Avoid type mismatch error where a variable is bound with different ref-ness

e.g.,

match x {
      opts::a(ref i) | opts::b(i) => {}
      //~^ ERROR variable `i` is bound with different mode in pattern #2 than in pattern #1
      //~^^ ERROR mismatched types

Where the field of a and b has the same type

cc #30320

1. Current output, no change:

   error[E0409]: variable `i` is bound in inconsistent ways within the same match arm
    --> src/main.rs:8:32
     |
   8 |       opts::a(ref i) | opts::b(i) => {}
     |                   -            ^ bound in different ways
     |                   |
     |                   first binding
   
   error[E0308]: mismatched types
    --> src/main.rs:8:32
     |
   8 |       opts::a(ref i) | opts::b(i) => {}
     |                                ^ expected &isize, found isize
     |
     = note: expected type `&isize`
                found type `isize`
   

   Esteban Kuber at 2018-03-15 01:14:46

2. Current output:

   error[E0409]: variable `i` is bound inconsistently across alternatives separated by `|`
    --> src/lib.rs:8:32
     |
   8 |       opts::a(ref i) | opts::b(i) => {}
     |                   -            ^ bound in different ways
     |                   |
     |                   first binding
   
   error[E0308]: mismatched types
    --> src/lib.rs:8:32
     |
   7 |     match x {
     |           - this expression has type `opts`
   8 |       opts::a(ref i) | opts::b(i) => {}
     |               -----            ^ expected `&isize`, found `isize`
     |               |
     |               first introduced with type `&isize` here
     |
     = note: in the same arm, a binding must have the same type in all alternatives
   help: consider adding `ref`
     |
   8 |       opts::a(ref i) | opts::b(ref i) => {}
     |                                +++
   

   I don't know what else we can do here beyond silencing the E0409.

   Esteban Kuber at 2022-12-28 22:59:31