Test for feature shadowing

Author: odersky

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -167,7 +167,8 @@ class CompilationTests {
       compileFile("tests/neg-custom-args/i5498-postfixOps.scala", defaultOptions withoutLanguageFeature "postfixOps"),
       compileFile("tests/neg-custom-args/deptypes.scala", defaultOptions.and("-language:experimental.dependent")),
       compileFile("tests/neg-custom-args/matchable.scala", defaultOptions.and("-Xfatal-warnings", "-source", "future")),
-      compileFile("tests/neg-custom-args/i7314.scala", defaultOptions.and("-Xfatal-warnings", "-source", "future"))
+      compileFile("tests/neg-custom-args/i7314.scala", defaultOptions.and("-Xfatal-warnings", "-source", "future")),
+      compileFile("tests/neg-custom-args/feature-shadowing.scala", defaultOptions.and("-Xfatal-warnings", "-feature")),
     ).checkExpectedErrors()
   }
 

tests/neg-custom-args/feature-shadowing.scala

@@ -0,0 +1,13 @@
+import language.implicitConversions
+given Conversion[Int, String] = _.toString
+
+object a:
+  val s: String = 1   // OK
+
+  object b:
+    import language.implicitConversions as _
+    val s: String = 2   // error
+
+    object c:
+      import language.implicitConversions
+      val s: String = 3   // OK again