Rollup merge of rust-lang#92584 - lcnr:query-stable-lint, r=estebank

add rustc lint, warning when iterating over hashmaps 2

first introduced in rust-lang#89558 and reverted in rust-lang#90380 due to its perf impact

r? ``@estebank``

Author: matthiaskrgr

std/src/collections/hash/map.rs

@@ -371,6 +371,7 @@ impl<K, V, S> HashMap<K, V, S> {
     /// assert_eq!(vec, ["a", "b", "c"]);
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "map_into_keys_values", since = "1.54.0")]
     pub fn into_keys(self) -> IntoKeys<K, V> {
         IntoKeys { inner: self.into_iter() }
@@ -448,6 +449,7 @@ impl<K, V, S> HashMap<K, V, S> {
     /// assert_eq!(vec, [1, 2, 3]);
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "map_into_keys_values", since = "1.54.0")]
     pub fn into_values(self) -> IntoValues<K, V> {
         IntoValues { inner: self.into_iter() }
@@ -471,6 +473,7 @@ impl<K, V, S> HashMap<K, V, S> {
     ///     println!("key: {} val: {}", key, val);
     /// }
     /// ```
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn iter(&self) -> Iter<'_, K, V> {
         Iter { base: self.base.iter() }
@@ -500,6 +503,7 @@ impl<K, V, S> HashMap<K, V, S> {
     ///     println!("key: {} val: {}", key, val);
     /// }
     /// ```
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
         IterMut { base: self.base.iter_mut() }
@@ -560,6 +564,7 @@ impl<K, V, S> HashMap<K, V, S> {
     /// assert!(a.is_empty());
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "drain", since = "1.6.0")]
     pub fn drain(&mut self) -> Drain<'_, K, V> {
         Drain { base: self.base.drain() }
@@ -601,6 +606,7 @@ impl<K, V, S> HashMap<K, V, S> {
     /// assert_eq!(odds, vec![1, 3, 5, 7]);
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[unstable(feature = "hash_drain_filter", issue = "59618")]
     pub fn drain_filter<F>(&mut self, pred: F) -> DrainFilter<'_, K, V, F>
     where
@@ -624,6 +630,7 @@ impl<K, V, S> HashMap<K, V, S> {
     /// assert_eq!(map.len(), 4);
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "retain_hash_collection", since = "1.18.0")]
     pub fn retain<F>(&mut self, f: F)
     where
@@ -1990,6 +1997,7 @@ impl<'a, K, V, S> IntoIterator for &'a HashMap<K, V, S> {
     type IntoIter = Iter<'a, K, V>;
 
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     fn into_iter(self) -> Iter<'a, K, V> {
         self.iter()
     }
@@ -2001,6 +2009,7 @@ impl<'a, K, V, S> IntoIterator for &'a mut HashMap<K, V, S> {
     type IntoIter = IterMut<'a, K, V>;
 
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     fn into_iter(self) -> IterMut<'a, K, V> {
         self.iter_mut()
     }
@@ -2030,6 +2039,7 @@ impl<K, V, S> IntoIterator for HashMap<K, V, S> {
     /// let vec: Vec<(&str, i32)> = map.into_iter().collect();
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     fn into_iter(self) -> IntoIter<K, V> {
         IntoIter { base: self.base.into_iter() }
     }

std/src/collections/hash/set.rs

@@ -185,6 +185,7 @@ impl<T, S> HashSet<T, S> {
     /// }
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn iter(&self) -> Iter<'_, T> {
         Iter { base: self.base.iter() }
@@ -244,6 +245,7 @@ impl<T, S> HashSet<T, S> {
     /// assert!(set.is_empty());
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "drain", since = "1.6.0")]
     pub fn drain(&mut self) -> Drain<'_, T> {
         Drain { base: self.base.drain() }
@@ -282,6 +284,7 @@ impl<T, S> HashSet<T, S> {
     /// assert_eq!(odds, vec![1, 3, 5, 7]);
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[unstable(feature = "hash_drain_filter", issue = "59618")]
     pub fn drain_filter<F>(&mut self, pred: F) -> DrainFilter<'_, T, F>
     where
@@ -304,6 +307,7 @@ impl<T, S> HashSet<T, S> {
     /// set.retain(|&k| k % 2 == 0);
     /// assert_eq!(set.len(), 3);
     /// ```
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "retain_hash_collection", since = "1.18.0")]
     pub fn retain<F>(&mut self, f: F)
     where
@@ -528,6 +532,7 @@ where
     /// assert_eq!(diff, [4].iter().collect());
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn difference<'a>(&'a self, other: &'a HashSet<T, S>) -> Difference<'a, T, S> {
         Difference { iter: self.iter(), other }
@@ -555,6 +560,7 @@ where
     /// assert_eq!(diff1, [1, 4].iter().collect());
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn symmetric_difference<'a>(
         &'a self,
@@ -582,6 +588,7 @@ where
     /// assert_eq!(intersection, [2, 3].iter().collect());
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn intersection<'a>(&'a self, other: &'a HashSet<T, S>) -> Intersection<'a, T, S> {
         if self.len() <= other.len() {
@@ -610,6 +617,7 @@ where
     /// assert_eq!(union, [1, 2, 3, 4].iter().collect());
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn union<'a>(&'a self, other: &'a HashSet<T, S>) -> Union<'a, T, S> {
         if self.len() >= other.len() {
@@ -1410,6 +1418,7 @@ impl<'a, T, S> IntoIterator for &'a HashSet<T, S> {
     type IntoIter = Iter<'a, T>;
 
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     fn into_iter(self) -> Iter<'a, T> {
         self.iter()
     }
@@ -1441,6 +1450,7 @@ impl<T, S> IntoIterator for HashSet<T, S> {
     /// }
     /// ```
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_lint_query_instability)]
     fn into_iter(self) -> IntoIter<T> {
         IntoIter { base: self.base.into_iter() }
     }