ServiceImp error:

‘getBaseMapper()’ in ‘com.baomidou.mybatisplus.extension.service.impl.ServiceImpl’ clashes with ‘getBaseMapper()’ in ‘com.baomidou.mybatisplus.extension.service.IService’; attempting to use incompatible return type

In MyBatis-plus, the general reference package is

com.baomidou.mybatisplus.core.mapper;

Looking at the source code, we can see that both the IService and its implementation class ServiceImpl require the Mapper

<M extends BaseMapper<T>, T>
ServiceImpl<M extends BaseMapper<T>, T> implements IService<T>

Problem solving: check whether the mapper used in the self-defined xxservicei is a subclass of basemapper, and

Mapper generic reference should be consistent with iservice.