Add option to specify custom location of .scalafmt.conf for fmt command.

Author: wleczny

modules/cli-options/src/main/scala/scala/cli/commands/FmtOptions.scala

@@ -46,6 +46,10 @@ final case class FmtOptions(
     scalafmtArg: List[String] = Nil,
 
   @Group("Format")
+  @HelpMessage("Custom path to the scalafmt configuration file.")
+  @Name("scalafmtConfig")
+    scalafmtConf: Option[String] = None,
+  @Group("Format")
   @HelpMessage("Pass a global dialect for scalafmt. This overrides whatever value is configured in the .scalafmt.conf file.")
   @Name("dialect")
     scalafmtDialect: Option[String] = None,

modules/cli/src/main/scala/scala/cli/commands/Fmt.scala

@@ -37,9 +37,10 @@ object Fmt extends ScalaCommand[FmtOptions] {
         (s, i.workspace, Some(i))
       }
     CurrentParams.workspaceOpt = Some(workspace)
-    val (versionMaybe, dialectMaybe, pathMaybe) = readVersionAndDialectFromFile(workspace, logger)
-    val cache                                   = options.shared.buildOptions().archiveCache
-    val buildOptions                            = options.buildOptions
+    val (versionMaybe, dialectMaybe, pathMaybe) =
+      readVersionAndDialectFromFile(workspace, options.scalafmtConf, logger)
+    val cache        = options.shared.buildOptions().archiveCache
+    val buildOptions = options.buildOptions
 
     if (sourceFiles.isEmpty)
       logger.debug("No source files, not formatting anything")

modules/cli/src/main/scala/scala/cli/commands/util/FmtUtil.scala

@@ -35,6 +35,7 @@ object FmtUtil {
     */
   def readVersionAndDialectFromFile(
     workspace: os.Path,
+    customConfPath: Option[String],
     logger: Logger
   ): (Option[String], Option[String], Option[os.Path]) = {
     case class RunnerMetaconfig(dialect: String = "")
@@ -58,17 +59,25 @@ object FmtUtil {
     }
 
     val confName = ".scalafmt.conf"
-    val pathMaybe = {
-      logger.debug(s"Checking for $confName in cwd.")
-      val confInCwd = workspace / confName
-      if (os.exists(confInCwd)) Some(confInCwd)
-      else {
-        logger.debug(s"Checking for $confName in git root.")
-        val gitRootMaybe       = getGitRoot(workspace, logger)
-        val confInGitRootMaybe = gitRootMaybe.map(os.Path(_) / confName)
-        confInGitRootMaybe.find(os.exists(_))
+    val pathMaybe =
+      customConfPath.flatMap { p =>
+        val confPath = os.Path(p, os.pwd)
+        logger.debug(s"Checking for $confPath.")
+        if (os.exists(confPath)) Some(confPath)
+        else
+          logger.message(s"WARNING: provided file doesn't exist $confPath")
+          None
+      }.orElse {
+        logger.debug(s"Checking for $confName in cwd.")
+        val confInCwd = workspace / confName
+        if (os.exists(confInCwd)) Some(confInCwd)
+        else {
+          logger.debug(s"Checking for $confName in git root.")
+          val gitRootMaybe       = getGitRoot(workspace, logger)
+          val confInGitRootMaybe = gitRootMaybe.map(os.Path(_) / confName)
+          confInGitRootMaybe.find(os.exists(_))
+        }
       }
-    }
 
     val confContentMaybe = pathMaybe.flatMap { path =>
       val either = metaconfig.Hocon.parseInput[ScalafmtMetaconfig](

modules/cli/src/test/scala/cli/tests/ScalafmtTest.scala

@@ -16,15 +16,15 @@ class ScalafmtTests extends munit.FunSuite {
       os.write(confFilePath, confFile)
 
       val readVersionAndDialect =
-        FmtUtil.readVersionAndDialectFromFile(workspace = dirPath, TestLogger())
+        FmtUtil.readVersionAndDialectFromFile(workspace = dirPath, None, TestLogger())
       expect(readVersionAndDialect == (Some("3.1.2"), Some("scala213"), Some(confFilePath)))
     }
   }
 
   test("readVersionFromFile with missing .scalafmt.conf file") {
     TestInputs.withTmpDir("temp-dir") { dirPath =>
       val readVersionAndDialect =
-        FmtUtil.readVersionAndDialectFromFile(workspace = dirPath, TestLogger())
+        FmtUtil.readVersionAndDialectFromFile(workspace = dirPath, None, TestLogger())
       expect(readVersionAndDialect == (None, None, None))
     }
   }

modules/integration/src/test/scala/scala/cli/integration/FmtTests.scala

@@ -54,6 +54,16 @@ class FmtTests extends ScalaCliSuite {
     os.rel / "Foo.scala"  -> simpleInputsUnformattedContent
   )
 
+  val simpleInputsWithCustomConfLocation: TestInputs = TestInputs(
+    Seq(
+      os.rel / "custom.conf" ->
+        s"""|version = "3.5.5"
+            |runner.dialect = scala213
+            |""".stripMargin,
+      os.rel / "Foo.scala" -> simpleInputsUnformattedContent
+    )
+  )
+
   private def noCrLf(input: String): String =
     input.replaceAll("\r\n", "\n")
 
@@ -139,6 +149,19 @@ class FmtTests extends ScalaCliSuite {
     }
   }
 
+  test("--scalafmt-conf") {
+    simpleInputsWithCustomConfLocation.fromRoot { root =>
+      os.proc(TestUtil.cli, "fmt", ".", "--scalafmt-conf", "custom.conf").call(cwd = root)
+      val confLines      = os.read.lines(root / Constants.workspaceDirName / confFileName)
+      val versionInConf  = confLines(0).stripPrefix("version = ").trim
+      val dialectInConf  = confLines(1).stripPrefix("runner.dialect = ").trim
+      val updatedContent = noCrLf(os.read(root / "Foo.scala"))
+      expect(versionInConf == "\"3.5.5\"")
+      expect(dialectInConf == "scala213")
+      expect(updatedContent == expectedSimpleInputsFormattedContent)
+    }
+  }
+
   test("creating workspace conf file") {
     simpleInputsWithDialectOnly.fromRoot { root =>
       val workspaceConfPath = root / Constants.workspaceDirName / confFileName

website/docs/commands/fmt.md

@@ -153,7 +153,7 @@ scala-cli fmt . --check --respect-project-filters=false
 
 The Scala CLI `fmt` command runs `scalafmt` under the hood, which *normally* requires `.scalafmt.conf` configuration file with explicitly specified **version** and **dialect** fields. The way it is handled by Scala CLI is as follows:
 
-At the beginning `fmt` looks for existing `.scalafmt.conf` file inside **current workspace** directory and if it doesn't find it - inside **git root** directory. There are 3 possible cases:
+At the beginning `fmt` looks for the configuration inside the file specified in the `--scalafmt-conf` option. If the option is not passed or the file doesn't exist, `fmt` looks for the existing configuration file inside **current workspace** directory. If the file is still not found, `fmt` looks for it inside **git root** directory. There are 3 possible cases:
 
 1. Configuration file with the specified version and dialect is found.
 2. Configuration file is found, but it doesn't have specified version or dialect.

website/docs/reference/cli-options.md

@@ -522,6 +522,12 @@ Show help for scalafmt. This is an alias for --scalafmt-arg -help
 
 Aliases: `-F`
 
+#### `--scalafmt-conf`
+
+Aliases: `--scalafmt-config`
+
+Custom path to the scalafmt configuration file.
+
 #### `--scalafmt-dialect`
 
 Aliases: `--dialect`