planner: fix panic when prepare and execute the insert on duplicate (#37924)

executor/insert_test.go

@@ -363,6 +363,20 @@ func TestUpdateDuplicateKey(t *testing.T) {
 	require.EqualError(t, err, "[kv:1062]Duplicate entry '1-2-4' for key 'PRIMARY'")
 }
 
+func TestIssue37187(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	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, clean := testkit.CreateMockStore(t)
 	defer clean()

planner/core/planbuilder.go

@@ -3824,6 +3824,11 @@ 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)
 			}
 		}
 	}