Merge pull request #699 from dotty-staging/fix/trait-constructors

Fix trait constructors

11 files changed, 19 insertions, 52 deletions

diff --git a/src/dotty/tools/dotc/Compiler.scala b/src/dotty/tools/dotc/Compiler.scala
index 6e2cab40d..a14aa3655 100644
--- a/src/dotty/tools/dotc/Compiler.scala
+++ b/src/dotty/tools/dotc/Compiler.scala
@@ -76,8 +76,7 @@ class Compiler {
       List(/*new PrivateToStatic,*/
            new ExpandPrivate,
            new CollectEntryPoints,
-           new LabelDefs,
-           new TraitConstructors),
+           new LabelDefs),
       List(new GenBCode)
     )
 
diff --git a/src/dotty/tools/dotc/core/Flags.scala b/src/dotty/tools/dotc/core/Flags.scala
index 759dff0d4..f39f2bac6 100644
--- a/src/dotty/tools/dotc/core/Flags.scala
+++ b/src/dotty/tools/dotc/core/Flags.scala
@@ -388,7 +388,7 @@ object Flags {
   /** Symbol is a self name */
   final val SelfName = termFlag(54, "<selfname>")
 
-  /** Symbol is an implementation class */
+  /** Symbol is an implementation class of a Scala2 trait */
   final val ImplClass = typeFlag(54, "<implclass>")
 
   final val SelfNameOrImplClass = SelfName.toCommonFlags
diff --git a/src/dotty/tools/dotc/core/NameOps.scala b/src/dotty/tools/dotc/core/NameOps.scala
index dc94f6db1..4d6cca61d 100644
--- a/src/dotty/tools/dotc/core/NameOps.scala
+++ b/src/dotty/tools/dotc/core/NameOps.scala
@@ -62,7 +62,7 @@ object NameOps {
     def likeTyped(n: Name): N =
       (if (name.isTermName) n.toTermName else n.toTypeName).asInstanceOf[N]
 
-    def isConstructorName = name == CONSTRUCTOR || name == IMPLCLASS_CONSTRUCTOR
+    def isConstructorName = name == CONSTRUCTOR || name == TRAIT_CONSTRUCTOR
     def isExceptionResultName = name startsWith EXCEPTION_RESULT_PREFIX
     def isImplClassName = name endsWith IMPL_CLASS_SUFFIX
     def isLocalDummyName = name startsWith LOCALDUMMY_PREFIX
diff --git a/src/dotty/tools/dotc/core/StdNames.scala b/src/dotty/tools/dotc/core/StdNames.scala
index eaf4ce1e2..eb1a73625 100644
--- a/src/dotty/tools/dotc/core/StdNames.scala
+++ b/src/dotty/tools/dotc/core/StdNames.scala
@@ -232,7 +232,6 @@ object StdNames {
     val EVT2U: N                    = "evt2u$"
     val EQEQ_LOCAL_VAR: N           = "eqEqTemp$"
     val FAKE_LOCAL_THIS: N          = "this$"
-    val IMPLCLASS_CONSTRUCTOR: N    = "$init$"
     val LAZY_LOCAL: N               = "$lzy"
     val LAZY_LOCAL_INIT: N          = "$lzyINIT"
     val LAZY_FIELD_OFFSET: N        = "OFFSET$"
@@ -261,6 +260,7 @@ object StdNames {
     val SKOLEM: N                   = "<skolem>"
     val SPECIALIZED_INSTANCE: N     = "specInstance$"
     val THIS: N                     = "_$this"
+    val TRAIT_CONSTRUCTOR: N        = "$init$"
     val U2EVT: N                    = "u2evt$"
 
     final val Nil: N                = "Nil"
diff --git a/src/dotty/tools/dotc/core/SymDenotations.scala b/src/dotty/tools/dotc/core/SymDenotations.scala
index d8dddb082..164b0b8f3 100644
--- a/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -530,7 +530,7 @@ object SymDenotations {
     final def isClassConstructor = name == nme.CONSTRUCTOR
 
     /** Is this the constructor of a trait? */
-    final def isImplClassConstructor = name == nme.IMPLCLASS_CONSTRUCTOR
+    final def isImplClassConstructor = name == nme.TRAIT_CONSTRUCTOR
 
     /** Is this the constructor of a trait or a class */
     final def isConstructor = name.isConstructorName
@@ -1630,8 +1630,11 @@ object SymDenotations {
     override def fullName(implicit ctx: Context): Name = super.fullName
 
     override def primaryConstructor(implicit ctx: Context): Symbol = {
-      val cname = if (this is ImplClass) nme.IMPLCLASS_CONSTRUCTOR else nme.CONSTRUCTOR
-      info.decls.denotsNamed(cname).last.symbol // denotsNamed returns Symbols in reverse order of occurrence
+      def constrNamed(cname: TermName) = info.decls.denotsNamed(cname).last.symbol
+        // denotsNamed returns Symbols in reverse order of occurrence
+      if (this.is(ImplClass)) constrNamed(nme.TRAIT_CONSTRUCTOR) // ignore normal constructor
+      else
+        constrNamed(nme.CONSTRUCTOR).orElse(constrNamed(nme.TRAIT_CONSTRUCTOR))
     }
 
     /** The parameter accessors of this class. Term and type accessors,
diff --git a/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala b/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
index 9498cf43c..53e8478fa 100644
--- a/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
+++ b/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
@@ -438,7 +438,7 @@ class Scala2Unpickler(bytes: Array[Byte], classRoot: ClassDenotation, moduleClas
     }
 
     val name1 = name0.adjustIfModuleClass(flags)
-    val name = if (name1 == nme.IMPLCLASS_CONSTRUCTOR) nme.CONSTRUCTOR else name1
+    val name = if (name1 == nme.TRAIT_CONSTRUCTOR) nme.CONSTRUCTOR else name1
 
     def isClassRoot = (name == classRoot.name) && (owner == classRoot.owner) && !(flags is ModuleClass)
     def isModuleClassRoot = (name == moduleClassRoot.name) && (owner == moduleClassRoot.owner) && (flags is Module)
diff --git a/src/dotty/tools/dotc/transform/AugmentScala2Traits.scala b/src/dotty/tools/dotc/transform/AugmentScala2Traits.scala
index 9f9d2dd67..116fee899 100644
--- a/src/dotty/tools/dotc/transform/AugmentScala2Traits.scala
+++ b/src/dotty/tools/dotc/transform/AugmentScala2Traits.scala
@@ -60,7 +60,7 @@ class AugmentScala2Traits extends MiniPhaseTransform with IdentityDenotTransform
         val mold =
           if (meth.isConstructor)
             meth.copySymDenotation(
-              name = nme.IMPLCLASS_CONSTRUCTOR,
+              name = nme.TRAIT_CONSTRUCTOR,
               info = MethodType(Nil, defn.UnitType))
           else meth.ensureNotPrivate
         meth.copy(
diff --git a/src/dotty/tools/dotc/transform/ExtensionMethods.scala b/src/dotty/tools/dotc/transform/ExtensionMethods.scala
index f50e3324d..087e15c71 100644
--- a/src/dotty/tools/dotc/transform/ExtensionMethods.scala
+++ b/src/dotty/tools/dotc/transform/ExtensionMethods.scala
@@ -14,7 +14,7 @@ import core._
 import Phases.Phase
 import Types._, Contexts._, Constants._, Names._, NameOps._, Flags._, DenotTransformers._
 import SymDenotations._, Symbols._, StdNames._, Annotations._, Trees._, Scopes._, Denotations._
-import TypeErasure.{ erasure, valueErasure, ErasedValueType }
+import TypeErasure.{ valueErasure, ErasedValueType }
 import TypeUtils._
 import util.Positions._
 import Decorators._
diff --git a/src/dotty/tools/dotc/transform/LinkScala2ImplClasses.scala b/src/dotty/tools/dotc/transform/LinkScala2ImplClasses.scala
index 8c247130a..60e8edc26 100644
--- a/src/dotty/tools/dotc/transform/LinkScala2ImplClasses.scala
+++ b/src/dotty/tools/dotc/transform/LinkScala2ImplClasses.scala
@@ -50,7 +50,7 @@ class LinkScala2ImplClasses extends MiniPhaseTransform with IdentityDenotTransfo
 
   private def implMethod(meth: Symbol)(implicit ctx: Context): Symbol =
     meth.owner.implClass.info
-      .decl(if (meth.isConstructor) nme.IMPLCLASS_CONSTRUCTOR else meth.name)
+      .decl(if (meth.isConstructor) nme.TRAIT_CONSTRUCTOR else meth.name)
       .suchThat(c => FullParameterization.memberSignature(c.info) == meth.signature)
       .symbol
 
diff --git a/src/dotty/tools/dotc/transform/Mixin.scala b/src/dotty/tools/dotc/transform/Mixin.scala
index de6cde8f2..bebaf44f4 100644
--- a/src/dotty/tools/dotc/transform/Mixin.scala
+++ b/src/dotty/tools/dotc/transform/Mixin.scala
@@ -100,8 +100,10 @@ class Mixin extends MiniPhaseTransform with SymTransformer { thisTransform =>
   override def transformSym(sym: SymDenotation)(implicit ctx: Context): SymDenotation =
     if (sym.is(Accessor, butNot = Deferred) && sym.owner.is(Trait))
       sym.copySymDenotation(initFlags = sym.flags &~ ParamAccessor | Deferred).ensureNotPrivate
-    else if (sym.isConstructor && sym.owner.is(Trait) && sym.info.firstParamTypes.nonEmpty)
-      sym.copySymDenotation(info = MethodType(Nil, sym.info.resultType))
+    else if (sym.isConstructor && sym.owner.is(Trait))
+      sym.copySymDenotation(
+        name = nme.TRAIT_CONSTRUCTOR,
+        info = MethodType(Nil, sym.info.resultType))
     else
       sym
 
@@ -231,8 +233,7 @@ class Mixin extends MiniPhaseTransform with SymTransformer { thisTransform =>
 
     cpy.Template(impl)(
       constr =
-        if (cls.is(Trait) && impl.constr.vparamss.flatten.nonEmpty)
-          cpy.DefDef(impl.constr)(vparamss = Nil :: Nil)
+        if (cls.is(Trait)) cpy.DefDef(impl.constr)(vparamss = Nil :: Nil)
         else impl.constr,
       parents = impl.parents.map(p => TypeTree(p.tpe).withPos(p.pos)),
       body =
diff --git a/src/dotty/tools/dotc/transform/TraitConstructors.scala b/src/dotty/tools/dotc/transform/TraitConstructors.scala
deleted file mode 100644
index 9fea468da..000000000
--- a/src/dotty/tools/dotc/transform/TraitConstructors.scala
+++ /dev/null
@@ -1,36 +0,0 @@
-package dotty.tools.dotc.transform
-
-import dotty.tools.dotc.ast.tpd
-import dotty.tools.dotc.core.Contexts.Context
-import dotty.tools.dotc.core.DenotTransformers.{SymTransformer, DenotTransformer}
-import dotty.tools.dotc.core.Denotations.SingleDenotation
-import dotty.tools.dotc.core.Phases.Phase
-import dotty.tools.dotc.core.StdNames._
-import dotty.tools.dotc.core.SymDenotations.SymDenotation
-import dotty.tools.dotc.core._
-import dotty.tools.dotc.transform.TreeTransforms.{MiniPhaseTransform, TransformerInfo}
-
-/***
-  * Renames constructors in traits so that backend will call them with invokeInterface
-  * Also makes sure that renamed constructor bodies conforms to type of method
- */
-class TraitConstructors extends MiniPhaseTransform with SymTransformer {
-  import dotty.tools.dotc.ast.tpd._
-  def phaseName: String = "traitConstructors"
-
-  override def treeTransformPhase: Phase = this.phase
-
-  def transformSym(sym: SymDenotation)(implicit ctx: Context): SymDenotation = {
-    if (sym.isPrimaryConstructor && (sym.owner is Flags.Trait))
-      sym.copySymDenotation(name = nme.IMPLCLASS_CONSTRUCTOR)
-    else sym
-  }
-
-  override def transformDefDef(tree: tpd.DefDef)(implicit ctx: Context, info: TransformerInfo): tpd.Tree = {
-    val sym = tree.symbol
-    if (sym.isPrimaryConstructor && (sym.owner is Flags.Trait))
-      cpy.DefDef(tree)(rhs = Block(List(tree.rhs), This(tree.symbol.enclosingClass.asClass)))
-    else tree
-  }
-
-}