Use triomphe::Arc in TokenStream.

Cargo.lock

@@ -3687,6 +3687,7 @@ dependencies = [
  "tempfile",
  "thin-vec",
  "tracing",
+ "triomphe",
  "windows 0.61.3",
 ]
 
@@ -4567,6 +4568,7 @@ dependencies = [
  "smallvec",
  "tempfile",
  "thin-vec",
+ "triomphe",
 ]
 
 [[package]]
@@ -5684,6 +5686,16 @@ dependencies = [
  "tracing-subscriber",
 ]
 
+[[package]]
+name = "triomphe"
+version = "0.1.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ef8f7726da4807b58ea5c96fdc122f80702030edc33b35aff9190a51148ccc85"
+dependencies = [
+ "serde",
+ "stable_deref_trait",
+]
+
 [[package]]
 name = "twox-hash"
 version = "1.6.3"

Cargo.toml

@@ -67,6 +67,7 @@ memchr = "2.7.5"
 rustc-literal-escaper = "0.0.5"
 thin-vec = "0.2.14"
 tracing = "0.1.37"
+triomphe = "0.1.14"
 # tidy-alphabetical-end
 
 [profile.release.package.rustc_thread_pool]

compiler/rustc_ast/src/tokenstream.rs

@@ -19,7 +19,7 @@ use std::sync::Arc;
 use std::{cmp, fmt, iter, mem};
 
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_data_structures::sync;
+use rustc_data_structures::sync::{self, TrArc};
 use rustc_macros::{Decodable, Encodable, HashStable_Generic, Walkable};
 use rustc_serialize::{Decodable, Encodable};
 use rustc_span::{DUMMY_SP, Span, SpanDecoder, SpanEncoder, Symbol, sym};
@@ -558,7 +558,7 @@ pub struct AttrsTarget {
 
 /// A `TokenStream` is an abstract sequence of tokens, organized into [`TokenTree`]s.
 #[derive(Clone, Debug, Default, Encodable, Decodable)]
-pub struct TokenStream(pub(crate) Arc<Vec<TokenTree>>);
+pub struct TokenStream(pub(crate) TrArc<Vec<TokenTree>>);
 
 /// Indicates whether a token can join with the following token to form a
 /// compound token. Used for conversions to `proc_macro::Spacing`. Also used to
@@ -675,7 +675,7 @@ impl PartialEq<TokenStream> for TokenStream {
 
 impl TokenStream {
     pub fn new(tts: Vec<TokenTree>) -> TokenStream {
-        TokenStream(Arc::new(tts))
+        TokenStream(TrArc::new(tts))
     }
 
     pub fn is_empty(&self) -> bool {
@@ -728,7 +728,7 @@ impl TokenStream {
     /// Push `tt` onto the end of the stream, possibly gluing it to the last
     /// token. Uses `make_mut` to maximize efficiency.
     pub fn push_tree(&mut self, tt: TokenTree) {
-        let vec_mut = Arc::make_mut(&mut self.0);
+        let vec_mut = TrArc::make_mut(&mut self.0);
 
         if Self::try_glue_to_last(vec_mut, &tt) {
             // nothing else to do
@@ -741,7 +741,7 @@ impl TokenStream {
     /// token tree to the last token. (No other token trees will be glued.)
     /// Uses `make_mut` to maximize efficiency.
     pub fn push_stream(&mut self, stream: TokenStream) {
-        let vec_mut = Arc::make_mut(&mut self.0);
+        let vec_mut = TrArc::make_mut(&mut self.0);
 
         let stream_iter = stream.0.iter().cloned();
 
@@ -761,7 +761,7 @@ impl TokenStream {
     }
 
     /// Desugar doc comments like `/// foo` in the stream into `#[doc =
-    /// r"foo"]`. Modifies the `TokenStream` via `Arc::make_mut`, but as little
+    /// r"foo"]`. Modifies the `TokenStream` via `TrArc::make_mut`, but as little
     /// as possible.
     pub fn desugar_doc_comments(&mut self) {
         if let Some(desugared_stream) = desugar_inner(self.clone()) {
@@ -780,7 +780,7 @@ impl TokenStream {
                     ) => {
                         let desugared = desugared_tts(attr_style, data, span);
                         let desugared_len = desugared.len();
-                        Arc::make_mut(&mut stream.0).splice(i..i + 1, desugared);
+                        TrArc::make_mut(&mut stream.0).splice(i..i + 1, desugared);
                         modified = true;
                         i += desugared_len;
                     }
@@ -791,7 +791,7 @@ impl TokenStream {
                         if let Some(desugared_delim_stream) = desugar_inner(delim_stream.clone()) {
                             let new_tt =
                                 TokenTree::Delimited(sp, spacing, delim, desugared_delim_stream);
-                            Arc::make_mut(&mut stream.0)[i] = new_tt;
+                            TrArc::make_mut(&mut stream.0)[i] = new_tt;
                             modified = true;
                         }
                         i += 1;

compiler/rustc_data_structures/Cargo.toml

@@ -27,6 +27,7 @@ stacker = "0.1.17"
 tempfile = "3.2"
 thin-vec.workspace = true
 tracing.workspace = true
+triomphe.workspace = true
 # tidy-alphabetical-end
 
 [dependencies.hashbrown]

compiler/rustc_data_structures/src/marker.rs

@@ -75,6 +75,9 @@ impl_dyn_send!(
     [std::sync::Mutex<T> where T: ?Sized+ DynSend]
     [std::sync::mpsc::Sender<T> where T: DynSend]
     [std::sync::Arc<T> where T: ?Sized + DynSync + DynSend]
+    [crate::sync::TrArc<T> where T: ?Sized + DynSync + DynSend]
+    [crate::sync::TrUniqueArc<T> where T: ?Sized + DynSync + DynSend]
+    [crate::sync::TrThinArc<H, T> where H: DynSync + DynSend, T: DynSync + DynSend]
     [std::sync::LazyLock<T, F> where T: DynSend, F: DynSend]
     [std::collections::HashSet<K, S> where K: DynSend, S: DynSend]
     [std::collections::HashMap<K, V, S> where K: DynSend, V: DynSend, S: DynSend]
@@ -157,6 +160,9 @@ impl_dyn_sync!(
     [std::sync::OnceLock<T> where T: DynSend + DynSync]
     [std::sync::Mutex<T> where T: ?Sized + DynSend]
     [std::sync::Arc<T> where T: ?Sized + DynSync + DynSend]
+    [crate::sync::TrArc<T> where T: ?Sized + DynSync + DynSend]
+    [crate::sync::TrUniqueArc<T> where T: ?Sized + DynSync + DynSend]
+    [crate::sync::TrThinArc<H, T> where H: DynSync + DynSend, T: DynSync + DynSend]
     [std::sync::LazyLock<T, F> where T: DynSend + DynSync, F: DynSend]
     [std::collections::HashSet<K, S> where K: DynSync, S: DynSync]
     [std::collections::HashMap<K, V, S> where K: DynSync, V: DynSync, S: DynSync]

compiler/rustc_data_structures/src/sync.rs

@@ -105,6 +105,15 @@ mod mode {
     }
 }
 
+/// Alternative form of `Arc` that lacks a weak ref count.
+pub type TrArc<T> = triomphe::Arc<T>;
+
+/// Alternative form of `UniqueArc` that lacks a weak ref count.
+pub type TrUniqueArc<T> = triomphe::UniqueArc<T>;
+
+/// Like `TrArc<(H, [T])>`, but with a thin pointer.
+pub type TrThinArc<H, T> = triomphe::ThinArc<H, T>;
+
 // FIXME(parallel_compiler): Get rid of these aliases across the compiler.
 
 #[derive(Debug, Default)]

compiler/rustc_serialize/Cargo.toml

@@ -9,6 +9,7 @@ indexmap = "2.0.0"
 rustc_hashes = { path = "../rustc_hashes" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
 thin-vec.workspace = true
+triomphe.workspace = true
 # tidy-alphabetical-end
 
 [dev-dependencies]

compiler/rustc_serialize/src/serialize.rs

@@ -509,6 +509,18 @@ impl<D: Decoder, T: Decodable<D>> Decodable<D> for Arc<T> {
     }
 }
 
+impl<S: Encoder, T: Encodable<S>> Encodable<S> for triomphe::Arc<T> {
+    fn encode(&self, s: &mut S) {
+        (**self).encode(s);
+    }
+}
+
+impl<D: Decoder, T: Decodable<D>> Decodable<D> for triomphe::Arc<T> {
+    fn decode(d: &mut D) -> triomphe::Arc<T> {
+        triomphe::Arc::new(Decodable::decode(d))
+    }
+}
+
 impl<S: Encoder, T: ?Sized + Encodable<S>> Encodable<S> for Box<T> {
     fn encode(&self, s: &mut S) {
         (**self).encode(s)

src/tools/tidy/src/deps.rs

@@ -394,6 +394,7 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     "tracing-log",
     "tracing-subscriber",
     "tracing-tree",
+    "triomphe",
     "twox-hash",
     "type-map",
     "typenum",