```rust
#[cortex_m_rt::exception]
unsafe fn HardFault(frame: &cortex_m_rt::ExceptionFrame) -> ! { }
```

This compiles, and `frame` gets a value of `0x0000_0001`, which explodes my handler. You made the trampoline optional, and the macro is supposed to a reject a function with the wrong arguments, but it didn't reject my function.