[SR-13026] Formatted string initializer doesn't handle indexed arguments correctly

[swift-ci]

Previous ID	SR-13026
Radar	None
Original Reporter	arakul163 (JIRA User)
Type	Bug

Environment

Apple Swift version 5.1.3 (swiftlang-1100.0.282.1 clang-1100.0.33.15)

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Bug
Assignee	None
Priority	Medium

md5: d2dac59268fe35e55144f9eaa1453c67

Issue Description:

Description

Formatted string initializer doesn't handle indexed argument correctly if there's only one placeholder in format string.

Playground Code

import Foundation


let stringOne = String(format: "%2$@", "World", "Hello")
print(stringOne)


let stringTwo = String(format: "%2$@ %1$@", "World", "Hello", "!")
print(stringTwo)

Actual Output

World
Hello World

Expected Output

Hello
Hello World