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Similar to what gcc can do, make it possible for m4 to output Makefile fragments that track the files that were included during processing, in order to automatically rebuild files in the correct dependency chains later on. * NEWS: Document the feature. * THANKS: Update. * checks/get-them: Add support for declaring a test's auxfile. * checks/check-them: Add code for handling auxilliary files, to make testing the feature possible. * doc/m4.texi (auxresult): New macro. (Make dependency generation): New chapter. * src/m4.h (makedep_gen_missing, REF_CMD_LINE, REF_INCLUDE) (REF_SINCLUDE, REF_ALL, REF_NONE): Prepare for new options. (record_dependency, generate_make_dependencies): New prototypes. * src/m4.c (makedep_path, makedep_target, makedep_gen_missing) (makedep_phony): Track new options. (usage): Document new options. (process_file): Track dependencies. (main): Parse new options. * src/builtin.c (include, m4_include, m4_sinclude): Track include source. * src/path.c (struct dependency): New struct. (dependency_list, dependency_list_end): New variables. (record_dependency, generate_make_dependencies): Output dependencies. Co-developed-by: Lorenzo Di Gregorio <lorenzo.digregorio@gmail.com>
GNU `m4' is an implementation of the traditional Unix macro processor. It is mostly SVR4 compatible, although it has some extensions (for example, handling more than 9 positional parameters to macros). `m4' also has built-in functions for including files, running shell commands, doing arithmetic, etc. Autoconf needs GNU `m4' for generating `configure' scripts, but not for running them. GNU `m4' was originally written by René Seindal, from Denmark. This is a beta release on the stable branch. If GNU `m4' is meant to serve GNU `autoconf', beware that `m4' should be fully installed *prior to* configuring `autoconf' itself. Likewise, if you intend on hacking GNU `m4' from git, the bootstrap process requires that you first install a released copy of GNU `m4'. If you are just trying to build `m4' from a released tarball, you should not normally need to run `./bootstrap' or `autoreconf'; just go ahead and start with `./configure'. If you are trying to build `m4' from git, more information can be found in the version-control-only file HACKING. M4 has an optional dependency on the libsigsegv library: https://www.gnu.org/software/libsigsegv/ If the library has not been installed in the standard location, you can use `./configure --with-libsigsegv-prefix=/path/to/dir', to make the build of `m4' use /path/to/dir/include/sigsegv.h as appropriate. The use of this library is optional; the only difference in having it available is that it increases the number of platforms where `m4' can correctly distinguish stack overflow from an internal bug. It is recommended that you use version 2.9 or newer. In the subdirectory `examples' you will find various m4 files, ranging from trivial test files to rather advanced macros. If you intend to use m4 seriously, you might find useful material down there. See file `COPYING' for copying conditions. Note that M4 is distributed under the GNU Public License version 3 or later. Some files in the distribution are copied from the gnulib project, and hence bear the designation version 2 or later because they are unmodified from gnulib; however, if you modify these files using M4 rather than gnulib as the source, you must update the license to be GPLv3 or later. See file `INSTALL' for compilation and installation instructions. See file `NEWS' for a list of major changes in the current release. See file `THANKS' for a list of contributors. By default, the `syscmd' and `esyscmd' macros try to use the first instance of `sh' found by `command -p getconf PATH' at configure time, with a default of `/bin/sh'. If that default is inappropriate, you can use `./configure --with-syscmd-shell=location' to specify the shell to use. Send bug reports to `bug-m4@gnu.org'. A bug report is an adequate description of the problem: your input, what you expected, what you got, and why this is wrong. Diffs are welcome, but they only describe a solution, from which the problem might be uneasy to infer. For any copyright year range specified as YYYY-ZZZZ in this package note that the range specifies every single year in that closed interval. GNU Project notice ================== GNU M4 is part of the GNU Operating System, developed by the GNU Project. If you are the author of an awesome program and want to join us in writing Free (libre) Software, please consider making it an official GNU program and become a GNU Maintainer. Instructions on how to do this are here: https://www.gnu.org/help/evaluation Don't have a program to contribute? Look at all the other ways to help: https://www.gnu.org/help/help.html And to learn more about Free (libre) Software in general, please read and share this page: https://gnu.org/philosophy/free-sw.html We are looking forward to hacking with you! ======================================================================== Copyright (C) 2000, 2005-2014, 2016-2017, 2020-2025 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the ``GNU Free Documentation License'' file as part of this distribution.