don't pass CFLAGS to underlying compiler

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Version 1.1

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    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
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    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
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    in the file; or

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    it.

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flake.nix

@@ -0,0 +1,30 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs = {
+        nixpkgs.follows = "nixpkgs";
+      };
+    };
+  };
+  outputs = { self, nixpkgs, flake-utils, rust-overlay, zombienet }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        overlays = [ (import rust-overlay) ];
+        pkgs = import nixpkgs {
+          inherit system overlays;
+        };
+        rustToolchain = pkgs.pkgsBuildHost.rust-bin.stable.latest.default;
+        buildInputs = with pkgs; [
+          rustToolchain
+        ];
+      in
+      with pkgs;
+      {
+        devShells.default = mkShell {
+          inherit buildInputs;
+        };
+      }
+    );
+}

jemalloc-sys/build.rs

@@ -145,18 +145,10 @@ fn main() {
         println!("cargo:rustc-link-lib={}={}", kind, &stem[3..]);
         return;
     }
-    // Disable -Wextra warnings - jemalloc doesn't compile free of warnings with
-    // it enabled: https://github.com/jemalloc/jemalloc/issues/1196
-    let compiler = cc::Build::new().extra_warnings(false).get_compiler();
-    let cflags = compiler
-        .args()
-        .iter()
-        .map(|s| s.to_str().unwrap())
-        .collect::<Vec<_>>()
-        .join(" ");
-    info!("CC={:?}", compiler.path());
-    info!("CFLAGS={:?}", cflags);
 
+    let compiler = cc::Build::new().get_compiler();
+    info!("CC={:?}", compiler.path());
+
     assert!(out_dir.exists(), "OUT_DIR does not exist");
     let jemalloc_repo_dir = PathBuf::from("jemalloc");
     info!("JEMALLOC_REPO_DIR={:?}", jemalloc_repo_dir);
@@ -190,9 +182,6 @@ fn main() {
     )
     .current_dir(&build_dir)
     .env("CC", compiler.path())
-    .env("CFLAGS", cflags.clone())
-    .env("LDFLAGS", cflags.clone())
-    .env("CPPFLAGS", cflags)
     .arg(format!("--with-version={je_version}"))
     .arg("--disable-cxx")
     .arg("--enable-doc=no")