SI-4986 SIP-27 Trailing Comma (multi-line only) support

3 files changed, 314 insertions, 0 deletions

diff --git a/test/files/neg/trailing-commas.check b/test/files/neg/trailing-commas.check
new file mode 100644
index 0000000000..e2677dc3f5
--- /dev/null
+++ b/test/files/neg/trailing-commas.check
@@ -0,0 +1,130 @@
+trailing-commas.scala:10: error: illegal start of simple expression
+trait ArgumentExprs1 { f(23, "bar", )(Ev0, Ev1) }
+                                    ^
+trailing-commas.scala:10: error: ')' expected but '}' found.
+trait ArgumentExprs1 { f(23, "bar", )(Ev0, Ev1) }
+                                                ^
+trailing-commas.scala:11: error: illegal start of simple expression
+trait ArgumentExprs2 { f(23, "bar")(Ev0, Ev1, ) }
+                                              ^
+trailing-commas.scala:11: error: ')' expected but '}' found.
+trait ArgumentExprs2 { f(23, "bar")(Ev0, Ev1, ) }
+                                                ^
+trailing-commas.scala:12: error: illegal start of simple expression
+trait ArgumentExprs3 { new C(23, "bar", )(Ev0, Ev1) }
+                                        ^
+trailing-commas.scala:12: error: ')' expected but '}' found.
+trait ArgumentExprs3 { new C(23, "bar", )(Ev0, Ev1) }
+                                                    ^
+trailing-commas.scala:13: error: illegal start of simple expression
+trait ArgumentExprs4 { new C(23, "bar")(Ev0, Ev1, ) }
+                                                  ^
+trailing-commas.scala:13: error: ')' expected but '}' found.
+trait ArgumentExprs4 { new C(23, "bar")(Ev0, Ev1, ) }
+                                                    ^
+trailing-commas.scala:15: error: identifier expected but ')' found.
+trait Params1 { def f(foo: Int, bar: String, )(implicit ev0: Ev0, ev1: Ev1, ) = 1 }
+                                             ^
+trailing-commas.scala:15: error: ':' expected but '}' found.
+trait Params1 { def f(foo: Int, bar: String, )(implicit ev0: Ev0, ev1: Ev1, ) = 1 }
+                                                                                  ^
+trailing-commas.scala:16: error: identifier expected but ')' found.
+trait Params2 { def f(foo: Int, bar: String, )(implicit ev0: Ev0, ev1: Ev1, ) = 1 }
+                                             ^
+trailing-commas.scala:16: error: ':' expected but '}' found.
+trait Params2 { def f(foo: Int, bar: String, )(implicit ev0: Ev0, ev1: Ev1, ) = 1 }
+                                                                                  ^
+trailing-commas.scala:17: error: identifier expected but ')' found.
+trait ClassParams1 { final class C(foo: Int, bar: String, )(implicit ev0: Ev0, ev1: Ev1) }
+                                                          ^
+trailing-commas.scala:17: error: ':' expected but '}' found.
+trait ClassParams1 { final class C(foo: Int, bar: String, )(implicit ev0: Ev0, ev1: Ev1) }
+                                                                                         ^
+trailing-commas.scala:18: error: identifier expected but ')' found.
+trait ClassParams2 { final class C(foo: Int, bar: String)(implicit ev0: Ev0, ev1: Ev1, ) }
+                                                                                       ^
+trailing-commas.scala:18: error: ':' expected but '}' found.
+trait ClassParams2 { final class C(foo: Int, bar: String)(implicit ev0: Ev0, ev1: Ev1, ) }
+                                                                                         ^
+trailing-commas.scala:20: error: illegal start of simple expression
+trait SimpleExpr { (23, "bar", ) }
+                               ^
+trailing-commas.scala:20: error: ')' expected but '}' found.
+trait SimpleExpr { (23, "bar", ) }
+                                 ^
+trailing-commas.scala:22: error: identifier expected but ']' found.
+trait TypeArgs { def f: C[Int, String, ] }
+                                       ^
+trailing-commas.scala:22: error: ']' expected but '}' found.
+trait TypeArgs { def f: C[Int, String, ] }
+                                         ^
+trailing-commas.scala:23: error: identifier expected but ']' found.
+trait TypeParamClause { type C[A, B, ] }
+                                     ^
+trailing-commas.scala:23: error: ']' expected but '}' found.
+trait TypeParamClause { type C[A, B, ] }
+                                       ^
+trailing-commas.scala:24: error: identifier expected but ']' found.
+trait FunTypeParamClause { def f[A, B, ] }
+                                       ^
+trailing-commas.scala:24: error: ']' expected but '}' found.
+trait FunTypeParamClause { def f[A, B, ] }
+                                         ^
+trailing-commas.scala:26: error: identifier expected but ')' found.
+trait SimpleType { def f: (Int, String, ) }
+                                        ^
+trailing-commas.scala:26: error: ')' expected but '}' found.
+trait SimpleType { def f: (Int, String, ) }
+                                          ^
+trailing-commas.scala:27: error: identifier expected but ')' found.
+trait FunctionArgTypes { def f: (Int, String, ) => Boolean }
+                                              ^
+trailing-commas.scala:27: error: ')' expected but '}' found.
+trait FunctionArgTypes { def f: (Int, String, ) => Boolean }
+                                                           ^
+trailing-commas.scala:29: error: illegal start of simple pattern
+trait SimplePattern { val (foo, bar, ) = null: Any }
+                                     ^
+trailing-commas.scala:31: error: identifier expected but '}' found.
+trait ImportSelectors { import foo.{ Ev0, Ev1, } }
+                                               ^
+trailing-commas.scala:33: error: identifier expected but '}' found.
+trait Import { import foo.Ev0, foo.Ev1, }
+                                        ^
+trailing-commas.scala:35: error: illegal start of simple pattern
+trait ValDcl { val foo, bar, = 23 }
+                             ^
+trailing-commas.scala:35: error: '=' expected but '}' found.
+trait ValDcl { val foo, bar, = 23 }
+                                  ^
+trailing-commas.scala:36: error: illegal start of simple pattern
+trait VarDcl { var foo, bar, = 23 }
+                             ^
+trailing-commas.scala:36: error: '=' expected but '}' found.
+trait VarDcl { var foo, bar, = 23 }
+                                  ^
+trailing-commas.scala:37: error: illegal start of simple pattern
+trait VarDef { var foo, bar, = _ }
+                             ^
+trailing-commas.scala:37: error: '=' expected but '}' found.
+trait VarDef { var foo, bar, = _ }
+                                 ^
+trailing-commas.scala:38: error: illegal start of simple pattern
+trait PatDef { val Foo(foo), Bar(bar), = bippy }
+                                       ^
+trailing-commas.scala:38: error: '=' expected but '}' found.
+trait PatDef { val Foo(foo), Bar(bar), = bippy }
+                                               ^
+trailing-commas.scala:45: error: illegal start of simple expression
+trait SimpleExpr2 { (23, ) }
+                         ^
+trailing-commas.scala:45: error: ')' expected but '}' found.
+trait SimpleExpr2 { (23, ) }
+                           ^
+trailing-commas.scala:48: error: identifier expected but ')' found.
+trait SimpleType2 { def f: (Int, ) }
+                                 ^
+trailing-commas.scala:48: error: ')' expected but '}' found.
+trait SimpleType2 { def f: (Int, ) }
+                                   ^
+43 errors found
diff --git a/test/files/neg/trailing-commas.scala b/test/files/neg/trailing-commas.scala
new file mode 100644
index 0000000000..a873cb1e39
--- /dev/null
+++ b/test/files/neg/trailing-commas.scala
@@ -0,0 +1,56 @@
+package foo
+
+// Note: Using traits to get distinct errors
+// (instead of sharing one single "')' expected but '}' found." at the end)
+
+
+
+//// Multi-line only cases: make sure trailing commas are only supported when multi-line
+
+trait ArgumentExprs1 { f(23, "bar", )(Ev0, Ev1) }
+trait ArgumentExprs2 { f(23, "bar")(Ev0, Ev1, ) }
+trait ArgumentExprs3 { new C(23, "bar", )(Ev0, Ev1) }
+trait ArgumentExprs4 { new C(23, "bar")(Ev0, Ev1, ) }
+
+trait Params1 { def f(foo: Int, bar: String, )(implicit ev0: Ev0, ev1: Ev1, ) = 1 }
+trait Params2 { def f(foo: Int, bar: String, )(implicit ev0: Ev0, ev1: Ev1, ) = 1 }
+trait ClassParams1 { final class C(foo: Int, bar: String, )(implicit ev0: Ev0, ev1: Ev1) }
+trait ClassParams2 { final class C(foo: Int, bar: String)(implicit ev0: Ev0, ev1: Ev1, ) }
+
+trait SimpleExpr { (23, "bar", ) }
+
+trait TypeArgs { def f: C[Int, String, ] }
+trait TypeParamClause { type C[A, B, ] }
+trait FunTypeParamClause { def f[A, B, ] }
+
+trait SimpleType { def f: (Int, String, ) }
+trait FunctionArgTypes { def f: (Int, String, ) => Boolean }
+
+trait SimplePattern { val (foo, bar, ) = null: Any }
+
+trait ImportSelectors { import foo.{ Ev0, Ev1, } }
+
+trait Import { import foo.Ev0, foo.Ev1, }
+
+trait ValDcl { val foo, bar, = 23 }
+trait VarDcl { var foo, bar, = 23 }
+trait VarDef { var foo, bar, = _ }
+trait PatDef { val Foo(foo), Bar(bar), = bippy }
+
+
+
+//// The Tuple 1 cases
+
+// the Tuple1 value case: make sure that the possible "(23, )" syntax for Tuple1 doesn't compile to "23"
+trait SimpleExpr2 { (23, ) }
+
+// the Tuple1 type case: make sure that the possible "(Int, )" syntax for Tuple1[Int] doesn't compile to "Int"
+trait SimpleType2 { def f: (Int, ) }
+
+
+
+//// Test utilities
+object `package` {
+  sealed trait Ev0; implicit object Ev0 extends Ev0
+  sealed trait Ev1; implicit object Ev1 extends Ev1
+}
diff --git a/test/files/pos/trailing-commas.scala b/test/files/pos/trailing-commas.scala
new file mode 100644
index 0000000000..125dda35fb
--- /dev/null
+++ b/test/files/pos/trailing-commas.scala
@@ -0,0 +1,128 @@
+package foo
+
+trait ArgumentExprs1 {
+  def f(foo: Int, bar: String)(implicit ev0: Ev0, ev1: Ev1) = 1
+  f(
+    23,
+    "bar",
+  )(
+    Ev0,
+    Ev1,
+  )
+}
+
+trait ArgumentExprs2 {
+  class C(foo: Int, bar: String)(implicit ev0: Ev0, ev1: Ev1)
+  new C(
+    23,
+    "bar",
+  )(
+    Ev0,
+    Ev1,
+  )
+}
+
+trait Params {
+  def f(
+    foo: Int,
+    bar: String,
+  )(implicit
+    ev0: Ev0,
+    ev1: Ev1,
+  )
+}
+
+trait ClassParams {
+  class C(
+    foo: Int,
+    bar: String,
+  )(implicit
+    ev0: Ev0,
+    ev1: Ev1,
+  )
+}
+
+trait SimpleExpr1 {
+  def f: (Int, String) = (
+    23,
+    "bar",
+  )
+
+  // the Tuple1 value case, the trailing comma is ignored so the type is Int and the value 23
+  def g: Int = (
+    23,
+  )
+}
+
+trait TypeArgs {
+  class C[A, B]
+  def f: C[
+    Int,
+    String,
+  ]
+}
+
+trait TypeParamClause {
+  class C[
+    A,
+    B,
+  ]
+}
+
+trait FunTypeParamClause {
+  def f[
+    A,
+    B,
+  ]
+}
+
+trait SimpleType {
+  def f: (
+    Int,
+    String,
+  )
+
+  // the Tuple1 type case, the trailing comma is ignored so the type is Int and the value 23
+  def g: (
+    Int,
+  ) = 23
+}
+
+trait FunctionArgTypes {
+  def f: (
+    Int,
+    String,
+  ) => Boolean
+}
+
+trait SimplePattern {
+  val (
+    foo,
+    bar,
+  ) = null: Any
+}
+
+trait ImportSelectors {
+  import foo.{
+    Ev0,
+    Ev1,
+  }
+}
+
+trait Bindings {
+  def g(f: (Int, String) => Boolean)
+
+  g((
+    foo,
+    bar,
+  ) => true)
+}
+
+// Import, ids, ValDcl, VarDcl, VarDef, PatDef use commas, but not inside paren, bracket or brace,
+// so they don't support an optional trailing comma
+
+// test utilities
+object `package` {
+  sealed trait Ev0; implicit object Ev0 extends Ev0
+  sealed trait Ev1; implicit object Ev1 extends Ev1
+}