Auto merge of #9386 - smoelius:further-enhance-needless-borrow, r=Jarcho

Further enhance `needless_borrow`, mildly refactor `redundant_clone`

This PR does the following:
* Moves some code from `redundant_clone` into a new `clippy_utils` module called `mir`, and wraps that code in a function called `dropped_without_further_use`.
* Relaxes the "is copyable" condition condition from #9136 by also suggesting to remove borrows from values dropped without further use. The changes involve the just mentioned function.
* Separates `redundant_clone` into modules.

Strictly speaking, the last bullet is independent of the others. `redundant_clone` is somewhat hairy, IMO. Separating it into modules makes it slightly less so, by helping to delineate what depends upon what.

I've tried to break everything up into digestible commits.

r? `@Jarcho`

(`@Jarcho` I hope you don't mind.)

changelog: continuation of #9136

2 files changed, 2 insertions, 2 deletions

diff --git a/clippy_dev/src/serve.rs b/clippy_dev/src/serve.rs
index 2e0794f12fa..535c25e69f1 100644
--- a/clippy_dev/src/serve.rs
+++ b/clippy_dev/src/serve.rs
@@ -49,7 +49,7 @@ fn mtime(path: impl AsRef<Path>) -> SystemTime {
             .into_iter()
             .flatten()
             .flatten()
-            .map(|entry| mtime(&entry.path()))
+            .map(|entry| mtime(entry.path()))
             .max()
             .unwrap_or(SystemTime::UNIX_EPOCH)
     } else {
diff --git a/clippy_dev/src/update_lints.rs b/clippy_dev/src/update_lints.rs
index 0eb443167ec..8d1bfacd1dc 100644
--- a/clippy_dev/src/update_lints.rs
+++ b/clippy_dev/src/update_lints.rs
@@ -128,7 +128,7 @@ fn generate_lint_files(
     for (lint_group, lints) in Lint::by_lint_group(usable_lints.into_iter().chain(internal_lints)) {
         let content = gen_lint_group_list(&lint_group, lints.iter());
         process_file(
-            &format!("clippy_lints/src/lib.register_{lint_group}.rs"),
+            format!("clippy_lints/src/lib.register_{lint_group}.rs"),
             update_mode,
             &content,
         );