Make script wrapper satisfy compiler checks

modules/build/src/main/scala/scala/build/internal/ClassCodeWrapper.scala

@@ -30,7 +30,7 @@ case object ClassCodeWrapper extends CodeWrapper {
                                     |
                                     |  def main(args: Array[String]): Unit = {
                                     |    args$$set(args)
-                                    |    script.hashCode() // hashCode to clear scalac warning about pure expression in statement position
+                                    |    val _ = script.hashCode() // hashCode to clear scalac warning about pure expression in statement position
                                     |  }
                                     |}
                                     |

modules/build/src/main/scala/scala/build/internal/ObjectCodeWrapper.scala

@@ -31,7 +31,7 @@ case object ObjectCodeWrapper extends CodeWrapper {
                                     |  }
                                     |  def main(args: Array[String]): Unit = {
                                     |    args$$set(args)
-                                    |    $funHashCodeMethod // hasCode to clear scalac warning about pure expression in statement position
+                                    |    val _ = $funHashCodeMethod // hashCode to clear scalac warning about pure expression in statement position
                                     |  }
                                     |}
                                     |""".stripMargin)

modules/integration/src/test/scala/scala/cli/integration/RunScriptTestDefinitions.scala

@@ -518,4 +518,31 @@ trait RunScriptTestDefinitions { _: RunTestDefinitions =>
       }
     }
   }
+
+  test("script wrappers satisfy strict compiler flags") {
+    val inputs = TestInputs(
+      os.rel / "strictClassWrapper.sc" ->
+      """//> using scala 3.3.1
+        |//> using options -Werror -Wnonunit-statement -Wunused:all -Wvalue-discard
+        |//> using options -Yno-experimental -Ysafe-init -deprecation -feature -language:strictEquality
+        |//> using options -new-syntax -old-syntax -unchecked -no-indent
+        |
+        |println(strictObjectWrapper.Foo(42).x)
+        |""".stripMargin,
+
+      os.rel / "strictObjectWrapper.sc" ->
+      """//> using objectWrapper
+        |//> using scala 3.3.1
+        |//> using options -Werror -Wnonunit-statement -Wunused:all -Wvalue-discard
+        |//> using options -Yno-experimental -Ysafe-init -deprecation -feature -language:strictEquality
+        |//> using options -new-syntax -old-syntax -unchecked -no-indent
+        |
+        |case class Foo(x: Int)
+        |""".stripMargin
+    )
+    inputs.fromRoot { root =>
+      val p = os.proc(TestUtil.cli, "--power", "strictClassWrapper.sc", "strictObjectWrapper.sc").call(cwd = root)
+      expect(p.out.trim() == "42")
+    }
+  }
 }