diff options
| -rw-r--r-- | clippy_lints/src/collection_is_never_read.rs | 9 | ||||
| -rw-r--r-- | tests/ui/collection_is_never_read.rs | 3 | ||||
| -rw-r--r-- | tests/ui/collection_is_never_read.stderr | 20 |
3 files changed, 23 insertions, 9 deletions
diff --git a/clippy_lints/src/collection_is_never_read.rs b/clippy_lints/src/collection_is_never_read.rs index a5feffa3106..5e2eb5789f6 100644 --- a/clippy_lints/src/collection_is_never_read.rs +++ b/clippy_lints/src/collection_is_never_read.rs @@ -120,6 +120,15 @@ fn has_no_read_access<'tcx>(cx: &LateContext<'tcx>, id: HirId, block: &'tcx Bloc if let Some(Node::Stmt(..)) = get_parent_node(cx.tcx, parent.hir_id) { return ControlFlow::Continue(()); } + + // The method call is not a statement, so its return value is used somehow but its type is the + // unit type, so this is not a real read access. Examples: + // + // let y = x.clear(); + // println!("{:?}", x.clear()); + if cx.typeck_results().expr_ty(parent).is_unit() { + return ControlFlow::Continue(()); + } } // Any other access to `id` is a read access. Stop searching. diff --git a/tests/ui/collection_is_never_read.rs b/tests/ui/collection_is_never_read.rs index ca20031bfbe..4f9431be72a 100644 --- a/tests/ui/collection_is_never_read.rs +++ b/tests/ui/collection_is_never_read.rs @@ -85,9 +85,8 @@ fn shadowing_2() { #[allow(clippy::let_unit_value)] fn fake_read() { - let mut x = vec![1, 2, 3]; // Ok + let mut x = vec![1, 2, 3]; // WARNING x.reverse(); - // `collection_is_never_read` gets fooled, but other lints should catch this. let _: () = x.clear(); } diff --git a/tests/ui/collection_is_never_read.stderr b/tests/ui/collection_is_never_read.stderr index f5dea96116f..cfb39298339 100644 --- a/tests/ui/collection_is_never_read.stderr +++ b/tests/ui/collection_is_never_read.stderr @@ -25,40 +25,46 @@ LL | let mut x = HashMap::new(); // WARNING | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: collection is never read - --> $DIR/collection_is_never_read.rs:95:5 + --> $DIR/collection_is_never_read.rs:88:5 | LL | let mut x = vec![1, 2, 3]; // WARNING | ^^^^^^^^^^^^^^^^^^^^^^^^^^ error: collection is never read - --> $DIR/collection_is_never_read.rs:102:5 + --> $DIR/collection_is_never_read.rs:94:5 | LL | let mut x = vec![1, 2, 3]; // WARNING | ^^^^^^^^^^^^^^^^^^^^^^^^^^ error: collection is never read - --> $DIR/collection_is_never_read.rs:119:5 + --> $DIR/collection_is_never_read.rs:101:5 + | +LL | let mut x = vec![1, 2, 3]; // WARNING + | ^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: collection is never read + --> $DIR/collection_is_never_read.rs:118:5 | LL | let mut x = HashSet::new(); // WARNING | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: collection is never read - --> $DIR/collection_is_never_read.rs:133:5 + --> $DIR/collection_is_never_read.rs:132:5 | LL | let x = vec![1, 2, 3]; // WARNING | ^^^^^^^^^^^^^^^^^^^^^^ error: collection is never read - --> $DIR/collection_is_never_read.rs:169:5 + --> $DIR/collection_is_never_read.rs:168:5 | LL | let mut s = String::new(); | ^^^^^^^^^^^^^^^^^^^^^^^^^^ error: collection is never read - --> $DIR/collection_is_never_read.rs:182:5 + --> $DIR/collection_is_never_read.rs:181:5 | LL | let mut s = String::from("Hello, World!"); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -error: aborting due to 10 previous errors +error: aborting due to 11 previous errors |