Autoconf (newbie) -- building with static library
- by EB
I am trying to migrate from manual build to autoconf, which is working very nicely so far. But I have one static library that I can't figure out how to integrate. That library will NOT be located in the usual library locations - the location of the binary (.a file) and header (.h file) will be given as a configure argument. (Notably, even if I move the .a file to /usr/lib or anywhere else I can think of, it still won't work.)
Manual compilation is working with these:
gcc ... -I/path/to/header/file/directory /full/path/to/the/.a/file/itself
(Uh, I actually don't understand why the .a file is referenced directly, not with -L or anything. Yes, I have a half-baked understanding of building C programs.)
I can use the configure argument to successfully find the header (.h file) using AC_CHECK_HEADER. Inside the AC_CHECK_HEADER I then add the location to CPFLAGS and the #include of the header file in the actual C code picks it up nicely.
Given a configure argument that has been put into $location and the name of the needed files are myprog.h and myprog.a (which are both in the same directory), here is what works so far:
AC_CHECK_HEADER([$location/myprog.h], [AC_DEFINE([HAVE_MYPROG_H], [1], [found myprog.h]) CFLAGS="$CFLAGS -I$location"])
Where I run into difficulties is getting the binary (.a file) linked in. No matter what I try, I always get an error about undefined references to the function calls for that library. I'm pretty sure it's a linkage issue, because I can fuss with the C code and make an intentional error in the function calls to that library which produces earlier errors that indicate that the function prototypes have been loaded and used to compile.
I tried adding the location that contains the .a file to LDFLAGS and then doing a AC_CHECK_LIB but it is not found.
Maybe my syntax is wrong, or maybe I'm missing something more fundamental, which would not be surprising since I'm a newbie and don't really know what I'm doing.
Here is what I have tried:
AC_CHECK_HEADER([$location/myprog.h], [AC_DEFINE([HAVE_MYPROG_H], [1], [found myprog.h]) CFLAGS="$CFLAGS -I$location"; LDFLAGS="$LDFLAGS -L$location"; AC_CHECK_LIB(myprog)])
No dice. AC_CHECK_LIB is looking for -lmyprog I guess (or libmyprog?) so I'm not sure if that's a problem, so I tried this, too (omit AC_CHECK_LIB and include the .a directly in LDFLAGS), without luck:
AC_CHECK_HEADER([$location/myprog.h], [AC_DEFINE([HAVE_MYPROG_H], [1], [found myprog.h]) CFLAGS="$CFLAGS -I$location"; LDFLAGS="$LDFLAGS -L$location/myprog.a"])
To emulate the manual compilation, I tried removing the -L but that doesn't help:
AC_CHECK_HEADER([$location/myprog.h], [AC_DEFINE([HAVE_MYPROG_H], [1], [found myprog.h]) CFLAGS="$CFLAGS -I$location"; LDFLAGS="$LDFLAGS $location/myprog.a"])
I tried other combinations and permutations, but I think I might be missing something more fundamental....
