On Friday 03 April 2009 2:29:36 pm Ralf Wildenhues wrote: > Hello Gerald, > > * Gerald I. Evenden wrote on Fri, Apr 03, 2009 at 08:11:22PM CEST: > > One added note, that bothers me a little. > > > > If the system checks for an entry being present in a particular iibrary > > by compiling/linking a test program using the function *and* linking to > > the specified library,----> what if the library under test heavily > > references another library such as -lm?? IF -lm is not in the test run > > would the test not fail??????? Thus the entry under test fails also. > > I haven't read the thread in full, but this is probably the issue > bothering you: > > AC_CHECK_LIB and AC_SEARCH_LIBS both have an optional 5th argument where > one can supply additional needed libraries. So of libfoo needs libm, > then a check for libfoo could look like > > AC_SEARCH_LIBS([function_from_libfoo], [foo], [], [], [-lm]) > > and after this macro, $LIBS would contain -lfoo if the test was > successful. Of course, you can check for both in sequence, > AC_SEARCH_LIBS([cos], [m]) > AC_SEARCH_LIBS([function_from_libfoo], [foo]) > > and in this case you don't need to specify -lm in the second macro, > because the first macro will have added that to $LIBS (and $LIBS is used > for linking). > > And yes, library linking order *always* matters. The bugs are just more > obscure with GNU/Linux and shared linking than they are under other > circumstances. > > Cheers, > Ralf
Many, many thanks. That did it so everything looks pretty now. I used the second method rather than use an undocumented feature. -- The whole religious complexion of the modern world is due to the absence from Jerusalem of a lunatic asylum. -- Havelock Ellis (1859-1939) British psychologist
