Fix for Bug#6024 "Test "client_test" fails in 4.1.6-gamma build (1)":

let's not assume that char is signed (its signedness is not defined).
The server was also affected by the wrong typedef.

include/my_global.h

@@ -713,7 +713,7 @@ typedef void	*gptr;		/* Generic pointer */
 typedef char	*gptr;		/* Generic pointer */
 #endif
 #ifndef HAVE_INT_8_16_32
-typedef char	int8;		/* Signed integer >= 8	bits */
+typedef signed char int8;       /* Signed integer >= 8  bits */
 typedef short	int16;		/* Signed integer >= 16 bits */
 #endif
 #ifndef HAVE_UCHAR

libmysql/libmysql.c

@@ -3611,9 +3611,10 @@ static void fetch_result_with_conversion(MYSQL_BIND *param, MYSQL_FIELD *field,
   switch (field_type) {
   case MYSQL_TYPE_TINY:
   {
-    char value= (char) **row;
-    longlong data= field_is_unsigned ? (longlong) (unsigned char) value :
-                                       (longlong) value;
+    uchar value= **row;
+    /* sic: we need to cast to 'signed char' as 'char' may be unsigned */
+    longlong data= field_is_unsigned ? (longlong) value :
+                                       (longlong) (signed char) value;
     fetch_long_with_conversion(param, field, data);
     *row+= 1;
     break;