objc_runtime_name is ignored: class!(SourceName) looks up a class that does not exist

Input C/C++ Header

__attribute__((objc_root_class))
__attribute__((objc_runtime_name("BNRuntimeFoo")))
@interface BNSourceFoo {
    Class isa;
}
+ (int)bar:(int)x;
@end

Bindgen Invocation

$ bindgen input.h -- -x objective-c -fobjc-arc

Actual Results

bindgen 0.72.1 and 0.73.1 both emit class!(BNSourceFoo) — the source identifier — and never mention BNRuntimeFoo:

unsafe fn bar_(x: c_int) -> c_int {
    msg_send!(class!(BNSourceFoo), bar: x)
}

Clang registers the class under the runtime name. nm on the implementation:

_OBJC_CLASS_$_BNRuntimeFoo
+[BNSourceFoo bar:]

LLVM has c"BNRuntimeFoo\00" as the classname string. objc_getClass("BNSourceFoo") therefore returns nil.

A C caller [BNSourceFoo bar:7] prints v=17 (the compiler uses the runtime name). The generated Rust method does objc_getClass("BNSourceFoo") + objc_msgSend and prints v=0 (message to nil). Same numbers twice on both bindgen versions.

ir/objc.rs ObjCInterface::from_ty sets interface.name = cursor.spelling() and codegen does class!(#class_name). There is no read of objc_runtime_name / ObjCRuntimeNameAttr.

Expected Results

class! / the Objective-C class lookup should use the runtime name (BNRuntimeFoo), not the source name, so objc_getClass finds the class clang actually registered.

Environment

bindgen: 0.72.1 and 0.73.1 (rust-lang/rust-bindgen 77cbc723)
clang/libclang: Homebrew clang 21.1.8
rustc: 1.97.1
target: aarch64-apple-darwin
OS: macOS

Start in ir/objc.rs at ObjCInterface::from_ty and follow the codegen path that emits class!(...). Inspect the ObjC runtime-name attribute represented by ObjCRuntimeNameAttr, then run bindgen on the shown header. Done when the generated lookup uses BNRuntimeFoo rather than BNSourceFoo, matching the class registered by Clang.