SI-7695 Macro debug output on -explaintypes

It looks like checkConforms should wait for error before
using explainTypes, rather than turning on macro debug
trace if explaintypes is set.

In particular, macro debug output is Console.println
instead of reporter.echo or similar, so partest can't
test it.

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