From 6e3d2ecb48a931e835ad4826013e915051c6ebc4 Mon Sep 17 00:00:00 2001
From: Zhuhe Fang <fzhedu@gmail.com>
Date: Fri, 13 Nov 2020 15:42:19 +0800
Subject: [PATCH] expression: avoid unnecessary warnings/errors when folding
 constants in shortcut-able expressions (#19797)

---
 expression/function_traits.go       | 10 +++++++---
 expression/integration_test.go      |  9 +++++++++
 planner/core/expression_rewriter.go | 10 ++++++++++
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/expression/function_traits.go b/expression/function_traits.go
index 12631d357e6ff..8ba1ea7d0b91e 100644
--- a/expression/function_traits.go
+++ b/expression/function_traits.go
@@ -60,9 +60,13 @@ var DisableFoldFunctions = map[string]struct{}{
 // otherwise, the child functions do not fold constant.
 // Note: the function itself should fold constant.
 var TryFoldFunctions = map[string]struct{}{
-	ast.If:     {},
-	ast.Ifnull: {},
-	ast.Case:   {},
+	ast.If:       {},
+	ast.Ifnull:   {},
+	ast.Case:     {},
+	ast.LogicAnd: {},
+	ast.LogicOr:  {},
+	ast.Coalesce: {},
+	ast.Interval: {},
 }
 
 // IllegalFunctions4GeneratedColumns stores functions that is illegal for generated columns.
diff --git a/expression/integration_test.go b/expression/integration_test.go
index 63159b0f508a3..02e18b492e4d8 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -2899,6 +2899,15 @@ func (s *testIntegrationSuite2) TestBuiltin(c *C) {
 	tk.MustQuery("select 1 or b/0 from t")
 	tk.MustQuery("show warnings").Check(testkit.Rows())
 
+	tk.MustQuery("select 1 or 1/0")
+	tk.MustQuery("show warnings").Check(testkit.Rows())
+	tk.MustQuery("select 0 and 1/0")
+	tk.MustQuery("show warnings").Check(testkit.Rows())
+	tk.MustQuery("select COALESCE(1, 1/0)")
+	tk.MustQuery("show warnings").Check(testkit.Rows())
+	tk.MustQuery("select interval(1,0,1,2,1/0)")
+	tk.MustQuery("show warnings").Check(testkit.Rows())
+
 	tk.MustQuery("select case 2.0 when 2.0 then 3.0 when 3.0 then 2.0 end").Check(testkit.Rows("3.0"))
 	tk.MustQuery("select case 2.0 when 3.0 then 2.0 when 4.0 then 3.0 else 5.0 end").Check(testkit.Rows("5.0"))
 	tk.MustQuery("select case cast('2011-01-01' as date) when cast('2011-01-01' as date) then cast('2011-02-02' as date) end").Check(testkit.Rows("2011-02-02"))
diff --git a/planner/core/expression_rewriter.go b/planner/core/expression_rewriter.go
index 2ca683182b78b..a8e04c2999bd2 100644
--- a/planner/core/expression_rewriter.go
+++ b/planner/core/expression_rewriter.go
@@ -410,6 +410,7 @@ func (er *expressionRewriter) Enter(inNode ast.Node) (ast.Node, bool) {
 		er.ctxStackAppend(er.schema.Columns[index], er.names[index])
 		return inNode, true
 	case *ast.FuncCallExpr:
+		er.asScalar = true
 		if _, ok := expression.DisableFoldFunctions[v.FnName.L]; ok {
 			er.disableFoldCounter++
 		}
@@ -417,12 +418,18 @@ func (er *expressionRewriter) Enter(inNode ast.Node) (ast.Node, bool) {
 			er.tryFoldCounter++
 		}
 	case *ast.CaseExpr:
+		er.asScalar = true
 		if _, ok := expression.DisableFoldFunctions["case"]; ok {
 			er.disableFoldCounter++
 		}
 		if _, ok := expression.TryFoldFunctions["case"]; ok {
 			er.tryFoldCounter++
 		}
+	case *ast.BinaryOperationExpr:
+		er.asScalar = true
+		if v.Op == opcode.LogicAnd || v.Op == opcode.LogicOr {
+			er.tryFoldCounter++
+		}
 	case *ast.SetCollationExpr:
 		// Do nothing
 	default:
@@ -1021,6 +1028,9 @@ func (er *expressionRewriter) Leave(originInNode ast.Node) (retNode ast.Node, ok
 	case *ast.UnaryOperationExpr:
 		er.unaryOpToExpression(v)
 	case *ast.BinaryOperationExpr:
+		if v.Op == opcode.LogicAnd || v.Op == opcode.LogicOr {
+			er.tryFoldCounter--
+		}
 		er.binaryOpToExpression(v)
 	case *ast.BetweenExpr:
 		er.betweenToExpression(v)