[E0426] Use of undeclared label

[MahadMuhammad]

Use of undeclared label in break or continue statement - E0426

• Refactored error message to print more userfriendly message and added error code.

---

Code Tested

// ErrorCode::E0426
#![allow(unused)]
fn resolve_label_continue() -> () {
    loop {
        continue 'a; // { dg-error "use of undeclared label .a. in .continue." }
    }
}
fn resolve_label_break() -> () {
    loop {
        break 'crabby; // { dg-error "use of undeclared label .crabby. in .break." }
    }
}
fn main() {
    resolve_label_continue();
    resolve_label_break();
}

---

Output:

/home/mahad/Desktop/mahad/gccrs/gcc/testsuite/rust/compile/undeclared_label.rs:5:18: error: use of undeclared label ‘a’ in ‘continue’ [E0426]
    5 |         continue 'a; // { dg-error "use of undeclared label .a. in .continue." }
      |                  ^~
/home/mahad/Desktop/mahad/gccrs/gcc/testsuite/rust/compile/undeclared_label.rs:10:15: error: use of undeclared label ‘crabby’ in ‘break’ [E0426]
   10 |         break 'crabby; // { dg-error "use of undeclared label .crabby. in .break." }

---

gcc/rust/ChangeLog:

* resolve/rust-ast-resolve-expr.cc (ResolveExpr::visit): refactored message and called error function.

gcc/testsuite/ChangeLog:

* rust/compile/undeclared_label.rs: New test for E0426.

---

[CohenArthur]

As a side note, I really like the new error message!

[MahadMuhammad]

I personally like this %qs instead of this %<%s%> (as it is cumbersome to write these strange symbols :D ), but these %qs are not always tend to work. Maybe I was a bit lazy to try both, so I just add these %<%s%> (strange symbols) instead of this %qs. As they always work :)