SI-8275 allow to directly extract block contents of the case def

Due to the fact that blocks in cases are implicit one might expect to be
able to extract its contents with `..$`.

src/compiler/scala/tools/reflect/quasiquotes/Reifiers.scala

@@ -206,6 +206,8 @@ trait Reifiers { self: Quasiquotes =>
         reifyBuildCall(nme.SyntacticTry, block, catches, finalizer)
       case Match(selector, cases) =>
         reifyBuildCall(nme.SyntacticMatch, selector, cases)
+      case CaseDef(pat, guard, body) if fillListHole.isDefinedAt(body) =>
+        mirrorCall(nme.CaseDef, reify(pat), reify(guard), mirrorBuildCall(nme.SyntacticBlock, fillListHole(body)))
       // parser emits trees with scala package symbol to ensure
       // that some names hygienically point to various scala package
       // members; we need to preserve this symbol to preserve

src/reflect/scala/reflect/internal/StdNames.scala

@@ -580,6 +580,7 @@ trait StdNames {
     val AnyVal: NameType               = "AnyVal"
     val Apply: NameType                = "Apply"
     val ArrayAnnotArg: NameType        = "ArrayAnnotArg"
+    val CaseDef: NameType              = "CaseDef"
     val ClassInfoType: NameType        = "ClassInfoType"
     val ConstantType: NameType         = "ConstantType"
     val EmptyPackage: NameType         = "EmptyPackage"

test/files/scalacheck/quasiquotes/TermDeconstructionProps.scala

@@ -175,4 +175,15 @@ object TermDeconstructionProps extends QuasiquoteProperties("term deconstruction
     assert(x ≈ q"x")
     val q"{ _ * _ }" = q"{ _ * _ }"
   }
+
+  property("si-8275 a") = test {
+    val cq"_ => ..$stats" = cq"_ => foo; bar"
+    assert(stats ≈ List(q"foo", q"bar"))
+  }
+
+  property("si-8275 b") = test {
+    val cq"_ => ..$init; $last" = cq"_ => a; b; c"
+    assert(init ≈ List(q"a", q"b"))
+    assert(last ≈ q"c")
+  }
 }