Must char16_t strings use UTF-16 encoding?
c++, c++11, encoding, utf-8
Solution
The `__STDC_UTF_16__` bits did not make it into the standard text. That is in the proposal probably because it was taken from a similar proposal for the C language. The C++ standard simply removed any and all of this nonsense and made it UTF-16 or GTFO.
Problem
I've been digging the specification for a while now and cannot find any conclusive clauses to support either yes/no. Does the following statement: ``` char16_t *s = u"asdf"; ``` imply/enforce that the string literal "asdf" must be encoded in UTF-16? From all I can deduce, it's a yes. However, in this proposal n2018 it says only when "`__STDC_UTF_16__`" is defined that `char16_t` literals are UTF-16 encoded, so that leaves open the door that when "`__STDC_UTF_16__`" is undefined, `char16_t` literals can be encoded anyway the compiler wants. After all, the standard only guarantees the size, signed-ness and underlying representation of `char16_t`, it mentions nothing about how a compiler must encode a `char16_t` literal or string literal. In the spec, it says The size of a `char16_t` string literal is the total number of escape sequences, universal-character-names, and other characters, plus one for each character requiring a surrogate pair, plus one for the terminating u’\0’. [Note: The size of a `char16_t` string literal is the number of code units, not the number of characters. —end note ] This seems to mean that it is implicitly assumed that `char16_t` string literals are UTF16 encoded because "surrogate pair" is a UTF-16 concept. Let me know if there's anything vague in the question.