From 72da305329d3a8889e4e5f8d81a0ecad04b097ad Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Wed, 18 Jun 2008 15:39:36 +0000
Subject: gixed gilles' gadt problems. Added some tests

---
 src/compiler/scala/tools/nsc/symtab/Types.scala      |  1 -
 src/compiler/scala/tools/nsc/typechecker/Infer.scala | 20 +++++++++++++++-----
 .../scala/tools/nsc/typechecker/Typers.scala         |  5 +++--
 3 files changed, 18 insertions(+), 8 deletions(-)

(limited to 'src/compiler')

diff --git a/src/compiler/scala/tools/nsc/symtab/Types.scala b/src/compiler/scala/tools/nsc/symtab/Types.scala
index b1acd9f1d0..3221fa8601 100644
--- a/src/compiler/scala/tools/nsc/symtab/Types.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Types.scala
@@ -3759,7 +3759,6 @@ A type's typeSymbol should never be inspected directly.
    *  @param variances  The variances of type parameters; need to reverse
    *                    solution direction for all contravariant variables.
    *  @param upper      When `true' search for max solution else min.
-   *  @throws NoInstance
    */
   def solve(tvars: List[TypeVar], tparams: List[Symbol],
             variances: List[Int], upper: Boolean): Boolean = {
diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index 1cec94d0d0..c6e069bf01 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -1055,9 +1055,16 @@ trait Infer {
       (lo, hi)
     }
 
-    def isInstantiatable(tvar: TypeVar) = {
-      val (lo, hi) = instBounds(tvar)
-      lo <:< hi
+    def isInstantiatable(tvars: List[TypeVar]) = {
+      def cloneTypeVar(tv: TypeVar) = {
+        val tv1 = TypeVar(tv.origin, new TypeConstraint(tv.constr.lobounds, tv.constr.hibounds))
+        tv1.constr.inst = tv.constr.inst
+        tv1
+      }
+      val tvars1 = tvars map cloneTypeVar
+      // Note: right now it's not clear that solving is complete, or how it can be made complete!
+      // So we should come back to this and investigate.
+      solve(tvars1, tvars1 map (_.origin.typeSymbol), tvars1 map (x => COVARIANT), false)
     }
 
     def instantiateTypeVar(tvar: TypeVar) {
@@ -1160,14 +1167,17 @@ trait Infer {
         if (settings.debug.value) log("free type params (1) = " + tpparams)
         var tvars = tpparams map freshVar
         var tp = pattp.instantiateTypeParams(tpparams, tvars)
-        if (!((tp <:< pt) && (tvars forall isInstantiatable))) {
+        if (!((tp <:< pt) && isInstantiatable(tvars))) {
           tvars = tpparams map freshVar
           tp = pattp.instantiateTypeParams(tpparams, tvars)
           val ptparams = freeTypeParamsOfTerms.collect(pt)
           if (settings.debug.value) log("free type params (2) = " + ptparams)
           val ptvars = ptparams map freshVar
           val pt1 = pt.instantiateTypeParams(ptparams, ptvars)
-          if (!(isPopulated(tp, pt1) && (tvars forall isInstantiatable) && (ptvars forall isInstantiatable))) {
+          if (!(isPopulated(tp, pt1) && isInstantiatable(tvars ::: ptvars))) {
+            //println(tpparams)
+            //println(tvars map instBounds)
+            //println(ptvars map instBounds)
             error(pos, "pattern type is incompatible with expected type"+foundReqMsg(pattp, pt))
             return pattp
           }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 40db3dd4a8..9f1d11f425 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -2977,8 +2977,9 @@ trait Typers { self: Analyzer =>
               case Bind(_, _) =>
                 if (arg.symbol.isAbstractType)
                   arg.symbol setInfo // XXX, feedback. don't trackSymInfo here!
-                  TypeBounds(lub(List(arg.symbol.info.bounds.lo, tparam.info.bounds.lo)),
-                             glb(List(arg.symbol.info.bounds.hi, tparam.info.bounds.hi)))
+                    TypeBounds(
+                      lub(List(arg.symbol.info.bounds.lo, tparam.info.bounds.lo.subst(tparams, argtypes))),
+                      glb(List(arg.symbol.info.bounds.hi, tparam.info.bounds.hi.subst(tparams, argtypes))))
               case _ =>
             }}
             TypeTree(owntype) setOriginal(tree) // setPos tree.pos
-- 
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