Upgrade to scalameta 3.7.0 with default settings.

build.sbt

@@ -1,4 +1,3 @@
-import sbt.ScriptedPlugin
 import sbt.ScriptedPlugin._
 import Dependencies._
 
@@ -147,6 +146,7 @@ val cli = MultiScalaProject(
     mainClass in assembly := Some("scalafix.cli.Cli"),
     assemblyJarName in assembly := "scalafix.jar",
     libraryDependencies ++= Seq(
+      metacp,
       "com.github.alexarchambault" %% "case-app" % "1.2.0",
       "org.typelevel" %% "paiges-core" % "0.2.0",
       "com.martiansoftware" % "nailgun-server" % "0.9.1",
@@ -207,10 +207,18 @@ val scalafixSbt = MultiSbtProject(
   ).enablePlugins(BuildInfoPlugin)
     .disablePlugins(ScalafixPlugin)
 )
-lazy val scalafixSbt1 =
-  scalafixSbt(scala212, sbt1, _.dependsOn(testUtils212 % Test))
-lazy val scalafixSbt013 =
-  scalafixSbt(scala210, sbt013, _.dependsOn(testUtils210 % Test))
+lazy val scalafixSbt1 = scalafixSbt(
+  scala212,
+  sbt1,
+  _.dependsOn(testUtils212 % Test)
+)
+lazy val scalafixSbt013 = scalafixSbt(
+  scala210,
+  sbt013,
+  _.settings(
+    scalacOptions -= warnUnusedImports
+  ).dependsOn(testUtils210 % Test)
+)
 
 val testUtils = MultiScalaProject(
   "test-utils",
@@ -221,7 +229,12 @@ val testUtils = MultiScalaProject(
     )
   )
 )
-lazy val testUtils210 = testUtils(scala210)
+lazy val testUtils210 = testUtils(
+  scala210,
+  _.settings(
+    scalacOptions -= warnUnusedImports
+  )
+)
 lazy val testUtils211 = testUtils(scala211)
 lazy val testUtils212 = testUtils(scala212)
 
@@ -259,10 +272,13 @@ val testsInput = TestProject(
     project.settings(
       noPublish,
       semanticdbSettings,
-      scalacOptions += {
-        val sourceroot = baseDirectory.in(ThisBuild).value / srcMain
-        s"-P:semanticdb:sourceroot:$sourceroot"
-      },
+      scalacOptions ++= List(
+        {
+          val sourceroot = baseDirectory.in(ThisBuild).value / srcMain
+          s"-P:semanticdb:sourceroot:$sourceroot"
+        },
+        s"-P:semanticdb:denotations:all"
+      ),
       scalacOptions ~= (_.filterNot(_ == "-Yno-adapted-args")),
       scalacOptions += "-Ywarn-adapted-args", // For NoAutoTupling
       scalacOptions += "-Ywarn-unused-import", // For RemoveUnusedImports
@@ -325,8 +341,8 @@ def unit(
         javaOptions := Nil,
         buildInfoPackage := "scalafix.tests",
         buildInfoObject := "BuildInfo",
-        sources.in(Test) += (baseDirectory
-          .in(ThisBuild))
+        sources.in(Test) += baseDirectory
+          .in(ThisBuild)
           .value / "scalafix-sbt" / "src" / "main" / "scala" / "scalafix" / "internal" / "sbt" / "ScalafixJarFetcher.scala",
         libraryDependencies ++= coursierDeps ++ testsDeps
       ).enablePlugins(BuildInfoPlugin)

project/Dependencies.scala

@@ -3,7 +3,7 @@ import org.scalajs.sbtplugin.ScalaJSPlugin.autoImport._
 /* scalafmt: { maxColumn = 120 }*/
 
 object Dependencies {
-  val scalametaV = "3.3.1"
+  val scalametaV = "3.7.2"
   val metaconfigV = "0.6.0-RC1"
   def dotty = "0.1.1-bin-20170530-f8f52cc-NIGHTLY"
   def scala210 = "2.10.6"
@@ -26,6 +26,7 @@ object Dependencies {
   def ammonite = "com.lihaoyi" %% "ammonite-ops" % "0.9.0"
   def googleDiff = "com.googlecode.java-diff-utils" % "diffutils" % "1.3.0"
 
+  def metacp = "org.scalameta" %% "metacp" % scalametaV
   def scalameta = Def.setting("org.scalameta" %%% "contrib" % scalametaV)
   val scalatest = "org.scalatest" %% "scalatest" % "3.0.0"
 

project/ScalafixBuild.scala

@@ -39,7 +39,7 @@ object ScalafixBuild extends AutoPlugin with GhpagesKeys {
     )
     lazy val warnUnusedImports = "-Ywarn-unused-import"
     lazy val compilerOptions = Seq(
-      "-Xlint",
+      warnUnusedImports,
       "-deprecation",
       "-encoding",
       "UTF-8",

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

@@ -13,7 +13,6 @@ import java.util.concurrent.atomic.AtomicReference
 import java.util.function.UnaryOperator
 import java.util.regex.Pattern
 import java.util.regex.PatternSyntaxException
-
 import scala.meta._
 import scala.meta.inputs.Input
 import scala.meta.internal.inputs._
@@ -42,6 +41,7 @@ import scalafix.syntax._
 import metaconfig.Configured.Ok
 import metaconfig._
 import metaconfig.ConfError
+import scalafix.internal.cli.ClasspathOps
 
 sealed abstract case class CliRunner(
     sourceroot: AbsolutePath,
@@ -89,7 +89,11 @@ sealed abstract case class CliRunner(
       val code = exitCode.get()
       if (config.lint.reporter.hasErrors) {
         ExitStatus.merge(ExitStatus.LinterError, code)
-      } else code
+      } else if (config.reporter.hasErrors) {
+        ExitStatus.merge(ExitStatus.UnexpectedError, code)
+      } else {
+        code
+      }
     }
     display.completedTask(msg, exit == ExitStatus.Ok)
     display.stop()
@@ -315,7 +319,7 @@ object CliRunner {
         .map(path => AbsolutePath(path)(common.workingPath))
         .toList
 
-    def resolveClasspath: Configured[Classpath] =
+    def resolveClasspath: Configured[Classpath] = {
       classpath match {
         case Some(cp) =>
           val paths = toClasspath(cp)
@@ -336,6 +340,7 @@ object CliRunner {
               .notOk
           }
       }
+    }
 
     val resolvedSourceroot: Configured[AbsolutePath] = {
       val result = sourceroot
@@ -357,18 +362,37 @@ object CliRunner {
       val result: Configured[SemanticdbIndex] = cachedDatabase.getOrElse {
         (resolveClasspath |@| resolvedSourceroot).andThen {
           case (classpath, root) =>
-            val patched = Database.load(classpath, Sourcepath(root))
-            val db =
-              EagerInMemorySemanticdbIndex(patched, Sourcepath(root), classpath)
-            if (verbose) {
-              common.err.println(
-                s"Loaded database with ${db.documents.length} documents.")
-            }
-            if (db.documents.nonEmpty) Ok(db)
-            else {
-              ConfError
-                .message("Missing SemanticdbIndex, found no semanticdb files!")
-                .notOk
+            val index = Database.load(classpath, Sourcepath(root))
+            val deps = dependencyClasspath.map(toClasspath).getOrElse(Nil)
+            val symbolTable = ClasspathOps.newSymbolTable(
+              classpath = Classpath(classpath.shallow ++ deps),
+              cacheDirectory = metacpCacheDir.map(AbsolutePath(_)),
+              parallel = !metacpNoPar,
+              out = common.out)
+            symbolTable match {
+              case None =>
+                ConfError
+                  .message(
+                    "Failed to load symbol table from --dependency-classpath")
+                  .notOk
+              case Some(symtab) =>
+                val db = EagerInMemorySemanticdbIndex(
+                  index,
+                  Sourcepath(root),
+                  classpath,
+                  symtab
+                )
+                if (verbose) {
+                  common.err.println(
+                    s"Loaded database with ${db.documents.length} documents.")
+                }
+                if (db.documents.nonEmpty) Ok(db)
+                else {
+                  ConfError
+                    .message(
+                      "Missing SemanticdbIndex, found no semanticdb files!")
+                    .notOk
+                }
             }
         }
       }

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

@@ -1,8 +1,54 @@
 package scalafix.internal.cli
 
 import java.io.File
+import java.io.OutputStream
+import java.io.PrintStream
+import org.langmeta.io.AbsolutePath
+import scala.meta.Classpath
+import scala.meta.metacp
+import scalafix.internal.util.LazySymbolTable
+import scalafix.internal.util.SymbolTable
 
 object ClasspathOps {
+
+  def bootClasspath: Option[Classpath] = sys.props.collectFirst {
+    case (k, v) if k.endsWith(".boot.class.path") => Classpath(v)
+  }
+
+  val devNull = new PrintStream(new OutputStream {
+    override def write(b: Int): Unit = ()
+  })
+
+  /** Process classpath with metacp to build semanticdbs of global symbols. **/
+  def toMetaClasspath(
+      sclasspath: Classpath,
+      cacheDirectory: Option[AbsolutePath],
+      parallel: Boolean, // unused until we upgrade scalameta for https://github.com/scalameta/scalameta/pull/1474
+      out: PrintStream): Option[Classpath] = {
+    val withJDK = Classpath(
+      bootClasspath.fold(sclasspath.shallow)(_.shallow ::: sclasspath.shallow))
+    val default = metacp.Settings()
+    val settings = default
+      .withClasspath(withJDK)
+      .withScalaLibrarySynthetics(true)
+      .withCacheDir(cacheDirectory.getOrElse(default.cacheDir))
+    val reporter = metacp
+      .Reporter()
+      .withOut(devNull) // out prints classpath of proccessed classpath, which is not relevant for scalafix.
+      .withErr(out)
+    val mclasspath = scala.meta.cli.Metacp.process(settings, reporter)
+    mclasspath
+  }
+
+  def newSymbolTable(
+      classpath: Classpath,
+      cacheDirectory: Option[AbsolutePath] = None,
+      parallel: Boolean = true,
+      out: PrintStream = System.out): Option[SymbolTable] = {
+    toMetaClasspath(classpath, cacheDirectory, parallel, out)
+      .map(new LazySymbolTable(_))
+  }
+
   def getCurrentClasspath: String = {
     Thread.currentThread.getContextClassLoader match {
       case url: java.net.URLClassLoader =>

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

@@ -55,12 +55,30 @@ case class ScalafixOptions(
     sourceroot: Option[String] = None,
     @HelpMessage(
       "java.io.File.pathSeparator separated list of directories or jars containing " +
-        "'.semanticdb' files. The 'semanticdb' files are emitted by the " +
+        "META-INF/semanticdb/**/*.semanticdb files. SemanticDB files are emitted by the " +
         "semanticdb-scalac compiler plugin and are necessary for semantic rules " +
         "like ExplicitResultTypes to function."
     )
     @ValueDescription("entry1.jar:entry2.jar:target/scala-2.12/classes/")
     classpath: Option[String] = None,
+    @HelpMessage(
+      "Same as --classpath except for dependencies that do not need to be compiled with SemanticDB. " +
+        "Must be accompanied with --classpath. " +
+        "This option is required for rules like ExplicitResultTypes to lookup symbol information from the classpath." +
+        "This option is processed with metacp and produced artifacts are globally cached using --metacp-cache-dir"
+    )
+    @ValueDescription("entry1.jar:entry2.jar:target/scala-2.12/classes/")
+    dependencyClasspath: Option[String] = None,
+    @HelpMessage(
+      "Global cache location to persist metacp artifacts produced by analyzing --dependency-classpath. " +
+        "The default location depends on the OS and is computed with https://github.com/soc/directories-jvm " +
+        "using the project name 'semanticdb'. " +
+        "On macOS the default cache directory is ~/Library/Caches/semanticdb. ")
+    metacpCacheDir: Option[String] = None,
+    @HelpMessage(
+      "Set this flag to disable parallel processing with metacp. " +
+        "Metacp uses the standard library parallel collections, which may enter deadlocks.")
+    metacpNoPar: Boolean = false,
     @HelpMessage(
       "Automatically infer --classpath starting from these directories. " +
         "Ignored if --classpath is provided.")

scalafix-core/shared/src/main/scala/scala/meta/internal/scalafix/ScalafixScalametaHacks.scala

@@ -3,8 +3,12 @@ package scala.meta.internal.scalafix
 import scala.meta.Dialect
 import scala.meta.Tree
 import scala.meta.internal.trees.Origin
+import scala.meta.dialects
 
 object ScalafixScalametaHacks {
-  def dialect(language: String): Dialect = Dialect.standards(language)
+  def dialect(language: String): Dialect =
+    if (language == "Scala") dialects.Scala212
+    else if (language.isEmpty) dialects.Scala212
+    else Dialect.standards(language)
   def resetOrigin(tree: Tree): Tree = tree.withOrigin(Origin.None)
 }

scalafix-core/shared/src/main/scala/scalafix/internal/rule/ExplicitResultTypes.scala

@@ -17,6 +17,7 @@ import scalafix.syntax._
 import scalafix.util.TokenOps
 import metaconfig.Conf
 import metaconfig.Configured
+import org.langmeta.internal.semanticdb.XtensionDenotationsInternal
 
 case class ExplicitResultTypes(
     index: SemanticdbIndex,
@@ -74,9 +75,16 @@ case class ExplicitResultTypes(
     def defnType(defn: Defn): Option[(Type, Patch)] =
       for {
         name <- defnName(defn)
-        symbol <- name.symbol
-        typ <- symbol.resultType
-      } yield TypeSyntax.prettify(typ, ctx, config.unsafeShortenNames)
+        denot <- name.denotation
+        tpe <- denot.tpeInternal
+        // Skip existential types for now since they cause problems.
+        if !tpe.tag.isExistentialType
+        result <- TypeSyntax.prettify(
+          tpe,
+          ctx,
+          config.unsafeShortenNames,
+          name.pos)
+      } yield result
     import scala.meta._
     def fix(defn: Defn, body: Term): Patch = {
       val lst = ctx.tokenList