6 files changed, 33 insertions, 9 deletions
diff --git a/src/compiler/scala/reflect/macros/compiler/Errors.scala b/src/compiler/scala/reflect/macros/compiler/Errors.scala
index a60a2c2306..6ec111cf7c 100644
--- a/src/compiler/scala/reflect/macros/compiler/Errors.scala
+++ b/src/compiler/scala/reflect/macros/compiler/Errors.scala
@@ -53,7 +53,7 @@ trait Errors extends Traces {
   // not exactly an error generator, but very related
   // and I dearly wanted to push it away from Macros.scala
   private def checkConforms(slot: String, rtpe: Type, atpe: Type) = {
-    val verbose = macroDebugVerbose || settings.explaintypes.value
+    val verbose = macroDebugVerbose
 
     def check(rtpe: Type, atpe: Type): Boolean = {
       def success() = { if (verbose) println(rtpe + " <: " + atpe + "?" + EOL + "true"); true }
@@ -70,9 +70,12 @@ trait Errors extends Traces {
       if (verbose) withTypesExplained(check(rtpe, atpe))
       else check(rtpe, atpe)
     if (!ok) {
-      if (!macroDebugVerbose)
-        explainTypes(rtpe, atpe)
-      compatibilityError("type mismatch for %s: %s does not conform to %s".format(slot, abbreviateCoreAliases(rtpe.toString), abbreviateCoreAliases(atpe.toString)))
+      if (!verbose) explainTypes(rtpe, atpe)
+      val msg = {
+        val ss = Seq(rtpe, atpe) map (this abbreviateCoreAliases _.toString)
+        s"type mismatch for $slot: ${ss(0)} does not conform to ${ss(1)}"
+      }
+      compatibilityError(msg)
     }
   }
 
@@ -106,8 +109,8 @@ trait Errors extends Traces {
   def MacroImplTargMismatchError(atargs: List[Type], atparams: List[Symbol]) =
     compatibilityError(NotWithinBoundsErrorMessage("", atargs, atparams, macroDebugVerbose || settings.explaintypes.value))
 
-  def MacroImplTparamInstantiationError(atparams: List[Symbol], ex: NoInstance) =
-    compatibilityError(
-      "type parameters "+(atparams map (_.defString) mkString ", ")+" cannot be instantiated\n"+
-      ex.getMessage)
-}
-\ No newline at end of file
+  def MacroImplTparamInstantiationError(atparams: List[Symbol], e: NoInstance) = {
+    val badps = atparams map (_.defString) mkString ", "
+    compatibilityError(f"type parameters $badps cannot be instantiated%n${e.getMessage}")
+  }
+}
diff --git a/test/files/neg/t6123-explaintypes-macros.check b/test/files/neg/t6123-explaintypes-macros.check
new file mode 100644
index 0000000000..ebcb8069d5
--- /dev/null
+++ b/test/files/neg/t6123-explaintypes-macros.check
@@ -0,0 +1,9 @@
+c.universe.Expr[Any]* <: c.universe.Expr[String]*?
+false
+BadMac_2.scala:6: error: macro implementation has wrong shape:
+ required: (c: scala.reflect.macros.Context)(format: c.Expr[String], params: c.Expr[Any]*): c.Expr[Unit]
+ found   : (c: scala.reflect.macros.Context)(format: c.Expr[String], params: c.Expr[String]*): c.Expr[Unit]
+type mismatch for parameter params: c.Expr[Any]* does not conform to c.Expr[String]*
+  def printf(format: String, params: Any*): Unit = macro printf_impl
+      ^
+one error found
diff --git a/test/files/pos/t6123-explaintypes-macros.flags b/test/files/neg/t6123-explaintypes-macros/BadMac_2.flags
index b36707c7cf..b36707c7cf 100644
--- a/test/files/pos/t6123-explaintypes-macros.flags
+++ b/test/files/neg/t6123-explaintypes-macros/BadMac_2.flags
diff --git a/test/files/neg/t6123-explaintypes-macros/BadMac_2.scala b/test/files/neg/t6123-explaintypes-macros/BadMac_2.scala
new file mode 100644
index 0000000000..38b8e24444
--- /dev/null
+++ b/test/files/neg/t6123-explaintypes-macros/BadMac_2.scala
@@ -0,0 +1,8 @@
+import scala.language.experimental.macros
+import scala.reflect.macros.Context
+
+// explain some macro types to me
+object BadMac {
+  def printf(format: String, params: Any*): Unit = macro printf_impl
+  def printf_impl(c: Context)(format: c.Expr[String], params: c.Expr[String]*): c.Expr[Unit] = ???
+}
diff --git a/test/files/neg/t6123-explaintypes-macros/Macros.flags b/test/files/neg/t6123-explaintypes-macros/Macros.flags
new file mode 100644
index 0000000000..b36707c7cf
--- /dev/null
+++ b/test/files/neg/t6123-explaintypes-macros/Macros.flags
@@ -0,0 +1 @@
+-explaintypes
diff --git a/test/files/pos/t6123-explaintypes-macros.scala b/test/files/neg/t6123-explaintypes-macros/Macros.scala
index e650ad2038..a12c277c86 100644
--- a/test/files/pos/t6123-explaintypes-macros.scala
+++ b/test/files/neg/t6123-explaintypes-macros/Macros.scala
@@ -5,3 +5,6 @@ object Macros {
   def printf(format: String, params: Any*): Unit = macro printf_impl
   def printf_impl(c: Context)(format: c.Expr[String], params: c.Expr[Any]*): c.Expr[Unit] = ???
 }
+
+// something trivial to run
+object Test extends App