From 191094c758ae97c517952a2a038745b7581b6464 Mon Sep 17 00:00:00 2001
From: Dylan Sturgeon <dylansturg@google.com>
Date: Tue, 6 Oct 2020 16:57:56 -0700
Subject: [PATCH] Handle #if clauses inside of switch statements.

The special IfConfigDecl, aka `#if`, can exist in the `cases` of a SwitchStmtSyntax because the `#if` "wraps" one or more switch cases. These weren't being considered for the purposes of indenting the cases. There were also no breaks between the switch statement's left brace and `#if` when `#if` was the first "case" which caused malformed code.

I have opted to treat `indentSwitchCaseLabels` as also indenting the `#if` cases in a switch statement, because that makes the `#if` here consistent with other locations.
---
 .../TokenStreamCreator.swift                  | 11 +++
 .../SwitchStmtTests.swift                     | 95 +++++++++++++++++++
 2 files changed, 106 insertions(+)

diff --git a/Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift b/Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift
index 1b7eb32a0..a6d50aec6 100644
--- a/Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift
+++ b/Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift
@@ -640,6 +640,17 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     before(node.leftBrace, tokens: .break(.reset))
     after(node.leftBrace, tokens: .close)
 
+    // An if-configuration clause around a switch-case encloses the case's node, so an
+    // if-configuration clause requires a break here in order to be allowed on a new line.
+    for ifConfigDecl in node.cases.filter({ $0.is(IfConfigDeclSyntax.self) }) {
+      if config.indentSwitchCaseLabels {
+        before(ifConfigDecl.firstToken, tokens: .break(.open))
+        after(ifConfigDecl.lastToken, tokens: .break(.close, size: 0))
+      } else {
+        before(ifConfigDecl.firstToken, tokens: .break(.same))
+      }
+    }
+
     let newlines: NewlineBehavior =
       areBracesCompletelyEmpty(node, contentsKeyPath: \.cases) ? .elective : .soft
     before(node.rightBrace, tokens: .break(.same, size: 0, newlines: newlines))
diff --git a/Tests/SwiftFormatPrettyPrintTests/SwitchStmtTests.swift b/Tests/SwiftFormatPrettyPrintTests/SwitchStmtTests.swift
index 44f51097c..365e8ce36 100644
--- a/Tests/SwiftFormatPrettyPrintTests/SwitchStmtTests.swift
+++ b/Tests/SwiftFormatPrettyPrintTests/SwitchStmtTests.swift
@@ -1,3 +1,5 @@
+import SwiftFormatConfiguration
+
 final class SwitchStmtTests: PrettyPrintTestCase {
   func testBasicSwitch() {
     let input =
@@ -332,4 +334,97 @@ final class SwitchStmtTests: PrettyPrintTestCase {
 
     assertPrettyPrintEqual(input: input, expected: expected, linelength: 20)
   }
+
+  func testConditionalCases() {
+    let input =
+      """
+      switch foo {
+      #if CONDITION_A
+      case bar:
+        callForBar()
+      #endif
+      case baz:
+        callForBaz()
+      }
+      switch foo2 {
+      case bar2:
+        callForBar()
+      #if CONDITION_B
+      case baz2:
+        callForBaz()
+      #endif
+      }
+      """
+
+    let expected =
+      """
+      switch foo {
+      #if CONDITION_A
+        case bar:
+          callForBar()
+      #endif
+      case baz:
+        callForBaz()
+      }
+      switch foo2 {
+      case bar2:
+        callForBar()
+      #if CONDITION_B
+        case baz2:
+          callForBaz()
+      #endif
+      }
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 40)
+  }
+
+  func testConditionalCasesIndenting() {
+    let input =
+      """
+      switch foo {
+      #if CONDITION_A
+      case bar:
+        callForBar()
+      #endif
+      case baz:
+        callForBaz()
+      }
+      switch foo2 {
+      case bar2:
+        callForBar()
+      #if CONDITION_B
+      case baz2:
+        callForBaz()
+      #endif
+      }
+      """
+
+    let expected =
+      """
+      switch foo {
+        #if CONDITION_A
+          case bar:
+            callForBar()
+        #endif
+        case baz:
+          callForBaz()
+      }
+      switch foo2 {
+        case bar2:
+          callForBar()
+        #if CONDITION_B
+          case baz2:
+            callForBaz()
+        #endif
+      }
+
+      """
+
+    var configuration = Configuration()
+    configuration.indentSwitchCaseLabels = true
+    assertPrettyPrintEqual(
+      input: input, expected: expected, linelength: 40, configuration: configuration)
+  }
 }