auto merge of #19378 : japaric/rust/no-as-slice, r=alexcrichton

Now that we have an overloaded comparison (`==`) operator, and that `Vec`/`String` deref to `[T]`/`str` on method calls, many `as_slice()`/`as_mut_slice()`/`to_string()` calls have become redundant. This patch removes them. These were the most common patterns:

- `assert_eq(test_output.as_slice(), "ground truth")` -> `assert_eq(test_output, "ground truth")`
- `assert_eq(test_output, "ground truth".to_string())` -> `assert_eq(test_output, "ground truth")`
- `vec.as_mut_slice().sort()` -> `vec.sort()`
- `vec.as_slice().slice(from, to)` -> `vec.slice(from_to)`

---

Note that e.g. `a_string.push_str(b_string.as_slice())` has been left untouched in this PR, since we first need to settle down whether we want to favor the `&*b_string` or the `b_string[]` notation.

This is rebased on top of #19167

cc @alexcrichton @aturon 

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libregex/vm.rs b/src/libregex/vm.rs
index 79019d213b8..4315c0f7b40 100644
--- a/src/libregex/vm.rs
+++ b/src/libregex/vm.rs
@@ -147,7 +147,7 @@ impl<'r, 't> Nfa<'r, 't> {
                 // jump ahead quickly. If it can't be found, then we can bail
                 // out early.
                 if self.prog.prefix.len() > 0 && clist.size == 0 {
-                    let needle = self.prog.prefix.as_slice().as_bytes();
+                    let needle = self.prog.prefix.as_bytes();
                     let haystack = self.input.as_bytes()[self.ic..];
                     match find_prefix(needle, haystack) {
                         None => break,