Some refactorings and additions on error reporting.

Also, removed redundant Trees. prefixes in patterns.

1 files changed, 66 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/typer/ErrorReporting.scala b/src/dotty/tools/dotc/typer/ErrorReporting.scala
new file mode 100644
index 000000000..ef6184394
--- /dev/null
+++ b/src/dotty/tools/dotc/typer/ErrorReporting.scala
@@ -0,0 +1,66 @@
+package dotty.tools
+package dotc
+package typer
+
+import ast._
+import core._
+import Trees._
+import Types._, Contexts._, Decorators._, Denotations._
+import Applications._
+import util.Positions._
+
+object ErrorReporting {
+
+  import tpd._
+
+  def errorTree(tree: Trees.Tree[_], msg: => String)(implicit ctx: Context): tpd.Tree = {
+    ctx.error(msg, tree.pos)
+    tree withType ErrorType
+  }
+
+  class Errors(implicit ctx: Context) {
+
+    def expectedTypeStr(tp: Type): String = tp match {
+      case tp: FunProtoType =>
+        val result = tp.resultType match {
+          case tp: WildcardType => ""
+          case tp => s"and expected result type $tp"
+        }
+        s"arguments (${tp.typedArgs map (_.tpe.show) mkString ", "})$result"
+      case _ =>
+        s"expected type ${tp.show}"
+    }
+
+    def anonymousTypeMemberStr(tpe: Type) = {
+      val kind = tpe match {
+          case _: TypeBounds => "type with bounds"
+          case _: PolyType | _: MethodType => "method"
+          case _ => "value of type"
+        }
+        s"$kind $tpe"
+    }
+
+    def overloadedAltsStr(alts: List[SingleDenotation]) =
+      s"overloaded alternatives of ${denotStr(alts.head)} with types\n" +
+      s" ${alts map (_.info) mkString "\n "}"
+
+    def denotStr(denot: Denotation): String =
+      if (denot.isOverloaded) overloadedAltsStr(denot.alternatives)
+      else if (denot.symbol.exists) denot.symbol.showLocated
+      else anonymousTypeMemberStr(denot.info)
+
+    def refStr(tp: Type): String = tp match {
+      case tp: NamedType => denotStr(tp.denot)
+      case _ => anonymousTypeMemberStr(tp)
+    }
+
+    def typeMismatch(tree: Tree, pt: Type): Tree =
+      errorTree(tree,
+        s"""type mismatch:
+           | found   : ${tree.tpe.show}
+           | required: ${pt.show}""".stripMargin)
+
+  }
+
+  def err(implicit ctx: Context): Errors = new Errors
+}
\ No newline at end of file