Extend argument pretyping to case-closures

4 files changed, 32 insertions, 37 deletions

diff --git a/compiler/src/dotty/tools/dotc/ast/TreeInfo.scala b/compiler/src/dotty/tools/dotc/ast/TreeInfo.scala
index bcda4b92f..e48b1039b 100644
--- a/compiler/src/dotty/tools/dotc/ast/TreeInfo.scala
+++ b/compiler/src/dotty/tools/dotc/ast/TreeInfo.scala
@@ -287,6 +287,8 @@ trait UntypedTreeInfo extends TreeInfo[Untyped] { self: Trees.Instance[Untyped]
         case ValDef(_, tpt, _) => tpt.isEmpty
         case _ => false
       }
+    case Match(EmptyTree, _) =>
+      true
     case _ => false
   }
 
diff --git a/compiler/src/dotty/tools/dotc/typer/Applications.scala b/compiler/src/dotty/tools/dotc/typer/Applications.scala
index 2cfe01616..b2c4e2f45 100644
--- a/compiler/src/dotty/tools/dotc/typer/Applications.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Applications.scala
@@ -1272,13 +1272,8 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
         def narrowBySize(alts: List[TermRef]): List[TermRef] =
           alts filter (alt => sizeFits(alt, alt.widen))
 
-        def isFunArg(arg: untpd.Tree) = arg match {
-          case untpd.Function(_, _) | Match(EmptyTree, _) => true
-          case _ => false
-        }
-
         def narrowByShapes(alts: List[TermRef]): List[TermRef] = {
-          if (normArgs exists isFunArg)
+          if (normArgs exists untpd.isFunctionWithUnknownParamType)
             if (hasNamedArg(args)) narrowByTrees(alts, args map treeShape, resultType)
             else narrowByTypes(alts, normArgs map typeShape, resultType)
           else
@@ -1358,33 +1353,31 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
           case ValDef(_, tpt, _) => tpt.isEmpty
           case _ => false
         }
-        arg match {
-          case arg: untpd.Function if arg.args.exists(isUnknownParamType) =>
-            def isUniform[T](xs: List[T])(p: (T, T) => Boolean) = xs.forall(p(_, xs.head))
-            val formalsForArg: List[Type] = altFormals.map(_.head)
-            // For alternatives alt_1, ..., alt_n, test whether formal types for current argument are of the form
-            //   (p_1_1, ..., p_m_1) => r_1
-            //   ...
-            //   (p_1_n, ..., p_m_n) => r_n
-            val decomposedFormalsForArg: List[Option[(List[Type], Type, Boolean)]] =
-              formalsForArg.map(defn.FunctionOf.unapply)
-            if (decomposedFormalsForArg.forall(_.isDefined)) {
-              val formalParamTypessForArg: List[List[Type]] =
-                decomposedFormalsForArg.map(_.get._1)
-              if (isUniform(formalParamTypessForArg)((x, y) => x.length == y.length)) {
-                val commonParamTypes = formalParamTypessForArg.transpose.map(ps =>
-                  // Given definitions above, for i = 1,...,m,
-                  //   ps(i) = List(p_i_1, ..., p_i_n)  -- i.e. a column
-                  // If all p_i_k's are the same, assume the type as formal parameter
-                  // type of the i'th parameter of the closure.
-                  if (isUniform(ps)(ctx.typeComparer.isSameTypeWhenFrozen(_, _))) ps.head
-                  else WildcardType)
-                val commonFormal = defn.FunctionOf(commonParamTypes, WildcardType)
-                overload.println(i"pretype arg $arg with expected type $commonFormal")
-                pt.typedArg(arg, commonFormal)
-              }
+        if (untpd.isFunctionWithUnknownParamType(arg)) {
+          def isUniform[T](xs: List[T])(p: (T, T) => Boolean) = xs.forall(p(_, xs.head))
+          val formalsForArg: List[Type] = altFormals.map(_.head)
+          // For alternatives alt_1, ..., alt_n, test whether formal types for current argument are of the form
+          //   (p_1_1, ..., p_m_1) => r_1
+          //   ...
+          //   (p_1_n, ..., p_m_n) => r_n
+          val decomposedFormalsForArg: List[Option[(List[Type], Type, Boolean)]] =
+            formalsForArg.map(defn.FunctionOf.unapply)
+          if (decomposedFormalsForArg.forall(_.isDefined)) {
+            val formalParamTypessForArg: List[List[Type]] =
+              decomposedFormalsForArg.map(_.get._1)
+            if (isUniform(formalParamTypessForArg)((x, y) => x.length == y.length)) {
+              val commonParamTypes = formalParamTypessForArg.transpose.map(ps =>
+                // Given definitions above, for i = 1,...,m,
+                //   ps(i) = List(p_i_1, ..., p_i_n)  -- i.e. a column
+                // If all p_i_k's are the same, assume the type as formal parameter
+                // type of the i'th parameter of the closure.
+                if (isUniform(ps)(ctx.typeComparer.isSameTypeWhenFrozen(_, _))) ps.head
+                else WildcardType)
+              val commonFormal = defn.FunctionOf(commonParamTypes, WildcardType)
+              println(i"pretype arg $arg with expected type $commonFormal")
+              pt.typedArg(arg, commonFormal)
             }
-          case _ =>
+          }
         }
         recur(altFormals.map(_.tail), args1)
       case _ =>
diff --git a/compiler/test/dotty/tools/dotc/EntryPointsTest.scala b/compiler/test/dotty/tools/dotc/EntryPointsTest.scala.disabled
index 00918a282..00918a282 100644
--- a/compiler/test/dotty/tools/dotc/EntryPointsTest.scala
+++ b/compiler/test/dotty/tools/dotc/EntryPointsTest.scala.disabled
diff --git a/tests/pos/inferOverloaded.scala b/tests/pos/inferOverloaded.scala
index e5e800644..e7179a04a 100644
--- a/tests/pos/inferOverloaded.scala
+++ b/tests/pos/inferOverloaded.scala
@@ -28,11 +28,11 @@ object Test {
   m.map1({ case (k, v) => k - 1 }: PartialFunction[(Int, String), Int])
   m.map2({ case (k, v) => k - 1 }: PartialFunction[(Int, String), Int])
 
-  // These ones did not work before, still don't work in dotty:
-  //m.map1 { case (k, v) => k }
-  //val r = m.map1 { case (k, v) => (k, k*10) }
-  //val rt: MyMap[Int, Int] = r
-  //m.foo { case (k, v) => k - 1 }
+  // These ones did not work before:
+  m.map1 { case (k, v) => k }
+  val r = m.map1 { case (k, v) => (k, k*10) }
+  val rt: MyMap[Int, Int] = r
+  m.foo { case (k, v) => k - 1 }
 
   // Used to be ambiguous but overload resolution now favors PartialFunction
   def h[R](pf: Function2[Int, String, R]): Unit = ()