src/test/ui/consts/const-mut-refs/mut_ref_in_final_dynamic_check.rs

   1 #![feature(const_mut_refs)]
   2 #![feature(raw_ref_op)]
   3 #![feature(const_raw_ptr_deref)]
   4
   5 // This file checks that our dynamic checks catch things that the static checks miss.
   6 // We do not have static checks for these, because we do not look into function bodies.
   7 // We treat all functions as not returning a mutable reference, because there is no way to
   8 // do that without causing the borrow checker to complain (see the B4/helper test in
   9 // mut_ref_in_final.rs).
  10
  11 const fn helper() -> Option<&'static mut i32> { unsafe {
  12     // Undefined behaviour (integer as pointer), who doesn't love tests like this.
  13     // This code never gets executed, because the static checks fail before that.
  14     Some(&mut *(42 as *mut i32)) //~ ERROR evaluation of constant value failed
  15     //~| 0x2a is not a valid pointer
  16 } }
  17 // The error is an evaluation error and not a validation error, so the error is reported
  18 // directly at the site where it occurs.
  19 const A: Option<&mut i32> = helper();
  20
  21 const fn helper2() -> Option<&'static mut i32> { unsafe {
  22     // Undefined behaviour (dangling pointer), who doesn't love tests like this.
  23     // This code never gets executed, because the static checks fail before that.
  24     Some(&mut *(&mut 42 as *mut i32))
  25 } }
  26 const B: Option<&mut i32> = helper2(); //~ ERROR encountered dangling pointer in final constant
  27
  28 fn main() {}