Avoid g++-3.1 offsetof warnings.

ChangeLog

@@ -1,5 +1,9 @@
 2002-05-05  Bruno Haible  <bruno@clisp.org>
 
+	Avoid g++ 3.1 warnings.
+	* src/base/cl_offsetof.h (offsetof): Redefine each time.
+	* src/base/digitseq/cl_DS.h: Include "cl_offsetof.h" after <gmp.h>.
+
 	Avoid g++ 3.1 warnings.
 	* src/base/hash/cl_hash.h (struct cl_heap_hashtable): Use typename
 	where needed.

src/base/cl_offsetof.h

@@ -1,7 +1,9 @@
 // offsetof() and friends
 
-#ifndef _CL_OFFSETOF_H
-#define _CL_OFFSETOF_H
+// <stddef.h> in GCC 3.0/3.1 has the obscure property of redefining
+// offsetof every time it is included, not just the first time.
+// Therefore we do the same thing here, and make sure that this file
+// gets included after each include of <stddef.h>.
 
 #undef offsetof
 #if defined(__GNUG__)
@@ -9,6 +11,10 @@
 #else
   #define offsetof(type,ident)  ((long)&(((type*)0)->ident))
 #endif
+
+#ifndef _CL_OFFSETOF_H
+#define _CL_OFFSETOF_H
+
 #define offsetofa(type,ident)  offsetof(type,ident[0])
 
 #endif /* _CL_OFFSETOF_H */

src/base/digitseq/cl_DS.h

@@ -354,6 +354,9 @@ extern void shiftxor_loop_up (uintD* xptr, const uintD* yptr, uintC count, uintC
 }  // namespace cln
 
 #include <gmp.h>
+// Argh, gmp.h includes <stddef.h> which erases the definition of offsetof
+// that we have provided in cl_offsetof.h. Restore it.
+#include "cl_offsetof.h"
 
 namespace cln {