cherry pick pingcap#29563 to release-5.0

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

expression/builtin_cast.go

@@ -290,6 +290,9 @@ func (c *castAsStringFunctionClass) getFunction(ctx sessionctx.Context, args []E
 	argTp := args[0].GetType().EvalType()
 	switch argTp {
 	case types.ETInt:
+		if bf.tp.Flen == types.UnspecifiedLength {
+			bf.tp.Flen = args[0].GetType().Flen
+		}
 		sig = &builtinCastIntAsStringSig{bf}
 		sig.setPbCode(tipb.ScalarFuncSig_CastIntAsString)
 	case types.ETReal:

expression/integration_test.go

@@ -9274,3 +9274,16 @@ func (s *testIntegrationSuite) TestConstPropNullFunctions(c *C) {
 	tk.MustExec("insert into t2 values (0, 'c', null), (1, null, 0.1), (3, 'b', 0.01), (2, 'q', 0.12), (null, 'a', -0.1), (null, null, null)")
 	tk.MustQuery("select * from t2 where t2.i2=((select count(1) from t1 where t1.i1=t2.i2))").Check(testkit.Rows("1 <nil> 0.1"))
 }
+
+func (s *testIntegrationSuite) TestIssue29513(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustQuery("select '123' union select cast(45678 as char);").Sort().Check(testkit.Rows("123", "45678"))
+	tk.MustQuery("select '123' union select cast(45678 as char(2));").Sort().Check(testkit.Rows("123", "45"))
+
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a int);")
+	tk.MustExec("insert into t values(45678);")
+	tk.MustQuery("select '123' union select cast(a as char) from t;").Sort().Check(testkit.Rows("123", "45678"))
+	tk.MustQuery("select '123' union select cast(a as char(2)) from t;").Sort().Check(testkit.Rows("123", "45"))
+}

expression/typeinfer_test.go

@@ -181,9 +181,9 @@ func (s *testInferTypeSuite) createTestCase4Constants() []typeInferTestCase {
 
 func (s *testInferTypeSuite) createTestCase4Cast() []typeInferTestCase {
 	return []typeInferTestCase{
-		{"CAST(c_int_d AS BINARY)", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag, -1, -1}, // TODO: Flen should be 11.
+		{"CAST(c_int_d AS BINARY)", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag, 11, -1},
 		{"CAST(c_int_d AS BINARY(5))", mysql.TypeString, charset.CharsetBin, mysql.BinaryFlag, 5, -1},
-		{"CAST(c_int_d AS CHAR)", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, -1, -1}, // TODO: Flen should be 11.
+		{"CAST(c_int_d AS CHAR)", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 11, -1},
 		{"CAST(c_int_d AS CHAR(5))", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 5, -1},
 		{"CAST(c_int_d AS DATE)", mysql.TypeDate, charset.CharsetBin, mysql.BinaryFlag, 10, 0},
 		{"CAST(c_int_d AS DATETIME)", mysql.TypeDatetime, charset.CharsetBin, mysql.BinaryFlag, 19, 0},
@@ -406,9 +406,15 @@ func (s *testInferTypeSuite) createTestCase4StrFuncs() []typeInferTestCase {
 
 		{"reverse(c_int_d      )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 20, types.UnspecifiedLength},
 		{"reverse(c_bigint_d   )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 20, types.UnspecifiedLength},
+<<<<<<< HEAD
 		{"reverse(c_float_d    )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, -1, types.UnspecifiedLength},
 		{"reverse(c_double_d   )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, -1, types.UnspecifiedLength},
 		{"reverse(c_decimal    )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 8, types.UnspecifiedLength},
+=======
+		{"reverse(c_float_d    )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, types.UnspecifiedLength, types.UnspecifiedLength},
+		{"reverse(c_double_d   )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, types.UnspecifiedLength, types.UnspecifiedLength},
+		{"reverse(c_decimal    )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 9, types.UnspecifiedLength},
+>>>>>>> 8858592f7... expression: fix wrong flen for CastAsString funtion (#29563)
 		{"reverse(c_char       )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 20, types.UnspecifiedLength},
 		{"reverse(c_varchar    )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 20, types.UnspecifiedLength},
 		{"reverse(c_text_d     )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 65535, types.UnspecifiedLength},