planner: fix plus prefix for select constant (#9707)

Author: wjhuang2016

cmd/explaintest/r/select.result

@@ -140,8 +140,24 @@ select + - 1, --1, +-+-+1, + "123";
 + - 1	--1	+-+-+1	123
 -1	1	1	123
 select --------------------1, ++++++++++++++++++++1;
---------------------1	++++++++++++++++++++1
+--------------------1	1
 1	1
+select +(+(1)), (-+1), ((+1)), +1.23, +1e23, +1E23, +null, +true, +false, + ( ( 1 ) );
+1	(-+1)	1	1.23	1e23	1E23	NULL	TRUE	FALSE	1
+1	-1	1	1.23	1e23	1e23	NULL	1	0	1
+select +
+(
++
+(
+1
+)
+)
+;
+1
+1
+select +	(	+	1	);
+1
+1
 select --+(1 + 1), +-+-(1 * 1);
 --+(1 + 1)	+-+-(1 * 1)
 2	1

cmd/explaintest/t/select.test

@@ -89,6 +89,16 @@ select !(1 + 2);
 # - +
 select + - 1, --1, +-+-+1, + "123";
 select --------------------1, ++++++++++++++++++++1;
+select +(+(1)), (-+1), ((+1)), +1.23, +1e23, +1E23, +null, +true, +false, + ( ( 1 ) );
+select +
+(
++
+(
+1
+)
+)
+;
+select +	(	+	1	);
 select --+(1 + 1), +-+-(1 * 1);
 
 # where static condition

planner/core/logical_plan_builder.go

@@ -610,12 +610,25 @@ func (b *PlanBuilder) buildProjectionFieldNameFromExpressions(field *ast.SelectF
 	case types.KindNull:
 		// See #4053, #3685
 		return model.NewCIStr("NULL"), nil
-	default:
-		// Keep as it is.
-		if innerExpr.Text() != "" {
-			return model.NewCIStr(innerExpr.Text()), nil
-		}
+	case types.KindBinaryLiteral:
+		// Don't rewrite BIT literal or HEX literals
 		return model.NewCIStr(field.Text()), nil
+	case types.KindInt64:
+		// See #9683
+		// TRUE or FALSE can be a int64
+		if mysql.HasIsBooleanFlag(valueExpr.Type.Flag) {
+			if i := valueExpr.GetValue().(int64); i == 0 {
+				return model.NewCIStr("FALSE"), nil
+			}
+			return model.NewCIStr("TRUE"), nil
+		}
+		fallthrough
+
+	default:
+		fieldName := field.Text()
+		fieldName = strings.TrimLeft(fieldName, "\t\n +(")
+		fieldName = strings.TrimRight(fieldName, "\t\n )")
+		return model.NewCIStr(fieldName), nil
 	}
 }