diff options
Diffstat (limited to 'manual/lang.texi')
| -rw-r--r-- | manual/lang.texi | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/manual/lang.texi b/manual/lang.texi index baaccaa..ee04e23 100644 --- a/manual/lang.texi +++ b/manual/lang.texi @@ -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 |