MDEV-26691 SFORMAT: Pass down FLOAT as FLOAT, without upcast to DOUBLE

mysql-test/main/func_sformat.result

@@ -449,3 +449,9 @@ sformat("={:d}=", ?)
 NULL
 Warnings:
 Warning	4183	SFORMAT error: invalid type specifier
+#
+# MDEV-26691 SFORMAT: Pass down FLOAT as FLOAT, without upcast to DOUBLE
+#
+select sformat('{}', cast(1.1 as float));
+sformat('{}', cast(1.1 as float))
+1.1

mysql-test/main/func_sformat.test

@@ -207,3 +207,9 @@ echo #;
 prepare s from 'select sformat("={:d}=", ?)';
 execute s using 100;
 execute s using 'abc';
+
+echo #;
+echo # MDEV-26691 SFORMAT: Pass down FLOAT as FLOAT, without upcast to DOUBLE;
+echo #;
+
+select sformat('{}', cast(1.1 as float));

sql/item_strfunc.cc

@@ -1393,7 +1393,10 @@ String *Item_func_sformat::val_str(String *res)
       break;
     case DECIMAL_RESULT: // TODO
     case REAL_RESULT:
-      vargs[carg-1]= fmt::detail::make_arg<ctx>(args[carg]->val_real());
+      if (args[carg]->field_type() == MYSQL_TYPE_FLOAT)
+        vargs[carg-1]= fmt::detail::make_arg<ctx>((float)args[carg]->val_real());
+      else
+        vargs[carg-1]= fmt::detail::make_arg<ctx>(args[carg]->val_real());
       break;
     case STRING_RESULT:
       if (!(parg= args[carg]->val_str(&val_arg[carg-1])))