Control Characters In String

Reports a string literal whose source contains a raw control or zero-width (invisible) Unicode rune.

Control characters and zero-width / directional format characters are invisible in most editors and code-review tools. Embedded raw in a string literal they silently change its value, and because no one can see them they are a common source of confusing bugs (a string that "looks right" but does not compare equal) and a known vector for hiding malicious differences in a review. Writing the same character as an explicit escape keeps the value identical while making it visible. The check flags only raw runes embedded directly in the source; an escaped control character is left alone, as are ordinary tab/newline whitespace in raw string literals.

Replace the raw rune with its explicit escape (for example ​ or \a), or remove it if it was pasted in by accident.