diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index 81a5e9ee90d72..dd6adb17c5e47 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -1120,7 +1120,7 @@ fn check_type_defn<'tcx>(
                     } else {
                         // Evaluate the constant proactively, to emit an error if the constant has
                         // an unconditional error. We only do so if the const has no type params.
-                        let _ = tcx.const_eval_poly(def_id.into());
+                        let _ = tcx.const_eval_poly(def_id);
                     }
                 }
                 let field_id = field.did.expect_local();
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index ba4b786aca218..fb3cf5afad038 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -1303,9 +1303,9 @@ impl UnreachablePub {
                 cx.effective_visibilities.effective_vis(def_id).map(|effective_vis| {
                     effective_vis.at_level(rustc_middle::middle::privacy::Level::Reachable)
                 })
-                && let parent_parent = cx.tcx.parent_module_from_def_id(
-                    cx.tcx.parent_module_from_def_id(def_id.into()).into(),
-                )
+                && let parent_parent = cx
+                    .tcx
+                    .parent_module_from_def_id(cx.tcx.parent_module_from_def_id(def_id).into())
                 && *restricted_did == parent_parent.to_local_def_id()
                 && !restricted_did.to_def_id().is_crate_root()
             {
diff --git a/compiler/rustc_parse/src/parser/tests.rs b/compiler/rustc_parse/src/parser/tests.rs
index 3f8d66c2c9580..b810bb4e3bbd9 100644
--- a/compiler/rustc_parse/src/parser/tests.rs
+++ b/compiler/rustc_parse/src/parser/tests.rs
@@ -2366,8 +2366,7 @@ fn string_to_tts_1() {
                         token::Ident(sym::i32, IdentIsRaw::No),
                         sp(8, 11),
                     ),
-                ])
-                .into(),
+                ]),
             ),
             TokenTree::Delimited(
                 DelimSpan::from_pair(sp(13, 14), sp(18, 19)),
@@ -2383,8 +2382,7 @@ fn string_to_tts_1() {
                     ),
                     // `Alone` because the `;` is followed by whitespace.
                     TokenTree::token_alone(token::Semi, sp(16, 17)),
-                ])
-                .into(),
+                ]),
             ),
         ]);
 
diff --git a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
index 15eb5d74cbfa5..446f9eaa348c0 100644
--- a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
+++ b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
@@ -79,7 +79,7 @@ pub fn is_const_evaluatable<'tcx>(
                     Err(
                         EvaluateConstErr::EvaluationFailure(e)
                         | EvaluateConstErr::InvalidConstParamTy(e),
-                    ) => Err(NotConstEvaluatable::Error(e.into())),
+                    ) => Err(NotConstEvaluatable::Error(e)),
                     Ok(_) => Ok(()),
                 }
             }
@@ -140,7 +140,7 @@ pub fn is_const_evaluatable<'tcx>(
             }
             Err(
                 EvaluateConstErr::EvaluationFailure(e) | EvaluateConstErr::InvalidConstParamTy(e),
-            ) => Err(NotConstEvaluatable::Error(e.into())),
+            ) => Err(NotConstEvaluatable::Error(e)),
             Ok(_) => Ok(()),
         }
     }
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index e014404eff35b..08a7b32579868 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -1789,7 +1789,7 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> {
     /// let x: Rc<&str> = Rc::new("Hello, world!");
     /// {
     ///     let s = String::from("Oh, no!");
-    ///     let mut y: Rc<&str> = x.clone().into();
+    ///     let mut y: Rc<&str> = x.clone();
     ///     unsafe {
     ///         // this is Undefined Behavior, because x's inner type
     ///         // is &'long str, not &'short str
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index b34a6d3f660c8..30761739dbff2 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -2468,7 +2468,7 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
     /// let x: Arc<&str> = Arc::new("Hello, world!");
     /// {
     ///     let s = String::from("Oh, no!");
-    ///     let mut y: Arc<&str> = x.clone().into();
+    ///     let mut y: Arc<&str> = x.clone();
     ///     unsafe {
     ///         // this is Undefined Behavior, because x's inner type
     ///         // is &'long str, not &'short str
diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs
index 85ee369ca2b66..b6ee00a253a95 100644
--- a/library/std/src/thread/mod.rs
+++ b/library/std/src/thread/mod.rs
@@ -502,7 +502,7 @@ impl Builder {
 
         let id = ThreadId::new();
         let my_thread = match name {
-            Some(name) => Thread::new(id, name.into()),
+            Some(name) => Thread::new(id, name),
             None => Thread::new_unnamed(id),
         };