This option was removed in revision 191551 of clang (Sep 27, 2013).
Property synthesizing seems to now be default, it’s unclear to me what revision of clang made the behavior default, but since we require a fairly recent version for other things (like Cap’n’proto) I don’t think this change will cause a problem.
@executable_path is the originally-executed program, whereas @loader_path is the program that caused the load to occur (e.g. a Quick Look generator). @rpath can be changed at link time — a QL generator can specify a value that points to the enclosing app bundle’s Frameworks directory.
This is for oniguruma and ideally we would set this only for the oniguruma target, but then we need special precompiled headers for that target, so this is a practical way to achieve the goal (there are no other C sources in the build tree).
I never understood what this option was good for and now it gives a warning about being unused during compilation (even though it was set only during linking).
Basically libraries referenced indirectly will be setup as a requirement of the target and this option strips that. Doesn’t really matter, but enabling it rather than deleting the line (which was previously commented).
We now explicitly disable it for targets that hasn’t yet been upgraded to ARC. This way, it’s easier to get an overview of which targets hasn’t yet been upgraded and ensures new targets has ARC enabled.
