@noindent
Files used in preparing a software package for distribution:
@example
-@group
your source files --> [autoscan*] --> [configure.scan] --> configure.in
-configure.in --. .------> autoconf* -----> configure
- +---+
-[aclocal.m4] --+ `---.
-[acsite.m4] ---' |
- +--> [autoheader*] -> [config.h.in]
-[acconfig.h] ----. |
- +-----'
-[config.h.top] --+
-[config.h.bot] --'
+@group
+configure.in --.
+ | .------> autoconf* -----> configure
+[aclocal.m4] --+---+
+ | `-----> [autoheader*] --> [config.h.in]
+[acsite.m4] ---'
+@end group
Makefile.in -------------------------------> Makefile.in
-@end group
@end example
@noindent
# autoheader might not change config.h.in, so touch a stamp file.
$(srcdir)/config.h.in: stamp-h.in
-$(srcdir)/stamp-h.in: configure.in aclocal.m4 acconfig.h \
- config.h.top config.h.bot
+$(srcdir)/stamp-h.in: configure.in aclocal.m4
cd $(srcdir) && autoheader
echo timestamp > $(srcdir)/stamp-h.in
characters @samp{[} or @samp{]}), use @code{AC_DEFINE_UNQUOTED} instead.
@var{description} is only useful if you are using
@code{AC_CONFIG_HEADERS}. In this case, @var{description} is put into
-the generated @file{config.h.in} as the comment before the macro define;
-the macro need not be mentioned in @file{acconfig.h}. The following
-example defines the C preprocessor variable @code{EQUATION} to be the
-string constant @samp{"$a > $b"}:
+the generated @file{config.h.in} as the comment before the macro define.
+The following example defines the C preprocessor variable
+@code{EQUATION} to be the string constant @samp{"$a > $b"}:
@example
AC_DEFINE(EQUATION, "$a > $b")
@cindex @file{config.h.top}
@cindex @file{config.h.bot}
-@code{autoheader} scans @file{configure.in} and figures out which C
-preprocessor symbols it might define. It copies comments and
-@code{#define} and @code{#undef} statements from a file called
-@file{acconfig.h} in the current directory, if present. This file used
-to be mandatory if you @code{AC_DEFINE} any additional symbols. Now,
-you are encouraged to use the @code{AH} series of macros
-(@pxref{Autoheader Macros}).
-
-The file that @code{autoheader} creates contains mainly @code{#define}
-and @code{#undef} statements and their accompanying comments. If
-@file{./acconfig.h} contains the string @samp{@@TOP@@},
+In order to produce @file{config.h.in}, @command{autoheader} needs to
+build or to find templates for each symbol. Modern releases of Autoconf
+use @code{AH_VERBATIM} and @code{AH_TEMPLATE} (@pxref{Autoheader
+Macros}), but in older releases a file, @file{acconfig.h}, contained the
+list of needed templates. @code{autoheader} copies comments and
+@code{#define} and @code{#undef} statements from @file{acconfig.h} in
+the current directory, if present. This file used to be mandatory if
+you @code{AC_DEFINE} any additional symbols.
+
+Modern releases of Autoconf also provide @code{AH_TOP} and
+@code{AH_BOTTOM} if you need to prepend/append some information to
+@file{config.h.in}. Ancient versions of Autoconf had a similar feature:
+if @file{./acconfig.h} contains the string @samp{@@TOP@@},
@code{autoheader} copies the lines before the line containing
@samp{@@TOP@@} into the top of the file that it generates. Similarly,
if @file{./acconfig.h} contains the string @samp{@@BOTTOM@@},
@code{autoheader} copies the lines after that line to the end of the
-file it generates. Either or both of those strings may be omitted.
+file it generates. Either or both of those strings may be omitted. An
+even older alternate way to produce the same effect in jurasik versions
+of Autoconf is to create the files @file{@var{file}.top} (typically
+@file{config.h.top}) and/or @file{@var{file}.bot} in the current
+directory. If they exist, @code{autoheader} copies them to the
+beginning and end, respectively, of its output.
+
+In former versions of Autoconf, the files used in preparing a software
+package for distribution were:
+@example
+@group
+configure.in --. .------> autoconf* -----> configure
+ +---+
+[aclocal.m4] --+ `---.
+[acsite.m4] ---' |
+ +--> [autoheader*] -> [config.h.in]
+[acconfig.h] ----. |
+ +-----'
+[config.h.top] --+
+[config.h.bot] --'
+@end group
+@end example
-An alternate way to produce the same effect is to create the files
-@file{@var{file}.top} (typically @file{config.h.top}) and/or
-@file{@var{file}.bot} in the current directory. If they exist,
-@code{autoheader} copies them to the beginning and end, respectively, of
-its output. Their use is discouraged because they have file names that
-contain two periods, and so cannot be stored on MS-DOS; also, they are
-two more files to clutter up the directory. But if you use the
-@option{--localdir=@var{dir}} option to use an @file{acconfig.h} in
-another directory, they give you a way to put custom boilerplate in each
-individual @file{config.h.in}.
+Use only the @code{AH_} macros, @file{configure.in} should be
+self-contained, and should not depend upon @file{acconfig.h} etc.
@node autoupdate Invocation, Obsolete Macros, acconfig.h, Obsolete Constructs
create a file called @file{install} from it. @code{AC_PROG_INSTALL}
looks for the script under both names, but it is best to use the new name.
-If you were using @file{config.h.top} or @file{config.h.bot}, you still
-can, but you will have less clutter if you merge them into
-@file{acconfig.h}. @xref{autoheader Invocation}.
+If you were using @file{config.h.top}, @file{config.h.bot}, or
+@file{acconfig.h}, you still can, but you will have less clutter if you
+use the @code{AH_} macros. @xref{Autoheader Macros}.
@node Changed Makefiles, Changed Macros, Changed File Names, Autoconf 1
@subsection Changed Makefiles
Of the other files that might be used with @code{configure},
@file{config.h.in} is under whatever copyright you use for your
-@file{configure.in}, since it is derived from that file and from the
-public domain file @file{acconfig.h}. @file{config.sub} and
-@file{config.guess} have an exception to the GPL when they are used with
-an Autoconf-generated @code{configure} script, which permits you to
-distribute them under the same terms as the rest of your package.
-@file{install-sh} is from the X Consortium and is not copyrighted.
+@file{configure.in}. @file{config.sub} and @file{config.guess} have an
+exception to the GPL when they are used with an Autoconf-generated
+@code{configure} script, which permits you to distribute them under the
+same terms as the rest of your package. @file{install-sh} is from the X
+Consortium and is not copyrighted.
@node Why GNU m4, Bootstrapping, Distributing, Questions
@section Why Require GNU M4?
projects / thirdparty / autoconf.git / commitdiff
