@example
AC_CHECK_HEADER([stdio.h],
- [AC_DEFINE([HAVE_STDIO_H])],
+ [AC_DEFINE([HAVE_STDIO_H], [1],
+ [Define to 1 if you have <stdio.h>.])],
[AC_MSG_ERROR([Sorry, can't do anything for you])])
@end example
@example
AC_CHECK_HEADER(stdio.h,
- [AC_DEFINE(HAVE_STDIO_H)],
+ [AC_DEFINE(HAVE_STDIO_H, 1,
+ Define to 1 if you have <stdio.h>.)],
[AC_MSG_ERROR([Sorry, can't do anything for you])])
@end example
@example
AC_CHECK_HEADER(stdio.h,
- AC_DEFINE(HAVE_STDIO_H),
+ AC_DEFINE(HAVE_STDIO_H, 1,
+ Define to 1 if you have <stdio.h>.),
AC_MSG_ERROR([Sorry, can't do anything for you]))
@end example
A corollary is that you should not use these variables except in
Makefiles. For instance, instead of trying to evaluate @code{datadir}
in @file{configure} and hard-coding it in Makefiles using
-e.g., @samp{AC_DEFINE_UNQUOTED(DATADIR, "$datadir")}, you should add
+e.g., @samp{AC_DEFINE_UNQUOTED(DATADIR, "$datadir", [Data directory.])},
+you should add
@samp{-DDATADIR="$(datadir)"} to your @code{CPPFLAGS}.
Similarly you should not rely on @code{AC_OUTPUT_FILES} to replace
from @command{configure}. Associate the commands with @var{tag}.
Since typically the @var{cmds} create a file, @var{tag} should
naturally be the name of that file. If needed, the directory hosting
-@var{tag} is created. This macro is one of the instantiating macros;
+@var{tag} is created. This macro is one of the instantiating macros;
see @ref{Configuration Actions}.
Here is an unrealistic example:
@c @fuindex free
@prindex @code{free}
The ISO C99 standard says a call @code{free(NULL)} does nothing, but
-some old systems don't support this (eg.@: NextStep).
+some old systems don't support this (e.g., NextStep).
@item @code{isinf}
@itemx @code{isnan}
@c @fuindex malloc
@prindex @code{malloc}
The ISO C99 standard says a call @code{malloc(0)} is implementation
-dependent, it may either return @code{NULL} (eg.@: OSF 4) or
-non-@code{NULL} (eg.@: @acronym{GNU} C Library). @code{AC_FUNC_MALLOC}
+dependent, it may either return @code{NULL} (e.g., OSF 4) or
+non-@code{NULL} (e.g., @acronym{GNU} C Library). @code{AC_FUNC_MALLOC}
can be used to insist on non-@code{NULL} (@pxref{Particular Functions}).
@item @code{putenv}
@c @fuindex putenv
@prindex @code{putenv}
POSIX specifies that @code{putenv} puts the given string directly in
-@code{environ}, but some systems make a copy of it instead (eg.@:
+@code{environ}, but some systems make a copy of it instead (e.g.,
glibc 2.0, or BSD). And when a copy is made, @code{unsetenv} might
-not free it, causing a memory leak (eg.@: FreeBSD 4).
+not free it, causing a memory leak (e.g., FreeBSD 4).
POSIX specifies that @code{putenv("FOO")} removes @samp{FOO} from the
-environment, but on some systems (eg.@: FreeBSD 4) this is not the
+environment, but on some systems (e.g., FreeBSD 4) this is not the
case and instead @code{unsetenv} must be used.
On MINGW, a call @code{putenv("FOO=")} removes @samp{FOO} from the
@c @fuindex realloc
@prindex @code{realloc}
The ISO C99 standard says a call @code{realloc(NULL,size)} is equivalent
-to a @code{malloc(size)}, but some old systems don't support this (eg.@:
+to a @code{malloc(size)}, but some old systems don't support this (e.g.,
NextStep).
@item @code{signal} handler
@c @fuindex strerror_r
@prindex @code{strerror_r}
POSIX specifies that @code{strerror_r} returns an @code{int}, but many
-systems (eg.@: @acronym{GNU} C Library version 2.2.4) provide a
+systems (e.g., @acronym{GNU} C Library version 2.2.4) provide a
different version returning a @code{char *}. @code{AC_FUNC_STRERROR_R}
can detect which is in use (@pxref{Particular Functions}).
@item @code{sysconf}
@c @fuindex sysconf
@prindex @code{sysconf}
-@code{_SC_PAGESIZE} is standard, but some older systems (eg.@: HP-UX
+@code{_SC_PAGESIZE} is standard, but some older systems (e.g., HP-UX
9) have @code{_SC_PAGE_SIZE} instead. This can be tested with
@code{#ifdef}.
@prindex @code{fseeko}
If the @code{fseeko} function is available, define @code{HAVE_FSEEKO}.
Define @code{_LARGEFILE_SOURCE} if necessary to make the prototype
-visible on some systems (e.g. glibc 2.2). Otherwise linkage problems
+visible on some systems (e.g., glibc 2.2). Otherwise linkage problems
may occur when compiling with @code{AC_SYS_LARGEFILE} on
largefile-sensitive systems where @code{off_t} does not default to a
64bit entity.
@example
#ifdef __STDC__
/\
-* A comment with backslash-newlines in it. %@{ %@} *\
+* A comment with backslash-newlines in it. %@{ %@} *\
\
/
char str[] = "\\
By default, newer dialects are preferred over older dialects, but if
@code{dialect} is specified then older dialects are preferred starting
-with the specified dialect. @code{dialect} can currently be one of
+with the specified dialect. @code{dialect} can currently be one of
Fortran 77, Fortran 90, or Fortran 95. However, this is only a hint of
-which compiler @emph{name} to prefer (e.g. @code{f90} or @code{f95}),
+which compiler @emph{name} to prefer (e.g., @code{f90} or @code{f95}),
and no attempt is made to guarantee that a particular language standard
is actually supported. Thus, it is preferable that you avoid the
@code{dialect} option, and use AC_PROG_FC only for code compatible with
@acindex{FC_SRCEXT}
By default, the @code{FC} macros perform their tests using a @file{.f}
extension for source-code files. Some compilers, however, only enable
-newer language features for appropriately named files, e.g. Fortran 90
+newer language features for appropriately named files, e.g., Fortran 90
features only for @file{.f90} files. On the other hand, some other
compilers expect all source files to end in @file{.f} and require
special flags to support other file name extensions. The
@code{AC_FC_SRCEXT} macro deals with both of these issues.
The @code{AC_FC_SRCEXT} tries to get the @code{FC} compiler to accept files
-ending with the extension .@var{ext} (i.e. @var{ext} does @emph{not}
+ending with the extension .@var{ext} (i.e., @var{ext} does @emph{not}
contain the dot). If any special compiler flags are needed for this, it
stores them in the output variable @code{FCFLAGS_}@var{ext}. This
extension and these flags are then used for all subsequent @code{FC} tests
succeed without modifying @code{FCFLAGS}.
If @code{AC_FC_FREEFORM} succeeds in compiling free-form source, it
-calls @ovar{action-if-success} (defaults to nothing). If it fails, it
+calls @ovar{action-if-success} (defaults to nothing). If it fails, it
calls @ovar{action-if-failure} (defaults to exiting with an error
message).
@end defmac
The LFS introduced the @code{fseeko} and @code{ftello} functions to
replace their C counterparts @code{fseek} and @code{ftell} that do not
-use @code{off_t}. Take care to use @code{AC_FUNC_FSEEKO} to make their
+use @code{off_t}. Take care to use @code{AC_FUNC_FSEEKO} to make their
prototypes available when using them and large-file support is
enabled.
@end defmac
@example
AC_INIT(Autoconf Documentation, @value{VERSION}, bug-autoconf@@gnu.org)
-AC_DEFINE([HELLO_WORLD], ["Hello, World\n"])
+AC_DEFINE([HELLO_WORLD], ["Hello, World\n"],
+ [Greetings string.])
AC_LANG_CONFTEST(
[AC_LANG_SOURCE([[const char hw[] = "Hello, World\n";]])])
gcc -E -dD -o - conftest.c
@example
AC_INIT(Autoconf Documentation, @value{VERSION}, bug-autoconf@@gnu.org)
-AC_DEFINE([HELLO_WORLD], ["Hello, World\n"])
+AC_DEFINE([HELLO_WORLD], ["Hello, World\n"],
+ [Greetings string.])
AC_LANG_CONFTEST(
[AC_LANG_PROGRAM([[const char hw[] = "Hello, World\n";]],
[[fputs (hw, stdout);]])])
@example
AC_INIT(Autoconf Documentation, @value{VERSION}, bug-autoconf@@gnu.org)
-AC_DEFINE([HELLO_WORLD], ["Hello, World\n"])
+AC_DEFINE([HELLO_WORLD], ["Hello, World\n"],
+ [Greetings string.])
AC_PREPROC_IFELSE(
[AC_LANG_PROGRAM([[const char hw[] = "Hello, World\n";]],
[[fputs (hw, stdout);]])],
# The order of these tests is important.
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/statvfs.h>
#include <sys/fstyp.h>]])],
- [AC_DEFINE(FSTYPE_STATVFS) fstype=SVR4])
+ [AC_DEFINE(FSTYPE_STATVFS, 1,
+ [Define if statvfs exists.])
+ fstype=SVR4])
if test $fstype = no; then
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/statfs.h>
#include <sys/fstyp.h>]])],
- [AC_DEFINE(FSTYPE_USG_STATFS) fstype=SVR3])
+ [AC_DEFINE(FSTYPE_USG_STATFS, 1,
+ [Define if USG statfs.])
+ fstype=SVR3])
fi
if test $fstype = no; then
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/statfs.h>
#include <sys/vmount.h>]])]),
- [AC_DEFINE(FSTYPE_AIX_STATFS) fstype=AIX])
+ [AC_DEFINE(FSTYPE_AIX_STATFS, 1,
+ [Define if AIX statfs.])
+ fstype=AIX])
fi
# (more cases omitted here)
AC_MSG_RESULT([$fstype])
appropriate cache variable, as in this example:
@example
-AC_CHECK_FUNC(vprintf, [AC_DEFINE(HAVE_VPRINTF)])
+AC_CHECK_FUNC(vprintf, [AC_DEFINE(HAVE_VPRINTF, 1,
+ [Define if vprintf exists.])])
if test "$ac_cv_func_vprintf" != yes; then
- AC_CHECK_FUNC(_doprnt, [AC_DEFINE(HAVE_DOPRNT)])
+ AC_CHECK_FUNC(_doprnt, [AC_DEFINE(HAVE_DOPRNT, 1,
+ [Define if _doprnt exists.])])
fi
@end example
@code{EQUATION} to be the string constant @samp{"$a > $b"}:
@example
-AC_DEFINE(EQUATION, "$a > $b")
+AC_DEFINE(EQUATION, "$a > $b",
+ [Equation string.])
@end example
If neither @var{value} nor @var{description} are given, then
@var{variable} or @var{value} is a shell variable. Examples:
@example
-AC_DEFINE_UNQUOTED(config_machfile, "$machfile")
-AC_DEFINE_UNQUOTED(GETGROUPS_T, $ac_cv_type_getgroups)
-AC_DEFINE_UNQUOTED($ac_tr_hdr)
+AC_DEFINE_UNQUOTED(config_machfile, "$machfile",
+ [Configuration machine file.])
+AC_DEFINE_UNQUOTED(GETGROUPS_T, $ac_cv_type_getgroups,
+ [getgroups return type.])
+AC_DEFINE_UNQUOTED($ac_tr_hdr, 1,
+ [Translated header name.])
@end example
@end defmac
newlines. That is, do this:
@example
-AC_CHECK_HEADER(elf.h, [AC_DEFINE(SVR4) LIBS="$LIBS -lelf"])
+AC_CHECK_HEADER(elf.h,
+ [AC_DEFINE(SVR4, 1, [System V Release 4]) LIBS="$LIBS -lelf"])
@end example
@noindent
@example
AC_CHECK_HEADER(elf.h,
- [AC_DEFINE(SVR4)
- LIBS="$LIBS -lelf"])
+ [AC_DEFINE(SVR4, 1, [System V Release 4])
+ LIBS="$LIBS -lelf"])
@end example
@noindent
instead of this:
@example
-AC_CHECK_HEADER(elf.h, [AC_DEFINE(SVR4); LIBS="$LIBS -lelf"])
+AC_CHECK_HEADER(elf.h,
+ [AC_DEFINE(SVR4, 1, [System V Release 4]); LIBS="$LIBS -lelf"])
@end example
@node Setting Output Variables
@quotation
Mash \Mash\, n. [Akin to G. meisch, maisch, meische, maische, mash,
-wash, and prob.@: to AS.@: miscian to mix. See ``Mix''.]
+wash, and prob.@: to AS. miscian to mix. See ``Mix''.]
@enumerate 1
@item
@c ------------------
@prindex @command{printf}
A format string starting with a @samp{-} can cause problems.
-Bash (eg. 2.05b) will interpret it as an options string and
+Bash (e.g., 2.05b) will interpret it as an options string and
give an error. And @samp{--} to mark the end of options is not good
-in the NetBSD Almquist shell (eg. 0.4.6) which will take that
+in the NetBSD Almquist shell (e.g., 0.4.6) which will take that
literally as the format string. Putting the @samp{-} in a @samp{%c}
or @samp{%s} is probably the easiest way to avoid doubt,
projects / thirdparty / autoconf.git / commitdiff
