You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/vulkano/vulkano/src/sync
    
    the code of the file until where you have to start completion: //! Synchronization on the GPU.
//!
//! Just like for CPU code, you have t
    
    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), std::fmt::Error> {
        match self {
            Self::AccessConflict(_) => {
                write!(f, "the resource is already in use in a conflicting way")
            }
            Self::Unmanaged => write!(f, "the resource is not managed by vulkano"),
            HostAccessError::Invalidate(_) => write!(f, "invalidating the device memory failed"),
            HostAccessError::NotHostMapped => {
                write!(f, "the device memory is not current host-mapped")
            }
            HostAccessError::OutOfMappedRange => write!(
                f,
                "the requested range is not within the currently mapped range of device memory",
            ),
        }
    }