Invisible Character

Disallows invisible characters like zero-width space (U+200B), zero-width non-joiner (U+200C), and FEFF formatting character (U+FEFF) in string literals as they can cause hard-to-debug issues.

• Identifier: invisible_character
• Enabled by default: Yes
• Supports autocorrection: Yes
• Kind: lint
• Analyzer rule: No
• Minimum Swift compiler version: 5.0.0
• Default configuration:

  Key	Value
  severity	error
  additional_code_points	[“200B”, “200C”, “FEFF”]

Non Triggering Examples

let s = "HelloWorld"

let s = "Hello World"

let url = "https://example.com/api"

let s = #"Hello World"#

let multiline = """
Hello
World
"""

let empty = ""

let tab = "Hello\tWorld"

let newline = "Hello\nWorld"

let unicode = "Hello 👋 World"

Triggering Examples

let s = "Hello↓​World" // U+200B zero-width space

let s = "Hello↓‌World" // U+200C zero-width non-joiner

let s = "Hello↓World" // U+FEFF formatting character

let url = "https://example↓​.com" // U+200B in URL

// U+200B in multiline string
let multiline = """
Hello↓​World
"""

let s = "Test↓​String↓Here" // Multiple invisible characters

let s = "Hel↓‌lo" + "World" // string concatenation with U+200C

let s = "Hel↓‌lo \(name)" // U+200C in interpolated string

//
// additional_code_points: ["AD", "200B", "200C", "FEFF"]
//

//
// additional_code_points: ["00AD"]
//
let s = "Hello↓­World"

//
// additional_code_points: ["200B", "200C", "200D", "FEFF"]
//

//
// additional_code_points: ["200D"]
//
let s = "Hello↓‍World"