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| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/doc/extend.texi | 17 |
2 files changed, 23 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index b146480..9450599 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,4 +1,10 @@ 2019-02-25 Sandra Loosemore <sandra@codesourcery.com> + + PR c/80409 + + * doc/extend.texi (Variadic Pointer Args): New section. + +2019-02-25 Sandra Loosemore <sandra@codesourcery.com> Martin Sebor <msebor@gmail.com> * c-family/c.opt (Wmissing-attributes): Clean up doc string. diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index d9c78a3..696d892c 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -47,6 +47,7 @@ extensions, accepted by GCC in C90 mode and in C++. * Escaped Newlines:: Slightly looser rules for escaped newlines. * Subscripting:: Any array can be subscripted, even if not an lvalue. * Pointer Arith:: Arithmetic on @code{void}-pointers and function pointers. +* Variadic Pointer Args:: Pointer arguments to variadic functions. * Pointers to Arrays:: Pointers to arrays with qualifiers work as expected. * Initializers:: Non-constant initializers. * Compound Literals:: Compound literals give structures, unions @@ -1944,6 +1945,22 @@ and on function types, and returns 1. The option @option{-Wpointer-arith} requests a warning if these extensions are used. +@node Variadic Pointer Args +@section Pointer Arguments in Variadic Functions +@cindex pointer arguments in variadic functions +@cindex variadic functions, pointer arguments + +Standard C requires that pointer types used with @code{va_arg} in +functions with variable argument lists either must be compatible with +that of the actual argument, or that one type must be a pointer to +@code{void} and the other a pointer to a character type. GNU C +implements the POSIX XSI extension that additionally permits the use +of @code{va_arg} with a pointer type to receive arguments of any other +pointer type. + +In particular, in GNU C @samp{va_arg (ap, void *)} can safely be used +to consume an argument of any pointer type. + @node Pointers to Arrays @section Pointers to Arrays with Qualifiers Work as Expected @cindex pointers to arrays |