src/librustc_error_codes/error_codes/E0669.md

   1 Cannot convert inline assembly operand to a single LLVM value.
   2
   3 Erroneous code example:
   4
   5 ```compile_fail,E0669
   6 #![feature(llvm_asm)]
   7
   8 fn main() {
   9     unsafe {
  10         llvm_asm!("" :: "r"("")); // error!
  11     }
  12 }
  13 ```
  14
  15 This error usually happens when trying to pass in a value to an input inline
  16 assembly operand that is actually a pair of values. In particular, this can
  17 happen when trying to pass in a slice, for instance a `&str`. In Rust, these
  18 values are represented internally as a pair of values, the pointer and its
  19 length. When passed as an input operand, this pair of values can not be
  20 coerced into a register and thus we must fail with an error.