We started seeing a complaint from LLVM17 sanitizer via some application nominally using OpenSSL:

crypto/lhash/lhash.c:299:12: runtime error: call to function err_string_data_hash through pointer to incorrect function type 'unsigned long (*)(const void *)'
[...]/crypto/err/err.c:184: note: err_string_data_hash defined here
    #0 0x7fa569e3a434 in getrn [...]/crypto/lhash/lhash.c:299:12
    #1 0x7fa569e39a46 in OPENSSL_LH_insert [...]/crypto/lhash/lhash.c:119:10
    #2 0x7fa569d866ee in err_load_strings [...]/crypto/err/err.c:280:15
[...]

Strangely there were not other reports, despite the fact that obviously this idiom is used for various LHASH and in STACK also.

Unsurprisingly this seems to be impacting many other C-based projects whose authors are not especially thrilled either:

systemd/systemd#29972
python/cpython#111178
php/php-src@ca22505

There seems also to even be some conversation in the original LLVM thread on whether or not this is truly UB: https://reviews.llvm.org/D148827