From 0d5c2f76ea30c6a45471dac635f035e931075453 Mon Sep 17 00:00:00 2001 From: Eugene Burmako Date: Wed, 2 Oct 2013 17:22:07 +0200 Subject: blackbox restriction #3: can't affect implicit search When an application of a blackbox macro is used as an implicit candidate, no expansion is performed until the macro is selected as the result of the implicit search. This makes it impossible to dynamically calculate availability of implicit macros. --- .../Macros_1.scala | 25 ++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 test/files/run/macro-whitebox-dynamic-materialization/Macros_1.scala (limited to 'test/files/run/macro-whitebox-dynamic-materialization/Macros_1.scala') diff --git a/test/files/run/macro-whitebox-dynamic-materialization/Macros_1.scala b/test/files/run/macro-whitebox-dynamic-materialization/Macros_1.scala new file mode 100644 index 0000000000..87cd310b09 --- /dev/null +++ b/test/files/run/macro-whitebox-dynamic-materialization/Macros_1.scala @@ -0,0 +1,25 @@ +import scala.reflect.macros.WhiteboxContext +import scala.language.experimental.macros + +trait Foo[T] + +class C1(val x: Int) +class C2(val x: String) + +trait LowPriority { + implicit def lessSpecific[T]: Foo[T] = null +} + +object Foo extends LowPriority { + implicit def moreSpecific[T]: Foo[T] = macro Macros.impl[T] +} + +object Macros { + def impl[T: c.WeakTypeTag](c: WhiteboxContext) = { + import c.universe._ + val tpe = weakTypeOf[T] + if (tpe.members.exists(_.typeSignature =:= typeOf[Int])) + c.abort(c.enclosingPosition, "I don't like classes that contain integers") + q"new Foo[$tpe]{ override def toString = ${tpe.toString} }" + } +} \ No newline at end of file -- cgit v1.2.3