Codegen results in function call with incorrect number of arguments

[paulyoung]

Describe the bug
The build fails with the following:

cargo:warning=In file included from /Users/py/projects/paulyoung/autocxx-bug/main/target/debug/build/autocxx-bug-94a6f68b4aecae68/out/autocxx-build-dir/cxx/gen0.cxx:2:

cargo:warning=/Users/py/projects/paulyoung/autocxx-bug/main/target/debug/build/autocxx-bug-94a6f68b4aecae68/out/autocxx-build-dir/include/autocxxgen_ffi.h:57:144: error: no matching function for call to 'operator new'

cargo:warning=inline void MySubclassCpp_new_autocxx_autocxx_wrapper_0xc63676881d849a16(MySubclassCpp* autocxx_gen_this, rust::Box<MySubclassHolder> arg1)  { new (autocxx_gen_this) MySubclassCpp(std::move(arg1)); }

cargo:warning=                                                                                                                                               ^   ~~~~~~~~~~~~~~~~~~

cargo:warning=include/MyClass.h:12:15: note: candidate function not viable: requires single argument 'size', but 2 arguments were provided

cargo:warning=        static void* operator new( size_t size );

cargo:warning=                     ^

To Reproduce
Try to build the project at https://github.com/paulyoung/autocxx-bug

Expected behavior
Codegen results in code supplying the correct number of arguments.

Additional context
In reality I don't control the header files so any potential workarounds would preferably not involve modifying them.

[paulyoung]

I just updated the repo to use generate! instead of subclass! since I figured that would be a more minimal example, even though my use case is subclassing.

The build now fails with:

cargo:warning=In file included from /Users/py/projects/paulyoung/autocxx-bug/main/target/debug/build/autocxx-bug-94a6f68b4aecae68/out/autocxx-build-dir/cxx/gen0.cxx:2:

cargo:warning=/Users/py/projects/paulyoung/autocxx-bug/main/target/debug/build/autocxx-bug-94a6f68b4aecae68/out/autocxx-build-dir/include/autocxxgen_ffi.h:43:148: error: no matching function for call to 'operator new'

cargo:warning=inline void new_synthetic_const_copy_ctor_0x42aaa771a89cc55d_autocxx_wrapper_0x42aaa771a89cc55d(MyClass* autocxx_gen_this, const MyClass& arg1)  { new (autocxx_gen_this) MyClass(arg1); }

cargo:warning=                                                                                                                                                   ^   ~~~~~~~~~~~~~~~~~~

cargo:warning=include/MyClass.h:12:15: note: candidate function not viable: requires single argument 'size', but 2 arguments were provided

cargo:warning=        static void* operator new( size_t size );

cargo:warning=                     ^

[stevefan1999-personal]

Here's a concrete real life example (attemping to use autocxx with Half-Life SDK) stevefan1999-personal/autocxx-bug-operator-new (github.com)

[pevers]

I just updated the repo to use generate! instead of subclass! since I figured that would be a more minimal example, even though my use case is subclassing.

The build now fails with:

cargo:warning=In file included from /Users/py/projects/paulyoung/autocxx-bug/main/target/debug/build/autocxx-bug-94a6f68b4aecae68/out/autocxx-build-dir/cxx/gen0.cxx:2:

cargo:warning=/Users/py/projects/paulyoung/autocxx-bug/main/target/debug/build/autocxx-bug-94a6f68b4aecae68/out/autocxx-build-dir/include/autocxxgen_ffi.h:43:148: error: no matching function for call to 'operator new'

cargo:warning=inline void new_synthetic_const_copy_ctor_0x42aaa771a89cc55d_autocxx_wrapper_0x42aaa771a89cc55d(MyClass* autocxx_gen_this, const MyClass& arg1)  { new (autocxx_gen_this) MyClass(arg1); }

cargo:warning=                                                                                                                                                   ^   ~~~~~~~~~~~~~~~~~~

cargo:warning=include/MyClass.h:12:15: note: candidate function not viable: requires single argument 'size', but 2 arguments were provided

cargo:warning=        static void* operator new( size_t size );

cargo:warning=                     ^

Hi @paulyoung , did you manage to solve this in the end? I'm also running into this issue.

[paulyoung]

@pevers I didn't.

I thought about trying to fix the issue and submitting a PR or writing something by hand instead but my project is fairly low priority so I haven't invested any more time into it.

[paulyoung]

I might at least add some failing test cases.

[adetaylor]

Please do!

[paulyoung]

@adetaylor was just thinking about doing this again yesterday.

[paulyoung]

I tried following the steps at https://github.com/google/autocxx/blob/ca48925c04ae84cc3c61153fa230db9c899fcb53/book/src/reporting_bugs.md

I wasn't able to produce a reduce test case. The command in the above document appears to be out of date but even with that I kept getting an error. Perhaps I was doing something wrong.

Error:   × the include_cpp! macro couldn't be expanded into Rust bindings to C++: The 'generate' or 'generate_pod' directive for 'A' did not result in any code being generated. Perhaps this was mis-spelled or you didn't qualify the name with any namespaces?
  │ Otherwise please report a bug.

I figured the test case at https://github.com/paulyoung/autocxx-bug is probably minimal enough so moved on to the next step.

---

With bindgen, I ran into this:

cargo run -- ~/projects/paulyoung/autocxx-bug/main/include/MyClass.h --no-layout-tests --enable-cxx-namespaces --allowlist-type MyClass -- -std=c++14                                                                                    ✘ 101
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.04s
     Running `target/debug/bindgen /Users/py/projects/paulyoung/autocxx-bug/main/include/MyClass.h --no-layout-tests --enable-cxx-namespaces --allowlist-type MyClass -- -std=c++14`
panicked at bindgen/ir/context.rs:562:15:
libclang error; possible causes include:
- Invalid flag syntax
- Unrecognized flags
- Invalid flag arguments
- File I/O errors
- Host vs. target architecture mismatch
If you encounter an error missing from this list, please file an issue or a PR!

Apparently I needed to add the -x c++ flag:

cargo run -- ~/projects/paulyoung/autocxx-bug/main/include/MyClass.h --no-layout-tests --enable-cxx-namespaces --allowlist-type MyClass -- -x c++ -std=c++14                                                                             ✘ 101
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.04s
     Running `target/debug/bindgen /Users/py/projects/paulyoung/autocxx-bug/main/include/MyClass.h --no-layout-tests --enable-cxx-namespaces --allowlist-type MyClass -- -x c++ -std=c++14`
clang diag: /nix/store/j3dhkx4m14m38drh3f40bccrwrgzlsg5-libcxx-19.1.7-dev/include/c++/v1/__configuration/compiler.h:41:8: warning: "Libc++ only supports AppleClang 15 and later" [-W#warnings]
Warning: can't set `binop_separator = Back`, unstable features are only available in nightly channel.
/* automatically generated by rust-bindgen 0.71.1 */

#[allow(non_snake_case, non_camel_case_types, non_upper_case_globals)]
pub mod root {
    #[allow(unused_imports)]
    use self::super::root;
    #[repr(C)]
    pub struct MyClass__bindgen_vtable(::std::os::raw::c_void);
    #[repr(C)]
    #[derive(Debug)]
    pub struct MyClass {
        pub vtable_: *const MyClass__bindgen_vtable,
    }
    unsafe extern "C" {
        #[link_name = "\u{1}__ZN7MyClassC1Ev"]
        pub fn MyClass_MyClass(this: *mut root::MyClass);
    }
    impl MyClass {
        #[inline]
        pub unsafe fn new() -> Self {
            let mut __bindgen_tmp = ::std::mem::MaybeUninit::uninit();
            MyClass_MyClass(__bindgen_tmp.as_mut_ptr());
            __bindgen_tmp.assume_init()
        }
    }
    unsafe extern "C" {
        #[link_name = "\u{1}__ZN7MyClassD1Ev"]
        pub fn MyClass_MyClass_destructor(this: *mut root::MyClass);
    }
}

---

I've created a draft PR at #1475 with some test cases I added. I've been running them with cargo test integration_test::test_generate_class -- --exact and cargo test integration_test::test_subclass -- --exact

Some of the existing tests (e.g. test_pv_subclass_mut and test_pv_subclass_const) fail for me locally so I wasn't able to verify if these demonstrate the issue yet.

clang diag: /nix/store/j3dhkx4m14m38drh3f40bccrwrgzlsg5-libcxx-19.1.7-dev/include/c++/v1/__configuration/compiler.h:41:8: warning: "Libc++ only supports AppleClang 15 and later" [-W#warnings]

thread 'integration_test::test_pv_subclass_mut' panicked at integration-tests/src/lib.rs:272:6:
called `Result::unwrap()` on an `Err` value: AutoCxx(ParseError(AutocxxCodegenError(Bindgen(ClangDiagnostic("/nix/store/j3dhkx4m14m38drh3f40bccrwrgzlsg5-libcxx-19.1.7-dev/include/c++/v1/cstdint:159:1: error: expected identifier or '{'\n/nix/store/j3dhkx4m14m38drh3f40bccrwrgzlsg5-libcxx-19.1.7-dev/include/c++/v1/cstdint:159:1: error: C++ requires a type specifier for all declarations\n/nix/store/j3dhkx4m14m38drh3f40bccrwrgzlsg5-libcxx-19.1.7-dev/include/c++/v1/cstdint:159:1: error: expected expression\n/var/folders/f1/rffgvyz94lqc3kl6wtx18w6w0000gn/T/.tmpgifwQG/input.h:4:1: error: expected ';' after top level declarator\n")))))