Merge pull request #3978 from weiznich/drop/vendored_once_cell

Drop our vendored copy of OnceCell

diesel/src/pg/connection/result.rs

@@ -11,7 +11,7 @@ use std::{slice, str};
 use super::raw::{RawConnection, RawResult};
 use super::row::PgRow;
 use crate::result::{DatabaseErrorInformation, DatabaseErrorKind, Error, QueryResult};
-use crate::util::OnceCell;
+use std::cell::OnceCell;
 
 #[allow(missing_debug_implementations)]
 pub struct PgResult {

diesel/src/sqlite/connection/stmt.rs

@@ -8,8 +8,8 @@ use crate::query_builder::{QueryFragment, QueryId};
 use crate::result::Error::DatabaseError;
 use crate::result::*;
 use crate::sqlite::{Sqlite, SqliteType};
-use crate::util::OnceCell;
 use libsqlite3_sys as ffi;
+use std::cell::OnceCell;
 use std::ffi::{CStr, CString};
 use std::io::{stderr, Write};
 use std::os::raw as libc;

diesel/src/util.rs

@@ -9,9 +9,3 @@ pub trait TupleAppend<T> {
 pub trait TupleSize {
     const SIZE: usize;
 }
-
-#[cfg(any(feature = "postgres", feature = "sqlite"))]
-mod once_cell;
-
-#[cfg(any(feature = "postgres", feature = "sqlite"))]
-pub(crate) use self::once_cell::OnceCell;