Show stable terms when completing types

Stable terms can be part of the path to a type, and should be shown in
completion when writing a type.

Author: Duhemm

compiler/src/dotty/tools/dotc/interactive/Completion.scala

@@ -3,6 +3,7 @@ package dotty.tools.dotc.interactive
 import dotty.tools.dotc.ast.Trees._
 import dotty.tools.dotc.config.Printers.interactiv
 import dotty.tools.dotc.core.Contexts.{Context, NoContext}
+import dotty.tools.dotc.core.CheckRealizable
 import dotty.tools.dotc.core.Decorators.StringInterpolators
 import dotty.tools.dotc.core.Denotations.SingleDenotation
 import dotty.tools.dotc.core.Flags._
@@ -13,7 +14,7 @@ import dotty.tools.dotc.core.Symbols.{defn, NoSymbol, Symbol}
 import dotty.tools.dotc.core.Scopes
 import dotty.tools.dotc.core.StdNames.{nme, tpnme}
 import dotty.tools.dotc.core.TypeError
-import dotty.tools.dotc.core.Types.{NamedType, NameFilter, Type, takeAllFilter}
+import dotty.tools.dotc.core.Types.{NamedType, Type, takeAllFilter}
 import dotty.tools.dotc.printing.Texts._
 import dotty.tools.dotc.util.{NoSourcePosition, SourcePosition}
 
@@ -219,9 +220,20 @@ object Completion {
       !sym.is(allOf(Mutable, Accessor)) &&
       (
            (mode.is(Mode.Term) && sym.isTerm)
+        || (mode.is(Mode.StableTerm) && sym.isTerm && validPathSegment(sym))
         || (mode.is(Mode.Type) && sym.isType)
       )
 
+    /** Can this symbol be part of a path? See SLS 3.1 for a definition of a valid path. */
+    private def validPathSegment(sym: Symbol)(implicit ctx: Context): Boolean = {
+      def isRealizable = {
+        val realizability = CheckRealizable.realizability(sym.info)
+        realizability == CheckRealizable.Realizable
+      }
+
+      !sym.is(Method) && isRealizable
+    }
+
     /**
      * Find all the members of `site` that are accessible and which should be included in `info`.
      *
@@ -298,11 +310,13 @@ object Completion {
     /** Term symbols are allowed */
     val Term: Mode = new Mode(1)
 
+    val StableTerm: Mode = new Mode(2)
+
     /** Type symbols are allowed */
-    val Type: Mode = new Mode(2)
+    val Type: Mode = new Mode(4) | StableTerm
 
     /** Both term and type symbols are allowed */
-    val Import: Mode = new Mode(4) | Term | Type
+    val Import: Mode = new Mode(8) | Term | Type
   }
 
 }

language-server/test/dotty/tools/languageserver/CompletionTest.scala

@@ -188,4 +188,15 @@ class CompletionTest {
         assertFalse(results.exists((label, _, _) => label == "Zig"))
       })
   }
+
+  @Test def typeCompletionShowsTerm: Unit = {
+    code"""class Bar
+          |object Foo {
+          |  val bar = new Bar
+          |  def baz = new Bar
+          |  object bat
+          |  val bizz: ba${m1}
+          |}""".withSource
+      .completion(m1, Set(("bar", Field, "Bar"), ("bat", Module, "Foo.bat")))
+  }
 }