Additional settings for error handling

build.sbt

@@ -34,7 +34,7 @@ inThisBuild(
 onLoadMessage := s"Welcome to sbt-scalafmt ${version.value}"
 skip in publish := true
 
-val scalafmtVersion = "3.2.0"
+val scalafmtVersion = "3.2.1"
 lazy val plugin = project
   .enablePlugins(SbtPlugin)
   .settings(

plugin/src/main/scala/org/scalafmt/sbt/ErrorHandling.scala

@@ -0,0 +1,7 @@
+package org.scalafmt.sbt
+
+private[sbt] class ErrorHandling(
+    val logOnEachError: Boolean,
+    val failOnErrors: Boolean,
+    val detailedErrorEnabled: Boolean
+)

plugin/src/main/scala/org/scalafmt/sbt/ScalafmtPlugin.scala

@@ -71,6 +71,12 @@ object ScalafmtPlugin extends AutoPlugin {
     val scalafmtFilter = settingKey[String](
       "File filtering mode when running scalafmt."
     )
+    val scalafmtLogOnEachError = settingKey[Boolean](
+      "Enables logging on an error."
+    )
+    val scalafmtFailOnErrors = settingKey[Boolean](
+      "Controls whether to fail in case of formatting errors."
+    )
   }
 
   import autoImport._
@@ -127,13 +133,13 @@ object ScalafmtPlugin extends AutoPlugin {
       resolvers: Seq[Resolver],
       currentProject: ResolvedProject,
       filterMode: String,
-      detailedErrorEnabled: Boolean
+      errorHandling: ErrorHandling
   ) {
     private val log = taskStreams.log
     private val reporter = new ScalafmtSbtReporter(
       log,
       new OutputStreamWriter(taskStreams.binary()),
-      detailedErrorEnabled
+      errorHandling
     )
 
     private val scalafmtSession = {
@@ -179,18 +185,28 @@ object ScalafmtPlugin extends AutoPlugin {
 
     private def withFormattedSources[T](sources: Seq[File])(
         onFormat: (File, Input, Output) => T
-    ): Seq[Option[T]] =
-      sources.map { file =>
+    ): Seq[Option[T]] = {
+      val res = sources.map { file =>
         val path = file.toPath.toAbsolutePath
         Try(IO.read(file)) match {
           case Failure(x) =>
             reporter.error(path, "Failed to read", x)
             None
           case Success(x) =>
-            val output = scalafmtSession.format(path, x)
-            Some(onFormat(file, x, output))
+            val output = scalafmtSession.formatOrError(path, x)
+            /* no need to report on exception since for all errors
+             * reporter.error would have been called already */
+            Option(output.value).map(o => onFormat(file, x, o))
         }
       }
+      val bad = res.count(_ eq None)
+      if (bad != 0) {
+        val err = s"scalafmt: failed for $bad sources"
+        if (errorHandling.failOnErrors) throw new MessageOnlyException(err)
+        log.error(err)
+      }
+      res
+    }
 
     def formatTrackedSources(
         cacheStoreFactory: CacheStoreFactory,
@@ -413,7 +429,11 @@ object ScalafmtPlugin extends AutoPlugin {
         fullResolvers.value,
         thisProject.value,
         scalafmtFilter.value,
-        scalafmtDetailedError.value
+        new ErrorHandling(
+          scalafmtLogOnEachError.value,
+          scalafmtFailOnErrors.value,
+          scalafmtDetailedError.value
+        )
       )
       func(files, session)
     }
@@ -453,7 +473,11 @@ object ScalafmtPlugin extends AutoPlugin {
         fullResolvers.value,
         thisProject.value,
         "",
-        scalafmtDetailedError.value
+        new ErrorHandling(
+          scalafmtLogOnEachError.value,
+          scalafmtFailOnErrors.value,
+          scalafmtDetailedError.value
+        )
       ).formatSources(absFiles)
     }
   )
@@ -480,6 +504,8 @@ object ScalafmtPlugin extends AutoPlugin {
     Seq(
       scalafmtFilter := "",
       scalafmtOnCompile := false,
+      scalafmtLogOnEachError := false,
+      scalafmtFailOnErrors := true,
       scalafmtDetailedError := false
     )
 

plugin/src/main/scala/org/scalafmt/sbt/ScalafmtSbtReporter.scala

@@ -12,7 +12,7 @@ import org.scalafmt.interfaces.ScalafmtReporter
 class ScalafmtSbtReporter(
     log: Logger,
     out: OutputStreamWriter,
-    detailedErrorEnabled: Boolean
+    errorHandling: ErrorHandling
 ) extends ScalafmtReporter {
   import ScalafmtSbtReporter._
 
@@ -23,25 +23,31 @@ class ScalafmtSbtReporter(
     error(file, null, e)
 
   override def error(file: Path, message: String, e: Throwable): Unit = {
-    def getMessage() = {
+    def getMessage(toThrow: Boolean) = {
       val res = new StringWriter()
-      res.write("scalafmt: ")
-      res.write(Option(message).getOrElse("failed"))
+      if (toThrow) res.write("scalafmt: ")
+      val nestedMessage = if (e == null) None else Option(e.getMessage)
+      val messageOpt = Option(message).orElse(nestedMessage)
+      res.write(messageOpt.getOrElse("failed"))
       res.write(" [")
       res.write(file.toString)
       res.write(']')
-      if (null != e) {
-        if (!detailedErrorEnabled)
-          Option(e.getMessage).foreach { x =>
-            res.write(" ")
-            res.write(x)
-          }
+      if (null != e && !toThrow) {
+        if (errorHandling.detailedErrorEnabled)
+          e.printStackTrace(new PrintWriter(res))
+        else if (messageOpt ne nestedMessage) nestedMessage.foreach { x =>
+          res.write(": ")
+          res.write(x)
+        }
       }
       res.toString
     }
 
-    val cause = if (detailedErrorEnabled) e else null
-    throw new ScalafmtSbtError(getMessage(), cause)
+    if (errorHandling.logOnEachError) log.error(getMessage(false))
+    else if (errorHandling.failOnErrors) {
+      val cause = if (errorHandling.detailedErrorEnabled) e else null
+      throw new ScalafmtSbtError(getMessage(true), cause)
+    }
   }
 
   override def excluded(file: Path): Unit =
@@ -57,6 +63,6 @@ class ScalafmtSbtReporter(
 object ScalafmtSbtReporter {
 
   private class ScalafmtSbtError(message: String, cause: Throwable)
-      extends RuntimeException(message, cause)
+      extends RuntimeException(message, cause, true, cause != null)
 
 }

plugin/src/sbt-test/scalafmt-sbt/sbt/changes/invalid.scala

@@ -0,0 +1,3 @@
+object Test {
+  foo(a, b // ) invalid
+}

plugin/src/sbt-test/scalafmt-sbt/sbt/test

@@ -176,6 +176,16 @@ $ exec git -C p17 add "src/main/scala/TestBad2.scala"
 # now commit it, no longer modified
 $ exec git -C p17 commit -m 'added TestBad2.scala'
 > p17/scalafmtCheck
+# don't filter but fail after all errors
+> set p17/scalafmtFilter := ("")
+$ copy-file changes/invalid.scala p17/src/main/scala/TestInvalid1.scala
+$ copy-file changes/invalid.scala p17/src/main/scala/TestInvalid2.scala
+-> p17/scalafmt
+# fail after all errors
+> set p17/scalafmtLogOnEachError := true
+-> p17/scalafmt
+> set p17/scalafmtFailOnErrors := false
+> p17/scalafmt
 
 $ copy-file changes/target/managed.scala project/target/managed.scala
 $ copy-file changes/x/Something.scala project/x/Something.scala