MDEV-22243 type_test.type_test_double fails with 'NUMERIC_SCALE NULL'

There where several reasons why the test failed:
- Constructors for Field_double and Field_float changed an argument
  to the constructor instead of a the correct class variable.
- gcc 7.5.0 produced wrong code when inlining Field_double constructor
  into Field_test_double constructor.

Fixed by changing the correct class variable and make the constructors
not inline to go around the gcc bug.

plugin/type_test/mysql-test/type_test/type_test_double.result

@@ -290,7 +290,7 @@ DATA_TYPE	test_double
 CHARACTER_MAXIMUM_LENGTH	NULL
 CHARACTER_OCTET_LENGTH	NULL
 NUMERIC_PRECISION	22
-NUMERIC_SCALE	31
+NUMERIC_SCALE	NULL
 DATETIME_PRECISION	NULL
 CHARACTER_SET_NAME	NULL
 COLLATION_NAME	NULL

sql/field.cc

@@ -4645,6 +4645,28 @@ bool Field_longlong::is_max()
   single precision float
 ****************************************************************************/
 
+Field_float::Field_float(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
+                         uchar null_bit_arg,
+                         enum utype unireg_check_arg,
+                         const LEX_CSTRING *field_name_arg,
+                         uint8 dec_arg,bool zero_arg,bool unsigned_arg)
+  :Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
+              unireg_check_arg, field_name_arg,
+              (dec_arg >= FLOATING_POINT_DECIMALS ? NOT_FIXED_DEC : dec_arg),
+              zero_arg, unsigned_arg)
+{
+}
+
+Field_float::Field_float(uint32 len_arg, bool maybe_null_arg,
+                         const LEX_CSTRING *field_name_arg, uint8 dec_arg)
+  :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "": 0, (uint) 0,
+              NONE, field_name_arg,
+              (dec_arg >= FLOATING_POINT_DECIMALS ? NOT_FIXED_DEC : dec_arg),
+              0, 0)
+{
+}
+
+
 int Field_float::store(const char *from,size_t len,CHARSET_INFO *cs)
 {
   int error;
@@ -4793,6 +4815,38 @@ Binlog_type_info Field_float::binlog_type_info() const
   double precision floating point numbers
 ****************************************************************************/
 
+Field_double::Field_double(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
+                           uchar null_bit_arg,
+                           enum utype unireg_check_arg,
+                           const LEX_CSTRING *field_name_arg,
+                           uint8 dec_arg,bool zero_arg,bool unsigned_arg)
+  :Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
+              unireg_check_arg, field_name_arg,
+              (dec_arg >= FLOATING_POINT_DECIMALS ? NOT_FIXED_DEC : dec_arg),
+              zero_arg, unsigned_arg)
+{
+}
+
+Field_double::Field_double(uint32 len_arg, bool maybe_null_arg,
+                           const LEX_CSTRING *field_name_arg, uint8 dec_arg)
+  :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "" : 0, (uint) 0,
+              NONE, field_name_arg,
+              (dec_arg >= FLOATING_POINT_DECIMALS ? NOT_FIXED_DEC : dec_arg),
+              0, 0)
+{
+}
+
+Field_double::Field_double(uint32 len_arg, bool maybe_null_arg,
+                           const LEX_CSTRING *field_name_arg,
+                           uint8 dec_arg, bool not_fixed_arg)
+  :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "" : 0, (uint) 0,
+              NONE, field_name_arg,
+              (dec_arg >= FLOATING_POINT_DECIMALS ? NOT_FIXED_DEC : dec_arg),
+              0, 0)
+{
+  not_fixed= not_fixed_arg;
+}
+
 int Field_double::store(const char *from,size_t len,CHARSET_INFO *cs)
 {
   int error;

sql/field.h

@@ -2842,22 +2842,9 @@ class Field_float final :public Field_real {
   Field_float(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
 	      uchar null_bit_arg,
 	      enum utype unireg_check_arg, const LEX_CSTRING *field_name_arg,
-              uint8 dec_arg,bool zero_arg,bool unsigned_arg)
-    :Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
-                unireg_check_arg, field_name_arg,
-                dec_arg, zero_arg, unsigned_arg)
-    {
-      if (dec_arg >= FLOATING_POINT_DECIMALS)
-        dec_arg= NOT_FIXED_DEC;
-    }
+              uint8 dec_arg,bool zero_arg,bool unsigned_arg);
   Field_float(uint32 len_arg, bool maybe_null_arg,
-              const LEX_CSTRING *field_name_arg, uint8 dec_arg)
-    :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "": 0, (uint) 0,
-                NONE, field_name_arg, dec_arg, 0, 0)
-    {
-      if (dec_arg >= FLOATING_POINT_DECIMALS)
-        dec_arg= NOT_FIXED_DEC;
-    }
+              const LEX_CSTRING *field_name_arg, uint8 dec_arg);
   const Type_handler *type_handler() const override
   { return &type_handler_float; }
   enum ha_base_keytype key_type() const override { return HA_KEYTYPE_FLOAT; }
@@ -2890,32 +2877,12 @@ class Field_double :public Field_real {
   Field_double(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
 	       uchar null_bit_arg,
 	       enum utype unireg_check_arg, const LEX_CSTRING *field_name_arg,
-	       uint8 dec_arg,bool zero_arg,bool unsigned_arg)
-    :Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
-                unireg_check_arg, field_name_arg,
-                dec_arg, zero_arg, unsigned_arg)
-    {
-      if (dec_arg >= FLOATING_POINT_DECIMALS)
-        dec_arg= NOT_FIXED_DEC;
-    }
+	       uint8 dec_arg,bool zero_arg,bool unsigned_arg);
   Field_double(uint32 len_arg, bool maybe_null_arg,
-               const LEX_CSTRING *field_name_arg, uint8 dec_arg)
-    :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "" : 0, (uint) 0,
-                NONE, field_name_arg, dec_arg, 0, 0)
-    {
-      if (dec_arg >= FLOATING_POINT_DECIMALS)
-        dec_arg= NOT_FIXED_DEC;
-    }
+               const LEX_CSTRING *field_name_arg, uint8 dec_arg);
   Field_double(uint32 len_arg, bool maybe_null_arg,
                const LEX_CSTRING *field_name_arg,
-	       uint8 dec_arg, bool not_fixed_arg)
-    :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "" : 0, (uint) 0,
-                NONE, field_name_arg, dec_arg, 0, 0)
-    {
-      not_fixed= not_fixed_arg;
-      if (dec_arg >= FLOATING_POINT_DECIMALS)
-        dec_arg= NOT_FIXED_DEC;
-    }
+	       uint8 dec_arg, bool not_fixed_arg);
   void init_for_tmp_table(Field *org_field, TABLE *new_table) override
   {
     Field::init_for_tmp_table(org_field, new_table);