From 3d9c46e13ceaecbc5c24a6bf1c4b6a3513dbe663 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20Ber=C3=A1nek?= <berykubik@gmail.com>
Date: Tue, 10 Jun 2025 11:09:54 +0200
Subject: [PATCH 1/2] Add jemalloc feature to Clippy

---
 src/tools/clippy/Cargo.toml    |  1 +
 src/tools/clippy/src/driver.rs | 35 ++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/src/tools/clippy/Cargo.toml b/src/tools/clippy/Cargo.toml
index 3a76c61489e24..13cf82a062b54 100644
--- a/src/tools/clippy/Cargo.toml
+++ b/src/tools/clippy/Cargo.toml
@@ -58,6 +58,7 @@ rustc_tools_util = { path = "rustc_tools_util", version = "0.4.2" }
 [features]
 integration = ["dep:tempfile"]
 internal = ["dep:clippy_lints_internal", "dep:tempfile"]
+jemalloc = []
 
 [package.metadata.rust-analyzer]
 # This package uses #[feature(rustc_private)]
diff --git a/src/tools/clippy/src/driver.rs b/src/tools/clippy/src/driver.rs
index 37adb14169a3f..426ba870f5f65 100644
--- a/src/tools/clippy/src/driver.rs
+++ b/src/tools/clippy/src/driver.rs
@@ -13,6 +13,11 @@ extern crate rustc_interface;
 extern crate rustc_session;
 extern crate rustc_span;
 
+// See docs in https://github.com/rust-lang/rust/blob/master/compiler/rustc/src/main.rs
+// about jemalloc.
+#[cfg(feature = "jemalloc")]
+extern crate tikv_jemalloc_sys as jemalloc_sys;
+
 use clippy_utils::sym;
 use rustc_interface::interface;
 use rustc_session::EarlyDiagCtxt;
@@ -181,6 +186,36 @@ const BUG_REPORT_URL: &str = "https://github.com/rust-lang/rust-clippy/issues/ne
 #[allow(clippy::too_many_lines)]
 #[allow(clippy::ignored_unit_patterns)]
 pub fn main() {
+    // See docs in https://github.com/rust-lang/rust/blob/master/compiler/rustc/src/main.rs
+    // about jemalloc.
+    #[cfg(feature = "jemalloc")]
+    {
+        use std::os::raw::{c_int, c_void};
+
+        #[used]
+        static _F1: unsafe extern "C" fn(usize, usize) -> *mut c_void = jemalloc_sys::calloc;
+        #[used]
+        static _F2: unsafe extern "C" fn(*mut *mut c_void, usize, usize) -> c_int = jemalloc_sys::posix_memalign;
+        #[used]
+        static _F3: unsafe extern "C" fn(usize, usize) -> *mut c_void = jemalloc_sys::aligned_alloc;
+        #[used]
+        static _F4: unsafe extern "C" fn(usize) -> *mut c_void = jemalloc_sys::malloc;
+        #[used]
+        static _F5: unsafe extern "C" fn(*mut c_void, usize) -> *mut c_void = jemalloc_sys::realloc;
+        #[used]
+        static _F6: unsafe extern "C" fn(*mut c_void) = jemalloc_sys::free;
+
+        #[cfg(target_os = "macos")]
+        {
+            unsafe extern "C" {
+                fn _rjem_je_zone_register();
+            }
+
+            #[used]
+            static _F7: unsafe extern "C" fn() = _rjem_je_zone_register;
+        }
+    }
+
     let early_dcx = EarlyDiagCtxt::new(ErrorOutputType::default());
 
     rustc_driver::init_rustc_env_logger(&early_dcx);

From 723dae84c18f512bfc4bbc65c51465d2dea14c03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20Ber=C3=A1nek?= <berykubik@gmail.com>
Date: Tue, 10 Jun 2025 11:19:46 +0200
Subject: [PATCH 2/2] Pass `jemalloc` feature to Clippy in bootstrap

---
 src/bootstrap/src/core/build_steps/tool.rs | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/bootstrap/src/core/build_steps/tool.rs b/src/bootstrap/src/core/build_steps/tool.rs
index 9861637d8c822..e0604135eca42 100644
--- a/src/bootstrap/src/core/build_steps/tool.rs
+++ b/src/bootstrap/src/core/build_steps/tool.rs
@@ -1117,6 +1117,7 @@ macro_rules! tool_extended {
             tool_name: $tool_name:expr,
             stable: $stable:expr
             $( , add_bins_to_sysroot: $add_bins_to_sysroot:expr )?
+            $( , add_features: $add_features:expr )?
             $( , )?
         }
     ) => {
@@ -1156,6 +1157,7 @@ macro_rules! tool_extended {
                     $tool_name,
                     $path,
                     None $( .or(Some(&$add_bins_to_sysroot)) )?,
+                    None $( .or(Some($add_features)) )?,
                 )
             }
         }
@@ -1193,7 +1195,13 @@ fn run_tool_build_step(
     tool_name: &'static str,
     path: &'static str,
     add_bins_to_sysroot: Option<&[&str]>,
+    add_features: Option<fn(&Builder<'_>, TargetSelection, &mut Vec<String>)>,
 ) -> ToolBuildResult {
+    let mut extra_features = Vec::new();
+    if let Some(func) = add_features {
+        func(builder, target, &mut extra_features);
+    }
+
     let ToolBuildResult { tool_path, build_compiler, target_compiler } =
         builder.ensure(ToolBuild {
             compiler,
@@ -1201,7 +1209,7 @@ fn run_tool_build_step(
             tool: tool_name,
             mode: Mode::ToolRustc,
             path,
-            extra_features: vec![],
+            extra_features,
             source_type: SourceType::InTree,
             allow_features: "",
             cargo_args: vec![],
@@ -1244,7 +1252,12 @@ tool_extended!(Clippy {
     path: "src/tools/clippy",
     tool_name: "clippy-driver",
     stable: true,
-    add_bins_to_sysroot: ["clippy-driver"]
+    add_bins_to_sysroot: ["clippy-driver"],
+    add_features: |builder, target, features| {
+        if builder.config.jemalloc(target) {
+            features.push("jemalloc".to_string());
+        }
+    }
 });
 tool_extended!(Miri {
     path: "src/tools/miri",