Backport "Use final result type to check selector bound" to 3.5.1 (#21016)

WojciechMazur · web-flow · commit 95847518d1d6 · 2024-07-04T15:43:36.000+02:00
Backport #20989 to 3.5.1-RC1 [skip ci]
diff --git a/compiler/src/dotty/tools/dotc/transform/CheckUnused.scala b/compiler/src/dotty/tools/dotc/transform/CheckUnused.scala
@@ -729,7 +729,7 @@ object CheckUnused:
             if selector.isGiven then
               // Further check that the symbol is a given or implicit and conforms to the bound
               sym.isOneOf(Given | Implicit)
-                && (selector.bound.isEmpty || sym.info <:< selector.boundTpe)
+                && (selector.bound.isEmpty || sym.info.finalResultType <:< selector.boundTpe)
             else
               // Normal wildcard, check that the symbol is not a given (but can be implicit)
               !sym.is(Given)
diff --git a/tests/pos/i20860.scala b/tests/pos/i20860.scala
@@ -0,0 +1,3 @@
+def `i20860 use result to check selector bound`: Unit =
+  import Ordering.Implicits.given Ordering[?]
+  summon[Ordering[Seq[Int]]]

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	+def `i20860 use result to check selector bound`: Unit =
	`2`	`+ import Ordering.Implicits.given Ordering[?]`
	`3`	`+ summon[Ordering[Seq[Int]]]`