On 2022-4-3 14:05 , Fred Wright wrote:
Building against the newer SDK doesn't cause weak-linking issues as long
as the code uses MIN_REQUIRED instead of MAX_ALLOWED to decide what
references to make. MIN_REQUIRED is the correct choice in most cases,
but code often gets that wrong. Having them the same mostly sweeps that
problem under the rug.
Most of the software in MacPorts has no knowledge of any of these
mechanisms, and simply checks if it can use functions by seeing if a
test program that uses them compiles.
Apple seems to think that using the newer SDK is OK, since it's set up
(in the CLT area) like this:
lrwxr-xr-x 1 root wheel 15 Sep 26 2020 MacOSX.sdk -> MacOSX10.15.sdk
drwxr-xr-x 7 root wheel 224 Sep 26 2020 MacOSX.sdk 1
lrwxr-xr-x 1 root wheel 10 Aug 17 2019 MacOSX10.14.sdk -> MacOSX.sdk
drwxr-xr-x 8 root wheel 256 Nov 7 2019 MacOSX10.15.sdk
Yes, Apple assumes you will always compile against the latest SDK with
an appropriate MACOSX_DEPLOYMENT_TARGET set, and use __builtin_available
or other mechanisms to ensure you don't call any functions that aren't
available on the current OS at runtime.
- Josh
