Make handling of tuples more consistent in quasi-quotes

On one hand we know that q"($expr)" is the same as q"$expr". On the
other if we wrap it into a list and splice as q"(..$expr)" we get a
Tuple1 constructor call which is inconsistent.

This pull request fixes this inconsistency by making q"(..$expr)" being
equivalent q"(${expr.head})" for single-element list.

We also add support for matching of expressions as single-element tuples
(similarly to blocks) and remove liftables and unliftables for Tuple1
(which aren't clearly defined any longer due to q"(foo)" == q"foo"
invariant).

6 files changed, 20 insertions, 3 deletions

diff --git a/test/files/scalacheck/quasiquotes/LiftableProps.scala b/test/files/scalacheck/quasiquotes/LiftableProps.scala
index bd631b8734..20cfcbe139 100644
--- a/test/files/scalacheck/quasiquotes/LiftableProps.scala
+++ b/test/files/scalacheck/quasiquotes/LiftableProps.scala
@@ -99,7 +99,6 @@ object LiftableProps extends QuasiquoteProperties("liftable") {
   }
 
   property("lift tuple") = test {
-    assert(q"${Tuple1(1)}" ≈ q"scala.Tuple1(1)")
     assert(q"${(1, 2)}" ≈ q"(1, 2)")
     assert(q"${(1, 2, 3)}" ≈ q"(1, 2, 3)")
     assert(q"${(1, 2, 3, 4)}" ≈ q"(1, 2, 3, 4)")
diff --git a/test/files/scalacheck/quasiquotes/TermConstructionProps.scala b/test/files/scalacheck/quasiquotes/TermConstructionProps.scala
index 058880a25c..c1aa23ac23 100644
--- a/test/files/scalacheck/quasiquotes/TermConstructionProps.scala
+++ b/test/files/scalacheck/quasiquotes/TermConstructionProps.scala
@@ -139,6 +139,11 @@ object TermConstructionProps extends QuasiquoteProperties("term construction") {
     assert(q"(..$empty)" ≈ q"()")
   }
 
+  property("splice single element list into tuple") = test {
+    val xs = q"x" :: Nil
+    assert(q"(..$xs)" ≈ xs.head)
+  }
+
   property("function param flags are the same") = test {
     val xy = q"val x: A" :: q"val y: B" :: Nil
     assertEqAst(q"(..$xy) => x + y", "(x: A, y: B) => x + y")
diff --git a/test/files/scalacheck/quasiquotes/TermDeconstructionProps.scala b/test/files/scalacheck/quasiquotes/TermDeconstructionProps.scala
index 148bb383b0..7c9b5ead20 100644
--- a/test/files/scalacheck/quasiquotes/TermDeconstructionProps.scala
+++ b/test/files/scalacheck/quasiquotes/TermDeconstructionProps.scala
@@ -82,6 +82,11 @@ object TermDeconstructionProps extends QuasiquoteProperties("term deconstruction
     assert(last ≈ q"d")
   }
 
+  property("deconstruct expr as tuple") = test {
+    val q"(..$elems)" = q"foo"
+    assert(elems ≈ List(q"foo"))
+  }
+
   property("deconstruct cases") = test {
     val q"$x match { case ..$cases }" = q"x match { case 1 => case 2 => }"
     assert(x ≈ q"x")
diff --git a/test/files/scalacheck/quasiquotes/TypeConstructionProps.scala b/test/files/scalacheck/quasiquotes/TypeConstructionProps.scala
index 78b54a4e49..08ed15e8a5 100644
--- a/test/files/scalacheck/quasiquotes/TypeConstructionProps.scala
+++ b/test/files/scalacheck/quasiquotes/TypeConstructionProps.scala
@@ -18,6 +18,11 @@ object TypeConstructionProps extends QuasiquoteProperties("type construction")
     assert(tq"(t0, ..$ts)" ≈ tq"scala.Tuple3[t0, t1, t2]")
   }
 
+  property("single-element tuple type") = test {
+    val ts = q"T" :: Nil
+    assert(tq"(..$ts)" ≈ ts.head)
+  }
+
   property("refined type") = test {
     val stats = q"def foo" :: q"val x: Int" :: q"type Y = String" :: Nil
     assert(tq"T { ..$stats }" ≈ tq"T { def foo; val x: Int; type Y = String }")
diff --git a/test/files/scalacheck/quasiquotes/TypeDeconstructionProps.scala b/test/files/scalacheck/quasiquotes/TypeDeconstructionProps.scala
index 0fdcc19052..8ec1779353 100644
--- a/test/files/scalacheck/quasiquotes/TypeDeconstructionProps.scala
+++ b/test/files/scalacheck/quasiquotes/TypeDeconstructionProps.scala
@@ -35,6 +35,11 @@ object TypeDeconstructionProps extends QuasiquoteProperties("type deconstruction
     assert(last ≈ tq"t2")
   }
 
+  property("tuple type (5)") = test {
+    val tq"(..$ts)" = tq"T"
+    assert(ts ≈ List(tq"T"))
+  }
+
   property("refined type") = test {
     val tq"T { ..$stats }" = tq"T { def foo; val x: Int; type Y = String }"
     assert(stats ≈ List(q"def foo", q"val x: Int", q"type Y = String"))
diff --git a/test/files/scalacheck/quasiquotes/UnliftableProps.scala b/test/files/scalacheck/quasiquotes/UnliftableProps.scala
index 8b827c98ff..4e996c90d7 100644
--- a/test/files/scalacheck/quasiquotes/UnliftableProps.scala
+++ b/test/files/scalacheck/quasiquotes/UnliftableProps.scala
@@ -111,8 +111,6 @@ object UnliftableProps extends QuasiquoteProperties("unliftable") {
   }
 
   property("unlift tuple") = test {
-    // fails due to SI-8045
-    // val q"${t1: Tuple1[Int]}" = q"_root_.scala.Tuple1(1)"
     val q"${t2: (Int, Int)}" = q"(1, 2)"
     val q"${t3: (Int, Int, Int)}" = q"(1, 2, 3)"
     val q"${t4: (Int, Int, Int, Int)}" = q"(1, 2, 3, 4)"