From d73015397dc43eb8067644ab2bbb1c2203c795d4 Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Sat, 27 Mar 2021 13:31:17 +0100
Subject: Fix Debug implementation for RwLock{Read,Write}Guard.

This would attempt to print the Debug representation of the lock that
the guard has locked, which will try to lock again, fail, and just print
"<locked>" unhelpfully.

After this change, this just prints the contents of the mutex, like the
other smart pointers (and MutexGuard) do.
---
 library/std/src/sync/rwlock.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'library/std/src/sync/rwlock.rs')

diff --git a/library/std/src/sync/rwlock.rs b/library/std/src/sync/rwlock.rs
index 0298f59228c..c6c753b103f 100644
--- a/library/std/src/sync/rwlock.rs
+++ b/library/std/src/sync/rwlock.rs
@@ -473,7 +473,7 @@ impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> {
 #[stable(feature = "std_debug", since = "1.16.0")]
 impl<T: fmt::Debug> fmt::Debug for RwLockReadGuard<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("RwLockReadGuard").field("lock", &self.lock).finish()
+        (**self).fmt(f)
     }
 }
 
@@ -487,7 +487,7 @@ impl<T: ?Sized + fmt::Display> fmt::Display for RwLockReadGuard<'_, T> {
 #[stable(feature = "std_debug", since = "1.16.0")]
 impl<T: fmt::Debug> fmt::Debug for RwLockWriteGuard<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("RwLockWriteGuard").field("lock", &self.lock).finish()
+        (**self).fmt(f)
     }
 }
 
-- 
cgit 1.4.1-3-g733a5


From 5402abc4937e77c69d8a94eaec86cbc764564cf7 Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Sat, 27 Mar 2021 13:47:11 +0100
Subject: Improve Debug implementations of Mutex and RwLock.

They now show the poison flag and use debug_non_exhaustive.
---
 library/std/src/sync/mutex.rs  | 12 ++++++++----
 library/std/src/sync/rwlock.rs | 12 ++++++++----
 2 files changed, 16 insertions(+), 8 deletions(-)

(limited to 'library/std/src/sync/rwlock.rs')

diff --git a/library/std/src/sync/mutex.rs b/library/std/src/sync/mutex.rs
index ab61618dc7d..98c34282e0c 100644
--- a/library/std/src/sync/mutex.rs
+++ b/library/std/src/sync/mutex.rs
@@ -441,10 +441,13 @@ impl<T: ?Sized + Default> Default for Mutex<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized + fmt::Debug> fmt::Debug for Mutex<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut d = f.debug_struct("Mutex");
         match self.try_lock() {
-            Ok(guard) => f.debug_struct("Mutex").field("data", &&*guard).finish(),
+            Ok(guard) => {
+                d.field("data", &&*guard);
+            }
             Err(TryLockError::Poisoned(err)) => {
-                f.debug_struct("Mutex").field("data", &&**err.get_ref()).finish()
+                d.field("data", &&**err.get_ref());
             }
             Err(TryLockError::WouldBlock) => {
                 struct LockedPlaceholder;
@@ -453,10 +456,11 @@ impl<T: ?Sized + fmt::Debug> fmt::Debug for Mutex<T> {
                         f.write_str("<locked>")
                     }
                 }
-
-                f.debug_struct("Mutex").field("data", &LockedPlaceholder).finish()
+                d.field("data", &LockedPlaceholder);
             }
         }
+        d.field("poisoned", &self.poison.get());
+        d.finish_non_exhaustive()
     }
 }
 
diff --git a/library/std/src/sync/rwlock.rs b/library/std/src/sync/rwlock.rs
index 0298f59228c..ee5fe06ac1e 100644
--- a/library/std/src/sync/rwlock.rs
+++ b/library/std/src/sync/rwlock.rs
@@ -422,10 +422,13 @@ unsafe impl<#[may_dangle] T: ?Sized> Drop for RwLock<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized + fmt::Debug> fmt::Debug for RwLock<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut d = f.debug_struct("RwLock");
         match self.try_read() {
-            Ok(guard) => f.debug_struct("RwLock").field("data", &&*guard).finish(),
+            Ok(guard) => {
+                d.field("data", &&*guard);
+            }
             Err(TryLockError::Poisoned(err)) => {
-                f.debug_struct("RwLock").field("data", &&**err.get_ref()).finish()
+                d.field("data", &&**err.get_ref());
             }
             Err(TryLockError::WouldBlock) => {
                 struct LockedPlaceholder;
@@ -434,10 +437,11 @@ impl<T: ?Sized + fmt::Debug> fmt::Debug for RwLock<T> {
                         f.write_str("<locked>")
                     }
                 }
-
-                f.debug_struct("RwLock").field("data", &LockedPlaceholder).finish()
+                d.field("data", &LockedPlaceholder);
             }
         }
+        d.field("poisoned", &self.poison.get());
+        d.finish_non_exhaustive()
     }
 }
 
-- 
cgit 1.4.1-3-g733a5