--represent-cxx-operators panics: "S_operator()" is not a valid Ident

Input C/C++ Header

struct S {
    int x;
    int operator()(int t) const;
};

Bindgen Invocation

$ bindgen input.h --represent-cxx-operators -- -x c++ -std=c++17

Actual Results

bindgen aborts:

panicked at bindgen/ir/context.rs:903:9:
"S_operator()" is not a valid Ident

Without the flag, operators are skipped. With --represent-cxx-operators, FunctionSig::from_ty keeps operator(), then codegen does rust_ident("S_operator()"). rust_mangle only rewrites @, ?, $, and keywords, so the parentheses reach Ident::new.

Same panic for operator[], operator+, operator==. operator int does not panic (that spelling is already a valid Ident).

The rustdoc for the flag says the names are not valid Rust and you need ParseCallbacks::generated_name_override. The CLI has no callback, so bindgen panics instead of emitting something or skipping. #3142 added the flag for post-processors that rename; it did not document an abort.

rust_mangle has the same hole for clang-accepted non-XID names, e.g. gnu11 struct 🐶 { int x; }; → "🐶" is not a valid Ident. CJK struct 测试 is fine (XID).

Expected Results

Do not abort. Mangle operator() to a valid Ident (or skip with a diagnostic). Callers can still rename via generated_name_override.

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

Reproduce the panic with the shown bindgen command, then inspect bindgen/ir/context.rs around the reported line, FunctionSig::from_ty, codegen, and rust_mangle. Check how operator() and other clang-accepted names reach Ident::new. Done means the command no longer aborts: invalid operator names are mangled to valid identifiers or skipped with a diagnostic, while generated_name_override can still rename them.