Trait name resolution does not work properly in the presence of trait type arguments

[anton-trunov]

Problem statement

Consider the following code snippet, which is basically the Eq trait parameterized with a dummy type parameter T (very similar to the example in issue #5018):

script;

trait Eq<T> {
    fn eq(self, other: Self) -> bool;
} {
    fn neq(self, other: Self) -> bool {
        __eq((self.eq(other)), false)
    }
}

impl Eq<u64> for u64 {
    fn eq(self, other: Self) -> bool {
        __eq(self, other)
    }
}

fn main() -> u64 {
    // block const evaluation for `x` (it does not currently support asm-blocks)
    let x = asm(x: 42u64) { x: u64 };
    let y = 1u64;
    if x.neq(y) {
        2
    } else {
        101
    }
}

This script fails to compile:

error
  --> /Users/anton/fuel/sway/test/src/e2e_vm_tests/test_programs/should_pass/language/name_resolution_after_monomorphization/name_resolution_inside_intrinsics/src/main.sw:4:8
  |
2 |
3 | trait Eq<T> {
4 |     fn eq(self, other: Self) -> bool;
  |        ^^ Internal compiler error: Method eq_1 is a trait method dummy and was not properly replaced.
Please file an issue on the repository and include the code that triggered this error.
5 | } {
6 |     fn neq(self, other: Self) -> bool {
  |
____

  Aborting due to 1 error.

Why this happens

This happens because the IR generator resolves eq into a dummy function with the empty body (just like in issue #4770).
In this particular case it happens because monomorphization of the Eq trait declaration during the typechecking of impl Eq<u64> for u64 creates the new version of the Eq trait with new decl refs, but the body of the neq impl method does not get updated with new references to the trait's interface surface, i.e. the monomorphized neq method keeps referring to the non-monomorphized eq method and name resolution fails.