Auto merge of #42854 - razielgn:relaxed-debug-constraints-on-maps-ite…

…rators, r=sfackler

Relaxed Debug constraints on {HashMap,BTreeMap}::{Keys,Values}.

I has hit by this yesterday too. 😄
And I've realised that Debug for BTreeMap::{Keys,Values} wasn't formatting just keys and values respectively, but the whole map. 🤔

Fixed #41924

r? @jonhoo

src/liballoc/btree/map.rs

@@ -334,9 +334,9 @@ pub struct Keys<'a, K: 'a, V: 'a> {
 }
 
 #[stable(feature = "collection_debug", since = "1.17.0")]
-impl<'a, K: 'a + fmt::Debug, V: 'a + fmt::Debug> fmt::Debug for Keys<'a, K, V> {
+impl<'a, K: 'a + fmt::Debug, V: 'a> fmt::Debug for Keys<'a, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_list().entries(self.inner.clone()).finish()
+        f.debug_list().entries(self.clone()).finish()
     }
 }
 
@@ -353,9 +353,9 @@ pub struct Values<'a, K: 'a, V: 'a> {
 }
 
 #[stable(feature = "collection_debug", since = "1.17.0")]
-impl<'a, K: 'a + fmt::Debug, V: 'a + fmt::Debug> fmt::Debug for Values<'a, K, V> {
+impl<'a, K: 'a, V: 'a + fmt::Debug> fmt::Debug for Values<'a, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_list().entries(self.inner.clone()).finish()
+        f.debug_list().entries(self.clone()).finish()
     }
 }
 

src/libstd/collections/hash/map.rs

@@ -1407,7 +1407,7 @@ impl<'a, K, V> Clone for Keys<'a, K, V> {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, K: Debug, V: Debug> fmt::Debug for Keys<'a, K, V> {
+impl<'a, K: Debug, V> fmt::Debug for Keys<'a, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_list()
             .entries(self.clone())
@@ -1436,7 +1436,7 @@ impl<'a, K, V> Clone for Values<'a, K, V> {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, K: Debug, V: Debug> fmt::Debug for Values<'a, K, V> {
+impl<'a, K, V: Debug> fmt::Debug for Values<'a, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_list()
             .entries(self.clone())