proc_macro bridge fxhash perf testing

library/proc_macro/src/bridge/handle.rs

@@ -6,7 +6,7 @@ use std::num::NonZero;
 use std::ops::{Index, IndexMut};
 use std::sync::atomic::{AtomicU32, Ordering};
 
-use super::fxhash::FxHashMap;
+use super::DeterministicHashMap;
 
 pub(super) type Handle = NonZero<u32>;
 
@@ -56,12 +56,12 @@ impl<T> IndexMut<Handle> for OwnedStore<T> {
 /// Like `OwnedStore`, but avoids storing any value more than once.
 pub(super) struct InternedStore<T: 'static> {
     owned: OwnedStore<T>,
-    interner: FxHashMap<T, Handle>,
+    interner: DeterministicHashMap<T, Handle>,
 }
 
 impl<T: Copy + Eq + Hash> InternedStore<T> {
     pub(super) fn new(counter: &'static AtomicU32) -> Self {
-        InternedStore { owned: OwnedStore::new(counter), interner: FxHashMap::default() }
+        InternedStore { owned: OwnedStore::new(counter), interner: DeterministicHashMap::default() }
     }
 
     pub(super) fn alloc(&mut self, x: T) -> Handle {

library/proc_macro/src/bridge/mod.rs

@@ -8,13 +8,16 @@
 
 #![deny(unsafe_code)]
 
-use std::hash::Hash;
+use std::collections::HashMap;
+use std::hash::{BuildHasherDefault, DefaultHasher, Hash};
 use std::ops::{Bound, Range};
 use std::sync::Once;
 use std::{fmt, marker, mem, panic, thread};
 
 use crate::{Delimiter, Level, Spacing};
 
+type DeterministicHashMap<K, V> = HashMap<K, V, BuildHasherDefault<DefaultHasher>>;
+
 /// Higher-order macro describing the server RPC API, allowing automatic
 /// generation of type-safe Rust APIs, both client-side and server-side.
 ///
@@ -155,8 +158,6 @@ pub mod client;
 #[allow(unsafe_code)]
 mod closure;
 #[forbid(unsafe_code)]
-mod fxhash;
-#[forbid(unsafe_code)]
 mod handle;
 #[macro_use]
 #[forbid(unsafe_code)]

library/proc_macro/src/bridge/symbol.rs

@@ -128,7 +128,7 @@ impl<S> DecodeMut<'_, '_, S> for Symbol {
 thread_local! {
     static INTERNER: RefCell<Interner> = RefCell::new(Interner {
         arena: arena::Arena::new(),
-        names: fxhash::FxHashMap::default(),
+        names: DeterministicHashMap::default(),
         strings: Vec::new(),
         // Start with a base of 1 to make sure that `NonZero<u32>` works.
         sym_base: NonZero::new(1).unwrap(),
@@ -141,7 +141,7 @@ struct Interner {
     // SAFETY: These `'static` lifetimes are actually references to data owned
     // by the Arena. This is safe, as we never return them as static references
     // from `Interner`.
-    names: fxhash::FxHashMap<&'static str, Symbol>,
+    names: DeterministicHashMap<&'static str, Symbol>,
     strings: Vec<&'static str>,
     // The offset to apply to symbol names stored in the interner. This is used
     // to ensure that symbol names are not re-used after the interner is