Fix completion for synthetic case modules and methods

I'm pretty sure the `isSynthetic` call added in 854de25 should
instead be `isArtifact`, so that's what I've implemented here.

`isSynthetic` used to also filter out error symbols, which are
created with the flags `SYNTHETIC | IS_ERROR`. I've added an addition
test for `isError`, which was needed to keep the output of
`presentation/scope-completion-import` unchanged.

The checkfile for `presentation/callcc-interpreter` is modified to
add the additional completion proposals: synthetic companion objects.

Author: retronym

src/interactive/scala/tools/nsc/interactive/Global.scala

@@ -1000,7 +1000,7 @@ class Global(settings: Settings, _reporter: Reporter, projectName: String = "")
     def add(sym: Symbol, pre: Type, implicitlyAdded: Boolean)(toMember: (Symbol, Type) => M) {
       if ((sym.isGetter || sym.isSetter) && sym.accessed != NoSymbol) {
         add(sym.accessed, pre, implicitlyAdded)(toMember)
-      } else if (!sym.name.decodedName.containsName("$") && !sym.isSynthetic && sym.hasRawInfo) {
+      } else if (!sym.name.decodedName.containsName("$") && !sym.isError && !sym.isArtifact && sym.hasRawInfo) {
         val symtpe = pre.memberType(sym) onTypeError ErrorType
         matching(sym, symtpe, this(sym.name)) match {
           case Some(m) =>

test/files/presentation/callcc-interpreter.check

@@ -3,7 +3,7 @@ reload: CallccInterpreter.scala
 askTypeCompletion at CallccInterpreter.scala(51,34)
 ================================================================================
 [response] askTypeCompletion at (51,34)
-retrieved 57 members
+retrieved 66 members
 abstract trait Term extends AnyRef
 abstract trait Value extends AnyRef
 case class Add extends callccInterpreter.Term with Product with Serializable
@@ -50,6 +50,15 @@ final def synchronized[T0](x$1: T0): T0
 final def wait(): Unit
 final def wait(x$1: Long): Unit
 final def wait(x$1: Long,x$2: Int): Unit
+object Add
+object App
+object Ccc
+object Con
+object Fun
+object Lam
+object M
+object Num
+object Var
 private[this] val term0: callccInterpreter.App
 private[this] val term1: callccInterpreter.App
 private[this] val term2: callccInterpreter.Add

test/junit/scala/tools/nsc/interpreter/CompletionTest.scala

@@ -81,6 +81,12 @@ class CompletionTest {
 
     checkExact(completer, "new C().x_y")("x_y_z")
     checkExact(completer, "(1 : O.T).toCha")("toChar")
+
+    intp.interpret("case class X_y_z()")
+    val completer1 = new PresentationCompilerCompleter(intp)
+    checkExact(completer1, "new X_y_")("X_y_z")
+    checkExact(completer1, "X_y_")("X_y_z")
+    checkExact(completer1, "X_y_z.app")("apply")
   }
 
   @Test
@@ -137,8 +143,8 @@ class CompletionTest {
   def firstCompletionWithNoPrefixHidesUniversalMethodsAndExtensionMethods(): Unit = {
     val intp = newIMain()
     val completer = new PresentationCompilerCompleter(intp)
-    checkExact(completer, "case class C(a: Int, b: Int) { this.")("a", "b")
-    assert(Set("asInstanceOf", "==").diff(completer.complete("case class C(a: Int, b: Int) { this.").candidates.toSet).isEmpty)
+    checkExact(completer, "class C(val a: Int, val b: Int) { this.")("a", "b")
+    assert(Set("asInstanceOf", "==").diff(completer.complete("class C(val a: Int, val b: Int) { this.").candidates.toSet).isEmpty)
     checkExact(completer, "case class D(a: Int, b: Int) { this.a")("a", "asInstanceOf")
   }