get auto traits for parallel rustc

Signed-off-by: SparrowLii <liyuan179@huawei.com>

Author: SparrowLii

compiler/rustc_ast/src/format.rs

@@ -67,12 +67,6 @@ pub struct FormatArguments {
     names: FxHashMap<Symbol, usize>,
 }
 
-// FIXME: Rustdoc has trouble proving Send/Sync for this. See #106930.
-#[cfg(parallel_compiler)]
-unsafe impl Sync for FormatArguments {}
-#[cfg(parallel_compiler)]
-unsafe impl Send for FormatArguments {}
-
 impl FormatArguments {
     pub fn new() -> Self {
         Self {

src/librustdoc/clean/utils.rs

@@ -480,12 +480,6 @@ pub(crate) fn get_auto_trait_and_blanket_impls(
     cx: &mut DocContext<'_>,
     item_def_id: DefId,
 ) -> impl Iterator<Item = Item> {
-    // FIXME: To be removed once `parallel_compiler` bugs are fixed!
-    // More information in <https://github.com/rust-lang/rust/pull/106930>.
-    if cfg!(parallel_compiler) {
-        return vec![].into_iter().chain(vec![].into_iter());
-    }
-
     let auto_impls = cx
         .sess()
         .prof