Auto merge of rust-lang#11511 - Jarcho:split_borrow, r=llogiq

Split `needless_borrow` into two lints

Splits off the case where the borrow is used as a generic argument to a function. I think the two cases are different  enough to warrant a separate lint.

The tests for the new lint have been reordered to group related parts together. Two warning have been dropped, one looked like it was testing the generic argument form, but it ends up triggering the auto-deref variant. The second was just a redundant test that didn't do anything interesting.

An issue with cycle detection is also included. The old version was checking if a cycle was reachable from a block when it should have been checking if the block is part or a cycle.

As a side note, I'm liking the style of just jamming all the tests into separate scopes in main.

changelog: Split off `needless_borrows_for_generic_args` from `needless_borrow`

CHANGELOG.md

@@ -5171,6 +5171,7 @@ Released 2018-09-13
 [`needless_bool_assign`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_bool_assign
 [`needless_borrow`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow
 [`needless_borrowed_reference`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrowed_reference
+[`needless_borrows_for_generic_args`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrows_for_generic_args
 [`needless_collect`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_collect
 [`needless_continue`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_continue
 [`needless_doctest_main`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_doctest_main

clippy_lints/src/declared_lints.rs

@@ -480,6 +480,7 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
     crate::needless_bool::NEEDLESS_BOOL_INFO,
     crate::needless_bool::NEEDLESS_BOOL_ASSIGN_INFO,
     crate::needless_borrowed_ref::NEEDLESS_BORROWED_REFERENCE_INFO,
+    crate::needless_borrows_for_generic_args::NEEDLESS_BORROWS_FOR_GENERIC_ARGS_INFO,
     crate::needless_continue::NEEDLESS_CONTINUE_INFO,
     crate::needless_else::NEEDLESS_ELSE_INFO,
     crate::needless_for_each::NEEDLESS_FOR_EACH_INFO,

clippy_lints/src/lib.rs

@@ -228,6 +228,7 @@ mod mutex_atomic;
 mod needless_arbitrary_self_type;
 mod needless_bool;
 mod needless_borrowed_ref;
+mod needless_borrows_for_generic_args;
 mod needless_continue;
 mod needless_else;
 mod needless_for_each;
@@ -887,7 +888,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(move |_| Box::new(wildcard_imports::WildcardImports::new(warn_on_all_wildcard_imports)));
     store.register_late_pass(|_| Box::<redundant_pub_crate::RedundantPubCrate>::default());
     store.register_late_pass(|_| Box::new(unnamed_address::UnnamedAddress));
-    store.register_late_pass(move |_| Box::new(dereference::Dereferencing::new(msrv())));
+    store.register_late_pass(|_| Box::<dereference::Dereferencing<'_>>::default());
     store.register_late_pass(|_| Box::new(option_if_let_else::OptionIfLetElse));
     store.register_late_pass(|_| Box::new(future_not_send::FutureNotSend));
     let future_size_threshold = conf.future_size_threshold;
@@ -1111,6 +1112,11 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|_| Box::new(implied_bounds_in_impls::ImpliedBoundsInImpls));
     store.register_late_pass(|_| Box::new(missing_asserts_for_indexing::MissingAssertsForIndexing));
     store.register_late_pass(|_| Box::new(unnecessary_map_on_constructor::UnnecessaryMapOnConstructor));
+    store.register_late_pass(move |_| {
+        Box::new(needless_borrows_for_generic_args::NeedlessBorrowsForGenericArgs::new(
+            msrv(),
+        ))
+    });
     // add lints here, do not remove this comment, it's used in `new_lint`
 }