Check bounds of inferred typevars in PostTyper.

Author: odersky

src/dotty/tools/dotc/transform/PostTyper.scala

@@ -68,7 +68,7 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer  { thisTran
     // TODO fill in
   }
 
-  /** Check bounds of AppliedTypeTrees.
+  /** Check bounds of AppliedTypeTrees and TypeApplys.
    *  Replace type trees with TypeTree nodes.
    *  Replace constant expressions with Literal nodes.
    *  Note: Demanding idempotency instead of purity in literalize is strictly speaking too loose.
@@ -114,6 +114,9 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer  { thisTran
           tparam.info.asSeenFrom(tycon.tpe.normalizedPrefix, tparam.owner.owner).bounds)
         Checking.checkBounds(args, bounds, _.substDealias(tparams, _))
         norm(tree)
+      case TypeApply(fn, args) =>
+        Checking.checkBounds(args, fn.tpe.widen.asInstanceOf[PolyType])
+        norm(tree)
       case _ =>
         norm(tree)
     }

src/dotty/tools/dotc/typer/Applications.scala

@@ -607,7 +607,7 @@ trait Applications extends Compatibility { self: Typer =>
       case pt: PolyType =>
         if (typedArgs.length <= pt.paramBounds.length)
           typedArgs = typedArgs.zipWithConserve(pt.paramBounds)(adaptTypeArg)
-        checkBounds(typedArgs, pt)
+        Checking.checkBounds(typedArgs, pt)
       case _ =>
     }
     assignType(cpy.TypeApply(tree)(typedFn, typedArgs), typedFn, typedArgs)

src/dotty/tools/dotc/typer/Checking.scala

@@ -41,6 +41,13 @@ object Checking {
           d"Type argument ${arg.tpe} does not conform to $which bound $bound ${err.whyNoMatchStr(arg.tpe, bound)}",
           arg.pos)
 
+  /** Check that type arguments `args` conform to corresponding bounds in `poly`
+   *  Note: This does not check the bounds of AppliedTypeTrees. These
+   *  are handled by method checkBounds in FirstTransform
+   */
+  def checkBounds(args: List[tpd.Tree], poly: PolyType)(implicit ctx: Context): Unit =
+    checkBounds(args, poly.paramBounds, _.substParams(poly, _))
+
   /** Check that `tp` refers to a nonAbstract class
    *  and that the instance conforms to the self type of the created class.
    */
@@ -295,13 +302,6 @@ trait Checking {
     tree
   }
 
-  /** Check that type arguments `args` conform to corresponding bounds in `poly`
-   *  Note: This does not check the bounds of AppliedTypeTrees. These
-   *  are handled by method checkBounds in FirstTransform
-   */
-  def checkBounds(args: List[tpd.Tree], poly: PolyType)(implicit ctx: Context): Unit =
-    Checking.checkBounds(args, poly.paramBounds, _.substParams(poly, _))
-
   /** Check that type `tp` is stable. */
   def checkStable(tp: Type, pos: Position)(implicit ctx: Context): Unit =
     if (!tp.isStable && !tp.isErroneous)
@@ -407,7 +407,6 @@ trait NoChecking extends Checking {
   import tpd._
   override def checkNonCyclic(sym: Symbol, info: TypeBounds, reportErrors: Boolean)(implicit ctx: Context): Type = info
   override def checkValue(tree: Tree, proto: Type)(implicit ctx: Context): tree.type = tree
-  override def checkBounds(args: List[tpd.Tree], poly: PolyType)(implicit ctx: Context): Unit = ()
   override def checkStable(tp: Type, pos: Position)(implicit ctx: Context): Unit = ()
   override def checkClassTypeWithStablePrefix(tp: Type, pos: Position, traitReq: Boolean)(implicit ctx: Context): Type = tp
   override def checkImplicitParamsNotSingletons(vparamss: List[List[ValDef]])(implicit ctx: Context): Unit = ()

test/dotc/tests.scala

@@ -107,6 +107,7 @@ class tests extends CompilerTest {
 
   @Test def neg_abstractOverride() = compileFile(negDir, "abstract-override", xerrors = 2)
   @Test def neg_blockescapes() = compileFile(negDir, "blockescapesNeg", xerrors = 1)
+  @Test def neg_bounds() = compileFile(negDir, "bounds", xerrors = 2)
   @Test def neg_typedapply() = compileFile(negDir, "typedapply", xerrors = 4)
   @Test def neg_typedIdents() = compileDir(negDir, "typedIdents", xerrors = 2)
   @Test def neg_assignments() = compileFile(negDir, "assignments", xerrors = 3)

tests/neg/bounds.scala

@@ -0,0 +1,8 @@
+object Test {
+  class C[B >: String <: Int](x: B)
+  def g[B >: String <: Int](x: B): Int = x
+  def main(args: Array[String]): Unit = {
+    g("foo")
+    new C("bar")
+  }
+}