よく忘れるので、自分のためにメモ。
だいたい、このあたりを指定しています。
scalacOptions ++= Seq( "-deprecation", "-feature", "-unchecked", "-Xlint", "-Ywarn-dead-code", "-Ywarn-nullary-unit", "-Ywarn-numeric-widen", "-Ywarn-unused", "-Ywarn-unused-import" )
確認しているScalacのバージョンは、こちら。
$ scalac -version Scala compiler version 2.12.4 -- Copyright 2002-2017, LAMP/EPFL and Lightbend, Inc.
- -deprecation … 非推奨警告
- -feature … SIP-18 - Modularizing Language Features - Scala Documentationのimportが必要な箇所を警告
- -unchecked … ある条件を満たす場合に、追加の警告を有効にする（？）
このあたりは、「scalac -help」で見ればOK。
$ scalac -help
よりadvancedな警告を有効にするのは「-Xlint」。どういうものが有効にされるのかは、「scalac -Xlint:help」で見れます。
$ scalac -Xlint:help Enable or disable specific warnings adapted-args Warn if an argument list is modified to match the receiver. nullary-unit Warn when nullary methods return Unit. inaccessible Warn about inaccessible types in method signatures. nullary-override Warn when non-nullary `def f()' overrides nullary `def f'. infer-any Warn when a type argument is inferred to be `Any`. missing-interpolator A string literal appears to be missing an interpolator id. doc-detached A Scaladoc comment appears to be detached from its element. private-shadow A private field (or class parameter) shadows a superclass field. type-parameter-shadow A local type parameter shadows a type already in scope. poly-implicit-overload Parameterized overloaded implicit methods are not visible as view bounds. option-implicit Option.apply used implicit view. delayedinit-select Selecting member of DelayedInit. by-name-right-associative By-name parameter of right associative operator. package-object-classes Class or object defined in package object. unsound-match Pattern match may not be typesafe. stars-align Pattern sequence wildcard must align with sequence component. constant Evaluation of a constant arithmetic expression results in an error. unused Enable -Ywarn-unused:imports,privates,locals,implicits. Default: All choices are enabled by default.
なお、「-X」なオプションにどのようなものがあるかは、「scalac -X」を使えば見ることができます。
$ scalac -X
最後、「-Y」はprivateなオプション。「-Ywarn-〜」なオプションをいくつか使います。「-Y」なオプションにどのようなものがあるかは、「scalac -Y」で
見ることができます。
$ scalac -Y
うち、「-Ywarn-〜」なものは、こちら。
-Ywarn-adapted-args Warn if an argument list is modified to match the receiver. -Ywarn-dead-code Warn when dead code is identified. -Ywarn-extra-implicit Warn when more than one implicit parameter section is defined. -Ywarn-inaccessible Warn about inaccessible types in method signatures. -Ywarn-infer-any Warn when a type argument is inferred to be `Any`. -Ywarn-macros:<mode> Enable lint warnings on macro expansions. Default: `before', `help' to list choices. -Ywarn-nullary-override Warn when non-nullary `def f()' overrides nullary `def f'. -Ywarn-nullary-unit Warn when nullary methods return Unit. -Ywarn-numeric-widen Warn when numerics are widened. -Ywarn-unused:<_,warning,-warning> Enable or disable specific `unused' warnings: `_' for all, `-Ywarn-unused:help' to list choices. -Ywarn-unused-import Warn when imports are unused. -Ywarn-value-discard Warn when non-Unit expression results are unused.
Mavenで指定する場合は、こんな感じで。
<plugin> <groupId>net.alchim31.maven</groupId> <artifactId>scala-maven-plugin</artifactId> <version>3.3.1</version> <executions> <execution> <goals> <goal>compile</goal> <goal>testCompile</goal> </goals> </execution> </executions> <configuration> <scalaVersion>2.12.4</scalaVersion> <args> <arg>-deprecation</arg> <arg>-feature</arg> <arg>-unchecked</arg> <arg>-Xlint</arg> <arg>-Ywarn-dead-code</arg> <arg>-Ywarn-nullary-unit</arg> <arg>-Ywarn-numeric-widen</arg> <arg>-Ywarn-unused</arg> <arg>-Ywarn-unused-import</arg> </args> <recompileMode>incremental</recompileMode> </configuration> </plugin>
