// stderr-per-bitwidth fn main() { extern "C" { // Use the wrong type(ie. not the pointer width) for the `size` // argument. #[cfg(target_pointer_width="64")] fn malloc(size: u32) -> *mut std::ffi::c_void; #[cfg(target_pointer_width="32")] fn malloc(size: u16) -> *mut std::ffi::c_void; } unsafe { let _p1 = malloc(42); //~ ERROR Undefined Behavior: scalar size mismatch }; }