Where should D programs look for .so files on Linux (by default)?

[Wyatt via Digitalmars-d]

On Wednesday, 17 September 2014 at 05:52:29 UTC, Chad Joan wrote:
> --- The Problem ---
>
> I was using Derelict to play around with SDL/OpenGL in D for a 
> bit, and I was initially unable to do so because DerelictSDL2's 
> search paths for .so files could not find libSDL2_ttf.so on my 
> Linux distribution (Gentoo).
>
If you're not using the slotted ebuild from:
https://bugs.gentoo.org/show_bug.cgi?id=481788
...you won't have that so file; only the version that links with 
SDL 1.2.  And if we look:

wyatt at Yue ~ $ ls -F -w66 /usr/lib/libSDL* |grep ttf
/usr/lib/libSDL_ttf-2.0.so.0@
/usr/lib/libSDL_ttf-2.0.so.0.10.1*
/usr/lib/libSDL_ttf.so@

Sure enough!  I'd suggest pinging that bug because SDL2 isn't 
going away any time soon.

> intelligent lookup of a system's .so files (or lack thereof) 
> could have a profound impact on user experience for anyone on 
> Linux using programs written in D.  Mike (aldacron) responded 
> with a request to gather input from the D community at large, 
> so here it is ;)
>
While I certainly couldn't blame you for harshing on the dynamic 
linker most days, this (surprisingly) isn't one of them.  It's 
innocent.  Shocking, I know.

> As an initial proposal, how about this:
> 1. Look in ./
> 2. Look in $LD_LIBRARY_PATH
> 3. Look in all directories listed in /etc/ld.so.conf
> 4. Look in a baked-in list of last-ditch fallback options. 
> Although I'm sure better could be done, my current suggestion 
> would look like this:
> 4a. ~/lib
> 4b. /usr/local/lib
> 4c. /usr/lib
>
As it happens, this is almost exactly what actually happens:
http://unix.stackexchange.com/a/22999

> This logic should probably end up in Phobos or somewhere 
> suitably common, and revised as needed, so that all D programs 
> can benefit from the community's research and experience on the 
> subject.
>
On Linux (and OSX?), at least, E_NOTOURPROBLEM.  I possibly 
recall there was some amount of hilarity related to this on 
Windows, but that's an area where I Just Don't Care™.

-Wyatt