As discussed at https://internals.rust-lang.org/t/improvements-to-asciiext/4689 I have added is_ascii_* equivalents of most (not quite all) of C's ctype.h's isxxx functions to the AsciiExt trait.

The new functions are

• is_ascii_alphabetic
• is_ascii_uppercase
• is_ascii_lowercase
• is_ascii_alphanumeric
• is_ascii_digit
• is_ascii_hexdigit
• is_ascii_punctuation
• is_ascii_graphic
• is_ascii_whitespace (matches the Infra Standard definition of ASCII whitespace, not POSIX)
• is_ascii_control

They are implemented for char, u8, str, and [u8], and, for backward compatibility with external trait implementations, have default implementations that call unimplemented!().

PR to follow, but I needed to file this bug in order to get an issue number to put in the stability annotations.