MDEV-24584 Selecting INT column with COLLATE utf8mb4_general_ci throws an error

Author: abarkov

mysql-test/main/ctype_ucs.result

@@ -6473,5 +6473,24 @@ CAST(_ucs2 0x0061E0030062 AS INT)
 Warnings:
 Warning	1292	Truncated incorrect INTEGER value: 'ab'
 #
+# MDEV-24584 Selecting INT column with COLLATE utf8mb4_general_ci throws an error
+#
+SET NAMES utf8, collation_connection=ucs2_general_ci;
+SELECT 1 COLLATE ucs2_general_ci;
+1 COLLATE ucs2_general_ci
+1
+SELECT 1 COLLATE ucs2_bin;
+1 COLLATE ucs2_bin
+1
+SELECT HEX(1 COLLATE ucs2_general_ci);
+HEX(1 COLLATE ucs2_general_ci)
+0031
+SELECT HEX(1 COLLATE ucs2_bin);
+HEX(1 COLLATE ucs2_bin)
+0031
+SELECT 1 COLLATE latin1_swedish_ci;
+ERROR 42000: COLLATION 'latin1_swedish_ci' is not valid for CHARACTER SET 'ucs2'
+SET NAMES utf8;
+#
 # End of 10.5 tests
 #

mysql-test/main/ctype_ucs.test

@@ -1146,6 +1146,19 @@ SELECT CAST(_ucs2 0x0061DFFF0062 AS INT);
 SELECT CAST(_ucs2 0x0061D7000062 AS INT);
 SELECT CAST(_ucs2 0x0061E0030062 AS INT);
 
+--echo #
+--echo # MDEV-24584 Selecting INT column with COLLATE utf8mb4_general_ci throws an error
+--echo #
+
+SET NAMES utf8, collation_connection=ucs2_general_ci;
+SELECT 1 COLLATE ucs2_general_ci;
+SELECT 1 COLLATE ucs2_bin;
+SELECT HEX(1 COLLATE ucs2_general_ci);
+SELECT HEX(1 COLLATE ucs2_bin);
+--error ER_COLLATION_CHARSET_MISMATCH
+SELECT 1 COLLATE latin1_swedish_ci;
+SET NAMES utf8;
+
 --echo #
 --echo # End of 10.5 tests
 --echo #

mysql-test/main/ctype_utf8mb4.result

@@ -4149,3 +4149,21 @@ c
 #
 # End of 10.2 tests
 #
+#
+# Start of 10.5 tests
+#
+#
+# MDEV-24584 Selecting INT column with COLLATE utf8mb4_general_ci throws an error
+#
+SET NAMES utf8mb4;
+SELECT 1 COLLATE utf8mb4_general_ci;
+1 COLLATE utf8mb4_general_ci
+1
+SELECT 1 COLLATE utf8mb4_bin;
+1 COLLATE utf8mb4_bin
+1
+SELECT 1 COLLATE latin1_swedish_ci;
+ERROR 42000: COLLATION 'latin1_swedish_ci' is not valid for CHARACTER SET 'utf8mb4'
+#
+# End of 10.5 tests
+#

mysql-test/main/ctype_utf8mb4.test

@@ -2043,3 +2043,22 @@ EXECUTE IMMEDIATE 'SELECT ''😎'' AS c';
 --echo #
 --echo # End of 10.2 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-24584 Selecting INT column with COLLATE utf8mb4_general_ci throws an error
+--echo #
+
+SET NAMES utf8mb4;
+SELECT 1 COLLATE utf8mb4_general_ci;
+SELECT 1 COLLATE utf8mb4_bin;
+--error ER_COLLATION_CHARSET_MISMATCH
+SELECT 1 COLLATE latin1_swedish_ci;
+
+--echo #
+--echo # End of 10.5 tests
+--echo #

sql/item_strfunc.cc

@@ -3552,10 +3552,12 @@ String *Item_func_set_collation::val_str(String *str)
 
 bool Item_func_set_collation::fix_length_and_dec()
 {
-  if (!my_charset_same(args[0]->collation.collation, m_set_collation))
+  if (agg_arg_charsets_for_string_result(collation, args, 1))
+    return true;
+  if (!my_charset_same(collation.collation, m_set_collation))
   {
     my_error(ER_COLLATION_CHARSET_MISMATCH, MYF(0),
-             m_set_collation->name, args[0]->collation.collation->csname);
+             m_set_collation->name, collation.collation->csname);
     return TRUE;
   }
   collation.set(m_set_collation, DERIVATION_EXPLICIT,