From f3c36ce6924f873c4d4bf02e4425b562091d3ac8 Mon Sep 17 00:00:00 2001
From: Amanieu d'Antras <amanieu@gmail.com>
Date: Mon, 22 Sep 2025 21:15:46 +0100
Subject: [PATCH] [EXPERIMENT] Test 8-bit tags for hashbrown

See rust-lang/hashbrown#653
---
 library/Cargo.lock                      | 12 +++++++++---
 library/std/Cargo.toml                  |  2 +-
 library/std/src/collections/hash/map.rs |  4 ++--
 src/tools/tidy/src/deps.rs              |  2 ++
 src/tools/tidy/src/extdeps.rs           |  1 +
 5 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/library/Cargo.lock b/library/Cargo.lock
index e4b3839847b1a..48d5eae286921 100644
--- a/library/Cargo.lock
+++ b/library/Cargo.lock
@@ -88,6 +88,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "foldhash"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77ce24cb58228fbb8aa041425bb1050850ac19177686ea6e0f41a70416f56fdb"
+
 [[package]]
 name = "fortanix-sgx-abi"
 version = "0.6.1"
@@ -119,10 +125,10 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.15.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9229cfe53dfd69f0609a49f65461bd93001ea1ef889cd5529dd176593f5338a1"
+version = "0.16.0"
+source = "git+https://github.com/gaujay/hashbrown.git?branch=8-bits-tag#fcce069967e957305ec8098c5f1e8280e9ce7c5b"
 dependencies = [
+ "foldhash",
  "rustc-std-workspace-alloc",
  "rustc-std-workspace-core",
 ]
diff --git a/library/std/Cargo.toml b/library/std/Cargo.toml
index d28a7f0b46022..c76a5691f4368 100644
--- a/library/std/Cargo.toml
+++ b/library/std/Cargo.toml
@@ -20,7 +20,7 @@ panic_unwind = { path = "../panic_unwind", optional = true }
 panic_abort = { path = "../panic_abort" }
 core = { path = "../core", public = true }
 unwind = { path = "../unwind" }
-hashbrown = { version = "0.15", default-features = false, features = [
+hashbrown = { git = "https://github.com/gaujay/hashbrown.git", branch = "8-bits-tag", default-features = false, features = [
     'rustc-dep-of-std',
 ] }
 std_detect = { path = "../std_detect", public = true }
diff --git a/library/std/src/collections/hash/map.rs b/library/std/src/collections/hash/map.rs
index fc0fef620e3b6..b2900f1033e04 100644
--- a/library/std/src/collections/hash/map.rs
+++ b/library/std/src/collections/hash/map.rs
@@ -1051,7 +1051,7 @@ where
         K: Borrow<Q>,
         Q: Hash + Eq,
     {
-        self.base.get_many_mut(ks)
+        self.base.get_disjoint_mut(ks)
     }
 
     /// Attempts to get mutable references to `N` values in the map at once, without validating that
@@ -1118,7 +1118,7 @@ where
         K: Borrow<Q>,
         Q: Hash + Eq,
     {
-        unsafe { self.base.get_many_unchecked_mut(ks) }
+        unsafe { self.base.get_disjoint_unchecked_mut(ks) }
     }
 
     /// Returns `true` if the map contains a value for the specified key.
diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index e275d3042cbba..ac0426aef20eb 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -45,6 +45,7 @@ const LICENSES: &[&str] = &[
     "Unlicense OR MIT",
     "Unlicense/MIT",
     "Zlib OR Apache-2.0 OR MIT",                           // tinyvec
+    "Zlib",
     // tidy-alphabetical-end
 ];
 
@@ -559,6 +560,7 @@ const PERMITTED_STDLIB_DEPENDENCIES: &[&str] = &[
     "cfg-if",
     "compiler_builtins",
     "dlmalloc",
+    "foldhash",
     "fortanix-sgx-abi",
     "getopts",
     "gimli",
diff --git a/src/tools/tidy/src/extdeps.rs b/src/tools/tidy/src/extdeps.rs
index f75de13b45ceb..02109f3a6dcdd 100644
--- a/src/tools/tidy/src/extdeps.rs
+++ b/src/tools/tidy/src/extdeps.rs
@@ -11,6 +11,7 @@ const ALLOWED_SOURCES: &[&str] = &[
     r#""registry+https://github.com/rust-lang/crates.io-index""#,
     // This is `rust_team_data` used by `site` in src/tools/rustc-perf,
     r#""git+https://github.com/rust-lang/team#a5260e76d3aa894c64c56e6ddc8545b9a98043ec""#,
+    r#""git+https://github.com/gaujay/hashbrown.git?branch=8-bits-tag#fcce069967e957305ec8098c5f1e8280e9ce7c5b""#,
 ];
 
 /// Checks for external package sources. `root` is the path to the directory that contains the