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Diffstat (limited to 'gcc/doc/extend.texi')
| -rw-r--r-- | gcc/doc/extend.texi | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index 0012740476b..9f306a44e48 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -556,6 +556,32 @@ the containing function. You should specify, for @var{result}, a value returned by @code{__builtin_apply}. @end deftypefn +@deftypefn {Built-in Function} __builtin_va_arg_pack () +This built-in function represents all anonymous arguments of an inline +function. It can be used only in inline functions which will be always +inlined, never compiled as a separate function, such as those using +@code{__attribute__ ((__always_inline__))} or +@code{__attribute__ ((__gnu_inline__))} extern inline functions. +It must be only passed as last argument to some other function +with variable arguments. This is useful for writing small wrapper +inlines for variable argument functions, when using preprocessor +macros is undesirable. For example: +@smallexample +extern int myprintf (FILE *f, const char *format, ...); +extern inline __attribute__ ((__gnu_inline__)) int +myprintf (FILE *f, const char *format, ...) +@{ + int r = fprintf (f, "myprintf: "); + if (r < 0) + return r; + int s = fprintf (f, format, __builtin_va_arg_pack ()); + if (s < 0) + return s; + return r + s; +@} +@end smallexample +@end deftypefn + @node Typeof @section Referring to a Type with @code{typeof} @findex typeof |