Unexpected panic in simplifyOuterJoin

[XuHuaiyu]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

create table t (pk varchar(14) primary key, a varchar(12));
select * from (select t1.pk or '/' as c from t as t1 left join t as t2 on t1.a = t2.pk) as t where t.c = 1;

2. What did you expect to see?
   query executes without panic

3. What did you see instead?

[2020/01/17 16:13:56.128 +08:00] [ERROR] [terror.go:360] ["encountered error"] [error="[expression:1305]FUNCTION amldb.sig_*expression.builtinrealistruesig does not exist"]
[2020/01/17 16:13:56.128 +08:00] [ERROR] [conn.go:625] ["connection running loop panic"] [conn=1] [lastSQL="select * from (select t1.pk or '/' as c from t as t1 left join t as t2 on t1.a = t2.pk) as t where t.c = 1"] [err="runtime error: invalid memory address or nil pointer dereference"] [stack="goroutine 274 [running]:\ngithub.com/pingcap/tidb/server.(*clientConn).Run.func1(0x5c609a0, 0xc001b62120, 0xc0001b2d00)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/server/conn.go:623 +0xee\npanic(0x565cd80, 0x6fd41d0)\n\t/Users/xuhuaiyu/.gvm/gos/go1.13/src/runtime/panic.go:679 +0x1b2\ngithub.com/pingcap/tidb/expression.wrapWithIsTrue(0x5cb5680, 0xc000cf0700, 0x1, 0x0, 0x0, 0x0, 0x5c25440, 0xc001727bd0, 0x400e3b6)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/expression/expression.go:722 +0x37\ngithub.com/pingcap/tidb/expression.(*logicOrFunctionClass).getFunction(0xc00031e300, 0x5cb5680, 0xc000cf0700, 0xc001708740, 0x2, 0x2, 0x2, 0x2, 0xc001708720, 0xc0015c7301)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/expression/builtin_op.go:120 +0xcc\ngithub.com/pingcap/tidb/expression.newFunctionImpl(0x5cb5680, 0xc000cf0700, 0xc0015c7301, 0x58ff240, 0x2, 0xc001712a80, 0xc0017086c0, 0x2, 0x2, 0x1, ...)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/expression/scalar_function.go:152 +0x21d\ngithub.com/pingcap/tidb/expression.NewFunction(...)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/expression/scalar_function.go:172\ngithub.com/pingcap/tidb/expression.NewFunctionInternal(0x5cb5680, 0xc000cf0700, 0x58ff240, 0x2, 0xc001712a80, 0xc0017086c0, 0x2, 0x2, 0x2, 0x2)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/expression/scalar_function.go:182 +0x92\ngithub.com/pingcap/tidb/expression.EvaluateExprWithNull(0x5cb5680, 0xc000cf0700, 0xc001609890, 0x5cb9b00, 0xc0016b0910, 0xc000cf0700, 0x4ffdaa1)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/expression/expression.go:585 +0x1e7\ngithub.com/pingcap/tidb/expression.EvaluateExprWithNull(0x5cb5680, 0xc000cf0700, 0xc001609890, 0x5cb9b00, 0xc0016b0a00, 0x5cb9b00, 0xc0016b0a00)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/expression/expression.go:583 +0x13e\ngithub.com/pingcap/tidb/planner/core.isNullRejected(0x5cb5680, 0xc000cf0700, 0xc001609890, 0x5cb9b00, 0xc0016b0a00, 0xc001727fe0)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/planner/core/rule_predicate_push_down.go:342 +0xbf\ngithub.com/pingcap/tidb/planner/core.simplifyOuterJoin(0xc001710000, 0xc0015c7380, 0x1, 0x1)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/planner/core/rule_predicate_push_down.go:322 +0x154\ngithub.com/pingcap/tidb/planner/core.(*LogicalJoin).PredicatePushDown(0xc001710000, 0xc0015c7380, 0x1, 0x1, 0x2, 0x2, 0xc001708600, 0x2, 0x2)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/planner/core/rule_predicate_push_down.go:113 +0x6a\ngithub.com/pingcap/tidb/planner/core.(*baseLogicalPlan).PredicatePushDown(0xc001673990, 0xc0015c7380, 0x1, 0x1, 0x1, 0x1, 0xc001708401, 0x5cb9b00, 0xc0016b0a00)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/planner/core/rule_predicate_push_down.go:55 +0xa6\ngithub.com/pingcap/tidb/planner/core.(*LogicalProjection).PredicatePushDown(0xc001673970, 0xc0015c7360, 0x1, 0x1, 0x705b448, 0x0, 0x0, 0x0, 0x1)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/planner/core/rule_predicate_push_down.go:374 +0x278\ngithub.com/pingcap/tidb/planner/core.(*LogicalSelection).PredicatePushDown(0xc00168f680, 0x705b448, 0x0, 0x0, 0x404869c, 0x0, 0x5832540, 0x5cb9701, 0x705b448)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/planner/core/rule_predicate_push_down.go:76 +0x166\ngithub.com/pingcap/tidb/planner/core.(*baseLogicalPlan).PredicatePushDown(0xc001673af0, 0x705b448, 0x0, 0x0, 0xc001673af0, 0xc0015c7310, 0x1, 0x1, 0x1)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/planner/core/rule_predicate_push_down.go:55 +0xa6\ngithub.com/pingcap/tidb/planner/core.(*LogicalProjection).PredicatePushDown(0xc001673ad0, 0x0, 0x0, 0x0, 0x705c7c0, 0xc001609f00, 0xc000d6d950, 0x5707c40, 0xc000d6d950)\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/planner/core/rule_predicate_push_down.go:374 +0x278\ngithub.com/pingcap/tidb/planner/core.(*ppdSolver).optimize(0x705b000, 0x5c6"]

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

Release Version: v4.0.0-alpha-1373-g74bc00dfa
Git Commit Hash: 74bc00dfa953da06d8e5823d0acbf6bf1858a680
Git Branch: master
UTC Build Time: 2020-01-17 04:49:16
GoVersion: go1.13
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false