Merge pull request #6500 from eed3si9n/wip/deprecate-view-bounds

scala/bug#10719. Deprecate view bounds without -Xfuture

Author: adriaanm

src/compiler/scala/tools/nsc/ast/parser/Parsers.scala

@@ -2425,10 +2425,11 @@ self =>
           TypeDef(mods, pname, tparams, typeBounds())
         }
         if (contextBoundBuf ne null) {
+          def msg(what: String) = s"""view bounds are $what; use an implicit parameter instead.
+                                     |  example: instead of `def f[A <% Int](a: A)` use `def f[A](a: A)(implicit ev: A => Int)`""".stripMargin
           while (in.token == VIEWBOUND) {
-            val msg = "Use an implicit parameter instead.\nExample: Instead of `def f[A <% Int](a: A)` use `def f[A](a: A)(implicit ev: A => Int)`."
-            if (settings.future)
-              deprecationWarning(in.offset, s"View bounds are deprecated. $msg", "2.12.0")
+            if (settings.isScala214) syntaxError(in.offset, msg("unsupported"))
+            else deprecationWarning(in.offset, msg("deprecated"), "2.12.0")
             contextBoundBuf += atPos(in.skipToken())(makeFunctionTypeTree(List(Ident(pname)), typ()))
           }
           while (in.token == COLON) {
@@ -2878,7 +2879,7 @@ self =>
           classContextBounds = contextBoundBuf.toList
           val tstart = (in.offset :: classContextBounds.map(_.pos.start)).min
           if (!classContextBounds.isEmpty && mods.isTrait) {
-            val viewBoundsExist = if (settings.future) "" else " nor view bounds `<% ...'"
+            val viewBoundsExist = if (settings.isScala214) "" else " nor view bounds `<% ...'"
               syntaxError(s"traits cannot have type parameters with context bounds `: ...'$viewBoundsExist", skipIt = false)
             classContextBounds = List()
           }

test/files/neg/overloaded-implicit.scala

@@ -2,13 +2,13 @@ object Test {
   implicit def imp1[T](x: List[T]): Map[T, T] = Map()
   implicit def imp1[T](x: Set[T]): Map[T, T] = Map()
 
-  def f[T <% Map[Int, Int]](x: T): Double = 1.0d
+  def f[T](x: T)(implicit ev: T => Map[Int, Int]): Double = 1.0d
 
   // not parameterized, no warning
   implicit def imp2(x: List[Int]): String = "a"
   implicit def imp2(x: Set[Int]): String = "b"
 
-  def g[T <% String](x: T): Double = 2.0d
+  def g[T](x: T)(implicit ev: T => String): Double = 2.0d
 
   def main(args: Array[String]): Unit = {
     // println(f(List(1)))

test/files/neg/t7629-view-bounds-deprecation.check

@@ -0,0 +1,11 @@
+view-bounds-deprecation.scala:2: warning: view bounds are deprecated; use an implicit parameter instead.
+  example: instead of `def f[A <% Int](a: A)` use `def f[A](a: A)(implicit ev: A => Int)`
+  def f[A <% Int](a: A) = null
+          ^
+view-bounds-deprecation.scala:3: warning: view bounds are deprecated; use an implicit parameter instead.
+  example: instead of `def f[A <% Int](a: A)` use `def f[A](a: A)(implicit ev: A => Int)`
+  def g[C, B <: C, A <% B : Numeric](a: A) = null
+                     ^
+error: No warnings can be incurred under -Xfatal-warnings.
+two warnings found
+one error found

test/files/neg/t7629-view-bounds-deprecation.flags

@@ -0,0 +1 @@
+-deprecation -Xfatal-warnings

test/files/neg/view-bounds-deprecation.check

@@ -0,0 +1,9 @@
+view-bounds-removal.scala:2: error: view bounds are unsupported; use an implicit parameter instead.
+  example: instead of `def f[A <% Int](a: A)` use `def f[A](a: A)(implicit ev: A => Int)`
+  def f[A <% Int](a: A) = null
+          ^
+view-bounds-removal.scala:3: error: view bounds are unsupported; use an implicit parameter instead.
+  example: instead of `def f[A <% Int](a: A)` use `def f[A](a: A)(implicit ev: A => Int)`
+  def g[C, B <: C, A <% B : Numeric](a: A) = null
+                     ^
+two errors found

test/files/neg/view-bounds-deprecation.flags

@@ -0,0 +1 @@
+-Xsource:2.14

test/files/neg/t7629-view-bounds-deprecation.scala renamed to test/files/neg/view-bounds-deprecation.scala

@@ -0,0 +1,4 @@
+object Test {
+  def f[A <% Int](a: A) = null
+  def g[C, B <: C, A <% B : Numeric](a: A) = null
+}

test/files/neg/view-bounds-removal.check

@@ -11,7 +11,7 @@ object Test extends App {
   val maxKey = 50
   val maxValue = 50
 
-  def testSet[A <% Ordered[A]](set: SortedSet[A], list: List[A]) {
+  def testSet[A](set: SortedSet[A], list: List[A])(implicit ev: A => Ordered[A]): Unit = {
     val distinctSorted = list.distinct.sorted
     assertEquals("Set size wasn't the same as list sze", set.size, distinctSorted.size)
 
@@ -24,7 +24,7 @@ object Test extends App {
     }
   }
 
-  def testMap[A <% Ordered[A], B](map: SortedMap[A, B], list: List[(A, B)]) {
+  def testMap[A, B](map: SortedMap[A, B], list: List[(A, B)])(implicit ev: A => Ordered[A]): Unit = {
     val distinctSorted = distinctByKey(list).sortBy(_._1)
     assertEquals("Map size wasn't the same as list sze", map.size, distinctSorted.size)
 
@@ -39,11 +39,11 @@ object Test extends App {
     }
   }
 
-  def check[A](clazz: Class[_], list: List[_], m1: String, m2: String, l1: List[A], l2: List[A]) {
+  def check[A](clazz: Class[_], list: List[_], m1: String, m2: String, l1: List[A], l2: List[A]): Unit = {
     assertEquals(s"$clazz: `$m1` didn't match `$m2` on list $list", l1, l2)
   }
 
-  def assertEquals[A](msg: String, x: A, y: A) {
+  def assertEquals[A](msg: String, x: A, y: A): Unit = {
     assert(x == y, s"$msg\n1: $x\n2: $y")
   }
 

test/files/neg/view-bounds-removal.flags

@@ -1 +1,5 @@
+Macros_Test_2.scala:10: warning: view bounds are deprecated; use an implicit parameter instead.
+  example: instead of `def f[A <% Int](a: A)` use `def f[A](a: A)(implicit ev: A => Int)`
+  def bar[T <% Option[Int]](x: T) = println(x)
+            ^
 2

test/files/neg/view-bounds-removal.scala

@@ -0,0 +1 @@
+-deprecation

test/files/run/iterator-from.scala

@@ -1,3 +1,4 @@
+warning: there were two deprecation warnings (since 2.12.0); re-run with -deprecation for details
 eqw
 List(0, 2)
 List(0, 2)