Router: handle parameter indent.fewerBraces

docs/configuration.md

@@ -589,6 +589,82 @@ foo // c1
 }
 ```
 
+#### `indent.fewerBraces`
+
+This parameter controls whether extra `indent.main` is added
+to the sole argument of a method call using the "fewer braces"
+syntax. The following values are supported:
+
+- `always`: always applies extra indent
+- `never`: doesn't apply any extra indent
+- `beforeSelect`: applies extra indent only to fewer-braces
+  expressions followed by a `.select`
+
+```scala mdoc:defaults
+indent.fewerBraces
+```
+
+> In Scala 3.3.0, only `never` provides compiler-compatible code.
+> Other options will work in 3.3.1-RC1 and later
+> (see [Parser section](https://github.com/lampepfl/dotty/releases/tag/3.3.1-RC1)).
+
+```scala mdoc:scalafmt
+runner.dialect = Scala3
+indent.significant = 3
+indent.fewerBraces = always
+---
+bar:
+  2 + 2
+
+foo.bar:
+  2 + 2
+
+foo:
+  2 + 2
+.bar:
+  3 + 3
+.baz // c
+.qux
+```
+
+```scala mdoc:scalafmt
+runner.dialect = Scala3
+indent.significant = 3
+indent.fewerBraces = never
+---
+bar:
+  2 + 2
+
+foo.bar:
+  2 + 2
+
+foo:
+  2 + 2
+.bar:
+  3 + 3
+.baz // c
+.qux
+```
+
+```scala mdoc:scalafmt
+runner.dialect = Scala3
+indent.significant = 3
+indent.fewerBraces = beforeSelect
+---
+bar:
+  2 + 2
+
+foo.bar:
+  2 + 2
+
+foo:
+  2 + 2
+.bar:
+  3 + 3
+.baz // c
+.qux
+```
+
 ### Indent for `binPack.unsafeCallSite`
 
 Normally, even when binpacking, there's a new level of indentation added for

scalafmt-core/shared/src/main/scala/org/scalafmt/config/Indents.scala

@@ -32,6 +32,7 @@ case class Indents(
     private[config] val ctorSite: Option[Int] = None,
     extraBeforeOpenParenDefnSite: Int = 0,
     relativeToLhsLastLine: Seq[Indents.RelativeToLhs] = Nil,
+    fewerBraces: Indents.FewerBraces = Indents.FewerBraces.never,
     @annotation.ExtraName("deriveSite")
     extendSite: Int = 4,
     withSiteRelativeToExtends: Int = 0,
@@ -62,4 +63,15 @@ object Indents {
     implicit val reader: ConfCodecEx[RelativeToLhs] = ReaderUtil
       .oneOf[RelativeToLhs](`match`, `infix`)
   }
+
+  sealed abstract class FewerBraces
+  object FewerBraces {
+    case object never extends FewerBraces
+    case object always extends FewerBraces
+    case object beforeSelect extends FewerBraces
+
+    implicit val reader: ConfCodecEx[FewerBraces] = ReaderUtil
+      .oneOf[FewerBraces](never, always, beforeSelect)
+  }
+
 }

scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala

@@ -4,6 +4,7 @@ import org.scalafmt.Error.UnexpectedTree
 import org.scalafmt.config.{
   BinPack,
   IndentOperator,
+  Indents,
   Newlines,
   ScalafmtConfig,
   ScalafmtRunner,
@@ -2076,17 +2077,34 @@ class FormatOps(
                 .withSingleLine(opt)
                 .andPolicy(decideNewlinesOnlyAfterToken(opt))
             }
+            val indent = t.parent match {
+              case Some(p: Term.Apply) =>
+                @tailrec
+                def isSelect(ma: Member.Apply): Boolean = ma.fun match {
+                  case x: Member.Apply => isSelect(x)
+                  case x => x.is[Term.Select]
+                }
+                val ok = (style.indent.fewerBraces match {
+                  case Indents.FewerBraces.never => true
+                  case Indents.FewerBraces.always => false
+                  case Indents.FewerBraces.beforeSelect =>
+                    !p.parent.exists(_.is[Term.Select])
+                }) || isSelect(p)
+                if (ok) None // select is taken care off elsewhere
+                else Some(style.indent.main + style.indent.getSignificant)
+              case _ => None
+            }
             Some(new OptionalBracesRegion {
               def owner = t.parent
               def splits = Some(t.values match {
                 case (tf: Term.FunctionTerm) :: Nil
                     if !style.newlines.alwaysBeforeCurlyLambdaParams &&
                       t.parent.exists(_.is[Term.Apply]) =>
-                  getSplits(ft, t, forceNL = false) match {
+                  getSplits(ft, t, forceNL = false, indentOpt = indent) match {
                     case s +: rs if !s.isNL => funcSplit(tf)(s.fileLine) +: rs
                     case ss => ss
                   }
-                case _ => getSplits(ft, t, forceNL = true)
+                case _ => getSplits(ft, t, forceNL = true, indentOpt = indent)
               })
               def rightBrace = treeLast(t)
             })

scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala

@@ -1,7 +1,7 @@
 package org.scalafmt.internal
 
 import org.scalafmt.Error.UnexpectedTree
-import org.scalafmt.config.{Align, BinPack}
+import org.scalafmt.config.{Align, BinPack, Indents}
 import org.scalafmt.config.{ImportSelectors, Newlines, ScalafmtConfig, Spaces}
 import org.scalafmt.internal.ExpiresOn.{After, Before}
 import org.scalafmt.internal.Length.{Num, StateColumn}
@@ -1770,11 +1770,18 @@ class Router(formatOps: FormatOps) {
         val baseSplits = style.newlines.getSelectChains match {
           case Newlines.classic =>
             def getNlMod = {
-              val endSelect = nextSelect.fold(expire) { x =>
-                nextDotIfSig.fold(getLastNonTrivialToken(x.qual))(_.left)
+              val endSelect = nextDotIfSig.fold {
+                nextSelect.fold {
+                  val ko = style.indent.fewerBraces ==
+                    Indents.FewerBraces.always && checkFewerBraces(expireTree)
+                  if (ko) None else Some(expire)
+                } { ns => Some(getLastNonTrivialToken(ns.qual)) }
+              } { nd =>
+                val ok = style.indent.fewerBraces == Indents.FewerBraces.never
+                if (ok) Some(nd.left) else None
               }
-              val altIndent = Indent(-indentLen, endSelect, After)
-              NewlineT(alt = Some(ModExt(NoSplit).withIndent(altIndent)))
+              val altIndent = endSelect.map(Indent(-indentLen, _, After))
+              NewlineT(alt = Some(ModExt(NoSplit).withIndentOpt(altIndent)))
             }
 
             val prevChain = inSelectChain(prevSelect, thisSelect, expireTree)
@@ -1902,8 +1909,8 @@ class Router(formatOps: FormatOps) {
         }
 
         // trigger indent only on the first newline
-        val noIndent =
-          checkFewerBraces(thisSelect.qual)
+        val fbIndent = style.indent.fewerBraces != Indents.FewerBraces.never
+        val noIndent = !fbIndent && checkFewerBraces(thisSelect.qual)
         val nlIndent =
           if (noIndent) Indent.Empty else Indent(indentLen, expire, After)
         val spcPolicy = delayedBreakPolicyOpt
@@ -1913,9 +1920,16 @@ class Router(formatOps: FormatOps) {
             // will break
             baseSplits.map(_.withIndent(nlIndent).andFirstPolicyOpt(nlPolicy))
           else {
+            val spcIndent = nextDotIfSig.fold {
+              val ok = style.indent.fewerBraces == Indents.FewerBraces.always &&
+                nextSelect.isEmpty && checkFewerBraces(expireTree)
+              if (ok) nlIndent else Indent.empty
+            } { x =>
+              if (fbIndent) Indent(indentLen, x.left, Before) else Indent.Empty
+            }
             baseSplits.map { s =>
               if (s.isNL) s.withIndent(nlIndent).andFirstPolicyOpt(nlPolicy)
-              else s.andFirstPolicyOpt(spcPolicy)
+              else s.withIndent(spcIndent).andFirstPolicyOpt(spcPolicy)
             }
           }