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Document va_copy in preference to __va_copy.

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Joseph Myers 2012-07-20 23:49:24 +00:00
parent b3404dbdeb
commit b5982523b1
3 changed files with 24 additions and 14 deletions
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8
ChangeLog
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@ -1,3 +1,11 @@
2012-07-20 Joseph Myers <joseph@codesourcery.com>
* manual/lang.texi (__va_copy): Document primarily as ISO C99
va_copy. Document allowing for unavailable va_copy only as
pre-C99 compatibility.
* manual/string.texi (Copying and Concatenation): Use va_copy
instead of __va_copy in concat example.
2012-07-20 Pino Toscano <toscano.pino@tiscali.it>
* sysdeps/mach/hurd/sendto.c (create_address_port): New subroutine.

25
manual/lang.texi
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@ -463,28 +463,33 @@ assign the value of one variable of type @code{va_list} to another variable
of the same type.
@comment stdarg.h
@comment GNU
@deftypefn {Macro} void __va_copy (va_list @var{dest}, va_list @var{src})
The @code{__va_copy} macro allows copying of objects of type
@comment ISO
@deftypefn {Macro} void va_copy (va_list @var{dest}, va_list @var{src})
@deftypefnx {Macro} void __va_copy (va_list @var{dest}, va_list @var{src})
The @code{va_copy} macro allows copying of objects of type
@code{va_list} even if this is not an integral type. The argument pointer
in @var{dest} is initialized to point to the same argument as the
pointer in @var{src}.
This macro is a GNU extension but it will hopefully also be available in
the next update of the ISO C standard.
This macro was added in ISO C99. When building for strict conformance
to ISO C90 (@samp{gcc -ansi}), it is not available. The macro
@code{__va_copy} is available as a GNU extension in any standards
mode; before GCC 3.0, it was the only macro for this functionality.
@end deftypefn
If you want to use @code{__va_copy} you should always be prepared for the
If you want to use @code{va_copy} and be portable to pre-C99 systems,
you should always be prepared for the
possibility that this macro will not be available. On architectures where a
simple assignment is invalid, hopefully @code{__va_copy} @emph{will} be available,
so one should always write something like this:
simple assignment is invalid, hopefully @code{va_copy} @emph{will} be available,
so one should always write something like this if concerned about
pre-C99 portability:
@smallexample
@{
va_list ap, save;
@dots{}
#ifdef __va_copy
__va_copy (save, ap);
#ifdef va_copy
va_copy (save, ap);
#else
save = ap;
#endif

5
manual/string.texi
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@ -824,7 +824,6 @@ to use @code{strcat}/@code{wcscat}. A lot of time is wasted finding the
end of the destination string so that the actual copying can start.
This is a common example:
@cindex __va_copy
@cindex va_copy
@smallexample
/* @r{This function concatenates arbitrarily many strings. The last}
@ -838,9 +837,7 @@ concat (const char *str, @dots{})
char *result;
va_start (ap, str);
/* @r{Actually @code{va_copy}, but this is the name more gcc versions}
@r{understand.} */
__va_copy (ap2, ap);
va_copy (ap2, ap);
/* @r{Determine how much space we need.} */
for (s = str; s != NULL; s = va_arg (ap, const char *))