Hi,
While working on 1e7fe06c, I wished I could make functions generate
compiler warnings:
pg_attribute_deprecated("use pg_mblen_{cstr,range,with_len,unbounded} instead")
extern int pg_mblen(const char *mbstr);
That'd avoid accidental reintroduction, and also get extension
maintainers' attention. $SUBJECT is C23/C++14's syntax, but you've
long been able to do that with in __attribute__ or __declspec for the
usual suspects so I looked into which compiler versions introduced
that and came up with the attached.
The idea would be to back-patch the deprecation warnings, and delete
the functions in, I guess now, v20. Then the deprecation notice
facility would always be there for next time we need it.
