Relaxing check that implicits must have explicit return type

Now this is required only for members of a template. Local statements can still have implicits with no result type. (Maybe we need to get back on this).

Also, changed Dotty itself and tests to adhere to the new restriction.

7 files changed, 10 insertions, 10 deletions

diff --git a/src/dotty/tools/dotc/ast/Desugar.scala b/src/dotty/tools/dotc/ast/Desugar.scala
index cfc7db1c3..0f1d1010a 100644
--- a/src/dotty/tools/dotc/ast/Desugar.scala
+++ b/src/dotty/tools/dotc/ast/Desugar.scala
@@ -274,7 +274,7 @@ object desugar {
       else Nil
 
     // For an implicit class C[Ts](p11: T11, ..., p1N: T1N) ... (pM1: TM1, .., pMN: TMN), the method
-    //     synthetic implicit C[Ts](p11: T11, ..., p1N: T1N) ... (pM1: TM1, ..., pMN: TMN) =
+    //     synthetic implicit C[Ts](p11: T11, ..., p1N: T1N) ... (pM1: TM1, ..., pMN: TMN): C[Ts] =
     //       new C[Ts](p11, ..., p1N) ... (pM1, ..., pMN) =
     val implicitWrappers =
       if (mods is Implicit) {
@@ -283,7 +283,7 @@ object desugar {
         if (mods is Case)
           ctx.error("implicit classes may not case classes", cdef.pos)
         DefDef(Modifiers(Synthetic | Implicit), name.toTermName,
-          tparams, vparamss, TypeTree(), creatorExpr) :: Nil
+          tparams, vparamss, classTypeRef, creatorExpr) :: Nil
       }
       else Nil
 
diff --git a/src/dotty/tools/dotc/core/Contexts.scala b/src/dotty/tools/dotc/core/Contexts.scala
index d82826277..1d78eaf02 100644
--- a/src/dotty/tools/dotc/core/Contexts.scala
+++ b/src/dotty/tools/dotc/core/Contexts.scala
@@ -477,7 +477,7 @@ object Contexts {
   object Context {
 
     /** Implicit conversion that injects all printer operations into a context */
-    implicit def toPrinter(ctx: Context) = ctx.printer
+    implicit def toPrinter(ctx: Context): Printer = ctx.printer
 
     /** implicit conversion that injects all ContextBase members into a context */
     implicit def toBase(ctx: Context): ContextBase = ctx.base
@@ -487,7 +487,7 @@ object Contexts {
 
   /** Info that changes on each compiler run */
   class RunInfo(initctx: Context) extends ImplicitRunInfo {
-    implicit val ctx = initctx
+    implicit val ctx: Context = initctx
   }
 
   /** Initial size of superId table */
diff --git a/src/dotty/tools/dotc/core/TypeComparer.scala b/src/dotty/tools/dotc/core/TypeComparer.scala
index 92d9b7748..9604e1531 100644
--- a/src/dotty/tools/dotc/core/TypeComparer.scala
+++ b/src/dotty/tools/dotc/core/TypeComparer.scala
@@ -16,7 +16,7 @@ import config.Printers._
 /** Provides methods to compare types.
  */
 class TypeComparer(initctx: Context) extends DotClass {
-  implicit val ctx = initctx
+  implicit val ctx: Context = initctx
 
   val state = ctx.typerState
   import state.constraint
diff --git a/src/dotty/tools/dotc/printing/PlainPrinter.scala b/src/dotty/tools/dotc/printing/PlainPrinter.scala
index a2e7b21e8..71c255c17 100644
--- a/src/dotty/tools/dotc/printing/PlainPrinter.scala
+++ b/src/dotty/tools/dotc/printing/PlainPrinter.scala
@@ -10,7 +10,7 @@ import java.lang.Integer.toOctalString
 import scala.annotation.switch
 
 class PlainPrinter(_ctx: Context) extends Printer {
-  protected[this] implicit val ctx = _ctx
+  protected[this] implicit val ctx: Context = _ctx
 
   protected def maxToTextRecursions = 100
 
diff --git a/src/dotty/tools/dotc/typer/Implicits.scala b/src/dotty/tools/dotc/typer/Implicits.scala
index 68ec9273a..ddd37a885 100644
--- a/src/dotty/tools/dotc/typer/Implicits.scala
+++ b/src/dotty/tools/dotc/typer/Implicits.scala
@@ -274,7 +274,7 @@ trait ImplicitRunInfo { self: RunInfo =>
      *  abstract types are eliminated.
      */
     object liftToClasses extends TypeMap {
-      private implicit val ctx = liftingCtx
+      private implicit val ctx: Context = liftingCtx
       def apply(tp: Type) = tp match {
         case tp: TypeRef if tp.symbol.isAbstractOrAliasType =>
           val pre = tp.prefix
diff --git a/src/dotty/tools/dotc/typer/Namer.scala b/src/dotty/tools/dotc/typer/Namer.scala
index 8e0b44b05..d67579408 100644
--- a/src/dotty/tools/dotc/typer/Namer.scala
+++ b/src/dotty/tools/dotc/typer/Namer.scala
@@ -378,7 +378,7 @@ class Namer { typer: Typer =>
   class ClassCompleter(cls: ClassSymbol, original: TypeDef)(ictx: Context) extends Completer(original)(ictx) {
     withDecls(newScope)
 
-    protected implicit val ctx = localContext(cls)
+    protected implicit val ctx: Context = localContext(cls)
 
     val TypeDef(_, name, impl @ Template(constr, parents, self, body)) = original
 
diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index 58522ddb3..8498e5e54 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -862,7 +862,7 @@ class Typer extends Namer with Applications with Implicits {
     val ValDef(mods, name, tpt, rhs) = vdef
     val mods1 = typedModifiers(mods)
     val tpt1 = typedType(tpt)
-    if (sym is Implicit) checkImplicitTptNonEmpty(vdef)
+    if ((sym is Implicit) && sym.owner.isType) checkImplicitTptNonEmpty(vdef)
     val rhs1 = rhs match {
       case Ident(nme.WILDCARD) => rhs withType tpt1.tpe
       case _ => typedExpr(rhs, tpt1.tpe)
@@ -877,7 +877,7 @@ class Typer extends Namer with Applications with Implicits {
     val tparams1 = tparams mapconserve (typed(_).asInstanceOf[TypeDef])
     val vparamss1 = vparamss nestedMapconserve (typed(_).asInstanceOf[ValDef])
     if (sym is Implicit) {
-      checkImplicitTptNonEmpty(ddef)
+      if (sym.owner.isType) checkImplicitTptNonEmpty(ddef)
       checkImplicitParamsNotSingletons(vparamss1)
     }
     val tpt1 = typedType(tpt)