expression: don't cast collation for in expression is the new collati…

…on is disabled (pingcap#52812) (pingcap#52864)

close pingcap#52772

cmd/explaintest/r/collation_misc_disabled.result

@@ -120,4 +120,16 @@ binary	binary	63	Yes	Yes	1
 ascii_bin	ascii	65	Yes	Yes	1
 utf8_bin	utf8	83	Yes	Yes	1
 gbk_bin	gbk	87	Yes	Yes	1
-use test;
+drop table if exists t1;
+drop table if exists t2;
+create table t1(code varchar(32)) CHARSET=utf8 COLLATE=utf8_general_ci;
+create table t2(code varchar(32)) CHARSET=utf8 COLLATE=utf8_bin;
+desc format=brief select * from t1 join t2 on t1.code=t2.code and t1.code in ('1') and t2.code in ('1');
+id	estRows	task	access object	operator info
+HashJoin	12.50	root		inner join, equal:[eq(cd_test_latin1.t1.code, cd_test_latin1.t2.code)]
+├─TableReader(Build)	10.00	root		data:Selection
+│ └─Selection	10.00	cop[tikv]		eq(cd_test_latin1.t2.code, "1"), not(isnull(cd_test_latin1.t2.code))
+│   └─TableFullScan	10000.00	cop[tikv]	table:t2	keep order:false, stats:pseudo
+└─TableReader(Probe)	10.00	root		data:Selection
+  └─Selection	10.00	cop[tikv]		eq(cd_test_latin1.t1.code, "1"), not(isnull(cd_test_latin1.t1.code))
+    └─TableFullScan	10000.00	cop[tikv]	table:t1	keep order:false, stats:pseudo

cmd/explaintest/r/collation_misc_enabled.result

@@ -133,4 +133,17 @@ utf8_unicode_ci	utf8	192		Yes	1
 utf8mb4_bin	utf8mb4	46	Yes	Yes	1
 utf8mb4_general_ci	utf8mb4	45		Yes	1
 utf8mb4_unicode_ci	utf8mb4	224		Yes	1
-use test;
+drop table if exists t1;
+drop table if exists t2;
+create table t1(code varchar(32)) CHARSET=utf8 COLLATE=utf8_general_ci;
+create table t2(code varchar(32)) CHARSET=utf8 COLLATE=utf8_bin;
+desc format=brief select * from t1 join t2 on t1.code=t2.code and t1.code in ('1') and t2.code in ('1');
+id	estRows	task	access object	operator info
+Projection	80000.00	root		cd_test_utf8.t1.code, cd_test_utf8.t2.code
+└─HashJoin	80000.00	root		CARTESIAN inner join
+  ├─TableReader(Build)	10.00	root		data:Selection
+  │ └─Selection	10.00	cop[tikv]		eq(cd_test_utf8.t2.code, "1")
+  │   └─TableFullScan	10000.00	cop[tikv]	table:t2	keep order:false, stats:pseudo
+  └─TableReader(Probe)	8000.00	root		data:Selection
+    └─Selection	8000.00	cop[tikv]		eq(cd_test_utf8.t1.code, "1")
+      └─TableFullScan	10000.00	cop[tikv]	table:t1	keep order:false, stats:pseudo

cmd/explaintest/t/collation_misc.test

@@ -86,4 +86,9 @@ select * from information_schema.COLLATION_CHARACTER_SET_APPLICABILITY where COL
 show charset;
 show collation;
 
-use test;
+# issue 52772
+drop table if exists t1;
+drop table if exists t2;
+create table t1(code varchar(32)) CHARSET=utf8 COLLATE=utf8_general_ci;
+create table t2(code varchar(32)) CHARSET=utf8 COLLATE=utf8_bin;
+desc format=brief select * from t1 join t2 on t1.code=t2.code and t1.code in ('1') and t2.code in ('1');

planner/core/expression_rewriter.go

@@ -1651,6 +1651,13 @@ func (er *expressionRewriter) castCollationForIn(colLen int, elemCnt int, stkLen
 	if colLen != 1 {
 		return
 	}
+	if !collate.NewCollationEnabled() {
+		// See https://github.com/pingcap/tidb/issues/52772
+		// This function will apply CoercibilityExplicit to the casted expression, but some checks(during ColumnSubstituteImpl) is missed when the new
+		// collation is disabled, then lead to panic.
+		// To work around this issue, we can skip the function, it should be good since the collation is disabled.
+		return
+	}
 	for i := stkLen - elemCnt; i < stkLen; i++ {
 		// todo: consider refining the code and reusing expression.BuildCollationFunction here
 		if er.ctxStack[i].GetType().EvalType() == types.ETString {