools/dotc/core/TypeComparer.scala
+++ b/src/dotty/tools/dotc/core/TypeComparer.scala
@@ -3,7 +3,6 @@ package dotc
 package core
 
 import Types._, Contexts._, Symbols._, Flags._, Names._, NameOps._, Denotations._
-import typer.Mode
 import Decorators._
 import StdNames.{nme, tpnme}
 import collection.mutable
diff --git a/src/dotty/tools/dotc/core/TypeErasure.scala b/src/dotty/tools/dotc/core/TypeErasure.scala
index 26cac4f72..a7d825131 100644
--- a/src/dotty/tools/dotc/core/TypeErasure.scala
+++ b/src/dotty/tools/dotc/core/TypeErasure.scala
@@ -6,7 +6,6 @@ import Symbols._, Types._, Contexts._, Flags._, Names._, StdNames._, Decorators.
 import Uniques.unique
 import dotc.transform.ExplicitOuter._
 import dotc.transform.ValueClasses._
-import typer.Mode
 import util.DotClass
 
 /** Erased types are:
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index 3801f1914..5dfe3a4f1 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -31,7 +31,6 @@ import config.Config
 import config.Printers._
 import annotation.tailrec
 import Flags.FlagSet
-import typer.Mode
 import language.implicitConversions
 import scala.util.hashing.{ MurmurHash3 => hashing }
 
@@ -3446,7 +3445,7 @@ object Types {
   object CyclicReference {
     def apply(denot: SymDenotation)(implicit ctx: Context): CyclicReference = {
       val ex = new CyclicReference(denot)
-      if (!(ctx.mode is typer.Mode.CheckCyclic)) {
+      if (!(ctx.mode is Mode.CheckCyclic)) {
         cyclicErrors.println(ex.getMessage)
         for (elem <- ex.getStackTrace take 200)
           cyclicErrors.println(elem.toString)
diff --git a/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala b/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala
index 25558a79a..f7a69aa53 100644
--- a/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala
+++ b/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala
@@ -12,7 +12,6 @@ import scala.collection.{ mutable, immutable }
 import scala.collection.mutable.{ ListBuffer, ArrayBuffer }
 import scala.annotation.switch
 import typer.Checking.checkNonCyclic
-import typer.Mode
 import io.AbstractFile
 import scala.util.control.NonFatal
 
diff --git a/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala b/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
index eb3369184..b547862b4 100644
--- a/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
+++ b/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
@@ -13,7 +13,6 @@ import TastyUnpickler._, TastyBuffer._, PositionPickler._
 import scala.annotation.{tailrec, switch}
 import scala.collection.mutable.ListBuffer
 import scala.collection.{ mutable, immutable }
-import typer.Mode
 import config.Printers.pickling
 
 /** Unpickler for typed trees
diff --git a/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala b/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
index 2831de3e0..e4c8d7d13 100644
--- a/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
+++ b/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
@@ -17,7 +17,6 @@ import printing.Printer
 import io.AbstractFile
 import util.common._
 import typer.Checking.checkNonCyclic
-import typer.Mode
 import PickleBuffer._
 import scala.reflect.internal.pickling.PickleFormat._
 import Decorators._