rust-bindgen 0.73.2 segfaults with nested types defined with `using`

In the following minimized example project:

$ ls -lR
total 16
-rw-r--r--@ 1 miriam  staff  808 Sep 10 17:22 build.rs
-rw-r--r--@ 1 miriam  staff  106 Sep 10 17:23 Cargo.toml
drwxr-xr-x  5 miriam  staff  160 Sep 10 17:22 src

./src:
total 16
-rw-r--r--  1 miriam  staff  212 Sep 10 17:22 bindgen_entry.h
-rw-r--r--@ 1 miriam  staff  210 Sep 10 16:56 lib.rs

build.rs:

use std::path::Path;
use std::env;

fn main() {
    let bindings = bindgen::Builder::default()
        .header("src/bindgen_entry.h")
        // Tell cargo to invalidate the built crate whenever any of the
        // included header files changed.
        .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
        .clang_args(["-x", "c++", "-std=c++23"])
        // prevent generating bindings for stdlib and the like
        .allowlist_file("src/bindgen_entry.h")
        .generate()
        .expect("Unable to generate bindings");

    // Write the bindings to the $OUT_DIR/bindings.rs file.
    let cargo_out = env::var("OUT_DIR").unwrap();
    let out_path = Path::new(&cargo_out);
    bindings
        .write_to_file(out_path.join("bindings.rs"))
        .expect("Couldn't write bindings!");
}

Cargo.toml:

[package]
name = "bindgen-segv"
version = "0.1.0"
edition = "2024"

[build-dependencies]
bindgen = "0.73"

src/bindgen_entry.h:

#ifndef BINDGEN_ENTRY_H__
#define BINDGEN_ENTRY_H__

template <typename T>
using Wrapper = T*;

typedef struct {
  Wrapper<Wrapper<const char>> char_arr;
  int arr_size;
} CharArr;


#endif // BINDGEN_ENTRY_H__

src/lib.rs (just the default generated by cargo init):

pub fn add(left: u64, right: u64) -> u64 {
    left + right
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn it_works() {
        let result = add(2, 2);
        assert_eq!(result, 4);
    }
}

cargo build fails as such:

$ cargo build
    Updating crates.io index
     Locking 24 packages to latest Rust 1.97.1 compatible versions
  Downloaded prettyplease v0.3.0
  Downloaded syn v3.0.5
  Downloaded 2 crates (376.2KiB) in 0.17s
   Compiling proc-macro2 v1.0.107
   Compiling unicode-ident v1.0.24
   Compiling quote v1.0.47
   Compiling glob v0.3.4
   Compiling libc v0.2.189
   Compiling prettyplease v0.3.0
   Compiling cfg-if v1.0.4
   Compiling regex-syntax v0.8.11
   Compiling memchr v2.8.3
   Compiling minimal-lexical v0.2.1
   Compiling bindgen v0.73.2
   Compiling log v0.4.34
   Compiling bitflags v2.13.2
   Compiling rustc-hash v2.1.3
   Compiling shlex v2.0.1
   Compiling libloading v0.8.9
   Compiling clang-sys v1.9.1
   Compiling nom v7.1.3
   Compiling regex-automata v0.4.18
   Compiling cexpr v0.6.0
   Compiling syn v3.0.5
   Compiling regex v1.13.1
   Compiling bindgen-segv v0.1.0 (/Users/miriam/bindgen-segv)
error: failed to run custom build command for `bindgen-segv v0.1.0 (/Users/miriam/bindgen-segv)`

Caused by:
  process didn't exit successfully: `/Users/miriam/bindgen-segv/target/debug/build/bindgen-segv-b96f88365a6bc922/build-script-build` (signal: 11, SIGSEGV: invalid memory reference)
  --- stdout
  cargo:rerun-if-env-changed=TARGET
  cargo:rerun-if-env-changed=BINDGEN_EXTRA_CLANG_ARGS_aarch64-apple-darwin
  cargo:rerun-if-env-changed=BINDGEN_EXTRA_CLANG_ARGS_aarch64_apple_darwin
  cargo:rerun-if-env-changed=BINDGEN_EXTRA_CLANG_ARGS
  cargo:rerun-if-changed=src/bindgen_entry.h

version info:

$ rustc --version --verbose
rustc 1.97.1 (8bab26f4f 2026-07-14)
binary: rustc
commit-hash: 8bab26f4f68e0e26f0bb7960be334d5b520ea452
commit-date: 2026-07-14
host: aarch64-apple-darwin
release: 1.97.1
LLVM version: 22.1.6

I am running on an M3 mac with macOS 26.6.2.

Start by reproducing the crash with the minimized project’s build.rs and src/bindgen_entry.h using cargo build, then trace bindgen’s C++ parsing and binding-generation entry points for the nested using aliases. Done means the example no longer segfaults and cargo build completes with bindings generated for CharArr.