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(Defining Symbols): Explain that AC_DEFINE(var) defaults to 1, but

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AC_DEFINE(var,,description) does not; and the AC_DEFINE(var) case is
obsolescent.
This commit is contained in:
Paul Eggert 2002-09-11 19:03:59 +00:00
parent d49b7acc2f
commit a223ff645d
1 changed files with 7 additions and 2 deletions
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9
doc/autoconf.texi
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@ -6087,8 +6087,7 @@ output.
@defmac AC_DEFINE (@var{variable}, @ovar{value}, @ovar{description})
@acindex DEFINE
Define C preprocessor variable @var{variable}. If @var{value} is given,
set @var{variable} to that value (verbatim), otherwise set it to 1.
Define the C preprocessor variable @var{variable} to @var{value} (verbatim).
@var{value} should not contain literal newlines, and if you are not
using @code{AC_CONFIG_HEADERS} it should not contain any @samp{#}
characters, as @command{make} tends to eat them. To use a shell variable
@ -6103,6 +6102,12 @@ The following example defines the C preprocessor variable
@example
AC_DEFINE(EQUATION, "$a > $b")
@end example
If neither @var{value} nor @var{description} are given, then
@var{value} defaults to 1 instead of to the empty string. This is for
backwards compatiblity with older versions of Autoconf, but this usage
is obsolescent and may be withdrawn in future versions of Autoconf.
@end defmac
@defmac AC_DEFINE_UNQUOTED (@var{variable}, @ovar{value}, @ovar{description})