Contribute candidates when the selection is a Select

Author: natsukagami

presentation-compiler/src/main/dotty/tools/pc/completions/Completions.scala

@@ -420,6 +420,20 @@ class Completions(
           ),
           false,
         )
+      case Select(_, name) :: (unapp : UnApply) :: _ =>
+        (
+          CaseKeywordCompletion.contribute(
+            EmptyTree, // no selector
+            completionPos,
+            indexedContext,
+            config,
+            search,
+            parent = unapp,
+            autoImports,
+            patternOnly = Some(name.decoded)
+          ),
+          false,
+        )
 
       // class FooImpl extends Foo:
       //   def x|

presentation-compiler/src/main/dotty/tools/pc/completions/MatchCaseCompletions.scala

@@ -90,8 +90,9 @@ object CaseKeywordCompletion:
                 val argPts = UnapplyArgs(fn.tpe.widen.finalResultType, fn, patterns, parent.srcPos).argTypes
                 patterns.zipWithIndex
                   .find:
-                    case (id@Ident(v), tpe) => v.decoded == value
-                    case _ => false
+                    case (Ident(v), tpe) => v.decoded == value
+                    case (Select(_, v), tpe) => v.decoded == value
+                    case t => false
                   .map((_, id) => argPts(id).widen.deepDealias)
           /* Parent is a function expecting a case match expression */
           case TreeApply(fun, _) if !fun.tpe.isErroneous =>