Rollup merge of #89786 - jkugelman:must-use-len-and-is_empty, r=joshtriplett

Add #[must_use] to len and is_empty

Parent issue: #89692

r? `@joshtriplett`

diff --git a/library/alloc/src/collections/binary_heap.rs b/library/alloc/src/collections/binary_heap.rs
index 4e991018bb4413b886971a8990cdcde4e971c9f3..7fb7686a6e29790a5320cddb774adcf73e92d91a 100644 (file)
--- a/library/alloc/src/collections/binary_heap.rs
+++ b/library/alloc/src/collections/binary_heap.rs
@@ -1052,6 +1052,7 @@ pub fn into_vec(self) -> Vec<T> {
     ///
     /// assert_eq!(heap.len(), 2);
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {
         self.data.len()
@@ -1075,6 +1076,7 @@ pub fn len(&self) -> usize {
     ///
     /// assert!(!heap.is_empty());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_empty(&self) -> bool {
         self.len() == 0

diff --git a/library/alloc/src/collections/btree/map.rs b/library/alloc/src/collections/btree/map.rs
index 224795876fe5bd5b952067a5b9f85371332923f0..2ff7b0fbb759c0c64cbb46210b749bc142afc94f 100644 (file)
--- a/library/alloc/src/collections/btree/map.rs
+++ b/library/alloc/src/collections/btree/map.rs
@@ -2212,6 +2212,7 @@ pub fn values_mut(&mut self) -> ValuesMut<'_, K, V> {
     /// a.insert(1, "a");
     /// assert_eq!(a.len(), 1);
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
     pub const fn len(&self) -> usize {
@@ -2232,6 +2233,7 @@ pub const fn len(&self) -> usize {
     /// a.insert(1, "a");
     /// assert!(!a.is_empty());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
     pub const fn is_empty(&self) -> bool {

diff --git a/library/alloc/src/collections/btree/set.rs b/library/alloc/src/collections/btree/set.rs
index 59f1ca76b0b928b915e3feb8e2d10354737020f1..0322cabccde4b0f830acaf9f423de435cc36f9db 100644 (file)
--- a/library/alloc/src/collections/btree/set.rs
+++ b/library/alloc/src/collections/btree/set.rs
@@ -1046,6 +1046,7 @@ pub fn iter(&self) -> Iter<'_, T> {
     /// v.insert(1);
     /// assert_eq!(v.len(), 1);
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
     pub const fn len(&self) -> usize {
@@ -1064,6 +1065,7 @@ pub const fn len(&self) -> usize {
     /// v.insert(1);
     /// assert!(!v.is_empty());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
     pub const fn is_empty(&self) -> bool {

diff --git a/library/alloc/src/collections/btree/set/tests.rs b/library/alloc/src/collections/btree/set/tests.rs
index 01cf62b32eccd5f02cb6ae204c8beb71d548174d..2fc17a7c8603fc0b32afab1a79058d9043554d95 100644 (file)
--- a/library/alloc/src/collections/btree/set/tests.rs
+++ b/library/alloc/src/collections/btree/set/tests.rs
@@ -610,8 +610,8 @@ fn union<T: Send + Sync + Ord>(v: &BTreeSet<T>) -> impl Send + '_ {
 #[test]
 fn test_ord_absence() {
     fn set<K>(mut set: BTreeSet<K>) {
-        set.is_empty();
-        set.len();
+        let _ = set.is_empty();
+        let _ = set.len();
         set.clear();
         let _ = set.iter();
         let _ = set.into_iter();

diff --git a/library/alloc/src/collections/linked_list.rs b/library/alloc/src/collections/linked_list.rs
index 4c74113338774a92f1e77b4852d2842cbefc59e8..e4913b16adbe7722b14e755f25e5954ecda47168 100644 (file)
--- a/library/alloc/src/collections/linked_list.rs
+++ b/library/alloc/src/collections/linked_list.rs
@@ -583,6 +583,7 @@ pub fn cursor_back_mut(&mut self) -> CursorMut<'_, T> {
     /// assert!(!dl.is_empty());
     /// ```
     #[inline]
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_empty(&self) -> bool {
         self.head.is_none()
@@ -609,6 +610,7 @@ pub fn is_empty(&self) -> bool {
     /// assert_eq!(dl.len(), 3);
     /// ```
     #[inline]
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {
         self.len

diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index 677942a1820c94e23588dff87bf526e236d82099..906b0187f7babf540932b2cd408f71b88b308782 100644 (file)
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -1547,6 +1547,7 @@ pub unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8> {
     /// assert_eq!(fancy_f.chars().count(), 3);
     /// ```
     #[inline]
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {
         self.vec.len()
@@ -1566,6 +1567,7 @@ pub fn len(&self) -> usize {
     /// assert!(!v.is_empty());
     /// ```
     #[inline]
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_empty(&self) -> bool {
         self.len() == 0

diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index 50dd451b5d1cca0d180337541b5288238debfa3c..58110b068094381e9ac2e74130dab235c9608bf2 100644 (file)
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs
@@ -449,6 +449,7 @@ pub const fn slice_from_raw_parts(data: NonNull<T>, len: usize) -> Self {
     /// ```
     #[unstable(feature = "slice_ptr_len", issue = "71146")]
     #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
+    #[must_use]
     #[inline]
     pub const fn len(self) -> usize {
         self.as_ptr().len()

diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
index 8f02ecbd009c4a528fc8139c8b275e1da42459ae..cd5ed35be79ba6769938b11624d94b99d941e7c8 100644 (file)
--- a/library/core/src/str/mod.rs
+++ b/library/core/src/str/mod.rs
@@ -140,6 +140,7 @@ impl str {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_str_len", since = "1.39.0")]
+    #[must_use]
     #[inline]
     pub const fn len(&self) -> usize {
         self.as_bytes().len()
@@ -158,9 +159,10 @@ pub const fn len(&self) -> usize {
     /// let s = "not empty";
     /// assert!(!s.is_empty());
     /// ```
-    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_str_is_empty", since = "1.39.0")]
+    #[must_use]
+    #[inline]
     pub const fn is_empty(&self) -> bool {
         self.len() == 0
     }

diff --git a/library/std/src/ffi/os_str.rs b/library/std/src/ffi/os_str.rs
index 49e268eb99bc85c503e1e5b17dbd83afa638b1ab..d7587e85c66841dc71e07144fb54dafba32808f8 100644 (file)
--- a/library/std/src/ffi/os_str.rs
+++ b/library/std/src/ffi/os_str.rs
@@ -669,6 +669,7 @@ pub fn to_os_string(&self) -> OsString {
     /// assert!(!os_str.is_empty());
     /// ```
     #[stable(feature = "osstring_simple_functions", since = "1.9.0")]
+    #[must_use]
     #[inline]
     pub fn is_empty(&self) -> bool {
         self.inner.inner.is_empty()
@@ -700,6 +701,7 @@ pub fn is_empty(&self) -> bool {
     /// assert_eq!(os_str.len(), 3);
     /// ```
     #[stable(feature = "osstring_simple_functions", since = "1.9.0")]
+    #[must_use]
     #[inline]
     pub fn len(&self) -> usize {
         self.inner.inner.len()

diff --git a/library/std/src/fs.rs b/library/std/src/fs.rs
index 2b76a411a0fd50dc8e16a9d35864edf28701f56b..69eca507c7117206539066a7e6565bdf8111b508 100644 (file)
--- a/library/std/src/fs.rs
+++ b/library/std/src/fs.rs
@@ -1080,6 +1080,7 @@ pub fn is_symlink(&self) -> bool {
     ///     Ok(())
     /// }
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> u64 {
         self.0.size()

diff --git a/library/std/src/os/unix/net/ancillary.rs b/library/std/src/os/unix/net/ancillary.rs
index 57bb61903c147964c6d74b08ed6ba788e1c075cb..353bf2f11665ab520409a081b2e31001c6eb7e56 100644 (file)
--- a/library/std/src/os/unix/net/ancillary.rs
+++ b/library/std/src/os/unix/net/ancillary.rs
@@ -431,12 +431,14 @@ pub fn capacity(&self) -> usize {
     }
 
     /// Returns `true` if the ancillary data is empty.
+    #[must_use]
     #[unstable(feature = "unix_socket_ancillary_data", issue = "76915")]
     pub fn is_empty(&self) -> bool {
         self.length == 0
     }
 
     /// Returns the number of used bytes.
+    #[must_use]
     #[unstable(feature = "unix_socket_ancillary_data", issue = "76915")]
     pub fn len(&self) -> usize {
         self.length

diff --git a/src/tools/clippy/tests/ui/iter_count.fixed b/src/tools/clippy/tests/ui/iter_count.fixed
index 97c5929783d882c51dd754244c8bec46ff292f5d..90a6eef75261f505c6fd517b1280c548581f2d8e 100644 (file)
--- a/src/tools/clippy/tests/ui/iter_count.fixed
+++ b/src/tools/clippy/tests/ui/iter_count.fixed
@@ -33,6 +33,7 @@ impl HasIter {
     }
 }
 
+#[allow(unused_must_use)]
 fn main() {
     let mut vec = vec![0, 1, 2, 3];
     let mut boxed_slice: Box<[u8]> = Box::new([0, 1, 2, 3]);
@@ -50,7 +51,7 @@ fn main() {
     linked_list.push_back(1);
     binary_heap.push(1);
 
-    let _ = &vec[..].len();
+    &vec[..].len();
     vec.len();
     boxed_slice.len();
     vec_deque.len();
@@ -62,13 +63,13 @@ fn main() {
     binary_heap.len();
 
     vec.len();
-    let _ = &vec[..].len();
+    &vec[..].len();
     vec_deque.len();
     hash_map.len();
     b_tree_map.len();
     linked_list.len();
 
-    let _ = &vec[..].len();
+    &vec[..].len();
     vec.len();
     vec_deque.len();
     hash_set.len();

diff --git a/src/tools/clippy/tests/ui/iter_count.rs b/src/tools/clippy/tests/ui/iter_count.rs
index 70bb734763f09bef26eb35bc4b45f9c196dce29b..6681a480a28c817472eb5bdb1976bb5a948cd61b 100644 (file)
--- a/src/tools/clippy/tests/ui/iter_count.rs
+++ b/src/tools/clippy/tests/ui/iter_count.rs
@@ -33,6 +33,7 @@ fn into_iter(self) -> IteratorFalsePositives {
     }
 }
 
+#[allow(unused_must_use)]
 fn main() {
     let mut vec = vec![0, 1, 2, 3];
     let mut boxed_slice: Box<[u8]> = Box::new([0, 1, 2, 3]);
@@ -50,7 +51,7 @@ fn main() {
     linked_list.push_back(1);
     binary_heap.push(1);
 
-    let _ = &vec[..].iter().count();
+    &vec[..].iter().count();
     vec.iter().count();
     boxed_slice.iter().count();
     vec_deque.iter().count();
@@ -62,13 +63,13 @@ fn main() {
     binary_heap.iter().count();
 
     vec.iter_mut().count();
-    let _ = &vec[..].iter_mut().count();
+    &vec[..].iter_mut().count();
     vec_deque.iter_mut().count();
     hash_map.iter_mut().count();
     b_tree_map.iter_mut().count();
     linked_list.iter_mut().count();
 
-    let _ = &vec[..].into_iter().count();
+    &vec[..].into_iter().count();
     vec.into_iter().count();
     vec_deque.into_iter().count();
     hash_set.into_iter().count();

diff --git a/src/tools/clippy/tests/ui/iter_count.stderr b/src/tools/clippy/tests/ui/iter_count.stderr
index 1d2c22f9dfad5470e0b1d478b439a26587bc7a1b..2e3d7fc35de9c0de17d3f712bbc87a892c90dbad 100644 (file)
--- a/src/tools/clippy/tests/ui/iter_count.stderr
+++ b/src/tools/clippy/tests/ui/iter_count.stderr
@@ -1,151 +1,151 @@
 error: called `.iter().count()` on a `slice`
-  --> $DIR/iter_count.rs:53:14
+  --> $DIR/iter_count.rs:54:6
    |
-LL |     let _ = &vec[..].iter().count();
-   |              ^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec[..].len()`
+LL |     &vec[..].iter().count();
+   |      ^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec[..].len()`
    |
    = note: `-D clippy::iter-count` implied by `-D warnings`
 
 error: called `.iter().count()` on a `Vec`
-  --> $DIR/iter_count.rs:54:5
+  --> $DIR/iter_count.rs:55:5
    |
 LL |     vec.iter().count();
    |     ^^^^^^^^^^^^^^^^^^ help: try: `vec.len()`
 
 error: called `.iter().count()` on a `slice`
-  --> $DIR/iter_count.rs:55:5
+  --> $DIR/iter_count.rs:56:5
    |
 LL |     boxed_slice.iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `boxed_slice.len()`
 
 error: called `.iter().count()` on a `VecDeque`
-  --> $DIR/iter_count.rs:56:5
+  --> $DIR/iter_count.rs:57:5
    |
 LL |     vec_deque.iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec_deque.len()`
 
 error: called `.iter().count()` on a `HashSet`
-  --> $DIR/iter_count.rs:57:5
+  --> $DIR/iter_count.rs:58:5
    |
 LL |     hash_set.iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `hash_set.len()`
 
 error: called `.iter().count()` on a `HashMap`
-  --> $DIR/iter_count.rs:58:5
+  --> $DIR/iter_count.rs:59:5
    |
 LL |     hash_map.iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `hash_map.len()`
 
 error: called `.iter().count()` on a `BTreeMap`
-  --> $DIR/iter_count.rs:59:5
+  --> $DIR/iter_count.rs:60:5
    |
 LL |     b_tree_map.iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `b_tree_map.len()`
 
 error: called `.iter().count()` on a `BTreeSet`
-  --> $DIR/iter_count.rs:60:5
+  --> $DIR/iter_count.rs:61:5
    |
 LL |     b_tree_set.iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `b_tree_set.len()`
 
 error: called `.iter().count()` on a `LinkedList`
-  --> $DIR/iter_count.rs:61:5
+  --> $DIR/iter_count.rs:62:5
    |
 LL |     linked_list.iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `linked_list.len()`
 
 error: called `.iter().count()` on a `BinaryHeap`
-  --> $DIR/iter_count.rs:62:5
+  --> $DIR/iter_count.rs:63:5
    |
 LL |     binary_heap.iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `binary_heap.len()`
 
 error: called `.iter_mut().count()` on a `Vec`
-  --> $DIR/iter_count.rs:64:5
+  --> $DIR/iter_count.rs:65:5
    |
 LL |     vec.iter_mut().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.len()`
 
 error: called `.iter_mut().count()` on a `slice`
-  --> $DIR/iter_count.rs:65:14
+  --> $DIR/iter_count.rs:66:6
    |
-LL |     let _ = &vec[..].iter_mut().count();
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec[..].len()`
+LL |     &vec[..].iter_mut().count();
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec[..].len()`
 
 error: called `.iter_mut().count()` on a `VecDeque`
-  --> $DIR/iter_count.rs:66:5
+  --> $DIR/iter_count.rs:67:5
    |
 LL |     vec_deque.iter_mut().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec_deque.len()`
 
 error: called `.iter_mut().count()` on a `HashMap`
-  --> $DIR/iter_count.rs:67:5
+  --> $DIR/iter_count.rs:68:5
    |
 LL |     hash_map.iter_mut().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `hash_map.len()`
 
 error: called `.iter_mut().count()` on a `BTreeMap`
-  --> $DIR/iter_count.rs:68:5
+  --> $DIR/iter_count.rs:69:5
    |
 LL |     b_tree_map.iter_mut().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `b_tree_map.len()`
 
 error: called `.iter_mut().count()` on a `LinkedList`
-  --> $DIR/iter_count.rs:69:5
+  --> $DIR/iter_count.rs:70:5
    |
 LL |     linked_list.iter_mut().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `linked_list.len()`
 
 error: called `.into_iter().count()` on a `slice`
-  --> $DIR/iter_count.rs:71:14
+  --> $DIR/iter_count.rs:72:6
    |
-LL |     let _ = &vec[..].into_iter().count();
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec[..].len()`
+LL |     &vec[..].into_iter().count();
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec[..].len()`
 
 error: called `.into_iter().count()` on a `Vec`
-  --> $DIR/iter_count.rs:72:5
+  --> $DIR/iter_count.rs:73:5
    |
 LL |     vec.into_iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.len()`
 
 error: called `.into_iter().count()` on a `VecDeque`
-  --> $DIR/iter_count.rs:73:5
+  --> $DIR/iter_count.rs:74:5
    |
 LL |     vec_deque.into_iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec_deque.len()`
 
 error: called `.into_iter().count()` on a `HashSet`
-  --> $DIR/iter_count.rs:74:5
+  --> $DIR/iter_count.rs:75:5
    |
 LL |     hash_set.into_iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `hash_set.len()`
 
 error: called `.into_iter().count()` on a `HashMap`
-  --> $DIR/iter_count.rs:75:5
+  --> $DIR/iter_count.rs:76:5
    |
 LL |     hash_map.into_iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `hash_map.len()`
 
 error: called `.into_iter().count()` on a `BTreeMap`
-  --> $DIR/iter_count.rs:76:5
+  --> $DIR/iter_count.rs:77:5
    |
 LL |     b_tree_map.into_iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `b_tree_map.len()`
 
 error: called `.into_iter().count()` on a `BTreeSet`
-  --> $DIR/iter_count.rs:77:5
+  --> $DIR/iter_count.rs:78:5
    |
 LL |     b_tree_set.into_iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `b_tree_set.len()`
 
 error: called `.into_iter().count()` on a `LinkedList`
-  --> $DIR/iter_count.rs:78:5
+  --> $DIR/iter_count.rs:79:5
    |
 LL |     linked_list.into_iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `linked_list.len()`
 
 error: called `.into_iter().count()` on a `BinaryHeap`
-  --> $DIR/iter_count.rs:79:5
+  --> $DIR/iter_count.rs:80:5
    |
 LL |     binary_heap.into_iter().count();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `binary_heap.len()`