feat: integrate chkstk_stub crate and simplify iOS stub handling in build script

Cargo.lock

@@ -25,6 +25,15 @@ dependencies = [
  "shlex",
 ]
 
+[[package]]
+name = "chkstk_stub"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "047f6ab2f3b9bcaf23b593d1580898e4244d27eadf1a1fae99212ee5735d3d1c"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "fnv"
 version = "1.0.7"
@@ -86,6 +95,7 @@ version = "0.1.1"
 dependencies = [
  "anyhow",
  "cc",
+ "chkstk_stub",
  "num-bigint",
  "num-traits",
 ]

crates/Cargo.toml

@@ -17,3 +17,4 @@ num-traits = "0.2.19"
 
 [build-dependencies]
 cc = "1.0"
+chkstk_stub = "0.1"

crates/build.rs

@@ -11,10 +11,8 @@ fn main() {
     let out_dir = env::var("OUT_DIR").expect("OUT_DIR not set");
     let arch = target.split('-').next().unwrap();
 
-    // Create the stub source file
-    if target.contains("apple-ios") {
-        stub_for_ios(&out_dir);
-    }
+    // See: https://github.com/zkmopro/chkstk_stub
+    chkstk_stub::build();
 
     // Try to list contents of the target directory
     let rapidsnark_path = Path::new(&out_dir).join(Path::new("rapidsnark"));
@@ -98,23 +96,3 @@ fn android() {
         fs::copy(lib_path, Path::new(&dest_dir).join("libc++_shared.so")).unwrap();
     }
 }
-
-fn stub_for_ios(out_dir: &str) {
-    let stub_path = Path::new(&out_dir).join("chkstk_stub.c");
-    fs::write(
-        &stub_path,
-        r#"
-        void __chkstk_darwin(void) {}
-        "#,
-    )
-    .unwrap();
-
-    // Compile the stub into a static lib
-    cc::Build::new()
-        .file(&stub_path)
-        .out_dir(out_dir)
-        .compile("chkstk_stub");
-
-    println!("cargo:rustc-link-search=native={out_dir}");
-    println!("cargo:rustc-link-lib=static=chkstk_stub");
-}