interface: use OnceCell from standard library

Author: marmeladema

Cargo.lock

@@ -3606,7 +3606,6 @@ name = "rustc_interface"
 version = "0.0.0"
 dependencies = [
  "libc",
- "once_cell",
  "rustc-rayon",
  "rustc_ast",
  "rustc_ast_lowering",

compiler/rustc_interface/Cargo.toml

@@ -43,7 +43,6 @@ rustc_resolve = { path = "../rustc_resolve" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
 rustc_ty = { path = "../rustc_ty" }
 tempfile = "3.0.5"
-once_cell = "1"
 
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3", features = ["libloaderapi"] }

compiler/rustc_interface/src/passes.rs

@@ -2,7 +2,6 @@ use crate::interface::{Compiler, Result};
 use crate::proc_macro_decls;
 use crate::util;
 
-use once_cell::sync::Lazy;
 use rustc_ast::mut_visit::MutVisitor;
 use rustc_ast::{self as ast, visit};
 use rustc_codegen_ssa::back::link::emit_metadata;
@@ -46,6 +45,7 @@ use std::any::Any;
 use std::cell::RefCell;
 use std::ffi::OsString;
 use std::io::{self, BufWriter, Write};
+use std::lazy::SyncLazy;
 use std::path::PathBuf;
 use std::rc::Rc;
 use std::{env, fs, iter, mem};
@@ -681,7 +681,7 @@ pub fn prepare_outputs(
     Ok(outputs)
 }
 
-pub static DEFAULT_QUERY_PROVIDERS: Lazy<Providers> = Lazy::new(|| {
+pub static DEFAULT_QUERY_PROVIDERS: SyncLazy<Providers> = SyncLazy::new(|| {
     let providers = &mut Providers::default();
     providers.analysis = analysis;
     proc_macro_decls::provide(providers);
@@ -704,7 +704,7 @@ pub static DEFAULT_QUERY_PROVIDERS: Lazy<Providers> = Lazy::new(|| {
     *providers
 });
 
-pub static DEFAULT_EXTERN_QUERY_PROVIDERS: Lazy<Providers> = Lazy::new(|| {
+pub static DEFAULT_EXTERN_QUERY_PROVIDERS: SyncLazy<Providers> = SyncLazy::new(|| {
     let mut extern_providers = *DEFAULT_QUERY_PROVIDERS;
     rustc_metadata::provide_extern(&mut extern_providers);
     rustc_codegen_ssa::provide_extern(&mut extern_providers);

compiler/rustc_interface/src/util.rs

@@ -25,6 +25,7 @@ use rustc_span::symbol::{sym, Symbol};
 use smallvec::SmallVec;
 use std::env;
 use std::io::{self, Write};
+use std::lazy::SyncOnceCell;
 use std::mem;
 use std::ops::DerefMut;
 use std::path::{Path, PathBuf};
@@ -243,8 +244,7 @@ pub fn get_codegen_backend(sess: &Session) -> Box<dyn CodegenBackend> {
 // loading, so we leave the code here. It is potentially useful for other tools
 // that want to invoke the rustc binary while linking to rustc as well.
 pub fn rustc_path<'a>() -> Option<&'a Path> {
-    static RUSTC_PATH: once_cell::sync::OnceCell<Option<PathBuf>> =
-        once_cell::sync::OnceCell::new();
+    static RUSTC_PATH: SyncOnceCell<Option<PathBuf>> = SyncOnceCell::new();
 
     const BIN_PATH: &str = env!("RUSTC_INSTALL_BINDIR");