Bug #57203 Assertion `field_length <= 255' failed.

After the fix for
Bug #55077 Assertion failed: width > 0 && to != ((void *)0), file .\dtoa.c
we no longer try to allocate a string of length 'field_length'
so the asserts are relevant only for ZEROFILL columns.

mysql-test/r/select.result

@@ -4887,3 +4887,22 @@ col_int_key
 DROP VIEW view_t1;
 DROP TABLE t1;
 # End of test BUG#54515
+#
+# Bug #57203 Assertion `field_length <= 255' failed.
+#
+SELECT coalesce((avg(distinct (geomfromtext("point(25379 -22010)"))))) 
+UNION ALL 
+SELECT coalesce((avg(distinct (geomfromtext("point(25379 -22010)")))))
+AS foo
+;
+coalesce((avg(distinct (geomfromtext("point(25379 -22010)")))))
+0.0000
+0.0000
+CREATE table t1(a text);
+INSERT INTO t1 VALUES (''), ('');
+SELECT avg(distinct(t1.a)) FROM t1, t1 t2
+GROUP BY t2.a ORDER BY t1.a;
+avg(distinct(t1.a))
+0
+DROP TABLE t1;
+# End of test BUG#57203

mysql-test/t/select.test

@@ -4147,3 +4147,22 @@ DROP VIEW view_t1;
 DROP TABLE t1;
 
 --echo # End of test BUG#54515
+
+--echo #
+--echo # Bug #57203 Assertion `field_length <= 255' failed.
+--echo #
+
+SELECT coalesce((avg(distinct (geomfromtext("point(25379 -22010)"))))) 
+UNION ALL 
+SELECT coalesce((avg(distinct (geomfromtext("point(25379 -22010)")))))
+AS foo
+;
+
+CREATE table t1(a text);
+INSERT INTO t1 VALUES (''), ('');
+SELECT avg(distinct(t1.a)) FROM t1, t1 t2
+GROUP BY t2.a ORDER BY t1.a;
+
+DROP TABLE t1;
+
+--echo # End of test BUG#57203

sql/field.cc

@@ -4189,7 +4189,7 @@ String *Field_float::val_str(String *val_buffer,
 			     String *val_ptr __attribute__((unused)))
 {
   ASSERT_COLUMN_MARKED_FOR_READ;
-  DBUG_ASSERT(field_length <= MAX_FIELD_CHARLENGTH);
+  DBUG_ASSERT(!zerofill || field_length <= MAX_FIELD_CHARLENGTH);
   float nr;
 #ifdef WORDS_BIGENDIAN
   if (table->s->db_low_byte_first)
@@ -4512,7 +4512,7 @@ String *Field_double::val_str(String *val_buffer,
 			      String *val_ptr __attribute__((unused)))
 {
   ASSERT_COLUMN_MARKED_FOR_READ;
-  DBUG_ASSERT(field_length <= MAX_FIELD_CHARLENGTH);
+  DBUG_ASSERT(!zerofill || field_length <= MAX_FIELD_CHARLENGTH);
   double nr;
 #ifdef WORDS_BIGENDIAN
   if (table->s->db_low_byte_first)