+ Sketch first (dirty) draft - not working

plugin/src/main/scala/org/dslparadise/annotations/Annotations.scala

@@ -0,0 +1,7 @@
+package org.dslparadise.annotations
+
+import scala.annotation.StaticAnnotation
+
+class Implicit extends StaticAnnotation
+
+class Import extends StaticAnnotation

plugin/src/main/scala/org/dslparadise/typechecker/Typers.scala

@@ -14,8 +14,23 @@ trait Typers {
     import infer._
 
     override def typedArgsForFormals(args: List[Tree], formals: List[Type], mode: Mode): List[Tree] = {
-      println("hello world")
-      super.typedArgsForFormals(args, formals, mode)
+      val Impl = typeOf[org.dslparadise.annotations.Implicit]
+      val Impo = typeOf[org.dslparadise.annotations.Import]
+      val desugared = (args zip formals) map {
+        case (tree, formal @ TypeRef(_, _, List(AnnotatedType(List(AnnotationInfo(Impl, _, _)), left, _), right))) ⇒
+          val tpe = typed(tree.duplicate).tpe
+          if (!(tpe <:< formal) || tpe.isError) {
+            val fixed = q"{ implicit u: $left ⇒ $tree }"
+            val fixedTpe = typed(fixed).tpe
+            println(tree, fixed, fixedTpe)
+            fixed
+          } else {
+            tree
+          }
+        case (tree, tp) ⇒ tree
+      }
+      println(s"desugared $args to $desugared")
+      super.typedArgsForFormals(desugared, formals, mode)
     }
   }
 }

project/build.scala

@@ -50,7 +50,7 @@ object build extends Build {
     base = file("sandbox")
   ) settings (
     sharedSettings ++ usePluginSettings: _*
-  )
+  ) dependsOn plugin
 
   lazy val tests = Project(
     id   = "tests",

sandbox/src/main/scala/Main.scala

@@ -0,0 +1,9 @@
+import org.dslparadise.annotations._
+
+object Main extends App {
+  def f(a: (Int @Implicit) ⇒ Int) = a(8)
+
+  def g(implicit x: Int) = x + 3
+
+  f(8 + g)
+}