Dealing with Xcode 9 + macOS <= 10.12 and missing functions

[Joshua Root]

On 2017-9-29 18:14 , Leonardo Brondani Schenkel wrote:
> This seems to be an issue in XCode 9 to me, since I believe that when 
> setting the deployment target to 10.12 or earlier it should not be 
> exposing symbols that are not available at runtime.

It is working correctly as far as it goes; autoconf just doesn't solve 
the entire problem. Symbols that are not available on all the OS 
versions being targeted must be checked for at runtime before use. That 
way a single binary can use newer APIs when they are available but still 
run on older OS releases.

- Josh