Auto merge of #14092 - Alexendoo:rustfix-separate-suggestions, r=weih…

…anglo

Add `CodeFix::apply_solution` and impl `Clone`

### What does this PR try to resolve?

In Clippy we have a good few lints that produce mutually exclusive suggestions e.g.

```
error: octal-looking escape in a literal
  --> tests/ui/octal_escapes.rs:6:19
   |
LL |     let _bad2 = b"\033[0m";
   |                   ^^^^
   |
help: if an octal escape is intended, use a hex escape instead
   |
LL |     let _bad2 = b"\x1b[0m";
   |                   ~~~~
help: if a null escape is intended, disambiguate using
   |
LL |     let _bad2 = b"\x0033[0m";
   |                   ~~~~~~
```

For these we have to disable rustfix tests since the suggestions are overlapping, this PR adds a method to `rustfix` that `ui_test` could use in order to produce multiple `.fixed` files, one for each alternative suggestion

### Additional information

It does not work for for multiple suggestions coming from a single subdiagnostic ([`Diag::span_suggestions`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_errors/diagnostic/struct.Diag.html#method.span_suggestions)) e.g.

```
help: consider importing one of these items
  |
1 + use std::collections::HashMap;
  |
1 + use ahash::HashMap;
```

Solving this would be blocked on rust-lang/rust#53934, on the Clippy side we only have one use of `span_suggestions` however so it's still very useful without this

The test cases use Clippy lints that I generated by setting the `parse_and_replace` test to use `clippy-driver` because of familiarity, if there's a rustc case that does multiple suggestions it would be good to go with that

crates/rustfix/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rustfix"
-version = "0.8.4"
+version = "0.8.5"
 authors = [
     "Pascal Hertleif <[email protected]>",
     "Oliver Schneider <[email protected]>",

crates/rustfix/src/lib.rs

@@ -213,6 +213,7 @@ pub fn collect_suggestions<S: ::std::hash::BuildHasher>(
 /// 1. Feeds the source of a file to [`CodeFix::new`].
 /// 2. Calls [`CodeFix::apply`] to apply suggestions to the source code.
 /// 3. Calls [`CodeFix::finish`] to get the "fixed" code.
+#[derive(Clone)]
 pub struct CodeFix {
     data: replace::Data,
     /// Whether or not the data has been modified.
@@ -230,12 +231,18 @@ impl CodeFix {
 
     /// Applies a suggestion to the code.
     pub fn apply(&mut self, suggestion: &Suggestion) -> Result<(), Error> {
-        for sol in &suggestion.solutions {
-            for r in &sol.replacements {
-                self.data
-                    .replace_range(r.snippet.range.clone(), r.replacement.as_bytes())?;
-                self.modified = true;
-            }
+        for solution in &suggestion.solutions {
+            self.apply_solution(solution)?;
+        }
+        Ok(())
+    }
+
+    /// Applies an individual solution from a [`Suggestion`].
+    pub fn apply_solution(&mut self, solution: &Solution) -> Result<(), Error> {
+        for r in &solution.replacements {
+            self.data
+                .replace_range(r.snippet.range.clone(), r.replacement.as_bytes())?;
+            self.modified = true;
         }
         Ok(())
     }