Create implicit closures to math expected implicit functions

When the expected type is an implicit function, create an
implicit closure to match it.

1 files changed, 10 insertions, 2 deletions

diff --git a/compiler/src/dotty/tools/dotc/ast/TreeInfo.scala b/compiler/src/dotty/tools/dotc/ast/TreeInfo.scala
index ae7c93784..da83d0644 100644
--- a/compiler/src/dotty/tools/dotc/ast/TreeInfo.scala
+++ b/compiler/src/dotty/tools/dotc/ast/TreeInfo.scala
@@ -290,6 +290,16 @@ trait UntypedTreeInfo extends TreeInfo[Untyped] { self: Trees.Instance[Untyped]
     case _ => false
   }
 
+  /** Is `tree` an implicit function or closure, possibly nested in a block? */
+  def isImplicitClosure(tree: Tree)(implicit ctx: Context): Boolean = unsplice(tree) match {
+    case Function((param: untpd.ValDef) :: _, _) => param.mods.is(Implicit)
+    case Closure(_, meth, _) => true
+    case Block(Nil, expr) => isImplicitClosure(expr)
+    case Block(DefDef(nme.ANON_FUN, _, (param :: _) :: _, _, _) :: Nil, _: Closure) =>
+      param.mods.is(Implicit)
+    case _ => false
+  }
+
   // todo: fill with other methods from TreeInfo that only apply to untpd.Tree's
 }
 
@@ -507,8 +517,6 @@ trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] =>
     }
   }
 
-  def isClosure(tree: Tree) = closure.unapply(tree).isDefined
-
   /** If tree is a closure, its body, otherwise tree itself */
   def closureBody(tree: Tree)(implicit ctx: Context): Tree = tree match {
     case Block((meth @ DefDef(nme.ANON_FUN, _, _, _, _)) :: Nil, Closure(_, _, _)) => meth.rhs