4 files changed, 10 insertions, 6 deletions
diff --git a/library/std/src/collections/hash/map.rs b/library/std/src/collections/hash/map.rs
index 233afa92389..ed32668456d 100644
--- a/library/std/src/collections/hash/map.rs
+++ b/library/std/src/collections/hash/map.rs
@@ -17,7 +17,7 @@ use crate::iter::{FromIterator, FusedIterator};
 use crate::ops::Index;
 use crate::sys;
 
-/// A hash map implemented with quadratic probing and SIMD lookup.
+/// A [hash map] implemented with quadratic probing and SIMD lookup.
 ///
 /// By default, `HashMap` uses a hashing algorithm selected to provide
 /// resistance against HashDoS attacks. The algorithm is randomly seeded, and a
@@ -62,6 +62,7 @@ use crate::sys;
 /// The original C++ version of SwissTable can be found [here], and this
 /// [CppCon talk] gives an overview of how the algorithm works.
 ///
+/// [hash map]: crate::collections#use-a-hashmap-when
 /// [hashing algorithms available on crates.io]: https://crates.io/keywords/hasher
 /// [SwissTable]: https://abseil.io/blog/20180927-swisstables
 /// [here]: https://github.com/abseil/abseil-cpp/blob/master/absl/container/internal/raw_hash_set.h
diff --git a/library/std/src/collections/hash/set.rs b/library/std/src/collections/hash/set.rs
index 912e975aa0a..8c801b9f128 100644
--- a/library/std/src/collections/hash/set.rs
+++ b/library/std/src/collections/hash/set.rs
@@ -19,7 +19,7 @@ use super::map::{map_try_reserve_error, RandomState};
 // for `bucket.val` in the case of HashSet. I suppose we would need HKT
 // to get rid of it properly.
 
-/// A hash set implemented as a `HashMap` where the value is `()`.
+/// A [hash set] implemented as a `HashMap` where the value is `()`.
 ///
 /// As with the [`HashMap`] type, a `HashSet` requires that the elements
 /// implement the [`Eq`] and [`Hash`] traits. This can frequently be achieved by
@@ -105,6 +105,7 @@ use super::map::{map_try_reserve_error, RandomState};
 /// // use the values stored in the set
 /// ```
 ///
+/// [hash set]: crate::collections#use-the-set-variant-of-any-of-these-maps-when
 /// [`HashMap`]: crate::collections::HashMap
 /// [`RefCell`]: crate::cell::RefCell
 /// [`Cell`]: crate::cell::Cell
diff --git a/library/std/src/sys/unix/stack_overflow.rs b/library/std/src/sys/unix/stack_overflow.rs
index d7bba50c76a..2a487fff54a 100644
--- a/library/std/src/sys/unix/stack_overflow.rs
+++ b/library/std/src/sys/unix/stack_overflow.rs
@@ -39,6 +39,7 @@ impl Drop for Handler {
 ))]
 mod imp {
     use super::Handler;
+    use crate::io;
     use crate::mem;
     use crate::ptr;
 
@@ -149,11 +150,11 @@ mod imp {
             0,
         );
         if stackp == MAP_FAILED {
-            panic!("failed to allocate an alternative stack");
+            panic!("failed to allocate an alternative stack: {}", io::Error::last_os_error());
         }
         let guard_result = libc::mprotect(stackp, page_size(), PROT_NONE);
         if guard_result != 0 {
-            panic!("failed to set up alternative stack guard page");
+            panic!("failed to set up alternative stack guard page: {}", io::Error::last_os_error());
         }
         stackp.add(page_size())
     }
diff --git a/library/std/src/sys/unix/thread.rs b/library/std/src/sys/unix/thread.rs
index 40c96307514..01a12dcf5a2 100644
--- a/library/std/src/sys/unix/thread.rs
+++ b/library/std/src/sys/unix/thread.rs
@@ -231,6 +231,7 @@ pub mod guard {
     use libc::{mmap, mprotect};
     use libc::{MAP_ANON, MAP_FAILED, MAP_FIXED, MAP_PRIVATE, PROT_NONE, PROT_READ, PROT_WRITE};
 
+    use crate::io;
     use crate::ops::Range;
     use crate::sync::atomic::{AtomicUsize, Ordering};
     use crate::sys::os;
@@ -361,12 +362,12 @@ pub mod guard {
                 0,
             );
             if result != stackaddr || result == MAP_FAILED {
-                panic!("failed to allocate a guard page");
+                panic!("failed to allocate a guard page: {}", io::Error::last_os_error());
             }
 
             let result = mprotect(stackaddr, page_size, PROT_NONE);
             if result != 0 {
-                panic!("failed to protect the guard page");
+                panic!("failed to protect the guard page: {}", io::Error::last_os_error());
             }
 
             let guardaddr = stackaddr as usize;