Merge pull request #1152 from bjaglin/interfaces-fetch

scalafix-interfaces: higher-level API for class loading

CONTRIBUTING.md

@@ -6,6 +6,7 @@ hesitate to ask in the [gitter channel](https://gitter.im/scalacenter/scalafix).
 
 ## Modules
 
+- `scalafix-interfaces` Java facade to run rules within an existing JVM instance.
 - `scalafix-core/` data structures for rewriting and linting Scala source code.
 - `scalafix-reflect/` utilities to compile and classload rules from
   configuration.

build.sbt

@@ -39,7 +39,6 @@ lazy val interfaces = project
           "scalafix-interfaces.properties"
       IO.write(props, "Scalafix version constants", out)
       List(out)
-
     },
     javacOptions.in(Compile) ++= List(
       "-Xlint:all",
@@ -48,9 +47,9 @@ lazy val interfaces = project
     javacOptions.in(Compile, doc) := List("-Xdoclint:none"),
     javaHome.in(Compile) := inferJavaHome(),
     javaHome.in(Compile, doc) := inferJavaHome(),
+    libraryDependencies += "io.get-coursier" % "interface" % coursierInterfaceV,
     moduleName := "scalafix-interfaces",
-    crossVersion := CrossVersion.disabled,
-    crossScalaVersions := List(scala213),
+    crossPaths := false,
     autoScalaLibrary := false
   )
 
@@ -243,7 +242,11 @@ lazy val unit = project
           "scalafix-tests" / "shared" / "src" / "main",
       "sharedClasspath" ->
         classDirectory.in(testsShared, Compile).value
-    )
+    ),
+    test.in(Test) := test
+      .in(Test)
+      .dependsOn(crossPublishLocalBinTransitive.in(cli))
+      .value
   )
   .enablePlugins(BuildInfoPlugin)
   .dependsOn(

project/Dependencies.scala

@@ -9,6 +9,7 @@ object Dependencies {
   def scala212 = "2.12.11"
   def scala213 = "2.13.2"
   def coursierV = "2.0.0-RC5-6"
+  def coursierInterfaceV = "0.0.22"
   val currentScalaVersion = scala213
 
   val jgit = "org.eclipse.jgit" % "org.eclipse.jgit" % "5.7.0.202003110725-r"

project/ScalafixBuild.scala

@@ -29,6 +29,11 @@ object ScalafixBuild extends AutoPlugin with GhpagesKeys {
       skip in publish := true
     ) ++ noMima
     lazy val supportedScalaVersions = List(scala213, scala211, scala212)
+    lazy val publishLocalTransitive =
+      taskKey[Unit]("Run publishLocal on this project and its dependencies")
+    lazy val crossPublishLocalBinTransitive = taskKey[Unit](
+      "Run, for each crossVersion, publishLocal without packageDoc & packageSrc, on this project and its dependencies"
+    )
     lazy val isFullCrossVersion = Seq(
       crossVersion := CrossVersion.full
     )
@@ -203,6 +208,7 @@ object ScalafixBuild extends AutoPlugin with GhpagesKeys {
     },
     commands += Command.command("ci-213-windows") { s =>
       s"++$scala213" ::
+        "cli/crossPublishLocalBinTransitive" :: // scalafix.tests.interfaces.ScalafixSuite
         s"unit/testOnly -- -l scalafix.internal.tests.utils.SkipWindows" ::
         s
     },
@@ -311,6 +317,31 @@ object ScalafixBuild extends AutoPlugin with GhpagesKeys {
         organization.value % s"${moduleName.value}_$binaryVersion" % previousArtifactVersion
       )
     },
-    mimaBinaryIssueFilters ++= Mima.ignoredABIProblems
+    mimaBinaryIssueFilters ++= Mima.ignoredABIProblems,
+    publishLocalTransitive := Def.taskDyn {
+      val ref = thisProjectRef.value
+      publishLocal.all(ScopeFilter(inDependencies(ref)))
+    }.value,
+    crossPublishLocalBinTransitive := {
+      val currentState = state.value
+      val ref = thisProjectRef.value
+      val versions = crossScalaVersions.value
+      versions.map {
+        version =>
+          val withScalaVersion = Project
+            .extract(currentState)
+            .appendWithoutSession(
+              Seq(
+                scalaVersion.in(ThisBuild) := version,
+                publishArtifact.in(ThisBuild, packageDoc) := false,
+                publishArtifact.in(ThisBuild, packageSrc) := false
+              ),
+              currentState
+            )
+          Project
+            .extract(withScalaVersion)
+            .runTask(publishLocalTransitive.in(ref), withScalaVersion)
+      }
+    }
   )
 }

scalafix-cli/src/main/scala/scalafix/internal/interfaces/ScalafixArgumentsImpl.scala

@@ -1,14 +1,17 @@
 package scalafix.internal.interfaces
 
 import java.io.PrintStream
-import java.net.URLClassLoader
+import java.net.{URL, URLClassLoader}
 import java.nio.charset.Charset
 import java.nio.file.Path
 import java.nio.file.PathMatcher
 import java.util
 import java.util.Optional
+
+import coursierapi.Repository
 import metaconfig.Conf
 import metaconfig.Configured
+
 import scala.jdk.CollectionConverters._
 import scala.meta.io.AbsolutePath
 import scala.meta.io.Classpath
@@ -23,6 +26,7 @@ import scalafix.internal.v1.Args
 import scalafix.internal.v1.MainOps
 import scalafix.internal.v1.Rules
 import scalafix.v1.RuleDecoder
+import scalafix.Versions
 
 final case class ScalafixArgumentsImpl(args: Args = Args.default)
     extends ScalafixArguments {
@@ -35,6 +39,41 @@ final case class ScalafixArgumentsImpl(args: Args = Args.default)
   override def withRules(rules: util.List[String]): ScalafixArguments =
     copy(args = args.copy(rules = rules.asScala.toList))
 
+  override def withToolClasspath(
+      customURLs: util.List[URL]
+  ): ScalafixArguments =
+    withToolClasspath(
+      new URLClassLoader(customURLs.asScala.toArray, getClass.getClassLoader)
+    )
+
+  override def withToolClasspath(
+      customURLs: util.List[URL],
+      customDependenciesCoordinates: util.List[String]
+  ): ScalafixArguments =
+    withToolClasspath(
+      customURLs,
+      customDependenciesCoordinates,
+      Repository.defaults()
+    )
+
+  override def withToolClasspath(
+      customURLs: util.List[URL],
+      customDependenciesCoordinates: util.List[String],
+      repositories: util.List[Repository]
+  ): ScalafixArguments = {
+    val customDependenciesJARs = ScalafixCoursier.toolClasspath(
+      repositories,
+      customDependenciesCoordinates,
+      Versions.scalaVersion
+    )
+    val extraURLs = customURLs.asScala ++ customDependenciesJARs.asScala
+    val classLoader = new URLClassLoader(
+      extraURLs.toArray,
+      getClass.getClassLoader
+    )
+    withToolClasspath(classLoader)
+  }
+
   override def withToolClasspath(
       classLoader: URLClassLoader
   ): ScalafixArguments =

scalafix-interfaces/src/main/java/scalafix/interfaces/Scalafix.java

@@ -1,21 +1,30 @@
 package scalafix.interfaces;
 
+import coursierapi.Repository;
+import scalafix.internal.interfaces.ScalafixCoursier;
+import scalafix.internal.interfaces.ScalafixInterfacesClassloader;
 
+import java.io.IOException;
+import java.io.InputStream;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.List;
+import java.util.Properties;
 
 /**
  * Public API for reflectively invoking Scalafix from a build tool or IDE integration.
- *
- * To obtain an instance of Scalafix, use {@link Scalafix#classloadInstance(ClassLoader)}.
+ * <p>
+ * To obtain an instance of Scalafix, use one of the static factory methods.
  *
  * @implNote This interface is not intended to be extended, the only implementation of this interface
  * should live in the Scalafix repository.
  */
 public interface Scalafix {
 
     /**
-     * @return Construct a new instance of {@link ScalafixArguments} that can be later passed to {@link #runMain(ScalafixArguments) }.
+     * @return Construct a new instance of {@link ScalafixArguments}.
      */
     ScalafixArguments newArguments();
 
@@ -58,15 +67,96 @@ public interface Scalafix {
      */
     String scala213();
 
+    /**
+     * Fetch JARs containing an implementation of {@link Scalafix} using Coursier and classload an instance of it via
+     * runtime reflection.
+     * <p>
+     * The custom classloader optionally provided with {@link ScalafixArguments#withToolClasspath} to compile and
+     * classload external rules must have the classloader of the returned instance as ancestor to share a common
+     * loaded instance of `scalafix-core`, and therefore have been compiled against the requested Scala binary version.
+     *
+     * @param scalaBinaryVersion The Scala binary version ("2.13" for example) available in the classloader of the
+     *                           returned instance. To be able to run advanced semantic rules using the Scala
+     *                           Presentation Compiler such as ExplicitResultTypes, this must match the binary
+     *                           version that the target classpath was built with, as provided with
+     *                           {@link ScalafixArguments#withScalaVersion}.
+     * @return An implementation of the {@link Scalafix} interface.
+     * @throws ScalafixException in case of errors during artifact resolution/fetching.
+     */
+    static Scalafix fetchAndClassloadInstance(String scalaBinaryVersion) throws ScalafixException {
+        return fetchAndClassloadInstance(scalaBinaryVersion, Repository.defaults());
+    }
+
+    /**
+     * Fetch JARs containing an implementation of {@link Scalafix} from the provided repositories using Coursier and
+     * classload an instance of it via runtime reflection.
+     * <p>
+     * The custom classloader optionally provided with {@link ScalafixArguments#withToolClasspath} to compile and
+     * classload external rules must have the classloader of the returned instance as ancestor to share a common
+     * loaded instance of `scalafix-core`, and therefore have been compiled against the requested Scala binary version.
+     *
+     * @param scalaBinaryVersion The Scala binary version ("2.13" for example) available in the classloader of the
+     *                           returned instance. To be able to run advanced semantic rules using the Scala
+     *                           Presentation Compiler such as ExplicitResultTypes, this must match the binary
+     *                           version that the target classpath was built with, as provided with
+     *                           {@link ScalafixArguments#withScalaVersion}.
+     * @param repositories       Maven/Ivy repositories to fetch the JARs from.
+     * @return An implementation of the {@link Scalafix} interface.
+     * @throws ScalafixException in case of errors during artifact resolution/fetching.
+     */
+    static Scalafix fetchAndClassloadInstance(String scalaBinaryVersion, List<Repository> repositories)
+            throws ScalafixException {
+
+        String scalaVersionKey;
+        switch (scalaBinaryVersion) {
+            case "2.11":
+                scalaVersionKey = "scala211";
+                break;
+            case "2.12":
+                scalaVersionKey = "scala212";
+                break;
+            case "2.13":
+                scalaVersionKey = "scala213";
+                break;
+            default:
+                throw new IllegalArgumentException("Unsupported scala version " + scalaBinaryVersion);
+        }
 
+        Properties properties = new Properties();
+        String propertiesPath = "scalafix-interfaces.properties";
+        InputStream stream = Scalafix.class.getClassLoader().getResourceAsStream(propertiesPath);
+        try {
+            properties.load(stream);
+        } catch (IOException | NullPointerException e) {
+            throw new ScalafixException("Failed to load '" + propertiesPath + "' to lookup versions", e);
+        }
+
+        String scalafixVersion = properties.getProperty("scalafixVersion");
+        String scalaVersion = properties.getProperty(scalaVersionKey);
+        if (scalafixVersion == null || scalaVersion == null)
+            throw new ScalafixException("Failed to lookup versions from '" + propertiesPath + "'");
+
+        List<URL> jars = ScalafixCoursier.scalafixCliJars(repositories, scalafixVersion, scalaVersion);
+        ClassLoader parent = new ScalafixInterfacesClassloader(Scalafix.class.getClassLoader());
+        return classloadInstance(new URLClassLoader(jars.stream().toArray(URL[]::new), parent));
+    }
 
     /**
      * JVM runtime reflection method helper to classload an instance of {@link Scalafix}.
+     * <p>
+     * The custom classloader optionally provided with {@link ScalafixArguments#withToolClasspath} to compile and
+     * classload external rules must have the provided classloader as ancestor to share a common loaded instance
+     * of `scalafix-core`, and therefore must have been compiled against the same Scala binary version as
+     * the one in the classLoader provided here.
      *
-     * @param classLoader Classloader containing the full Scalafix classpath, including the scalafix-cli module.
+     * @param classLoader Classloader containing the full Scalafix classpath, including the scalafix-cli module. To be
+     *                    able to run advanced semantic rules using the Scala Presentation Compiler such as
+     *                    ExplicitResultTypes, this Scala binary version in that classloader should match the one that
+     *                    the target classpath was built with, as provided with
+     *                    {@link ScalafixArguments#withScalaVersion}.
      * @return An implementation of the {@link Scalafix} interface.
      * @throws ScalafixException in case of errors during classloading, most likely caused
-     * by an incorrect classloader argument.
+     *                           by an incorrect classloader argument.
      */
     static Scalafix classloadInstance(ClassLoader classLoader) throws ScalafixException {
         try {