rust-lang/rust-bindgen

External functions are assumed to be unsafe (https://doc.rust-lang.org/reference/items/external-blocks.html#r-items.extern.fn.safety) but there should be an option to mark one as safe For example, for FFI bindings for the PHP source, the function zend_html_putc (https://github.com/php/php-src/blob/d03163dc0af54f9c0687ab345f5db2584563b2a7/Zend/zend_highlight.c#L28) is always going to be safe - it just prints a character. Similarly, zend_gdb_present (https://github.com/php/php-src/blob/PHP-8.5.10/Zend/zend_gdb.c#L110) takes no parameters and returns a boolean reporting if GDB is present - this function is always going to be safe to call There should be a way to indicate that a specific function should be marked as safe

Input C/C++ Header struct E {}; int take(E e, int x); int take(E e, int x) { (void)e; return x + 1; } Bindgen Invocation $ bindgen input.h --enable-cxx-namespaces --output bindings.rs -- -x c++ -std=c++20 Layout tests are left on (the default). Actual Results sizeof(E) is 1 in both clang++ and the generated Rust, so the layout tests compile. clang++ does not pass the empty class at all: define i32 @_Z4take1Ei(i32 noundef %0) ; caller: call i32 @_Z4take1Ei(i32 noundef 10) bindgen still emits a 1-byte argument: pub struct E { pub _address: u8 } pub fn take(e: root::E, x: c_int) -> c_int; rustc therefore calls with two arguments: declare i32 @"\01__Z4take1Ei"(i64, i32) call i32 @"\01__Z4take1Ei"(i64 %1, i32 10) Runtime, take(E{}, 10): C++: 11 Rust: 1 bindgen does not panic. rustc accepts the bindings, including the layout tests. Expected Results The generated signature should match the C++ ABI used by clang: the empty class parameter is not passed, so take is effectively fn(c_int) -> c_