added "diagnostic" to context.

3 files changed, 15 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index 5b98b070ce..114525aabc 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -110,6 +110,7 @@ trait Contexts { self: Analyzer =>
     var returnsSeen = false                 // for method context: were returns encountered?
     var reportAmbiguousErrors = false
     var reportGeneralErrors = false
+    var diagnostic: List[String] = Nil      // these messages are printed when issuing an error
     var implicitsEnabled = false
     var checking = false
     var retyping = false
@@ -208,6 +209,7 @@ trait Contexts { self: Analyzer =>
       c.imports = imports
       c.reportAmbiguousErrors = this.reportAmbiguousErrors
       c.reportGeneralErrors = this.reportGeneralErrors
+      c.diagnostic = this.diagnostic
       c.implicitsEnabled = this.implicitsEnabled
       c.checking = this.checking
       c.retyping = this.retyping
@@ -291,8 +293,12 @@ trait Contexts { self: Analyzer =>
       c
     }
 
+    private def diagString =
+      if (diagnostic.isEmpty) ""
+      else diagnostic.mkString("\n","\n", "")
+
     def error(pos: Position, err: Error) {
-      val msg = err.getMessage()
+      val msg = err.getMessage() + diagString
       if (reportGeneralErrors)
         unit.error(pos, if (checking) "**** ERROR DURING INTERNAL CHECKING ****\n" + msg else msg)
       else
@@ -300,10 +306,11 @@ trait Contexts { self: Analyzer =>
     }
 
     def error(pos: Position, msg: String) {
+      val msg1 = msg + diagString
       if (reportGeneralErrors)
-        unit.error(pos, if (checking) "**** ERROR DURING INTERNAL CHECKING ****\n" + msg else msg)
+        unit.error(pos, if (checking) "**** ERROR DURING INTERNAL CHECKING ****\n" + msg1 else msg1)
       else
-        throw new TypeError(pos, msg)
+        throw new TypeError(pos, msg1)
     }
 
     def warning(pos:  Position, msg: String) {
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index b0226af4e3..d6bcd4f6eb 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -2040,6 +2040,8 @@ trait Typers { self: Analyzer =>
                 }
                 val (allArgs, missing) = addDefaults(args, qual, targs, previousArgss, params, fun.pos)
                 if (allArgs.length == formals.length) {
+                  // useful when a default doesn't match parameter type, e.g. def f[T](x:T="a"); f[Int]()
+                  context.diagnostic = "Error occured in an application involving default arguments." :: context.diagnostic
                   doTypedApply(tree, if (blockIsEmpty) fun else fun1, allArgs, mode, pt)
                 } else {
                   tryTupleApply.getOrElse {
diff --git a/test/files/neg/names-defaults-neg.check b/test/files/neg/names-defaults-neg.check
index f4ab2e5f99..a6200419ce 100644
--- a/test/files/neg/names-defaults-neg.check
+++ b/test/files/neg/names-defaults-neg.check
@@ -90,11 +90,13 @@ names-defaults-neg.scala:70: error: wrong number of arguments for <none>: (x: In
                       ^
 names-defaults-neg.scala:77: error: inferred kinds of the type arguments (List[Int]) do not conform to the expected kinds of the type parameters (type T).
 List[Int]'s type parameters do not match type T's expected parameters: class List has one type parameter, but type T has one
+Error occured in an application involving default arguments.
   test4()
   ^
 error: type mismatch;
  found   : List[Int]
  required: List[List[scala.List[List[X forSome { type X }]]]]
+Error occured in an application involving default arguments.
 names-defaults-neg.scala:80: error: type mismatch;
  found   : List[Int]
  required: scala.List[scala.List[?]]
@@ -103,6 +105,7 @@ names-defaults-neg.scala:80: error: type mismatch;
 names-defaults-neg.scala:83: error: type mismatch;
  found   : Int
  required: String
+Error occured in an application involving default arguments.
   new A2[String]()
   ^
 names-defaults-neg.scala:95: error: multiple overloaded alternatives of method foo define default arguments