Newlines: add forceBeforeAssign

docs/configuration.md

@@ -1746,6 +1746,19 @@ class A {
 }
 ```
 
+### `newlines.forceBeforeAssign`
+
+> Since v3.5.9
+
+```scala mdoc:defaults
+newlines.forceBeforeAssign
+```
+
+This parameter takes precedence over
+[`newlines.forceBeforeMultilineAssign`](#newlinesforcebeforemultilineassign)
+and uses the same values. The difference is, the rule forces a newline before a
+matching assignment expression whether or not it can be formatted on a single line.
+
 ### `newlines.beforeTypeBounds`
 
 > Since v3.0.0

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

@@ -180,6 +180,8 @@ case class Newlines(
     @annotation.ExtraName("usingParamListModifierPrefer")
     implicitParamListModifierPrefer: Option[BeforeAfter] = None,
     alwaysBeforeElseAfterCurlyIf: Boolean = false,
+    forceBeforeAssign: ForceBeforeMultilineAssign =
+      ForceBeforeMultilineAssign.never,
     private val forceBeforeMultilineAssign: Option[ForceBeforeMultilineAssign] =
       None,
     @annotation.DeprecatedName(

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

@@ -2638,6 +2638,8 @@ class Router(formatOps: FormatOps) {
       Seq(CtrlBodySplits.withIndent(Split(Space.orNL(ft.noBreak), 0), ft, body))
     else if (isJsNative(body))
       Seq(Split(Space, 0).withSingleLine(expire))
+    else if (style.newlines.forceBeforeAssign(ft.meta.leftOwner))
+      Seq(CtrlBodySplits.withIndent(Split(Newline, 0), ft, body))
     else if (style.newlines.shouldForceBeforeMultilineAssign(ft.meta.leftOwner))
       CtrlBodySplits.slbOnly(ft, body, spaceIndents) { x =>
         CtrlBodySplits.withIndent(Split(Newline, x), ft, body)

scalafmt-tests/src/test/resources/newlines/source_unfold.stat

@@ -6121,3 +6121,11 @@ class Foo() {
         a + b
       }.foo
 }
+<<< #3271
+newlines.forceBeforeAssign = def
+===
+def sum(a: Int, b: Int): Int =
+  a + b
+>>>
+def sum(a: Int, b: Int): Int =
+  a + b