Add a consistent group around if-stmts.

The consistent group forces the bodies of if-stmts with else clauses to have breaks around all braces when the stmt spans multiple lines. Previously. the breaks around the braces only fired if the body didn't fit on the line. That behavior lead to hard to read if-stmts because if was unclear where conditions stopped and the body started.

Author: dylansturg

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -444,6 +444,12 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
   // MARK: - Control flow statement nodes
 
   override func visit(_ node: IfStmtSyntax) -> SyntaxVisitorContinueKind {
+    // There may be a consistent breaking group around this node, see `CodeBlockItemSyntax`. This
+    // group is necessary so that breaks around and inside of the conditions aren't forced to break
+    // when the if-stmt spans multiple lines.
+    before(node.conditions.firstToken, tokens: .open)
+    after(node.conditions.lastToken, tokens: .close)
+
     after(node.labelColon, tokens: .space)
     after(node.ifKeyword, tokens: .space)
 
@@ -1287,6 +1293,13 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
       appendFormatterIgnored(node: Syntax(node))
       return .skipChildren
     }
+
+    // This group applies to a top-level if-stmt so that all of the bodies will have the same
+    // breaking behavior.
+    if let ifStmt = node.item.as(IfStmtSyntax.self), ifStmt.elseBody != nil {
+      before(ifStmt.firstToken, tokens: .open(.consistent))
+      after(ifStmt.lastToken, tokens: .close)
+    }
     return .visitChildren
   }
 

Tests/SwiftFormatPrettyPrintTests/IfStmtTests.swift

@@ -515,4 +515,49 @@ final class IfStmtTests: PrettyPrintTestCase {
 
     assertPrettyPrintEqual(input: input, expected: expected, linelength: 50)
   }
+
+  func testMultipleIfStmts() {
+    let input =
+      """
+      if foo && bar { baz() } else if bar { baz() } else if foo { baz() } else { blargh() }
+      if foo && bar && quxxe { baz() } else if bar { baz() } else if foo { baz() } else if quxxe { baz() } else { blargh() }
+      if let foo = getmyfoo(), let bar = getmybar(), foo.baz && bar.baz { foo() } else { bar() }
+      if let foo = getmyfoo(), let bar = getmybar(), foo.baz && bar.baz && someOtherCondition { foo() } else { bar() }
+      if let foo = getmyfoo(), let bar = getmybar(), foo.baz && bar.baz && someOtherCondition { foo() }
+      """
+
+    let expected =
+      """
+      if foo && bar { baz() } else if bar { baz() } else if foo { baz() } else { blargh() }
+      if foo && bar && quxxe {
+        baz()
+      } else if bar {
+        baz()
+      } else if foo {
+        baz()
+      } else if quxxe {
+        baz()
+      } else {
+        blargh()
+      }
+      if let foo = getmyfoo(), let bar = getmybar(), foo.baz && bar.baz {
+        foo()
+      } else {
+        bar()
+      }
+      if let foo = getmyfoo(), let bar = getmybar(),
+        foo.baz && bar.baz && someOtherCondition
+      {
+        foo()
+      } else {
+        bar()
+      }
+      if let foo = getmyfoo(), let bar = getmybar(),
+        foo.baz && bar.baz && someOtherCondition
+      { foo() }
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 85)
+  }
 }

Tests/SwiftFormatPrettyPrintTests/XCTestManifests.swift

@@ -410,6 +410,7 @@ extension IfStmtTests {
         ("testIfStatement", testIfStatement),
         ("testLabeledIfStmt", testLabeledIfStmt),
         ("testMatchingPatternConditions", testMatchingPatternConditions),
+        ("testMultipleIfStmts", testMultipleIfStmts),
         ("testOptionalBindingConditions", testOptionalBindingConditions),
         ("testParenthesizedClauses", testParenthesizedClauses),
     ]