Add convenience initializer for ReturnClause

Author: kimdv

Sources/SwiftSyntaxBuilder/ReturnClauseConvenienceInitializers.swift

@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2021 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftSyntax
+
+extension ReturnClause: ExpressibleByStringLiteral {
+  public init(stringLiteral value: String) {
+    self.init(returnType: value)
+  }
+}

Sources/SwiftSyntaxBuilder/StringConvenienceInitializers.swift

@@ -34,6 +34,12 @@ extension String: ExpressibleAsStringLiteralExpr {
   }
 }
 
+extension String: ExpressibleAsReturnClause {
+  public func createReturnClause() -> ReturnClause {
+    ReturnClause(stringLiteral: self)
+  }
+}
+
 /// Default conformance to `ExpressibleByTypeBuildable`
 extension String {
   public func createTypeBuildable() -> TypeBuildable {

Tests/SwiftSyntaxBuilderTest/FunctionTests.swift

@@ -14,7 +14,7 @@ final class FunctionTests: XCTestCase {
       ReturnStmt(expression: IntegerLiteralExpr(digits: "n"))
     })
 
-    let signature = FunctionSignature(input: input, output: ReturnClause(returnType: "Int"))
+    let signature = FunctionSignature(input: input, output: "Int")
 
 
     let codeBlock = CodeBlock(statementsBuilder: {