Switch C++ std::hash<T> implementations to foldhash

Author: dtolnay

Cargo.toml

@@ -20,10 +20,11 @@ default = ["std", "cxxbridge-flags/default"] # c++11
 "c++17" = ["cxxbridge-flags/c++17"]
 "c++20" = ["cxxbridge-flags/c++20"]
 alloc = []
-std = ["alloc"]
+std = ["alloc", "foldhash/std"]
 
 [dependencies]
 cxxbridge-macro = { version = "=1.0.130", path = "macro" }
+foldhash = { version = "0.1", default-features = false }
 link-cplusplus = "1.0.9"
 
 [build-dependencies]

src/hash.rs

@@ -1,12 +1,6 @@
-use core::hash::{Hash, Hasher};
+use core::hash::{BuildHasher as _, Hash};
 
 #[doc(hidden)]
 pub fn hash<V: Hash>(value: &V) -> usize {
-    #[cfg(feature = "std")]
-    let mut hasher = std::collections::hash_map::DefaultHasher::new();
-    #[cfg(not(feature = "std"))]
-    let mut hasher = crate::sip::SipHasher13::new();
-
-    Hash::hash(value, &mut hasher);
-    Hasher::finish(&hasher) as usize
+    foldhash::quality::FixedState::default().hash_one(value) as usize
 }

src/lib.rs

@@ -466,7 +466,6 @@ mod rust_string;
 mod rust_type;
 mod rust_vec;
 mod shared_ptr;
-mod sip;
 #[path = "cxx_string.rs"]
 mod string;
 mod symbols;