Add jemalloc feature to Clippy

Author: Kobzol

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)]

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);