PCRE2 - Perl-compatible regular expressions (revised API)
#include <pcre2.h>
int pcre2_set_bsr(pcre2_compile_context *ccontext,
uint32_t value);This function sets the convention for processing \R within a compile context. The second argument must be one of PCRE2_BSR_ANYCRLF or PCRE2_BSR_UNICODE. The result is zero for success or PCRE2_ERROR_BADDATA if the second argument is invalid.
There is a complete description of the PCRE2 native API in the pcre2api page and a description of the POSIX API in the pcre2posix page.