REPL selectively trims prefix/suffix newline

ScalaRunTime.replStringOf adds extra newlines. Try not to
trim more than was added.

New API will not include the newlines.

Author: som-snytt

compiler/src/dotty/tools/repl/Rendering.scala

@@ -55,11 +55,29 @@ private[repl] class Rendering(parentClassLoader: Option[ClassLoader] = None) {
         // We need to use the ScalaRunTime class coming from the scala-library
         // on the user classpath, and not the one available in the current
         // classloader, so we use reflection instead of simply calling
-        // `ScalaRunTime.replStringOf`.
+        // `ScalaRunTime.replStringOf`. Probe for new API without extraneous newlines.
+        // For old API, try to clean up extraneous newlines by stripping suffix and maybe prefix newline.
         val scalaRuntime = Class.forName("scala.runtime.ScalaRunTime", true, myClassLoader)
-        val meth = scalaRuntime.getMethod("replStringOf", classOf[Object], classOf[Int])
-
-        (value: Object) => meth.invoke(null, value, Integer.valueOf(MaxStringElements)).asInstanceOf[String]
+        try {
+          val meth = scalaRuntime.getMethod("replStringOf", classOf[Object], classOf[Int], classOf[Boolean])
+          val truly = java.lang.Boolean.TRUE
+
+          (value: Object) => meth.invoke(null, value, Integer.valueOf(MaxStringElements), truly).asInstanceOf[String]
+        } catch {
+          case _: NoSuchMethodException =>
+            val meth = scalaRuntime.getMethod("replStringOf", classOf[Object], classOf[Int])
+
+            (value: Object) => {
+              val res = meth.invoke(null, value, Integer.valueOf(MaxStringElements)).asInstanceOf[String]
+              val len = res.length()
+              if len == 0 || res.charAt(len-1) != '\n' then
+                res
+              else if len == 1 || res.charAt(0) != '\n' then
+                res.substring(0, len-1)
+              else
+                res.substring(1, len-1)
+            }
+        }
       }
       myClassLoader
     }
@@ -82,7 +100,7 @@ private[repl] class Rendering(parentClassLoader: Option[ClassLoader] = None) {
       resObj
         .getDeclaredMethods.find(_.getName == sym.name.encode.toString)
         .map(_.invoke(null))
-    val string = value.map(replStringOf(_).trim)
+    val string = value.map(replStringOf(_))
     if (!sym.is(Flags.Method) && sym.info == defn.UnitType)
       None
     else

compiler/test-resources/repl/i1369

@@ -1,4 +1,4 @@
 scala> print("foo")
 foo
 scala> "Hello"
-val res0: String = Hello
+val res0: String = "Hello"

compiler/test-resources/repl/i3388

@@ -1,3 +1,3 @@
 scala> val foo = "1"; foo.toInt
-val foo: String = 1
+val foo: String = "1"
 val res0: Int = 1

compiler/test-resources/repl/i4852

@@ -1,6 +1,6 @@
 scala> inline def foo[T](t : T*) : Any = t
 def foo[T](t: T*): Any
 scala> foo(1, "hi", false)
-val res0: Any = ArraySeq(1, hi, false)
+val res0: Any = ArraySeq(1, "hi", false)
 scala> foo()
 val res1: Any = ArraySeq()

compiler/test-resources/repl/i5218

@@ -1,6 +1,6 @@
 scala> val tuple = (1, "2", 3L)
-val tuple: (Int, String, Long) = (1,2,3)
+val tuple: (Int, String, Long) = (1, "2", 3)
 scala> 0.0 *: tuple
-val res0: (Double, Int, String, Long) = (0.0,1,2,3)
+val res0: (Double, Int, String, Long) = (0.0, 1, "2", 3)
 scala> tuple ++ tuple
-val res1: Int *: scala.Tuple.Concat[(String, Long), tuple.type] = (1,2,3,1,2,3)
+val res1: Int *: scala.Tuple.Concat[(String, Long), tuple.type] = (1, "2", 3, 1, "2", 3)

compiler/test-resources/repl/i6474

@@ -5,18 +5,18 @@ scala> object Foo2 { type T[+A] = [B] =>> (A, B) }
 scala> object Foo3 { type T[+A] = [B] =>> [C] =>> (A, B) }
 // defined object Foo3
 scala> ((1, 2): Foo1.T[Int]): Foo1.T[Any]
-val res0: (Any, Int) = (1,2)
+val res0: (Any, Int) = (1, 2)
 scala> ((1, 2): Foo2.T[Int][Int]): Foo2.T[Any][Int]
-val res1: (Any, Int) = (1,2)
+val res1: (Any, Int) = (1, 2)
 scala> (1, 2): Foo3.T[Int][Int]
 1 | (1, 2): Foo3.T[Int][Int]
   |         ^^^^^^^^^^^^^^^^
   |         Missing type parameter for Foo3.T[Int][Int]
 scala> ((1, 2): Foo3.T[Int][Int][Int]): Foo3.T[Any][Int][Int]
-val res2: (Any, Int) = (1,2)
+val res2: (Any, Int) = (1, 2)
 scala> object Foo3 { type T[A] = [B] =>> [C] =>> (A, B) }
 // defined object Foo3
 scala> ((1, 2): Foo3.T[Int][Int][Int])
-val res3: (Int, Int) = (1,2)
+val res3: (Int, Int) = (1, 2)
 scala> ((1, 2): Foo3.T[Int][Int][Int])
-val res4: (Int, Int) = (1,2)
+val res4: (Int, Int) = (1, 2)

compiler/test-resources/repl/i6986

@@ -1,4 +1,4 @@
 scala> enum SingleCase { case TheCase }
 // defined class SingleCase
 scala> SingleCase.TheCase
-val res0: SingleCase = TheCase
+val res0: SingleCase = TheCase()

compiler/test-resources/repl/i7410

@@ -1,4 +1,4 @@
 scala> enum E { case A, B, C }
 // defined class E
 scala> E.A
-val res0: E = A
+val res0: E = A()

compiler/test-resources/repl/renderNothing

@@ -1,6 +1,6 @@
 scala> List()
 val res0: List[Nothing] = List()
 scala> Option.empty
-val res1: Option[Nothing] = None
+val res1: Option[Nothing] = None()
 scala> Map()
 val res2: Map[Nothing, Nothing] = Map()

compiler/test-resources/type-printer/prefixless

@@ -1,7 +1,7 @@
 scala> List(1,2,3)
 val res0: List[Int] = List(1, 2, 3)
 scala> Map("foo" -> 1)
-val res1: Map[String, Int] = Map(foo -> 1)
+val res1: Map[String, Int] = Map("foo" -> 1)
 scala> Seq('a','b')
 val res2: Seq[Char] = List(a, b)
 scala> Set(4, 5)

compiler/test-resources/type-printer/vals

@@ -7,4 +7,4 @@ val xs: List[Int] = List(1)
 scala> scala.util.Try(1)
 val res0: scala.util.Try[Int] = Success(1)
 scala> Map(1 -> "one")
-val res1: Map[Int, String] = Map(1 -> one)
+val res1: Map[Int, String] = Map(1 -> "one")