modernize-raw-string-literal

This check selectively replaces string literals containing escaped characters with raw string literals.

Example:

const char *const Quotes{"embedded \"quotes\""};
const char *const Paragraph{"Line one.\nLine two.\nLine three.\n"};
const char *const SingleLine{"Single line.\n"};
const char *const TrailingSpace{"Look here -> \n"};
const char *const Tab{"One\tTwo\n"};
const char *const Bell{"Hello!\a  And welcome!"};
const char *const Path{"C:\\Program Files\\Vendor\\Application.exe"};
const char *const RegEx{"\\w\\([a-z]\\)"};

becomes

const char *const Quotes{R"(embedded "quotes")"};
const char *const Paragraph{"Line one.\nLine two.\nLine three.\n"};
const char *const SingleLine{"Single line.\n"};
const char *const TrailingSpace{"Look here -> \n"};
const char *const Tab{"One\tTwo\n"};
const char *const Bell{"Hello!\a  And welcome!"};
const char *const Path{R"(C:\Program Files\Vendor\Application.exe)"};
const char *const RegEx{R"(\w\([a-z]\))"};

The presence of any of the following escapes can cause the string to be converted to a raw string literal: \\, \', \", \?, and octal or hexadecimal escapes for printable ASCII characters.

A string literal containing only escaped newlines is a common way of writing lines of text output. Introducing physical newlines with raw string literals in this case is likely to impede readability. These string literals are left unchanged.

An escaped horizontal tab, form feed, or vertical tab prevents the string literal from being converted. The presence of a horizontal tab, form feed or vertical tab in source code is not visually obvious.