Limit depth by Symbols instead of TermRefs in suggestionRoots

Author: mbovel

compiler/src/dotty/tools/dotc/typer/ImportSuggestions.scala

@@ -57,7 +57,7 @@ trait ImportSuggestions:
    *     skipped as an optimization, since they won't contain implicits anyway.
    */
   private def suggestionRoots(using Context) =
-    val seen = mutable.Set[TermRef]()
+    val seen = mutable.Set[Symbol]()
 
     def lookInside(root: Symbol)(using Context): Boolean =
       explore {
@@ -103,10 +103,10 @@ trait ImportSuggestions:
         .toList
 
     def rootsIn(ref: TermRef)(using Context): List[TermRef] =
-      if seen.contains(ref) then Nil
+      if seen.contains(ref.termSymbol) then Nil
       else
         implicitsDetailed.println(i"search for suggestions in ${ref.symbol.fullName}")
-        seen += ref
+        seen += ref.termSymbol
         ref :: rootsStrictlyIn(ref)
 
     def rootsOnPath(tp: Type)(using Context): List[TermRef] = tp match

tests/neg/22145c.check

@@ -0,0 +1,4 @@
+-- [E008] Not Found Error: tests/neg/22145c.scala:2:35 -----------------------------------------------------------------
+2 |  def bar(base: Collection) = base.foo // error
+  |                              ^^^^^^^^
+  |                              value foo is not a member of Collection

tests/neg/22145c.scala

@@ -0,0 +1,6 @@
+trait Collection:
+  def bar(base: Collection) = base.foo // error
+  object a extends Collection:
+    def foo: Int = 0
+  object b extends Collection:
+    def foo: Int = 1