Auto merge of #14747 - saites:rustfix-transactional, r=weihanglo

Add transactional semantics to `rustfix`

### What does this PR try to resolve?

This PR adds transactional semantics to `rustfix::Data`, enabling `rustfix::CodeFix` to apply `Suggestion`s as atomic units and rollback partially-applied changes when they conflict with existing ones. The basic approach and goals are discussed [in a comment on issue 14699](#14699 (comment)). In that comment, I proposed a solution which extended the existing `State` enumeration, but described an alternative that simplifies the overall tracking of incoming changes; this PR implements the latter.

### How should we test and review this PR?

I've added an additional test and updated the existing ones. The tests in `parse_and_replace` already cover this case, particularly thanks to #14765 added by `@weihanglo.` It's still a good idea to experiment with `cargo clippy --fix` on repos that match the cases described in these open issues.

### Additional information

Fixes #14699
Fixes rust-lang/rust-clippy/issues/13549

Author: bors

Cargo.lock

@@ -81,7 +81,7 @@ rand = "0.8.5"
 regex = "1.10.5"
 rusqlite = { version = "0.32.0", features = ["bundled"] }
 rustc-hash = "2.0.0"
-rustfix = { version = "0.8.2", path = "crates/rustfix" }
+rustfix = { version = "0.9.0", path = "crates/rustfix" }
 same-file = "1.0.6"
 schemars = "0.8.21"
 security-framework = "3.0.0"

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rustfix"
-version = "0.8.8"
+version = "0.9.0"
 authors = [
     "Pascal Hertleif <[email protected]>",
     "Oliver Schneider <[email protected]>",

crates/rustfix/Cargo.toml

@@ -2,6 +2,7 @@
 
 use std::ops::Range;
 
+#[non_exhaustive]
 #[derive(Debug, thiserror::Error)]
 pub enum Error {
     #[error("invalid range {0:?}, start is larger than end")]
@@ -10,9 +11,7 @@ pub enum Error {
     #[error("invalid range {0:?}, original data is only {1} byte long")]
     DataLengthExceeded(Range<usize>, usize),
 
-    #[error("could not replace range {0:?}, maybe parts of it were already replaced?")]
-    MaybeAlreadyReplaced(Range<usize>),
-
+    #[non_exhaustive] // There are plans to add fields to this variant at a later time.
     #[error("cannot replace slice of data that was already replaced")]
     AlreadyReplaced,
 

crates/rustfix/src/error.rs

@@ -243,9 +243,11 @@ impl CodeFix {
     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;
+                .replace_range(r.snippet.range.clone(), r.replacement.as_bytes())
+                .inspect_err(|_| self.data.restore())?;
         }
+        self.data.commit();
+        self.modified = true;
         Ok(())
     }