Compiler can't infer &str type when &String is inserted first in a collection with tuples

[zkkv]

Description: compiler can't infer &str type when String is inserted first in a collection with tuples.

Steps to reproduce: create a new array and fill it with tuples, where one of the elements is a string literal and one is a variable of type &String. Depending one the order, it might or might not compile because type can't be inferred.

let s = &String::from("foo");

let arr1 = [(1, s), (2, "bar")];  // This line contains a compilation error 
let arr2 = [(2, "bar"), (1, s)];  // Does compile; inferred type is [(i32, &str); 2]

Error message:

error[E0308]: mismatched types
   |
   |     let arr1 = [(1, s), (2, "bar")];
   |                             ^^^^^ expected `&String`, found `&str`
   |
   = note: expected reference `&String`
              found reference `&'static str`

Rust compiler version: rustc 1.80.1 (3f5fd8dd4 2024-08-06)

[workingjubilee]

I feel doubt about whether you actually want this to compile, because this sort of typechecking could imply much more effort for arrays based on the length of the array (as it would imply that for 3 items, 3 attempts are made, one for each item, to coerce the other 2 items to the same type...). This is non-linear in effort.