Spaces: add before{Apply,Infix}ArgInParens

docs/configuration.md

@@ -4298,6 +4298,68 @@ spaces.afterSymbolicDefs=true
 def +++(a: A): F[A]
 ```
 
+### `spaces.beforeXxxArgInParens`
+
+> Since v3.7.13.
+
+These parameters control whether a space should be added before an argument of
+a function call or infix expression, if the argument is enclosed in parentheses.
+
+They take the following values:
+
+- `Never`: no space is added
+- `Always`: space is added
+- `AfterSymbolic`: space is added if the infix operator or function name is
+  symbolic
+  - doesn't start with a letter or underscore
+  - for function name only (not for infix): not an
+    [unary operator](https://docs.scala-lang.org/scala3/reference/changed-features/operators.html#unary-operators):
+    `+`, `-`, `!`, `~`
+
+```scala mdoc:defaults
+spaces.beforeApplyArgInParens
+spaces.beforeInfixArgInParens
+```
+
+```scala mdoc:scalafmt
+spaces.beforeApplyArgInParens = Always
+spaces.beforeInfixArgInParens = Always
+---
++(baz)
+===(baz)
+bar(baz)
+
+foo +(baz)
+foo ===(baz)
+foo bar(baz)
+```
+
+```scala mdoc:scalafmt
+spaces.beforeApplyArgInParens = Never
+spaces.beforeInfixArgInParens = Never
+---
++ (baz)
+=== (baz)
+bar (baz)
+
+foo + (baz)
+foo === (baz)
+foo bar (baz)
+```
+
+```scala mdoc:scalafmt
+spaces.beforeApplyArgInParens = AfterSymbolic
+spaces.beforeInfixArgInParens = AfterSymbolic
+---
++ (baz)
+===(baz)
+bar (baz)
+
+foo +(baz)
+foo ===(baz)
+foo bar (baz)
+```
+
 ## Literals
 
 > Since v2.5.0.

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

@@ -3,6 +3,7 @@ package org.scalafmt.config
 import scala.meta.tokens.Token
 
 import metaconfig._
+import org.scalafmt.util.TokenOps
 
 /** @param beforeContextBoundColon
   *   formats [A: T] as [A : T]
@@ -47,6 +48,10 @@ import metaconfig._
 case class Spaces(
     beforeContextBoundColon: Spaces.BeforeContextBound =
       Spaces.BeforeContextBound.Never,
+    beforeApplyArgInParens: Spaces.BeforeArgInParens =
+      Spaces.BeforeArgInParens.Never,
+    beforeInfixArgInParens: Spaces.BeforeArgInParens =
+      Spaces.BeforeArgInParens.Always,
     afterTripleEquals: Boolean = false,
     inImportCurlyBraces: Boolean = false,
     inInterpolatedStringCurlyBraces: Boolean = false,
@@ -78,4 +83,25 @@ object Spaces {
     case object IfMultipleBounds extends BeforeContextBound
   }
 
+  sealed abstract class BeforeArgInParens {
+    def apply(name: => String): Boolean
+  }
+  private object BeforeArgInParens {
+    implicit val codec: ConfCodecEx[BeforeArgInParens] = ReaderUtil
+      .oneOfCustom[BeforeArgInParens](Never, Always, AfterSymbolic) {
+        case Conf.Bool(true) => Configured.ok(Always)
+        case Conf.Bool(false) => Configured.ok(Never)
+      }
+
+    case object Never extends BeforeArgInParens {
+      def apply(name: => String): Boolean = false
+    }
+    case object Always extends BeforeArgInParens {
+      def apply(name: => String): Boolean = true
+    }
+    case object AfterSymbolic extends BeforeArgInParens {
+      def apply(name: => String): Boolean = TokenOps.isSymbolicName(name)
+    }
+  }
+
 }

scalafmt-tests/src/test/resources/unit/Apply.stat

@@ -62,3 +62,81 @@ test("foo " +
   case baz =>
   case qux =>
 }
+<<< #3607 beforeApplyArgInParens=always
+spaces.beforeApplyArgInParens = always
+===
+object a {
+  + ()
+  === ()
+  bar ()
+  + (baz)
+  === (baz)
+  bar (baz)
+  + (baz, qux)
+  === (baz, qux)
+  bar (baz, qux)
+}
+>>>
+object a {
+  +()
+  ===()
+  bar()
+  +(baz)
+  ===(baz)
+  bar(baz)
+  +(baz, qux)
+  ===(baz, qux)
+  bar(baz, qux)
+}
+<<< #3607 beforeApplyArgInParens=never
+spaces.beforeApplyArgInParens = never
+===
+object a {
+  + ()
+  === ()
+  bar ()
+  + (baz)
+  === (baz)
+  bar (baz)
+  + (baz, qux)
+  === (baz, qux)
+  bar (baz, qux)
+}
+>>>
+object a {
+  +()
+  ===()
+  bar()
+  +(baz)
+  ===(baz)
+  bar(baz)
+  +(baz, qux)
+  ===(baz, qux)
+  bar(baz, qux)
+}
+<<< #3607 beforeApplyArgInParens=aftersymbolic
+spaces.beforeApplyArgInParens = aftersymbolic
+===
+object a {
+  + ()
+  === ()
+  bar ()
+  + (baz)
+  === (baz)
+  bar (baz)
+  + (baz, qux)
+  === (baz, qux)
+  bar (baz, qux)
+}
+>>>
+object a {
+  +()
+  ===()
+  bar()
+  +(baz)
+  ===(baz)
+  bar(baz)
+  +(baz, qux)
+  ===(baz, qux)
+  bar(baz, qux)
+}

scalafmt-tests/src/test/resources/unit/ApplyInfix.stat

@@ -181,3 +181,99 @@ type x = (X
 type x = (X
   :: Y
   :: Z)
+<<< #3607 beforeInfixArgInParens=always
+spaces.beforeInfixArgInParens = always
+===
+object a {
+  foo + baz
+  foo === baz
+  foo bar baz
+  foo + ()
+  foo === ()
+  foo bar ()
+  foo + (baz)
+  foo === (baz)
+  foo bar (baz)
+  foo + (baz, qux)
+  foo === (baz, qux)
+  foo bar (baz, qux)
+}
+>>>
+object a {
+  foo + baz
+  foo === baz
+  foo bar baz
+  foo + ()
+  foo === ()
+  foo bar ()
+  foo + (baz)
+  foo === (baz)
+  foo bar (baz)
+  foo + (baz, qux)
+  foo === (baz, qux)
+  foo bar (baz, qux)
+}
+<<< #3607 beforeInfixArgInParens=never
+spaces.beforeInfixArgInParens = never
+===
+object a {
+  foo + baz
+  foo === baz
+  foo bar baz
+  foo + ()
+  foo === ()
+  foo bar ()
+  foo + (baz)
+  foo === (baz)
+  foo bar (baz)
+  foo + (baz, qux)
+  foo === (baz, qux)
+  foo bar (baz, qux)
+}
+>>>
+object a {
+  foo + baz
+  foo === baz
+  foo bar baz
+  foo + ()
+  foo === ()
+  foo bar ()
+  foo + (baz)
+  foo === (baz)
+  foo bar (baz)
+  foo + (baz, qux)
+  foo === (baz, qux)
+  foo bar (baz, qux)
+}
+<<< #3607 beforeInfixArgInParens=aftersymbolic
+spaces.beforeInfixArgInParens = aftersymbolic
+===
+object a {
+  foo + baz
+  foo === baz
+  foo bar baz
+  foo + ()
+  foo === ()
+  foo bar ()
+  foo + (baz)
+  foo === (baz)
+  foo bar (baz)
+  foo + (baz, qux)
+  foo === (baz, qux)
+  foo bar (baz, qux)
+}
+>>>
+object a {
+  foo + baz
+  foo === baz
+  foo bar baz
+  foo + ()
+  foo === ()
+  foo bar ()
+  foo + (baz)
+  foo === (baz)
+  foo bar (baz)
+  foo + (baz, qux)
+  foo === (baz, qux)
+  foo bar (baz, qux)
+}