[tor-bugs] #6311 [Tor]: Migrate TOR_SEARCH_LIBRARY to use pkg-config

[Tor Bug Tracker & Wiki]

#6311: Migrate TOR_SEARCH_LIBRARY to use pkg-config
-----------------------------+----------------------------------------------
 Reporter:  nickm            |          Owner:  nickm             
     Type:  enhancement      |         Status:  assigned          
 Priority:  major            |      Milestone:  Tor: 0.2.5.x-final
Component:  Tor              |        Version:                    
 Keywords:  tor-relay build  |         Parent:                    
   Points:                   |   Actualpoints:                    
-----------------------------+----------------------------------------------

Comment(by nickm):

 Returning to look at this again, I think I actually need to do some design
 here.  So let's see.  The current behavior is, more or less:

  * Check the command line for a --with-libraryname-dir=xxx option. If so,
 set trylibrarydir to xxx.
  * Save the initial values of LDFLAGS, LIBS, and CPPFLAGS.
  * Iterating over $trylibrarydir, "", /usr/local, /usr/pkg, and other
 directories optionally specified in $8:
    * Try to extend the saved LDFLAGS and CPPFLAGS with appropriate -L and
 -I options for that directory.
    * Extend LIBS with the library options specified in $3
    * See if we can build and link a program that includes no headers for
 the library, and tries to require one of its identifiers
    * If so, see if we can compile a program that does include headers for
 the library
    * If so, this is the one we want: remember that directory, and break
 out of the loop.
  * Then, extend LDFLAGS and CPPFLAGS with the options given by the chosen
 directory, and extend LIBS with the chosen libs.
  * Additionally, set TOR_LDFLAGS_libraryname and TOR_CPPFLAGS_libraryname
 and TOR_LIBDIR_libraryname to appropriate values, and AC_SUBST the
 CPPDLAGS and LDFLAGS variables.
  * Then, see whether we need any rpath-style options to link the program
 by iterating over various possibilities and seeing if they make the test
 program runnable.

 So right now our outputs are a series of changes to LDFLAGS and CPPFLAGS
 and LIBS that carry across all the things we build (although some callers
 immediately roll them back), as well as the TOR_CPPFLAGS_* / TOR_LDFLAGS_*
 / TOR_LIBDIR_* values.

 We need to make our pkg-config alternative produce each of those, or
 remove the need for those.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6311#comment:7>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online