Merge pull request swiftlang#187 from google/format-func-signature-throws

Add a break before the `(re)throws` keyword in a function type.

Author: dabelknap

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -601,6 +601,7 @@ private final class TokenStreamCreator: SyntaxVisitor {
   override func visit(_ node: FunctionTypeSyntax) {
     after(node.leftParen, tokens: .break(size: 0, offset: 2), .open(.consistent, 0))
     before(node.rightParen, tokens: .break(size: 0, offset: -2), .close)
+    before(node.throwsOrRethrowsKeyword, tokens: .break)
     before(node.arrow, tokens: .break)
     before(node.returnType.firstToken, tokens: .break)
     super.visit(node)

Tests/SwiftFormatPrettyPrintTests/FunctionTypeTests.swift

@@ -61,4 +61,67 @@ public class FunctionTypeTests: PrettyPrintTestCase {
 
     assertPrettyPrintEqual(input: input, expected: expected, linelength: 60)
   }
+
+  public func testFunctionTypeThrows() {
+    let input =
+      """
+      func f(g: (_ somevalue: Int) throws -> String?) {
+        let a = 123
+        let b = "abc"
+      }
+      func f(g: (currentLevel: Int) throws -> String?) {
+        let a = 123
+        let b = "abc"
+      }
+      func f(g: (currentLevel: inout Int) throws -> String?) {
+        let a = 123
+        let b = "abc"
+      }
+      func f(g: (variable1: Int, variable2: Double, variable3: Bool) throws -> Double) {
+        let a = 123
+        let b = "abc"
+      }
+      func f(g: (variable1: Int, variable2: Double, variable3: Bool, variable4: String) throws -> Double) {
+        let a = 123
+        let b = "abc"
+      }
+      """
+    
+    let expected =
+      """
+      func f(g: (_ somevalue: Int) throws -> String?) {
+        let a = 123
+        let b = "abc"
+      }
+      func f(g: (currentLevel: Int) throws -> String?) {
+        let a = 123
+        let b = "abc"
+      }
+      func f(g: (currentLevel: inout Int) throws -> String?) {
+        let a = 123
+        let b = "abc"
+      }
+      func f(
+        g: (variable1: Int, variable2: Double, variable3: Bool) throws ->
+        Double
+      ) {
+        let a = 123
+        let b = "abc"
+      }
+      func f(
+        g: (
+          variable1: Int,
+          variable2: Double,
+          variable3: Bool,
+          variable4: String
+        ) throws -> Double
+      ) {
+        let a = 123
+        let b = "abc"
+      }
+
+      """
+    
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 67)
+  }
 }