From 899c2f05f67f67e3b1c191e7b14ea9591338b256 Mon Sep 17 00:00:00 2001
From: ti-srebot <66930949+ti-srebot@users.noreply.github.com>
Date: Thu, 12 Aug 2021 23:39:17 +0800
Subject: [PATCH] expression: fix wrong flen infer for bit constant (#23867)
 (#24267)

---
 expression/integration_test.go | 5 +++++
 expression/typeinfer_test.go   | 6 +++---
 types/field_type.go            | 2 +-
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/expression/integration_test.go b/expression/integration_test.go
index e5dfe15894c0f..fd90a59ac5fb8 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -4618,6 +4618,11 @@ func (s *testIntegrationSuite) TestIssues(c *C) {
 	tk.MustExec(`insert into t2 values(1,"1111"),(2,"2222"),(3,"3333"),(4,"4444"),(5,"5555"),(6,"6666"),(7,"7777"),(8,"8888"),(9,"9999"),(10,"0000")`)
 	tk.MustQuery(`select (@j := case when substr(t2.b,1,3)=@i then 1 else @j+1 end) from t2, (select @j := 0, @i := "0") tt limit 10`).Check(testkit.Rows(
 		"1", "2", "3", "4", "5", "6", "7", "8", "9", "10"))
+
+	// for issue #23479
+	tk.MustQuery("select b'10000000' DIV 10").Check(testkit.Rows("12"))
+	tk.MustQuery("select cast(b'10000000' as unsigned) / 10").Check(testkit.Rows("12.8000"))
+	tk.MustQuery("select b'10000000' / 10").Check(testkit.Rows("12.8000"))
 }
 
 func (s *testIntegrationSuite) TestInPredicate4UnsignedInt(c *C) {
diff --git a/expression/typeinfer_test.go b/expression/typeinfer_test.go
index 321598891d374..10e146d6189ab 100644
--- a/expression/typeinfer_test.go
+++ b/expression/typeinfer_test.go
@@ -170,9 +170,9 @@ func (s *testInferTypeSuite) createTestCase4Constants() []typeInferTestCase {
 		{"'1234'", mysql.TypeVarString, charset.CharsetUTF8MB4, 0 | mysql.NotNullFlag, 4, types.UnspecifiedLength},
 		{"_utf8'1234'", mysql.TypeVarString, charset.CharsetUTF8, 0 | mysql.NotNullFlag, 4, types.UnspecifiedLength},
 		{"_binary'1234'", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag | mysql.NotNullFlag, 4, types.UnspecifiedLength},
-		{"b'0001'", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag | mysql.NotNullFlag, 1, 0},
-		{"b'000100001'", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag | mysql.NotNullFlag, 2, 0},
-		{"b'0000000000010000'", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag | mysql.NotNullFlag, 2, 0},
+		{"b'0001'", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag | mysql.NotNullFlag, 3, 0},
+		{"b'000100001'", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag | mysql.NotNullFlag, 6, 0},
+		{"b'0000000000010000'", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag | mysql.NotNullFlag, 6, 0},
 		{"x'10'", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag | mysql.UnsignedFlag | mysql.NotNullFlag, 3, 0},
 		{"x'ff10'", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag | mysql.UnsignedFlag | mysql.NotNullFlag, 6, 0},
 		{"x'0000000000000000ff10'", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag | mysql.UnsignedFlag | mysql.NotNullFlag, 30, 0},
diff --git a/types/field_type.go b/types/field_type.go
index d73b05cbf8365..025b01ba8badf 100644
--- a/types/field_type.go
+++ b/types/field_type.go
@@ -250,7 +250,7 @@ func DefaultTypeForValue(value interface{}, tp *FieldType, char string, collate
 		SetBinChsClnFlag(tp)
 	case BitLiteral:
 		tp.Tp = mysql.TypeVarString
-		tp.Flen = len(x)
+		tp.Flen = len(x) * 3
 		tp.Decimal = 0
 		SetBinChsClnFlag(tp)
 	case HexLiteral: