Re: Tune rpath by env. variable

[Gary V. Vaughan]

Hi Pavel,

> On Dec 10, 2014, at 6:41 PM, Pavel Raiskup <address@hidden> wrote:
> 
> On Tuesday 09 of December 2014 19:38:53 Gary V. Vaughan wrote:
>>> .. however, maybe you think that quite problematic the share with ltdl.m4
>>> (via sys_lib_dlsearch_path).  That is ?clearly? configure-time only
>>> variable which generates variable LT_DLSEARCH_PATH in c-header file.
>> 
>> We will probably need to promote the macros required to support that to
>> libtool.m4 now that we care about setting sys_dlsearch_path_spec, without
>> requiring every package to use ltdl.m4.
>> 
>>> In this case, using LT_SYS_LIBRARY_PATH at runtime would differentiate
>>> LT_DLSEARCH_PATH with libtool's 'sys_dlsearch_path_spec' ... and could
>>> cause confusion later.
>> 
>> It's a lot of variables, but technically it seems sound to me.
>> 
>>> Hmm, due to its requirments, it seems like LT_SYS_LIBRARY_PATH should be
>>> AC_ARG_VAR-ed.  The system-wide libtool should be pre-configured correctly
>>> according to system's needs anyway.  WDYT?
>> 
>> I think it would be easier to have both installed and in-tree libtool
>> respect LT_SYS_LIBRARY_PATH, otherwise we have to edit the installed script
>> to take out the substitution code.
> 
> Hi Gary, I tried to patch libtool according to previous discussion.
> That requires good review, however.  Patch attached.
> 
> Pavel
> <0001-libtool-allow-adjusting-run-time-library-path.patch>

Many thanks for working on this.

I applied your patch with some fairly heavy-handed changes:

  1. Added a NEWS update.
  2. Simplified the new documentation.
  3. Changed the name of some internal API symbols.
  4. Fixed dollar quoting with quadrigraphs, and then expand the shared
     function directly into libtool.
  5. Remove the scripts for slicing and dicing that function out of one
     file and into another the hard way.

I still have some small concerns about the correctness.

Do we really want the configure time LT_SYS_LIBRARY_PATH adjusted
lt_lib_dlsearch_path_spec injected into the installed libtool script? That
makes me think that if LT_SYS_LIBRARY_PATH is set in /etc/profile or similar,
that the adjustment will happen twice.

I think it would work better to leave lt_lib_dlsearch_path_spec in the
generated file as it was before (just the heuristic configure time values),
and add to the top of libtool:

  : ${LT_SYS_LIBRARY_PATH="/configure/time:/path/list"}

Then installed libtool will work whether the user wants to set it differently,
or not at all, or if LT_SYS_LIBRARY_PATH is set in the environment for both
configure and libtool, without double adjusting.

WDYT?

Cheers,
-- 
Gary V. Vaughan (gary AT gnu DOT org)