ax_prefix_config_h (Autoconf Archive)

ax_prefix_config_h

Synopsis

AX_PREFIX_CONFIG_H [(OUTPUT-HEADER [,PREFIX [,ORIG-HEADER]])]

Description

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.

Defaults:

  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.

Example:

  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

Source Code

Download the latest version of ax_prefix_config_h.m4 or browse the macro’s revision history.

License

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>.

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