[arch-general] Default dtags in Arch

[Nicola Mori]

I'm tracking down an inconsistent behavior of my application when 
compiled under different distributions. It seems that under Arch the 
-Wl,-rpath, linker flag will set an RPATH into the library, while under 
Ubuntu 20.04 and 18.04 the same flag results in a RUNPATH being set. So 
it seems to me that the linker have different defaults on the two 
distributions, maybe set at linker compilation time; is this 
reasonable/correct? Also, since RUNPATH seems to be the modern and more 
secure way (see e.g. here: 
https://wiki.archlinux.org/index.php/Arch_package_guidelines/Security#RPATH/RUNPATH) 
I am wondering if there is a specific reason why RPATH is still the 
default on Arch and if there are plans to move to RUNPATH.

To further elaborate on this, if I'm correct the trend on Linux is 
towards RUNPATH, i.e. giving precedence to library folders specified by 
an environment variable (LD_LIBRARY_PATH) over those hard-coded in the 
binaries. Then on macOS it seems to be the opposite, namely deprecating 
DYLD_LIBRARY_PATH in favor of DYLD_FALLBACK_LIBRARY_PATH to give 
precedence to rpath. Both approaches are motivated by the potential 
security issues with the other approach, and all seems to depend on 
which security hole (a malicious environment variable or write access to 
library folders encoded in rpaths) is perceived as more important...

Thanks in advance for any clarification,

Nicola