Merge pull request #1958 from dotty-staging/add-enum

Add "enum" construct

6 files changed, 35 insertions, 12 deletions

diff --git a/compiler/src/dotty/tools/dotc/core/Contexts.scala b/compiler/src/dotty/tools/dotc/core/Contexts.scala
index 6b7be12be..8707b66f9 100644
--- a/compiler/src/dotty/tools/dotc/core/Contexts.scala
+++ b/compiler/src/dotty/tools/dotc/core/Contexts.scala
@@ -306,13 +306,14 @@ object Contexts {
         sb.append(str)
       }
 
-    /** The next outer context whose tree is a template or package definition */
+    /** The next outer context whose tree is a template or package definition
+     *  Note: Currently unused
     def enclTemplate: Context = {
       var c = this
       while (c != NoContext && !c.tree.isInstanceOf[Template[_]] && !c.tree.isInstanceOf[PackageDef[_]])
         c = c.outer
       c
-    }
+    }*/
 
     /** The context for a supercall. This context is used for elaborating
      *  the parents of a class and their arguments.
diff --git a/compiler/src/dotty/tools/dotc/core/Decorators.scala b/compiler/src/dotty/tools/dotc/core/Decorators.scala
index 0e8ae196a..c65dc5b97 100644
--- a/compiler/src/dotty/tools/dotc/core/Decorators.scala
+++ b/compiler/src/dotty/tools/dotc/core/Decorators.scala
@@ -185,7 +185,7 @@ object Decorators {
      *  give more info about type variables and to disambiguate where needed.
      */
     def ex(args: Any*)(implicit ctx: Context): String =
-      explained2(implicit ctx => em(args: _*))
+      explained(implicit ctx => em(args: _*))
 
     /** Formatter that adds syntax highlighting to all interpolated values */
     def hl(args: Any*)(implicit ctx: Context): String =
diff --git a/compiler/src/dotty/tools/dotc/core/Definitions.scala b/compiler/src/dotty/tools/dotc/core/Definitions.scala
index 4d4350f98..39b46cbfe 100644
--- a/compiler/src/dotty/tools/dotc/core/Definitions.scala
+++ b/compiler/src/dotty/tools/dotc/core/Definitions.scala
@@ -512,6 +512,10 @@ class Definitions {
   def DynamicClass(implicit ctx: Context) = DynamicType.symbol.asClass
   lazy val OptionType: TypeRef                  = ctx.requiredClassRef("scala.Option")
   def OptionClass(implicit ctx: Context) = OptionType.symbol.asClass
+  lazy val EnumType: TypeRef                    = ctx.requiredClassRef("scala.Enum")
+  def EnumClass(implicit ctx: Context) = EnumType.symbol.asClass
+  lazy val EnumValuesType: TypeRef              = ctx.requiredClassRef("scala.runtime.EnumValues")
+  def EnumValuesClass(implicit ctx: Context) = EnumValuesType.symbol.asClass
   lazy val ProductType: TypeRef                 = ctx.requiredClassRef("scala.Product")
   def ProductClass(implicit ctx: Context) = ProductType.symbol.asClass
     lazy val Product_canEqualR = ProductClass.requiredMethodRef(nme.canEqual_)
diff --git a/compiler/src/dotty/tools/dotc/core/Flags.scala b/compiler/src/dotty/tools/dotc/core/Flags.scala
index c1267d8a2..29f1078a2 100644
--- a/compiler/src/dotty/tools/dotc/core/Flags.scala
+++ b/compiler/src/dotty/tools/dotc/core/Flags.scala
@@ -450,13 +450,22 @@ object Flags {
 
   /** Flags guaranteed to be set upon symbol creation */
   final val FromStartFlags =
-    AccessFlags | Module | Package | Deferred | Final | MethodOrHKCommon | Param | ParamAccessor | Scala2ExistentialCommon |
-    Mutable.toCommonFlags | InSuperCall | Touched | JavaStatic | CovariantOrOuter | ContravariantOrLabel | ExpandedName | AccessorOrSealed |
-    CaseAccessorOrBaseTypeArg | Fresh | Frozen | Erroneous | ImplicitCommon | Permanent | Synthetic |
-    Inline | LazyOrTrait | SuperAccessorOrScala2x | SelfNameOrImplClass
+    Module | Package | Deferred | MethodOrHKCommon | Param | ParamAccessor |
+    Scala2ExistentialCommon | Mutable.toCommonFlags | InSuperCall | Touched | JavaStatic |
+    CovariantOrOuter | ContravariantOrLabel | ExpandedName | CaseAccessorOrBaseTypeArg |
+    Fresh | Frozen | Erroneous | ImplicitCommon | Permanent | Synthetic |
+    SuperAccessorOrScala2x | Inline
+
+  /** Flags guaranteed to be set upon symbol creation, or, if symbol is a top-level
+   *  class or object, when the class file defining the symbol is loaded (which
+   *  is generally before the symbol is completed
+   */
+  final val AfterLoadFlags =
+    FromStartFlags | AccessFlags | Final | AccessorOrSealed | LazyOrTrait | SelfNameOrImplClass
 
   assert(FromStartFlags.isTermFlags && FromStartFlags.isTypeFlags)
   // TODO: Should check that FromStartFlags do not change in completion
+  assert(AfterLoadFlags.isTermFlags && AfterLoadFlags.isTypeFlags)
 
   /** A value that's unstable unless complemented with a Stable flag */
   final val UnstableValue = Mutable | Method
diff --git a/compiler/src/dotty/tools/dotc/core/StdNames.scala b/compiler/src/dotty/tools/dotc/core/StdNames.scala
index 5b7dc3d1d..bc3f96d91 100644
--- a/compiler/src/dotty/tools/dotc/core/StdNames.scala
+++ b/compiler/src/dotty/tools/dotc/core/StdNames.scala
@@ -132,6 +132,8 @@ object StdNames {
     val TRAIT_SETTER_SEPARATOR: N     = "$_setter_$"
     val DIRECT_SUFFIX: N              = "$direct"
     val LAZY_IMPLICIT_PREFIX: N       = "$lazy_implicit$"
+    val DOLLAR_VALUES: N              = "$values"
+    val DOLLAR_NEW: N                 = "$new"
 
     // value types (and AnyRef) are all used as terms as well
     // as (at least) arguments to the @specialize annotation.
@@ -395,6 +397,7 @@ object StdNames {
     val elem: N                 = "elem"
     val emptyValDef: N          = "emptyValDef"
     val ensureAccessible : N    = "ensureAccessible"
+    val enumTag: N              = "enumTag"
     val eq: N                   = "eq"
     val equalsNumChar : N       = "equalsNumChar"
     val equalsNumNum : N        = "equalsNumNum"
@@ -499,6 +502,7 @@ object StdNames {
     val staticModule : N        = "staticModule"
     val staticPackage : N       = "staticPackage"
     val synchronized_ : N       = "synchronized"
+    val tag: N                  = "tag"
     val tail: N                 = "tail"
     val `then` : N              = "then"
     val this_ : N               = "this"
@@ -523,7 +527,7 @@ object StdNames {
     val updateDynamic: N        = "updateDynamic"
     val value: N                = "value"
     val valueOf : N             = "valueOf"
-    val values : N              = "values"
+    val values: N               = "values"
     val view_ : N               = "view"
     val wait_ : N               = "wait"
     val withFilter: N           = "withFilter"
diff --git a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
index db96463e0..27782698d 100644
--- a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -163,26 +163,31 @@ object SymDenotations {
       setFlag(flags & mask)
     }
 
+    private def isCurrent(fs: FlagSet) =
+      fs <= (
+        if (myInfo.isInstanceOf[SymbolLoader]) FromStartFlags
+        else AfterLoadFlags)
+
     /** Has this denotation one of the flags in `fs` set? */
     final def is(fs: FlagSet)(implicit ctx: Context) = {
-      (if (fs <= FromStartFlags) myFlags else flags) is fs
+      (if (isCurrent(fs)) myFlags else flags) is fs
     }
 
     /** Has this denotation one of the flags in `fs` set, whereas none of the flags
      *  in `butNot` are set?
      */
     final def is(fs: FlagSet, butNot: FlagSet)(implicit ctx: Context) =
-      (if (fs <= FromStartFlags && butNot <= FromStartFlags) myFlags else flags) is (fs, butNot)
+      (if (isCurrent(fs) && isCurrent(butNot)) myFlags else flags) is (fs, butNot)
 
     /** Has this denotation all of the flags in `fs` set? */
     final def is(fs: FlagConjunction)(implicit ctx: Context) =
-      (if (fs <= FromStartFlags) myFlags else flags) is fs
+      (if (isCurrent(fs)) myFlags else flags) is fs
 
     /** Has this denotation all of the flags in `fs` set, whereas none of the flags
      *  in `butNot` are set?
      */
     final def is(fs: FlagConjunction, butNot: FlagSet)(implicit ctx: Context) =
-      (if (fs <= FromStartFlags && butNot <= FromStartFlags) myFlags else flags) is (fs, butNot)
+      (if (isCurrent(fs) && isCurrent(butNot)) myFlags else flags) is (fs, butNot)
 
     /** The type info.
      *  The info is an instance of TypeType iff this is a type denotation