Merge pull request #13662 from dotty-staging/fix-12955

Allow using clauses to introduce Scala-2 conversions
scala · Oct 4, 2021 · d4ba729 · d4ba729
2 parents a19f5dc + f94e390
commit d4ba729
Show file tree

Hide file tree

Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/compiler/src/dotty/tools/dotc/typer/Implicits.scala b/compiler/src/dotty/tools/dotc/typer/Implicits.scala
@@ -1041,9 +1041,13 @@ trait Implicits:
           adapt(generated, pt.widenExpr, locked)
         else {
           def untpdGenerated = untpd.TypedSplice(generated)
+          def producesConversion(info: Type): Boolean = info match
+            case info: PolyType => producesConversion(info.resType)
+            case info: MethodType if info.isImplicitMethod => producesConversion(info.resType)
+            case _ => info.derivesFrom(defn.ConversionClass)
           def tryConversion(using Context) = {
             val untpdConv =
-              if (ref.symbol.is(Given))
+              if ref.symbol.is(Given) && producesConversion(ref.symbol.info) then
                 untpd.Select(
                   untpd.TypedSplice(
                     adapt(generated,

diff --git a/tests/pos/i12955.scala b/tests/pos/i12955.scala
@@ -0,0 +1,2 @@
+def test[A, B](using c: A <:< B) =
+  val b: B = ??? : A
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		def test[A, B](using c: A <:< B) =
		val b: B = ??? : A