refactors macro compilation

Upgrades the way that macro defs are compiled by factoring out most of
the logic in typedMacroBody and related errors in ContextErrors into an
standalone cake. This leads to tighter cohesion and better code reuse
as the cake is isolated from the rest of the compiler and is much easier
to evolve than just a method body.

Increased convenience of coding macro compilation allowed me to further
clarify the implementation of the macro engine (e.g. take a look at
Validators.scala) and to easily implement additional features, namely:

1) Parameters and return type of macro implementations can now be plain
c.Tree's instead of previously mandatory c.Expr's. This makes macros more
lightweight as there are a lot of situations when one doesn't need to
splice macro params (the only motivation to use exprs over trees). Also
as we're on the verge of having quasiquotes in trunk, there soon will be
no reason to use exprs at all, since quasiquotes can splice everything.

2) Macro implementations can now be defined in bundles, standalone cakes
built around a macro context: http://docs.scala-lang.org/overviews/macros/bundles.html.
This further reduces boilerplate by simplifying implementations complex
macros due to the fact that macro programmers no longer need to play
path-dependent games to use helpers.

1 files changed, 13 insertions, 13 deletions

diff --git a/test/files/neg/macro-invalidsig.check b/test/files/neg/macro-invalidsig.check
index 52074cf783..cbdaf51081 100644
--- a/test/files/neg/macro-invalidsig.check
+++ b/test/files/neg/macro-invalidsig.check
@@ -3,67 +3,67 @@ Macros_Test_2.scala:2: error: macro implementation has wrong shape:
  found   : (c: scala.reflect.macros.Context)(implicit evidence$2: Numeric[U]): c.universe.Literal
 macro implementations cannot have implicit parameters other than WeakTypeTag evidences
   def foo[U] = macro Impls1.foo[U]
-                            ^
+      ^
 Macros_Test_2.scala:6: error: macro implementation has wrong shape:
  required: (c: scala.reflect.macros.Context): c.Expr[Any]
  found   : : Nothing
 number of parameter sections differ
   def foo = macro Impls2.foo
-                         ^
+      ^
 Macros_Test_2.scala:10: error: macro implementation has wrong shape:
  required: (c: scala.reflect.macros.Context): c.Expr[Any]
  found   : (c: scala.reflect.api.Universe): Nothing
 type mismatch for parameter c: scala.reflect.macros.Context does not conform to scala.reflect.api.Universe
   def foo = macro Impls3.foo
-                         ^
+      ^
 Macros_Test_2.scala:14: error: macro implementation has wrong shape:
  required: (c: scala.reflect.macros.Context): c.Expr[Any]
  found   : (cs: scala.reflect.macros.Context*): Nothing
 types incompatible for parameter cs: corresponding is not a vararg parameter
   def foo = macro Impls4.foo
-                         ^
+      ^
 Macros_Test_2.scala:18: error: macro implementation has wrong shape:
  required: (c: scala.reflect.macros.Context)(x: c.Expr[Any]): c.Expr[Any]
  found   : (c: scala.reflect.macros.Context): Nothing
 number of parameter sections differ
   def foo(x: Any) = macro Impls5.foo
-                                 ^
+      ^
 Macros_Test_2.scala:22: error: macro implementation has wrong shape:
  required: (c: scala.reflect.macros.Context)(x: c.Expr[Int]): c.Expr[Unit]
  found   : (c: scala.reflect.macros.Context)(implicit x: c.Expr[Int]): c.Expr[Unit]
 macro implementations cannot have implicit parameters other than WeakTypeTag evidences
   def foo[U](x: Int) = macro Impls6.foo[T, U]
-                                    ^
+      ^
 Macros_Test_2.scala:26: error: macro implementation has wrong shape:
  required: (c: scala.reflect.macros.Context)(x: c.Expr[Int]): c.Expr[Any]
  found   : (c: scala.reflect.macros.Context)(x: c.Expr[Int], y: c.Expr[Int]): Nothing
 parameter lists have different length, found extra parameter y: c.Expr[Int]
   def foo(x: Int) = macro Impls7.foo
-                                 ^
+      ^
 Macros_Test_2.scala:30: error: macro implementation has wrong shape:
  required: (c: scala.reflect.macros.Context)(x: c.Expr[Int]): c.Expr[Any]
  found   : (c: scala.reflect.macros.Context)(x: c.universe.Symbol): Nothing
 type mismatch for parameter x: c.Expr[Int] does not conform to c.universe.Symbol
   def foo(x: Int) = macro Impls8.foo
-                                 ^
+      ^
 Macros_Test_2.scala:34: error: macro implementation has wrong shape:
  required: (c: scala.reflect.macros.Context)(x: c.Expr[Int], y: c.Expr[Int]): c.Expr[Any]
  found   : (c: scala.reflect.macros.Context)(xs: c.Expr[Int]*): Nothing
 parameter lists have different length, required extra parameter y: c.Expr[Int]
   def foo(x: Int, y: Int) = macro Impls9.foo
-                                         ^
+      ^
 Macros_Test_2.scala:38: error: macro implementation has wrong shape:
  required: (c: scala.reflect.macros.Context)(x: c.Expr[Int], y: c.Expr[Int]): c.Expr[Any]
  found   : (c: scala.reflect.macros.Context)(y: c.Expr[Int], x: c.Expr[Int]): Nothing
 parameter names differ: x != y
   def foo(x: Int, y: Int) = macro Impls10.foo
-                                          ^
+      ^
 Macros_Test_2.scala:42: error: macro implementation has wrong shape:
  required: (c: scala.reflect.macros.Context): c.Expr[Any]
  found   : (c: scala.reflect.macros.Context)(U: c.universe.Type): Nothing
 number of parameter sections differ
   def foo[U] = macro Impls11.foo[U]
-                             ^
+      ^
 Macros_Test_2.scala:46: error: type arguments [U] do not conform to method foo's type parameter bounds [U <: String]
   def foo[U] = macro Impls12.foo[U]
                                 ^
@@ -72,10 +72,10 @@ Macros_Test_2.scala:50: error: type arguments [U] do not conform to method foo's
                                        ^
 Macros_Test_2.scala:54: error: wrong number of type parameters for method foo: [U](c: scala.reflect.macros.Context)(implicit evidence$4: c.WeakTypeTag[U])Nothing
   def foo = macro Impls14.foo
-                          ^
+      ^
 Macros_Test_2.scala:59: error: wrong number of type parameters for method foo: [T, U, V](c: scala.reflect.macros.Context)(implicit evidence$5: c.WeakTypeTag[T], implicit evidence$6: c.WeakTypeTag[U], implicit V: c.WeakTypeTag[V])c.Expr[Unit]
     def foo15[V] = macro Impls15.foo
-                                 ^
+        ^
 Macros_Test_2.scala:60: error: wrong number of type parameters for method foo: [T, U, V](c: scala.reflect.macros.Context)(implicit evidence$7: c.WeakTypeTag[T], implicit evidence$8: c.WeakTypeTag[U], implicit V: c.WeakTypeTag[V])c.Expr[Unit]
     def foo16[V] = macro Impls16.foo[V]
                                     ^