Makefile.am seems to ignore AM_LDLIBS

Question

I'm currently grappling with understanding the autotools. I'm almost there, but I'm a bit stumped by the behavior of automake when it comes to the AM_CFLAGS and AM_LDLIBS macros.

Below is my very short Makefile.am

  1 bin_PROGRAMS = sqlmigrate
  2 sqlmigrate_SOURCES = sqlmigrate.c db.c
  3 
  4 AM_CFLAGS=-g -Wall -D_LARGEFILE64_SOURCE=1 -I/usr/local/apr/include/apr-1
  5 AM_LDLIBS=-lsqlite3 -lapr-1

My understanding is that AM_CFLAGS and AM_LDLIBS are used when no corresponding argument is passed to ./configure, but that they yield to such arguments when given.

After creating Makefile.in and running configure, however, make all is clearly not using the specified CFLAGS and LDLIBS even though I specified them.

Even stranger (to me anyway), is that my configure script can cause those libraries to be included if I happen to use the AC_CHECK_LIB macro.

  1 #                                               -*- Autoconf -*-
  2 # Process this file with autoconf to produce a configure script.
  3 
  4 AC_PREREQ([2.68])
  5 AC_INIT([sqlmigrate], [1.0], [])
  6 AM_INIT_AUTOMAKE(1.8)
  7 AC_CONFIG_SRCDIR([sqlmigrate.c])
  8 
  9 # Checks for programs.
 10 AC_PROG_CC
 11 AC_PROG_INSTALL
 12 
 13 # Checks for libraries.
 14 # AC_CHECK_LIB([sqlite3], [sqlite3_open])
 15 # AC_CHECK_LIB([apr-1], [apr_pool_initialize])
 16 
 17 # Checks for header files.
 18 AC_CHECK_HEADERS([stdlib.h string.h unistd.h])
 19 
 20 # Checks for typedefs, structures, and compiler characteristics.
 21 
 22 # Checks for library functions.
 23 
 24 AC_CONFIG_HEADER(config.h)
 25 AC_CONFIG_FILES([Makefile])
 26 AC_OUTPUT

So with the AC_CHECK_LIB lines commented out, gcc is invoked without linking the libraries.

I feel like I'm hanging on by a thread with autotools here. Feel free to explode my reality and show me the error of my ways.

Thanks for your time!

Things like -I/usr/local/apr/include/apr-1 do not belong in AM_CFLAGS or AM_CPPFLAGS. That path is specific to the machine on which the user builds the package, and therefore have no place in any of the autotool metafiles. — William Pursell

zchtodd zchtodd · Accepted Answer · 2012-08-22T21:43:25

Answering my own question, I think I just have the wrong variable in my Makefile.am. AM_LDLIBS doesn't appear to exist -- I should be using AM_LDFLAGS, although I still don't get why ./configure causes the libraries to be linked when I use the AC_CHECK_LIB macro.

Makefile.am seems to ignore AM_LDLIBS

1 Answers