lib curl compiled on OSX 10.13 failed to run on OSX 10.10

[arun-govindan]

I did this:
I compiled my application with curl (options : ./configure --with-gnutls) on Xcode 9.4. And when I tested the application on Mac OS version yosemite (OS X 10.10) the app crashed with the below output.

Crash report :
Dyld Error Message:
Symbol not found: _clock_gettime
Referenced from: */libcurl.4.dylib (which was built for Mac OS X 10.13)
Expected in: /usr/lib/libSystem.B.dylib

I expected the following:
Application to run normally

curl/libcurl version:
curl-7.40.0

Mac OS version: yosemite (OS X 10.10)

[bagder]

clock_gettime apparently wasn't added until 10.12. I don't know how this should be fixed properly (googling "clock_gettime macOS" shows this and related issues have bitten many projects but I found no clear solution).

Work-around

After you run configure, but before you invoke 'make', you can edit lib/curl_config.h and make sure HAVE_CLOCK_GETTIME_MONOTONIC is not defined. Then build.

[nickzman]

I think I know how to fix this. I looked at the time.h header, and noticed that the clock_* functions are all marked for weak-linking as of macOS 10.13.x, so there are two ways we can weak-link the symbol:

1. Use traditional weak-linking, which means checking to see if the symbol is not equal to null.
2. Use __builtin_available() to check if the user is using macOS 10.12 or later, or iOS 10.0 or later. We have the HAVE_BUILTIN_AVAILABLE preprocessor macro to check on this.

Method 2 is the method Apple wants developers to use from now on, but as we found out a while ago, it doesn't work with compilers other than Clang.

[arun-govindan]

I tried the workaround of removing HAVE_CLOCK_GETTIME_MONOTONIC and now the crash is not happening, but however when I tried to access the https url, it failed. It is able to access only http urls.
Can you please let me know why this behavior is occuring.