libcurl 7.54 build failure

[ygrek]

While building it on an oldish macOS, I got the error below. This macOS comes with libcurl/7.54.0, which according to your readme it's supported ("Minimum supported libcurl version : 7.28.0").

Using the homebrew libcurl, which is currently 7.80, it works. I had to manually set

export C_INCLUDE_PATH=/usr/local/Cellar/curl/7.80.0_1/include/
export LIBRARY_PATH=/usr/local/Cellar/curl/7.80.0_1/lib/:$LIBRARY_PATH

#=== ERROR while compiling ocurl.0.9.2 ========================================#
# context     2.1.1 | macos/x86_64 | ocaml.4.12.0 | https://opam.ocaml.org#f797da1a
# path        ~/.opam/default/.opam-switch/build/ocurl.0.9.2
# command     ~/.opam/opam-init/hooks/sandbox.sh build make
# exit-code   2
# env-file    ~/.opam/log/ocurl-67741-fd92ab.env
# output-file ~/.opam/log/ocurl-67741-fd92ab.out
### output ###
# curl-helper.c:1394:9: warning: implicit declaration of function 'curl_global_sslset' is invalid in C99 [-Wimplicit-function-declaration]
# [...]
#         ^
# curl-helper.c:1396:7: error: use of undeclared identifier 'res'
#   if (res != CURLSSLSET_UNKNOWN_BACKEND)
#       ^
# curl-helper.c:1396:14: error: use of undeclared identifier 'CURLSSLSET_UNKNOWN_BACKEND'
#   if (res != CURLSSLSET_UNKNOWN_BACKEND)
#              ^
# fatal error: too many errors emitted, stopping now [-ferror-limit=]
# 1 warning and 20 errors generated.
# make[1]: *** [curl-helper.o] Error 2
# make: *** [all] Error 2

[ygrek]

reported by orbifx
curl_global_sslset was added in libcurl 7.56, ie it's usage should be guarded by ifdefs