rust-lang / rust-lang/rust-clippy
Nightly regression: `clippy --fix` does no edits but suggests running the same `clippy --fix` command
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C-bug
- Dominant language
- Rust
- Stars
- 13.5k
- Forks
- 2.2k
- Avg merge
- 2d 10h
- Merged PRs (30d)
- 32
Description
Summary
If I run any of these commands:
cargo clippy --fix --workspace --all-targets --all-featurescargo clippy --fix --example "custom-backend"cargo clippy --fix --lib -p jj-lib
on https://github.com/jj-vcs/jj/tree/b09c243ba37a5ed9f05320de17b80ec74c69b02d, Clippy does not change anything in the repo, but suggests that I run clippy --fix again. E.g, it suggests:
- "run
cargo clippy --fix --example "custom-backend"to apply 1 suggestion" (which is the command I just ran). - "run
cargo clippy --fix --lib -p jj-libto apply 17 suggestions"
This seems to be connected with the mismatched_lifetime_syntaxes lint. A longer excerpt hidden inside <details> below. Again, in spite of it saying "Fixed", nothing is changed in the repo.
Fixed lib/testutils/src/test_backend.rs (0 fixes)
warning: lifetime flowing from input to output with different syntax can be confusing
--> lib/testutils/src/test_backend.rs:392:9
|
392 | &self,
| ^^^^^ this lifetime flows to the output
...
396 | ) -> BackendResult<BoxStream<BackendResult<CopyRecord>>> {
| ------------------------------------ the lifetime gets resolved as `'_`
|
= note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
396 | ) -> BackendResult<BoxStream<'_, BackendResult<CopyRecord>>> {
| +++
warning: `testutils` (lib test) generated 1 warning (run `cargo clippy --fix --lib -p testutils --tests` to apply 1 suggestion)
Fixed cli/src/config.rs (0 fixes)
Fixed cli/src/cli_util.rs (0 fixes)
Fixed cli/src/template_parser.rs (0 fixes)
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/cli_util.rs:827:40
|
827 | pub(crate) fn revset_parse_context(&self) -> RevsetParseContext {
| ^^^^^ ------------------ the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
= note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
827 | pub(crate) fn revset_parse_context(&self) -> RevsetParseContext<'_> {
| ++++
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/cli_util.rs:1244:9
|
1244 | &mut self,
| ^^^^^^^^^ this lifetime flows to the output
1245 | ) -> Result<(LockedWorkspace, Commit), CommandError> {
| --------------- the lifetime gets resolved as `'_`
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
1245 | ) -> Result<(LockedWorkspace<'_>, Commit), CommandError> {
| ++++
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/cli_util.rs:1259:9
|
1259 | &mut self,
| ^^^^^^^^^ this lifetime flows to the output
1260 | ) -> Result<(LockedWorkspace, Commit), CommandError> {
| --------------- the lifetime gets resolved as `'_`
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
1260 | ) -> Result<(LockedWorkspace<'_>, Commit), CommandError> {
| ++++
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/cli_util.rs:2047:30
|
2047 | pub fn start_transaction(&mut self) -> WorkspaceCommandTransaction {
| ^^^^^^^^^ --------------------------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
2047 | pub fn start_transaction(&mut self) -> WorkspaceCommandTransaction<'_> {
| ++++
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/config.rs:761:23
|
761 | pub fn split_name(&self) -> Cow<str> {
| ^^^^^ -------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
761 | pub fn split_name(&self) -> Cow<'_, str> {
| +++
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/config.rs:769:32
|
769 | pub fn split_name_and_args(&self) -> (Cow<str>, Cow<[String]>) {
| ^^^^^ -------- ------------- the lifetimes get resolved as `'_`
| | |
| | the lifetimes get resolved as `'_`
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
769 | pub fn split_name_and_args(&self) -> (Cow<'_, str>, Cow<'_, [String]>) {
| +++ +++
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/template_parser.rs:422:32
|
422 | fn parse_identifier_name(pair: Pair<Rule>) -> TemplateParseResult<&str> {
| ^^^^^^^^^^ ---- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
422 | fn parse_identifier_name(pair: Pair<'_, Rule>) -> TemplateParseResult<&str> {
| +++
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/template_parser.rs:431:41
|
431 | fn parse_formal_parameters(params_pair: Pair<Rule>) -> TemplateParseResult<Vec<&str>> {
| ^^^^^^^^^^ ---- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
431 | fn parse_formal_parameters(params_pair: Pair<'_, Rule>) -> TemplateParseResult<Vec<&str>> {
| +++
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/template_parser.rs:594:38
|
594 | pub fn parse_template(template_text: &str) -> TemplateParseResult<ExpressionNode> {
| ^^^^ -------------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
594 | pub fn parse_template(template_text: &str) -> TemplateParseResult<ExpressionNode<'_>> {
| ++++
warning: `jj-cli` (lib) generated 9 warnings (run `cargo clippy --fix --lib -p jj-cli` to apply 9 suggestions)
Fixed lib/testutils/src/test_backend.rs (0 fixes)
warning: `testutils` (lib) generated 1 warning (1 duplicate)
Fixed cli/examples/custom-backend/main.rs (0 fixes)
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/examples/custom-backend/main.rs:217:9
|
217 | &self,
| ^^^^^ this lifetime flows to the output
...
221 | ) -> BackendResult<BoxStream<BackendResult<CopyRecord>>> {
| ------------------------------------ the lifetime gets resolved as `'_`
|
= note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
221 | ) -> BackendResult<BoxStream<'_, BackendResult<CopyRecord>>> {
| +++
warning: `jj-cli` (example "custom-backend") generated 1 warning (run `cargo clippy --fix --example "custom-backend"` to apply 1 suggestion)
Fixed lib/src/default_index/readonly.rs (0 fixes)
Fixed lib/src/tree.rs (0 fixes)
Fixed lib/src/secret_backend.rs (0 fixes)
Fixed lib/src/backend.rs (0 fixes)
Fixed lib/src/store.rs (0 fixes)
Fixed lib/src/git_backend.rs (0 fixes)
Fixed lib/src/merged_tree.rs (0 fixes)
Fixed lib/src/fileset_parser.rs (0 fixes)
Fixed lib/src/config.rs (0 fixes)
Fixed lib/src/repo.rs (0 fixes)
Fixed lib/src/workspace.rs (0 fixes)
Fixed lib/src/revset_parser.rs (0 fixes)
Fixed lib/src/simple_backend.rs (0 fixes)
warning: lifetime flowing from input to output with different syntax can be confusing
--> lib/src/fileset_parser.rs:356:30
|
356 | fn parse_into_kind(text: &str) -> Result<ExpressionKind, FilesetParseErrorKind> {
| ^^^^ -------------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
356 | fn parse_into_kind(text: &str) -> Result<ExpressionKind<'_>, FilesetParseErrorKind> {
| ++++
warning: lifetime flowing from input to output with different syntax can be confusing
--> lib/src/fileset_parser.rs:362:41
|
362 | fn parse_maybe_bare_into_kind(text: &str) -> Result<ExpressionKind, FilesetParseErrorKind> {
| ^^^^ -------------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
362 | fn parse_maybe_bare_into_kind(text: &str) -> Result<ExpressionKind<'_>, FilesetParseErrorKind> {
| ++++
warning: lifetime flowing from input to output with different syntax can be confusing
--> lib/src/fileset_parser.rs:368:31
|
368 | fn parse_normalized(text: &str) -> ExpressionNode {
| ^^^^ -------------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
368 | fn parse_normalized(text: &str) -> ExpressionNode<'_> {
| ++++
warning: lifetime flowing from input to output with different syntax can be confusing
--> lib/src/fileset_parser.rs:372:42
|
372 | fn parse_maybe_bare_normalized(text: &str) -> ExpressionNode {
| ^^^^ -------------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
372 | fn parse_maybe_bare_normalized(text: &str) -> ExpressionNode<'_> {
| ++++
warning: lifetime flowing from input to output with different syntax can be confusing
--> lib/src/revset_parser.rs:888:30
|
888 | fn parse_into_kind(text: &str) -> Result<ExpressionKind, RevsetParseErrorKind> {
| ^^^^ -------------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
888 | fn parse_into_kind(text: &str) -> Result<ExpressionKind<'_>, RevsetParseErrorKind> {
| ++++
warning: lifetime flowing from input to output with different syntax can be confusing
--> lib/src/revset_parser.rs:894:31
|
894 | fn parse_normalized(text: &str) -> ExpressionNode {
| ^^^^ -------------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
894 | fn parse_normalized(text: &str) -> ExpressionNode<'_> {
| ++++
warning: `jj-lib` (lib test) generated 23 warnings (17 duplicates) (run `cargo clippy --fix --lib -p jj-lib --tests` to apply 6 suggestions)
Fixed cli/src/config.rs (0 fixes)
Fixed cli/src/cli_util.rs (0 fixes)
Fixed cli/src/template_parser.rs (0 fixes)
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/template_parser.rs:776:39
|
776 | fn parse_into_kind(template_text: &str) -> Result<ExpressionKind, TemplateParseErrorKind> {
| ^^^^ -------------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
776 | fn parse_into_kind(template_text: &str) -> Result<ExpressionKind<'_>, TemplateParseErrorKind> {
| ++++
warning: lifetime flowing from input to output with different syntax can be confusing
--> cli/src/template_parser.rs:782:40
|
782 | fn parse_normalized(template_text: &str) -> ExpressionNode {
| ^^^^ -------------- the lifetime gets resolved as `'_`
| |
| this lifetime flows to the output
|
help: one option is to remove the lifetime for references and use the anonymous lifetime for paths
|
782 | fn parse_normalized(template_text: &str) -> ExpressionNode<'_> {
| ++++
warning: `jj-cli` (lib test) generated 11 warnings (9 duplicates) (run `cargo clippy --fix --lib -p jj-cli --tests` to apply 2 suggestions)
Finished `dev` profile [unoptimized + debuginfo] target(s) in 56.59s
Reproducer
See above.
I just updated the nightly from rustc 1.89.0-nightly (4b27a04cc 2025-06-04) to today's nightly (see below).
I double-checked, and this was not a problem with rustc 1.89.0-nightly (59aa1e873 2025-06-03). These warnings are not generated at all with that version from a week ago (some unrelated cloned_refs_to_sliced_ref warnings are).
Version
rustc 1.89.0-nightly (d13a431a6 2025-06-09)
binary: rustc
commit-hash: d13a431a6cc69cd65efe7c3eb7808251d6fd7a46
commit-date: 2025-06-09
host: aarch64-apple-darwin
release: 1.89.0-nightly
LLVM version: 20.1.5
Additional Labels
No response
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the report at the referenced repository revision using the listed cargo clippy --fix commands, focusing on the mismatched_lifetime_syntaxes warnings. Compare Clippy's reported fixes with the affected paths, including lib/testutils/src/test_backend.rs, cli/src/cli_util.rs, and cli/examples/custom-backend/main.rs. Done means clippy --fix applies its suggestions and does not recommend rerunning the same command.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100