SI-7275 allow flattening of blocks with ..$

This commit extends current splicing rules to allow flattening of
trees into other trees.

Without such support it is impossible to correctly create vals with
patterns and use it in other location as they could expand into
multiple-statement blocks:

    scala> q"val (a, b) = (1, 2)"
    res0: reflect.runtime.universe.Tree =
    {
      <synthetic> <artifact> private[this] val x$1 = scala.Tuple2(1, 2):
    @scala.unchecked match {
        case scala.Tuple2((a @ _), (b @ _)) => scala.Tuple2(a, b)
      };
      val a = x$1._1;
      val b = x$1._2;
      ()
    }

    scala> q"..$res0; println(a + b)"
    res1: reflect.runtime.universe.Tree =
    {
      <synthetic> <artifact> private[this] val x$1 = scala.Tuple2(1, 2):
    @scala.unchecked match {
        case scala.Tuple2((a @ _), (b @ _)) => scala.Tuple2(a, b)
      };
      val a = x$1._1;
      val b = x$1._2;
      println(a.$plus(b))
    }

1 files changed, 39 insertions, 0 deletions

diff --git a/test/files/scalacheck/quasiquotes/TermConstructionProps.scala b/test/files/scalacheck/quasiquotes/TermConstructionProps.scala
index 38fbfa9f7f..7bbd7a85b3 100644
--- a/test/files/scalacheck/quasiquotes/TermConstructionProps.scala
+++ b/test/files/scalacheck/quasiquotes/TermConstructionProps.scala
@@ -229,4 +229,43 @@ object TermConstructionProps extends QuasiquoteProperties("term construction") {
     val q"($a, $b) => $_" = q"_ + _"
     assert(a.name != b.name)
   }
+
+  property("SI-7275 a") = test {
+    val t = q"stat1; stat2"
+    assertEqAst(q"..$t", "{stat1; stat2}")
+  }
+
+  property("SI-7275 b") = test {
+    def f(t: Tree) = q"..$t"
+    assertEqAst(f(q"stat1; stat2"), "{stat1; stat2}")
+  }
+
+  property("SI-7275 c1") = test {
+    object O
+    implicit val liftO = Liftable[O.type] { _ => q"foo; bar" }
+    assertEqAst(q"f(..$O)", "f(foo, bar)")
+  }
+
+  property("SI-7275 c2") = test {
+    object O
+    implicit val liftO = Liftable[O.type] { _ => q"{ foo; bar }; { baz; bax }" }
+    assertEqAst(q"f(...$O)", "f(foo, bar)(baz, bax)")
+  }
+
+  property("SI-7275 d") = test {
+    val l = q"a; b" :: q"c; d" :: Nil
+    assertEqAst(q"f(...$l)", "f(a, b)(c, d)")
+    val l2: Iterable[Tree] = l
+    assertEqAst(q"f(...$l2)", "f(a, b)(c, d)")
+  }
+
+  property("SI-7275 e") = test {
+    val t = q"{ a; b }; { c; d }"
+    assertEqAst(q"f(...$t)", "f(a, b)(c, d)")
+  }
+
+  property("SI-7275 e2") = test {
+    val t = q"{ a; b }; c; d"
+    assertEqAst(q"f(...$t)", "f(a, b)(c)(d)")
+  }
 }