planner: fix panic when prepare and execute the insert on duplicate

executor/insert_test.go

@@ -352,6 +352,19 @@ func TestUpdateDuplicateKey(t *testing.T) {
  "[kv:1062]Duplicate entry '1-2-4' for key 'PRIMARY'")
 }
 
+func TestIssue37187(t *testing.T) {
+ store := testkit.CreateMockStore(t)
+ tk := testkit.NewTestKit(t, store)
+ tk.MustExec("use test")
+
+ tk.MustExec("drop table if exists a, b")
+ tk.MustExec("create table t1 (a int(11) ,b varchar(100) ,primary key (a));")
+ tk.MustExec("create table t2 (c int(11) ,d varchar(100) ,primary key (c));")
+ tk.MustExec("prepare in1 from 'insert into t1 (a,b) select c,null from t2 t on duplicate key update b=t.d';")
+ err := tk.ExecToErr("execute in1;")
+ require.NoError(t, err)
+}
+
 func TestInsertWrongValueForField(t *testing.T) {
  store := testkit.CreateMockStore(t)
  tk := testkit.NewTestKit(t, store)

planner/core/planbuilder.go

@@ -3895,6 +3895,11 @@ func (b *PlanBuilder) buildSelectPlanOfInsert(ctx context.Context, insert *ast.I
  }
  sel.Fields.Fields = append(sel.Fields.Fields, &ast.SelectField{Expr: colName, Offset: len(sel.Fields.Fields)})
  }
+ defer func(originSelFieldLen int) {
+ // Revert the change for ast. Because when we use the 'prepare' and 'execute' statement it will both build plan which will cause problem.
+ // You can see the issue #37187 for more details.
+ sel.Fields.Fields = sel.Fields.Fields[:originSelFieldLen]
+ }(actualColLen)
  }
  }
  }