AX_PREFIX_CONFIG_H [(OUTPUT-HEADER [,PREFIX [,ORIG-HEADER]])]
Generate an installable config.h.
A package should not normally install its config.h as a system header, but if it must, this macro can be used to avoid namespace pollution by making a copy of config.h with a prefix added to all the macro names.
Each "#define SOMEDEF" line of the configuration header has the given prefix added, in the same case as the first character of the macro name.
OUTPUT-HEADER = $PACKAGE-config.h PREFIX = $PACKAGE ORIG-HEADER, from AM_CONFIG_HEADER(config.h)
Your configure.ac script should contain both macros in this order.
AC_INIT(config.h.in) # config.h.in as created by "autoheader" AM_INIT_AUTOMAKE(testpkg, 0.1.1) # makes #undef VERSION and PACKAGE AM_CONFIG_HEADER(config.h) # prep config.h from config.h.in AX_PREFIX_CONFIG_H(mylib/_config.h) # prep mylib/_config.h from it.. AC_MEMORY_H # makes "#undef NEED_MEMORY_H" AC_C_CONST_H # makes "#undef const" AC_OUTPUT(Makefile) # creates the "config.h" now # and also mylib/_config.h
If the argument to AX_PREFIX_CONFIG_H would have been omitted then the default output file would have been called simply "testpkg-config.h", but even under the name "mylib/_config.h" it contains prefix-defines like
#ifndef TESTPKG_VERSION #define TESTPKG_VERSION "0.1.1" #endif #ifndef TESTPKG_NEED_MEMORY_H #define TESTPKG_NEED_MEMORY_H 1 #endif #ifndef _testpkg_const #define _testpkg_const _const #endif
and this "mylib/_config.h" can be installed along with other header files, which is most convenient when creating a shared library (that has some headers) whose functionality depends on features detected at compile-time. No need to invent some "mylib-confdefs.h.in" manually.
Note that some AC_DEFINEs that end up in the config.h file are actually self-referential - e.g. AC_C_INLINE, AC_C_CONST, and the AC_TYPE_OFF_T say that they "will define inline|const|off_t if the system does not do it by itself". You might want to clean up about these - consider an extra mylib/conf.h that reads something like:
#include <mylib/_config.h> #ifndef _testpkg_const #define _testpkg_const const #endif
and then start using _testpkg_const in the header files. That is also a good thing to differentiate whether some library-user has starting to take up with a different compiler, so perhaps it could read something like this:
#ifdef _MSC_VER #include <mylib/_msvc.h> #else #include <mylib/_config.h> #endif #ifndef _testpkg_const #define _testpkg_const const #endif
Download the latest version of ax_prefix_config_h.m4 or browse the macro’s revision history.
Copyright © 2014 Reuben Thomas email@example.com
Copyright © 2008 Guido U. Draheim firstname.lastname@example.org
Copyright © 2008 Marten Svantesson
Copyright © 2008 Gerald Point Gerald.Point@labri.fr
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