improve iswdigit macro to diagnose errors

[musl] / include / wchar.h

diff --git a/include/wchar.h b/include/wchar.h
index ad727a8..0167dce 100644 (file)
--- a/include/wchar.h
+++ b/include/wchar.h
@@ -175,7 +175,7 @@ wctype_t  wctype(const char *);
 
 #ifndef __cplusplus
 #undef iswdigit
-#define iswdigit(a) ((unsigned)(a)-'0' < 10)
+#define iswdigit(a) (0 ? iswdigit(a) : ((unsigned)(a)-'0') < 10)
 #endif
 #endif