From b747209b10793a88ce09f4b89d90dd4c50b05896 Mon Sep 17 00:00:00 2001
From: Eugene Burmako <xeno.by@gmail.com>
Date: Sat, 31 Aug 2013 21:44:34 +0200
Subject: no longer warns on calls to vampire macros

As eloquently elaborated and cleverly named by Travis Brown, macros
defined in structural types are useful:
http://meta.plasm.us/posts/2013/07/12/vampire-methods-for-structural-types/.

However, since such macros are on the intersection of a number of language
features, as usual, there are bugs.

This commit fixes an unwanted interaction of macros defined in structural
types with the scala.language.reflectiveCalls guard. Since macro calls
aren't going to be carried to runtime, there's no need to warn about them.
---
 test/files/run/macro-vampire-false-warning.check   |  2 +
 test/files/run/macro-vampire-false-warning.flags   |  1 +
 .../run/macro-vampire-false-warning/Macros_1.scala | 52 ++++++++++++++++++++++
 .../run/macro-vampire-false-warning/Test_2.scala   |  6 +++
 4 files changed, 61 insertions(+)
 create mode 100644 test/files/run/macro-vampire-false-warning.check
 create mode 100644 test/files/run/macro-vampire-false-warning.flags
 create mode 100644 test/files/run/macro-vampire-false-warning/Macros_1.scala
 create mode 100644 test/files/run/macro-vampire-false-warning/Test_2.scala

(limited to 'test')

diff --git a/test/files/run/macro-vampire-false-warning.check b/test/files/run/macro-vampire-false-warning.check
new file mode 100644
index 0000000000..4792e70f33
--- /dev/null
+++ b/test/files/run/macro-vampire-false-warning.check
@@ -0,0 +1,2 @@
+2
+3
diff --git a/test/files/run/macro-vampire-false-warning.flags b/test/files/run/macro-vampire-false-warning.flags
new file mode 100644
index 0000000000..e8fb65d50c
--- /dev/null
+++ b/test/files/run/macro-vampire-false-warning.flags
@@ -0,0 +1 @@
+-Xfatal-warnings
\ No newline at end of file
diff --git a/test/files/run/macro-vampire-false-warning/Macros_1.scala b/test/files/run/macro-vampire-false-warning/Macros_1.scala
new file mode 100644
index 0000000000..2d384fbb85
--- /dev/null
+++ b/test/files/run/macro-vampire-false-warning/Macros_1.scala
@@ -0,0 +1,52 @@
+// As per http://meta.plasm.us/posts/2013/08/31/feeding-our-vampires/
+
+import scala.annotation.StaticAnnotation
+import scala.reflect.macros.Context
+import scala.language.experimental.macros
+
+class body(tree: Any) extends StaticAnnotation
+
+object Macros {
+  def selFieldImpl(c: Context) = {
+    import c.universe._
+    val field = c.macroApplication.symbol
+    val bodyAnn = field.annotations.filter(_.tpe <:< typeOf[body]).head
+    c.Expr[Any](bodyAnn.scalaArgs.head)
+  }
+
+  def mkObjectImpl(c: Context)(xs: c.Expr[Any]*) = {
+    import c.universe._
+    import Flag._
+    // val kvps = xs.toList map { case q"${_}(${Literal(Constant(name: String))}).->[${_}]($value)" => name -> value }
+    val kvps = xs.map(_.tree).toList map { case Apply(TypeApply(Select(Apply(_, List(Literal(Constant(name: String)))), _), _), List(value)) => name -> value }
+    // val fields = kvps map { case (k, v) => q"@body($v) def ${TermName(k)} = macro Macros.selFieldImpl" }
+    val fields = kvps map { case (k, v) => DefDef(
+      Modifiers(MACRO, tpnme.EMPTY, List(Apply(Select(New(Ident(TypeName("body"))), nme.CONSTRUCTOR), List(v)))),
+      TermName(k), Nil, Nil, TypeTree(), Select(Ident(TermName("Macros")), TermName("selFieldImpl"))) }
+    // q"import scala.language.experimental.macros; class Workaround { ..$fields }; new Workaround{}"
+    c.Expr[Any](Block(
+      List(
+        Import(Select(Select(Ident(TermName("scala")), TermName("language")), TermName("experimental")), List(ImportSelector(TermName("macros"), 51, TermName("macros"), 51))),
+        ClassDef(
+          NoMods, TypeName("Workaround"), Nil,
+          Template(
+            List(Select(Ident(TermName("scala")), TypeName("AnyRef"))), noSelfType,
+            DefDef(
+              NoMods, nme.CONSTRUCTOR, Nil, List(Nil), TypeTree(),
+              Block(List(Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR), List())), Literal(Constant(()))))
+            +: fields)),
+        ClassDef(
+          Modifiers(FINAL), TypeName("$anon"), Nil,
+          Template(
+            List(Ident(TypeName("Workaround"))), noSelfType,
+            List(
+              DefDef(
+                NoMods, nme.CONSTRUCTOR, Nil, List(Nil), TypeTree(),
+                Block(List(Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR), List())), Literal(Constant(())))))))),
+      Apply(Select(New(Ident(TypeName("$anon"))), nme.CONSTRUCTOR), List())))
+  }
+}
+
+object mkObject {
+  def apply(xs: Any*) = macro Macros.mkObjectImpl
+}
diff --git a/test/files/run/macro-vampire-false-warning/Test_2.scala b/test/files/run/macro-vampire-false-warning/Test_2.scala
new file mode 100644
index 0000000000..6e44b68635
--- /dev/null
+++ b/test/files/run/macro-vampire-false-warning/Test_2.scala
@@ -0,0 +1,6 @@
+object Test extends App {
+  val foo = mkObject("x" -> "2", "y" -> 3)
+  println(foo.x)
+  println(foo.y)
+  // println(foo.z) => will result in a compilation error
+}
\ No newline at end of file
-- 
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