ObjC selector with $ panics ("take$foo" is not a valid Ident)

Input C/C++ Header

__attribute__((objc_root_class))
@interface Foo
- (int)take$foo:(int)t;
@end

Bindgen Invocation

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

Actual Results

bindgen aborts:

panicked at bindgen/ir/objc.rs:264:30:
"take$foo" is not a valid Ident

clang accepts $ in the selector. C names with $ already go through rust_mangle ($ → _). ObjC format_method_call passes selector fragments to Ident::new / syn::parse_str without that.

This is not #2486 (keyword type / self) or #1703 (empty :: fragments).

Expected Results

Do not abort. Mangle $ in selector fragments the same way C identifiers are mangled.

Environment

bindgen: 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 bindgen/ir/objc.rs at format_method_call and the panic reported around line 264. Reproduce the issue with the provided Objective-C header and bindgen invocation, then verify that selector fragments containing $ no longer abort and are mangled consistently with the expected output.