Add support for linters

build.sbt

@@ -97,8 +97,8 @@ lazy val allSettings = List(
  stableVersion := version.value.replaceAll("\\+.*", ""),
  resolvers += Resolver.sonatypeRepo("releases"),
  triggeredMessage in ThisBuild := Watched.clearWhenTriggered,
- scalacOptions ++= compilerOptions,
- scalacOptions in (Compile, console) := compilerOptions :+ "-Yrepl-class-based",
+ scalacOptions ++= compilerOptions.value,
+ scalacOptions in (Compile, console) := compilerOptions.value :+ "-Yrepl-class-based",
  libraryDependencies += scalatest.value % Test,
  testOptions in Test += Tests.Argument("-oD"),
  scalaVersion := ciScalaVersion.getOrElse(scala212),
@@ -197,6 +197,7 @@ lazy val `scalafix-sbt` = project
  .configs(IntegrationTest)
  .settings(
  allSettings,
+ is210Only,
  publishSettings,
  buildInfoSettings,
  Defaults.itSettings,
@@ -220,8 +221,6 @@ lazy val `scalafix-sbt` = project
  "; very scalafix-sbt/scripted"
  )(state.value)
  },
- scalaVersion := scala210,
- crossScalaVersions := Seq(scala210),
  moduleName := "sbt-scalafix",
  scriptedLaunchOpts ++= Seq(
  "-Dplugin.version=" + version.value,
@@ -301,6 +300,7 @@ lazy val testsOutput = project
  allSettings,
  noPublish,
  semanticdbSettings,
+ scalacOptions -= warnUnusedImports,
  resolvers := resolvers.in(testsInput).value,
  libraryDependencies := libraryDependencies.in(testsInput).value
  )
@@ -324,7 +324,7 @@ lazy val testsInputSbt = project
  .settings(
  logLevel := Level.Error, // avoid flood of deprecation warnings.
  scalacOptions += "-Xplugin-require:sbthost",
- scalaVersion := scala210,
+ is210Only,
  sbtPlugin := true,
  scalacOptions += s"-P:sbthost:sourceroot:${sourceDirectory.in(Compile).value}",
  addCompilerPlugin(
@@ -336,8 +336,7 @@ lazy val testsOutputSbt = project
  .settings(
  allSettings,
  noPublish,
- scalaVersion := scala210,
- crossScalaVersions := Seq(scala210),
+ is210Only,
  sbtPlugin := true
  )
 
@@ -437,17 +436,27 @@ lazy val readme = scalatex
  .dependsOn(coreJVM, cli)
  .enablePlugins(GhpagesPlugin)
 
+lazy val is210Only = Seq(
+ scalaVersion := scala210,
+ crossScalaVersions := Seq(scala210),
+ scalacOptions -= warnUnusedImports
+)
+
 lazy val isFullCrossVersion = Seq(
  crossVersion := CrossVersion.full
 )
 
-lazy val compilerOptions = Seq(
- "-deprecation",
- "-encoding",
- "UTF-8",
- "-feature",
- "-unchecked"
-)
+lazy val warnUnusedImports = "-Ywarn-unused-import"
+lazy val compilerOptions = Def.setting {
+ Seq(
+ "-deprecation",
+ "-encoding",
+ "UTF-8",
+ "-feature",
+ warnUnusedImports,
+ "-unchecked"
+ )
+}
 
 lazy val gitPushTag = taskKey[Unit]("Push to git tag")
 

readme/Changelog03.scalatex

@@ -142,4 +142,4 @@
  Two rewrite rules:
  @sect.ref{ProcedureSyntax}
  and
- @sect.ref{VolatileLazyVal}.
+ @sect.ref{DottyVolatileLazyVal}.

readme/Changelog05.scalatex

@@ -23,6 +23,8 @@
  Scala.js support for @sect.ref{scalafix-core}, by @user{gabro}.
  @li
  Configurable @sect.ref{ExplicitReturnTypes}, by @user{taisuke}.
+ @li
+ Configurable @sect.ref{lint} reporting.
  @li
  @sect.ref{sbt-scalafix} rewrite tab completion.
  @li
@@ -42,6 +44,11 @@
  Ability to implement rewrites for sources of sbt builds, including
  @code{*.sbt} files. The API to write sbt rewrites is identical to
  regular Scala rewrites.
+ @li
+ Rewrites can now emit lint messages with @code{ctx.lint}, see
+ @sect.ref{LintMessage}.
+ @li
+ Rewrites can have multiple names with optional deprecation warnings.
  @li
  Thanks to upstream improvements in the
  @lnk("Scalameta v2.0 Semantic API", "http://scalameta.org/tutorial/#SemanticAPI"),
@@ -74,7 +81,7 @@
  @code{Predef.intArrayOps} and now it resolves to
  @code{IndexedSeqOptimized.head}.
 
- @h4{Breaking changes for rewrite authors}
+ @h4{Breaking changes}
  @p
  From 0.5 onwards, our CI will check binary breaking changes in the public API
  on every pull request.
@@ -96,4 +103,6 @@
  @li
  upgraded to Scalameta 2.0, which has several breaking changes
  in the Tree api.
+ @li
+ The @code{VolatileLazyVal} rewrite is now named @sect.ref{DottyVolatileLazyVal}.
 

readme/Configuration.scalatex

@@ -65,6 +65,16 @@
  @config
  rewrite = "https://gist.githubusercontent.com/olafurpg/fc6f43a695ac996bd02000f45ed02e63/raw/80218434edb85120a9c6fd6533a4418118de8ba7/ExampleRewrite.scala"
 
+ @sect{lint}
+ Override the default severity level of a @sect.ref{LintMessage} with @code{lint}
+ @config
+ // Assuming 'Foo' is a rewrite and 'warningID'/'errorID' are LintCategory IDs.
+ lint.error = [ Foo.warningID ] // promote Foo.warnigID to an error
+ lint.warning = [ Foo.errorID ] // demote Foo.errorID to a warning
+ lint.info = [ Foo.errorID ] // demote Foo.errorID to info
+ lint.ignore = [ Foo.errorID ] // don't report Foo.errorID
+ lint.explain = true // print out detailed explanation for lint messages.
+
  @sect{patches}
  For simple use-cases, it's possible to write custom rewrites directly in
  .scalafix.conf.

readme/ImplementingRewrites.scalatex

@@ -96,6 +96,11 @@
  @li
  Test failures are reported as unified diffs from the obtained output
  of the rewrite and the expected output in the @code{output} project.
+ @li
+ Assert that a @sect.ref{LintMessage} is expected at a particular line
+ by suffixing the line with the comment @code{// scalafix: <LintCategory>}.
+ The test fails if there exist reported lint messages that have no
+ associated assertion in the input file.
 
  @sect{Example rewrites}
  The Scalafix repository contains several example rewrites and tests,
@@ -140,6 +145,24 @@
  If you experience that it's difficult to implement something that
  seems simple then don't hesitate to ask on @gitter.
 
+ @sect{LintMessage}
+ Rewrites are able to emit "lint messages" with info/warn/error severity
+ using @code{ctx.lint(lintCategory.at(String/Position)): Patch}.
+ To report a lint message, first create a @sect.ref{LintCategory} and then
+ report it as a @code{Patch}
+ @hl.scala
+ val divisionByZero = LintCategory.error("Division by zero is unsafe!")
+ def rewrite(ctx: RewriteCtx): Patch = {
+ val tree: Tree = // ...
+ ctx.lint(divisionByZero.at(tree.pos))
+ }
+
+ @sect{LintCategory}
+ A LintCategory is group of lint messages of the same kind.
+ A LintCategory has a default severity level (info/warn/error) at which
+ it will be reported. Scalafix users can override the default severity
+ with @sect.ref{lint}.
+
  @sect{Scalameta}
  Scalafix uses @lnk("Scalameta", "http://scalameta.org/") to implement
  rewrites.

readme/Rewrites.scalatex

@@ -132,7 +132,7 @@
  println("Hello world!")
  }
 
- @sect(VolatileLazyVal.toString)
+ @sect(DottyVolatileLazyVal.toString)
  @p
  Adds a @code{@@volatile} annotation to lazy vals.
  The @code{@@volatile} annotation is needed to maintain thread-safe

readme/src/main/scala/scalafix/Readme.scala

@@ -7,7 +7,6 @@ import scalafix.internal.config.ScalafixMetaconfigReaders
 import scalafix.reflect.ScalafixReflect
 import scalatags.Text.TypedTag
 import scalatags.Text.all._
-import scalatex.Main
 import scalatex.site.Highlighter
 
 object Readme {

scalafix-cli/src/main/scala/scalafix/cli/Cli.scala

@@ -186,7 +186,7 @@ object ScalafixRewriteNames {
  filename.endsWith(".scala") || filename.endsWith(".sbt")
  }
 
- def parse(args: Seq[String]): CliCommand = {
+ def parse(args: Seq[String], common: CommonOptions): CliCommand = {
  import CliCommand._
  OptionsParser.withHelp.detailedParse(args) match {
  case Left(err) =>
@@ -209,12 +209,16 @@ object ScalafixRewriteNames {
  Files.write(path, sbtCompletions.getBytes)
  PrintAndExit(s"Sbt completions installed in $path", ExitStatus.Ok)
  case Right((WithHelp(_, _, options), extraFiles, _)) =>
- parseOptions(options.copy(files = options.files ++ extraFiles))
+ parseOptions(
+ options.copy(
+ common = common,
+ files = options.files ++ extraFiles
+ ))
  }
  }
 
- def runMain(args: Seq[String], commonOptions: CommonOptions): ExitStatus =
- runMain(parse(args), commonOptions)
+ def runMain(args: Seq[String], common: CommonOptions): ExitStatus =
+ runMain(parse(args, common), common)
 
  def runMain(
  cliCommand: CliCommand,
@@ -230,7 +234,11 @@ object ScalafixRewriteNames {
  }
  // This one accummulates a lot of garbage, scalameta needs to get rid of it.
  PlatformTokenizerCache.megaCache.clear()
- result
+ if (commonOptions.reporter.hasErrors) {
+ ExitStatus.merge(ExitStatus.InvalidCommandLineOption, result)
+ } else {
+ result
+ }
  }
 
  def nailMain(nGContext: NGContext): Unit = {

scalafix-cli/src/main/scala/scalafix/cli/CliRunner.scala

@@ -17,7 +17,6 @@ import java.util.regex.PatternSyntaxException
 import scala.meta._
 import scala.meta.inputs.Input
 import scala.meta.internal.inputs._
-import scala.meta.internal.tokenizers.PlatformTokenizerCache
 import scala.meta.io.AbsolutePath
 import scala.meta.sbthost.Sbthost
 import scala.util.Try
@@ -80,7 +79,10 @@ sealed abstract case class CliRunner(
  code
  }
  display.stop()
- exitCode.get()
+ val exit = exitCode.get()
+ if (config.reporter.hasErrors) {
+ ExitStatus.merge(ExitStatus.LinterError, exit)
+ } else exit
  }
 
  // safeguard to verify that the original file contents have not changed since the
@@ -114,7 +116,7 @@ sealed abstract case class CliRunner(
  }
  case parsers.Parsed.Success(tree) =>
  val ctx = RewriteCtx(tree, config)
- val fixed = rewrite(ctx)
+ val fixed = rewrite.apply(ctx)
  writeMode match {
  case WriteMode.Stdout =>
  common.out.write(fixed.getBytes)
@@ -170,7 +172,7 @@ sealed abstract case class CliRunner(
  path: AbsolutePath,
  cause: Throwable,
  options: ScalafixOptions): Unit = {
- options.common.reporter.error(s"Failed to fix $path")
+ config.reporter.error(s"Failed to fix $path")
  cause.setStackTrace(cause.getStackTrace.take(options.common.stackVerbosity))
  cause.printStackTrace(options.common.err)
  }
@@ -330,12 +332,14 @@ object CliRunner {
  if (kind.isSyntactic) None
  else computeAndCacheDatabase()
  }
- private val lazySemanticCtx: LazySemanticCtx = resolveDatabase
+ private val lazySemanticCtx: LazySemanticCtx =
+ new LazySemanticCtx(resolveDatabase, common.reporter)
 
  // expands a single file into a list of files.
  def expand(matcher: FilterMatcher)(path: AbsolutePath): Seq[FixFile] = {
  if (!path.toFile.exists()) {
- common.err.println(s"$path does not exist.")
+ common.reporter.error(
+ s"$path does not exist. ${common.workingDirectory}")
  Nil
  } else if (path.isDirectory) {
  val builder = Seq.newBuilder[FixFile]
@@ -426,7 +430,15 @@ object CliRunner {
  }
  }
  val resolvedRewrite: Configured[Rewrite] =
- resolvedRewriteAndConfig.map(_._1)
+ resolvedRewriteAndConfig.andThen {
+ case (rewrite, _) =>
+ if (rewrite.rewriteName.isEmpty)
+ ConfError
+ .msg(
+ "No rewrite was provided! Use --rewrite to specify a rewrite.")
+ .notOk
+ else Ok(rewrite)
+ }
  val resolvedConfig: Configured[ScalafixConfig] =
  resolvedRewriteAndConfig.map(_._2)
 

scalafix-cli/src/main/scala/scalafix/cli/ExitStatus.scala

@@ -30,7 +30,8 @@ object ExitStatus {
  InvalidCommandLineOption,
  MissingSemanticApi,
  StaleSemanticDB,
- TestFailed
+ TestFailed,
+ LinterError
  : ExitStatus = generateExitStatus
  // format: on
  lazy val all: List[ExitStatus] = allInternal.toList

scalafix-cli/src/main/scala/scalafix/internal/cli/ScalafixOptions.scala

@@ -18,12 +18,16 @@ case class CommonOptions(
  @Hidden err: PrintStream = System.err,
  @Hidden stackVerbosity: Int = 20
 ) {
- def reporter: PrintStreamReporter =
- ScalafixReporter.default.copy(outStream = err)
+ lazy val reporter: PrintStreamReporter =
+ ScalafixReporter.default.copy(outStream = out)
  def workingPath = AbsolutePath(workingDirectory)
  def workingDirectoryFile = new File(workingDirectory)
 }
 
+object CommonOptions {
+ lazy val default = CommonOptions()
+}
+
 // NOTE: Do not depend on this class as a library, the interface will change between
 // patch versions.
 @AppName("scalafix")