error: missing template arguments after 'make_index_sequence<...auto...>' in `gen0.cxx`

[barries]

Describe the bug Generating an FFI for a minimal header:

#pragma once

#include<array>

struct VersionRange {
};

...generates this error:

warning: [email protected]: /home/barrie/my/ui/../../tmp/ui/debug/build/my-ui-1b2780bae091e965/out/autocxx-build-dir/cxx/gen0.cxx:162:31: error: missing template arguments after 'make_index_sequence<...auto...>'
warning: [email protected]:   162 |   using make_index_sequence = ::std::make_index_sequence;
warning: [email protected]:       |                               ^~
warning: [email protected]: In file included from /usr/include/c++/11/array:38,
warning: [email protected]:                  from /home/barrie/my/ad/src/cg/adp_spec_defs.h:6,
warning: [email protected]:                  from /home/barrie/my/ui/../../tmp/ui/debug/build/my-ui-1b2780bae091e965/out/autocxx-build-dir/cxx/gen0.cxx:1:
warning: [email protected]: /usr/include/c++/11/utility:343:11: note: 'template<long unsigned int _Num> using make_index_sequence = std::make_integer_sequence<long unsigned int, _Num>' declared here
warning: [email protected]:   343 |     using make_index_sequence = make_integer_sequence<size_t, _Num>;
warning: [email protected]:       |           ^~~~~~~~~~~~~~~~~~~
error: failed to run custom build command for `my-ui v0.0.0 (/home/barrie/my/ui)`

Both g++ v11 and clang v14 compile that same header without errors.

To Reproduce

In build.rs:

    // Spec the include path here because bindgen's compiler instance
    // can't seem to find it based on a relative path from the source
    // directory. Maybe due to out-of-tree builds?
    let include_path = std::fs::canonicalize("../ad/src/cg").into_diagnostic()?;
    let bindings_path = "src/aa/adp/fw_integration_tests.rs";

    // This assumes all your C++ bindings are in main.rs
    let mut b = autocxx_build::Builder::new(
        bindings_path,
        [&include_path],
    )
        .build()?;

    b.compile("adp_cpp");

In src/aa/adp/fw_integration_tests.rs:

use autocxx::prelude::*;

include_cpp! {
    #include "adp_spec_defs.h" // include path set in build.rs
    safety!(unsafe_ffi)
    generate_all!()
}

fn test_adp() {
    let got = ffi::VersionRange::new();
}

Expected behavior

No warnings.

Additional context

rustc --version:

rustc 1.90.0 (1159e78c4 2025-09-14)

rustup show:

Default host: x86_64-unknown-linux-gnu
rustup home:  /home/barrie/.rustup

installed toolchains
--------------------
stable-x86_64-unknown-linux-gnu (active, default)
1.76.0-x86_64-unknown-linux-gnu

active toolchain
----------------
name: stable-x86_64-unknown-linux-gnu
active because: it's the default toolchain
installed targets:
  x86_64-unknown-linux-gnu

From Cargo.lock:

name = "autocxx"
version = "0.30.0"

name = "autocxx"
version = "0.30.0"

name = "cxx-gen"
version = "0.7.187"

name = "autocxx-bindgen"
version = "0.73.0"

name = "bindgen"
version = "0.70.1"