Patch for bug 12802

["Joseph S. Myers" <jsm at polyomino dot org dot uk>]

This patch fixes bug 12802 by adding documentation of what cases of 
anonymous structs/unions -fms-extensions is needed for.  It passes "make 
info" and "make dvi".  Applied to mainline.

-- 
Joseph S. Myers               http://www.srcf.ucam.org/~jsm28/gcc/
  http://www.srcf.ucam.org/~jsm28/gcc/#c90status - status of C90 for GCC 4.0
    jsm@polyomino.org.uk (personal mail)
    jsm28@gcc.gnu.org (Bugzilla assignments and CCs)

2004-09-24  Joseph S. Myers  <jsm@polyomino.org.uk>

	PR c/12802
	* doc/extend.texi (Unnamed Fields): Remove "." from end of long
	title.  Document interaction with -fms-extensions.
	* doc/invoke.texi (-fms-extensions): Refer to Unnamed Fields
	section.

diff -rupN doc.orig/extend.texi doc/extend.texi
--- doc.orig/extend.texi	2004-09-23 16:08:32.000000000 +0000
+++ doc/extend.texi	2004-09-24 20:24:15.000000000 +0000
@@ -8308,7 +8308,7 @@ multiple @code{#pragma pack(@var{n})} in
 @end enumerate
 
 @node Unnamed Fields
-@section Unnamed struct/union fields within structs/unions.
+@section Unnamed struct/union fields within structs/unions
 @cindex struct
 @cindex union
 
@@ -8348,6 +8348,15 @@ It is ambiguous which @code{a} is being 
 Such constructs are not supported and must be avoided.  In the future,
 such constructs may be detected and treated as compilation errors.
 
+@opindex fms-extensions
+Unless @option{-fms-extensions} is used, the unnamed field must be a
+structure or union definition without a tag (for example, @samp{struct
+@{ int a; @};}).  If @option{-fms-extensions} is used, the field may
+also be a definition with a tag such as @samp{struct foo @{ int a;
+@};}, a reference to a previously defined structure or union such as
+@samp{struct foo;}, or a reference to a @code{typedef} name for a
+previously defined structure or union type.
+
 @node Thread-Local
 @section Thread-Local Storage
 @cindex Thread-Local Storage
diff -rupN doc.orig/invoke.texi doc/invoke.texi
--- doc.orig/invoke.texi	2004-09-23 16:08:32.000000000 +0000
+++ doc/invoke.texi	2004-09-24 20:15:38.000000000 +0000
@@ -1223,6 +1223,10 @@ freestanding and hosted environments.
 @opindex fms-extensions
 Accept some non-standard constructs used in Microsoft header files.
 
+Some cases of unnamed fields in structures and unions are only
+accepted with this option.  @xref{Unnamed Fields,,Unnamed struct/union
+fields within structs/unions}, for details.
+
 @item -trigraphs
 @opindex trigraphs
 Support ISO C trigraphs.  The @option{-ansi} option (and @option{-std}