* c-parse.in (OFFSETOF, offsetof_member_designator): New.

        (primary): Handle offsetof.  Add error productions for faux functions.
        Move component_ref objc checking to build_component_ref.
        (reswords): Add offsetof.
        (rid_to_yy): Add offsetof.
        * c-tree.h (build_offsetof): Declare.
        * c-common.h (objc_is_public): Declare.
        * c-typeck.c (build_component_ref): Check objc_is_public.
        (build_offsetof): New.
        * stub-objc.c (objc_is_public): New.
        * objc/objc-act.c, objc/objc-act.h (objc_is_public): Rename
        from is_public.
        * ginclude/stddef.h (offsetof): Use __builtin_offsetof.
        * doc/extend.texi (Offsetof): Move from C++ section to C section
        and rewrite for __builtin_offsetof.
cp/
        * lex.c (reswords): Rename "__offsetof" to "__builtin_offsetof".
        * parser.c (struct cp_parser): Remove in_offsetof.
        (cp_parser_new): Don't set it.
        (cp_parser_unary_expression): Don't check it.
        (cp_parser_postfix_open_square_expression): Split out from ...
        (cp_parser_postfix_expression): ... here.
        (cp_parser_postfix_dot_deref_expression): Likewise.
        (cp_parser_builtin_offsetof): New.
        (cp_parser_primary_expression): Use it.
testsuite/
        * g++.dg/template/dependent-expr4.C: Use __builtin_offsetof.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@82549 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 28 insertions, 20 deletions

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 22f5f29efd1..204c64b1006 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -469,6 +469,7 @@ extensions, accepted by GCC in C89 mode and in C++.
 			 function.
 * Return Address::      Getting the return or frame address of a function.
 * Vector Extensions::   Using vector instructions through built-in functions.
+* Offsetof::            Special syntax for implementing @code{offsetof}.
 * Other Builtins::      Other built-in functions.
 * Target Builtins::     Built-in functions specific to particular targets.
 * Pragmas::             Pragmas accepted by GCC.
@@ -4704,6 +4705,33 @@ v4si f (v4si a, v4si b, v4si c)
 
 @end smallexample
 
+@node Offsetof
+@section Offsetof
+@findex __builtin_offsetof
+
+GCC implements for both C and C++ a syntactic extension to implement
+the @code{offsetof} macro.
+
+@smallexample
+primary:
+	"__builtin_offsetof" "(" @code{typename} "," offsetof_member_designator ")"
+
+offsetof_member_designator:
+	  @code{identifier}
+	| offsetof_member_designator "." @code{identifier}
+	| offsetof_member_designator "[" @code{expr} "]"
+@end smallexample
+
+This extension is sufficient such that
+
+@smallexample
+#define offsetof(@var{type}, @var{member})  __builtin_offsetof (@var{type}, @var{member})
+@end smallexample
+
+is a suitable definition of the @code{offsetof} macro.  In C++, @var{type}
+may be dependent.  In either case, @var{member} may consist of a single
+identifier, or a sequence of member accesses and array references.
+
 @node Other Builtins
 @section Other built-in functions provided by GCC
 @cindex built-in functions
@@ -7620,7 +7648,6 @@ Predefined Macros,cpp,The GNU C Preprocessor}).
                         method denoted by a @samp{->*} or @samp{.*} expression.
 * C++ Attributes::      Variable, function, and type attributes for C++ only.
 * Strong Using::      Strong using-directives for namespace composition.
-* Offsetof::            Special syntax for implementing @code{offsetof}.
 * Java Exceptions::     Tweaking exception handling to work with Java.
 * Deprecated Features:: Things will disappear from g++.
 * Backwards Compatibility:: Compatibilities with earlier definitions of C++.
@@ -8265,25 +8292,6 @@ int main()
 @}
 @end smallexample
 
-@node Offsetof
-@section Offsetof
-
-G++ uses a syntactic extension to implement the @code{offsetof} macro.
-
-In particular:
-
-@smallexample
-  __offsetof__ (expression)
-@end smallexample
-
-is equivalent to the parenthesized expression, except that the
-expression is considered an integral constant expression even if it
-contains certain operators that are not normally permitted in an
-integral constant expression.  Users should never use
-@code{__offsetof__} directly; the only valid use of
-@code{__offsetof__} is to implement the @code{offsetof} macro in
-@code{<stddef.h>}.
-
 @node Java Exceptions
 @section Java Exceptions