Re: [patches] RFC: Fix values of WCHAR_MIN and WCHAR_MAX

[Jim Blandy <jimb@xxxxxxxxxxxxxxxx>]

"Joseph S. Myers" <joseph@xxxxxxxxxxxxxxxx> writes:
> On Fri, 28 Sep 2007, Jim Blandy wrote:
>
>> +#ifdef __WCHAR_UNSIGNED__
>> +#define WCHAR_MIN       0
>> +
>> +/* Failing that, rely on the preprocessor's knowledge of the
>> +   signedness of wchar_t.  */
>> +#elif L'\0' - 1 > 0
>> +#define WCHAR_MIN       0
>
> Both these values of WCHAR_MIN should be L'\0' not plain 0, so they have 
> the correct (unsigned) type.  It looks correct with that change.

Thanks for the review.  I've committed the following:

ChangeLog.eglibc:
2007-09-27  Jim Blandy  <jimb@xxxxxxxxxxxxxxxx>

	* bits/wchar.h (__WCHAR_MIN, __WCHAR_MAX): Use information
	provided by GCC and the preprocessor's behavior to handle both
	signed and unsigned wchar_t ranges.

Index: bits/wchar.h
===================================================================
--- bits/wchar.h	(revision 3615)
+++ bits/wchar.h	(working copy)
@@ -20,7 +20,24 @@
 #ifndef _BITS_WCHAR_H
 #define _BITS_WCHAR_H	1
 
-#define __WCHAR_MIN	(-2147483647 - 1)
+/* Use GCC's __WCHAR_MAX__ when available.  */
+#ifdef __WCHAR_MAX__
+#define __WCHAR_MAX	__WCHAR_MAX__
+#else
 #define __WCHAR_MAX	(2147483647)
+#endif
 
+/* GCC may also define __WCHAR_UNSIGNED__.
+   Use L'\0' to give the expression the correct (unsigned) type.  */
+#ifdef __WCHAR_UNSIGNED__
+#define WCHAR_MIN       L'\0'
+
+/* Failing that, rely on the preprocessor's knowledge of the
+   signedness of wchar_t.  */
+#elif L'\0' - 1 > 0
+#define WCHAR_MIN       L'\0'
+#else
+#define WCHAR_MIN       (-WCHAR_MAX - 1)
+#endif
+
 #endif	/* bits/wchar.h */