From 94690cb76ecbeeb8418a86987b589b881d721c19 Mon Sep 17 00:00:00 2001
From: XuHuaiyu <391585975@qq.com>
Date: Tue, 20 Jun 2017 18:14:32 +0800
Subject: [PATCH] expression: remove inferType interface of functionClass

---
 expression/builtin.go             | 6 ------
 expression/builtin_string_test.go | 2 +-
 2 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/expression/builtin.go b/expression/builtin.go
index 70050ee687ad6..8787e2dacd1f5 100644
--- a/expression/builtin.go
+++ b/expression/builtin.go
@@ -451,16 +451,10 @@ func (b *baseFunctionClass) verifyArgs(args []Expression) error {
 	return nil
 }
 
-func (b *baseFunctionClass) inferType(args []Expression) *types.FieldType {
-	return nil
-}
-
 // functionClass is the interface for a function which may contains multiple functions.
 type functionClass interface {
 	// getFunction gets a function signature by the types and the counts of given arguments.
 	getFunction(args []Expression, ctx context.Context) (builtinFunc, error)
-	// inferType infers the return type of a function.
-	inferType(args []Expression) *types.FieldType
 }
 
 // BuiltinFunc is the function signature for builtin functions
diff --git a/expression/builtin_string_test.go b/expression/builtin_string_test.go
index 126553cdbd6b9..bb3705b0fce5a 100644
--- a/expression/builtin_string_test.go
+++ b/expression/builtin_string_test.go
@@ -148,7 +148,6 @@ func (s *testEvaluatorSuite) TestConcat(c *C) {
 		}
 	}
 
-	fc := funcs[fcName]
 	typeCases := []struct {
 		args    []Expression
 		retType *types.FieldType
@@ -170,6 +169,7 @@ func (s *testEvaluatorSuite) TestConcat(c *C) {
 			&types.FieldType{Tp: mysql.TypeBlob, Charset: charset.CharsetBin, Collate: charset.CollationBin, Flag: mysql.BinaryFlag},
 		},
 	}
+	fc := funcs[fcName].(*concatFunctionClass)
 	for _, t := range typeCases {
 		retType := fc.inferType(t.args)
 		c.Assert(retType.Tp, Equals, t.retType.Tp)