diff --git a/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl b/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl
index 62f004da0ca..74088f4dfbe 100644
--- a/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl
@@ -93,7 +93,7 @@ hir_analysis_expected_default_return_type = expected `()` because of default ret
 hir_analysis_expected_return_type = expected `{$expected}` because of return type
 
 hir_analysis_unconstrained_opaque_type = unconstrained opaque type
-    .note = `{$name}` must be used in combination with a concrete type within the same module
+    .note = `{$name}` must be used in combination with a concrete type within the same {$what}
 
 hir_analysis_missing_type_params =
     the type {$parameterCount ->
diff --git a/compiler/rustc_hir_analysis/src/collect/type_of.rs b/compiler/rustc_hir_analysis/src/collect/type_of.rs
index 20903a68d6d..45d2f23f36b 100644
--- a/compiler/rustc_hir_analysis/src/collect/type_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/type_of.rs
@@ -701,6 +701,12 @@ fn find_opaque_ty_constraints_for_tait(tcx: TyCtxt<'_>, def_id: LocalDefId) -> T
         tcx.sess.emit_err(UnconstrainedOpaqueType {
             span: tcx.def_span(def_id),
             name: tcx.item_name(tcx.local_parent(def_id).to_def_id()),
+            what: match tcx.hir().get(scope) {
+                _ if scope == hir::CRATE_HIR_ID => "module",
+                Node::Item(hir::Item { kind: hir::ItemKind::Mod(_), .. }) => "module",
+                Node::Item(hir::Item { kind: hir::ItemKind::Impl(_), .. }) => "impl",
+                _ => "item",
+            },
         });
         return tcx.ty_error();
     };
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index 6ed8244d119..d5b1a7ce1c2 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -143,6 +143,7 @@ pub struct UnconstrainedOpaqueType {
     #[primary_span]
     pub span: Span,
     pub name: Symbol,
+    pub what: &'static str,
 }
 
 pub struct MissingTypeParams {
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 3fe79370c37..7f16da52b44 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1901,6 +1901,13 @@ impl fmt::Display for Symbol {
     }
 }
 
+// takes advantage of `str::to_string` specialization
+impl ToString for Symbol {
+    fn to_string(&self) -> String {
+        self.as_str().to_string()
+    }
+}
+
 impl<S: Encoder> Encodable<S> for Symbol {
     default fn encode(&self, s: &mut S) {
         s.emit_str(self.as_str());
diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index 55e58c4e0ba..8923f548adf 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -221,9 +221,7 @@ impl CStr {
     /// # Examples
     ///
     /// ```ignore (extern-declaration)
-    /// # fn main() {
-    /// use std::ffi::CStr;
-    /// use std::os::raw::c_char;
+    /// use std::ffi::{c_char, CStr};
     ///
     /// extern "C" {
     ///     fn my_string() -> *const c_char;
@@ -233,14 +231,26 @@ impl CStr {
     ///     let slice = CStr::from_ptr(my_string());
     ///     println!("string returned: {}", slice.to_str().unwrap());
     /// }
-    /// # }
+    /// ```
+    ///
+    /// ```
+    /// #![feature(const_cstr_methods)]
+    ///
+    /// use std::ffi::{c_char, CStr};
+    ///
+    /// const HELLO_PTR: *const c_char = {
+    ///     const BYTES: &[u8] = b"Hello, world!\0";
+    ///     BYTES.as_ptr().cast()
+    /// };
+    /// const HELLO: &CStr = unsafe { CStr::from_ptr(HELLO_PTR) };
     /// ```
     ///
     /// [valid]: core::ptr#safety
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a CStr {
+    #[rustc_const_unstable(feature = "const_cstr_methods", issue = "101719")]
+    pub const unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a CStr {
         // SAFETY: The caller has provided a pointer that points to a valid C
         // string with a NUL terminator of size less than `isize::MAX`, whose
         // content remain valid and doesn't change for the lifetime of the
@@ -252,13 +262,29 @@ impl CStr {
         //
         // The cast from c_char to u8 is ok because a c_char is always one byte.
         unsafe {
-            extern "C" {
-                /// Provided by libc or compiler_builtins.
-                fn strlen(s: *const c_char) -> usize;
+            const fn strlen_ct(s: *const c_char) -> usize {
+                let mut len = 0;
+
+                // SAFETY: Outer caller has provided a pointer to a valid C string.
+                while unsafe { *s.add(len) } != 0 {
+                    len += 1;
+                }
+
+                len
             }
-            let len = strlen(ptr);
-            let ptr = ptr as *const u8;
-            CStr::from_bytes_with_nul_unchecked(slice::from_raw_parts(ptr, len as usize + 1))
+
+            fn strlen_rt(s: *const c_char) -> usize {
+                extern "C" {
+                    /// Provided by libc or compiler_builtins.
+                    fn strlen(s: *const c_char) -> usize;
+                }
+
+                // SAFETY: Outer caller has provided a pointer to a valid C string.
+                unsafe { strlen(s) }
+            }
+
+            let len = intrinsics::const_eval_select((ptr,), strlen_ct, strlen_rt);
+            Self::from_bytes_with_nul_unchecked(slice::from_raw_parts(ptr.cast(), len + 1))
         }
     }
 
diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index 09371dc027b..1cc954a98dc 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -683,13 +683,16 @@ nav.sub {
 	display: flex;
 	align-items: center;
 }
-nav.sub form {
+.search-form {
+	position: relative;
+	display: flex;
+	height: 34px;
 	flex-grow: 1;
 }
 .source nav.sub {
 	margin: 0 0 15px 0;
 }
-.source nav.sub form {
+.source .search-form {
 	margin-left: 32px;
 }
 
@@ -780,11 +783,6 @@ table,
 	padding-right: 1.25rem;
 }
 
-.search-container {
-	position: relative;
-	display: flex;
-	height: 34px;
-}
 .search-results-title {
 	margin-top: 0;
 	white-space: nowrap;
@@ -860,15 +858,12 @@ so that we can apply CSS-filters to change the arrow color in themes */
 	   -webkit-appearance: textfield for search inputs. That
 	   causes rounded corners and no border on iOS Safari. */
 	-webkit-appearance: none;
-	/* Override Normalize.css: we have margins and do
-	 not want to overflow */
-	box-sizing: border-box !important;
 	outline: none;
 	border: 1px solid var(--border-color);
 	border-radius: 2px;
 	padding: 8px;
 	font-size: 1rem;
-	width: 100%;
+	flex-grow: 1;
 	background-color: var(--button-background-color);
 	color: var(--search-color);
 }
@@ -1957,7 +1952,7 @@ in storage.js
 		flex-direction: column;
 	}
 
-	nav.sub form {
+	.search-form {
 		align-self: stretch;
 	}
 
diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index 0b816eace64..33480fa41cf 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -932,7 +932,7 @@ function loadCss(cssFileName) {
      * Hide all the popover menus.
      */
     window.hidePopoverMenus = function() {
-        onEachLazy(document.querySelectorAll(".search-container .popover"), elem => {
+        onEachLazy(document.querySelectorAll(".search-form .popover"), elem => {
             elem.style.display = "none";
         });
     };
diff --git a/src/librustdoc/html/templates/page.html b/src/librustdoc/html/templates/page.html
index ee8938ea603..c3238691687 100644
--- a/src/librustdoc/html/templates/page.html
+++ b/src/librustdoc/html/templates/page.html
@@ -115,24 +115,22 @@
                 </a> {#- -#}
                 {%- endif -%}
                 <form class="search-form"> {#- -#}
-                    <div class="search-container"> {#- -#}
-                        <span></span> {#- This empty span is a hacky fix for Safari - See #93184 -#}
-                        <input {# -#}
-                            class="search-input" {# -#}
-                            name="search" {# -#}
-                            autocomplete="off" {# -#}
-                            spellcheck="false" {# -#}
-                            placeholder="Click or press ‘S’ to search, ‘?’ for more options…" {# -#}
-                            type="search"> {#- -#}
-                        <div id="help-button" title="help" tabindex="-1"> {#- -#}
-                            <a href="{{page.root_path|safe}}help.html">?</a> {#- -#}
-                        </div> {#- -#}
-                        <div id="settings-menu" tabindex="-1"> {#- -#}
-                            <a href="{{page.root_path|safe}}settings.html" title="settings"> {#- -#}
-                                <img width="22" height="22" alt="Change settings" {# -#}
-                                 src="{{static_root_path|safe}}wheel{{page.resource_suffix}}.svg"> {#- -#}
-                            </a> {#- -#}
-                        </div> {#- -#}
+                    <span></span> {#- This empty span is a hacky fix for Safari - See #93184 -#}
+                    <input {# -#}
+                        class="search-input" {# -#}
+                        name="search" {# -#}
+                        autocomplete="off" {# -#}
+                        spellcheck="false" {# -#}
+                        placeholder="Click or press ‘S’ to search, ‘?’ for more options…" {# -#}
+                        type="search"> {#- -#}
+                    <div id="help-button" title="help" tabindex="-1"> {#- -#}
+                        <a href="{{page.root_path|safe}}help.html">?</a> {#- -#}
+                    </div> {#- -#}
+                    <div id="settings-menu" tabindex="-1"> {#- -#}
+                        <a href="{{page.root_path|safe}}settings.html" title="settings"> {#- -#}
+                            <img width="22" height="22" alt="Change settings" {# -#}
+                             src="{{static_root_path|safe}}wheel{{page.resource_suffix}}.svg"> {#- -#}
+                        </a> {#- -#}
                     </div> {#- -#}
                 </form> {#- -#}
             </nav> {#- -#}
diff --git a/src/rustdoc-json-types/lib.rs b/src/rustdoc-json-types/lib.rs
index 7379b04ad16..4bc91fc4030 100644
--- a/src/rustdoc-json-types/lib.rs
+++ b/src/rustdoc-json-types/lib.rs
@@ -51,6 +51,11 @@ pub struct ItemSummary {
     pub crate_id: u32,
     /// The list of path components for the fully qualified path of this item (e.g.
     /// `["std", "io", "lazy", "Lazy"]` for `std::io::lazy::Lazy`).
+    ///
+    /// Note that items can appear in multiple paths, and the one chosen is implementation
+    /// defined. Currenty, this is the full path to where the item was defined. Eg
+    /// [`String`] is currently `["alloc", "string", "String"]` and [`HashMap`] is
+    /// `["std", "collections", "hash", "map", "HashMap"]`, but this is subject to change.
     pub path: Vec<String>,
     /// Whether this item is a struct, trait, macro, etc.
     pub kind: ItemKind,
diff --git a/src/test/ui/async-await/issue-98634.rs b/src/test/ui/async-await/issue-98634.rs
new file mode 100644
index 00000000000..b0d38687f01
--- /dev/null
+++ b/src/test/ui/async-await/issue-98634.rs
@@ -0,0 +1,50 @@
+// edition: 2021
+
+use std::{
+    future::Future,
+    pin::Pin,
+    task::{Context, Poll, Waker},
+};
+
+pub struct StructAsync<F: Fn() -> Pin<Box<dyn Future<Output = ()>>>> {
+    pub callback: F,
+}
+
+impl<F> Future for StructAsync<F>
+where
+    F: Fn() -> Pin<Box<dyn Future<Output = ()>>>,
+{
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+        Poll::Pending
+    }
+}
+
+async fn callback() {}
+
+struct Runtime;
+
+fn waker() -> &'static Waker {
+    todo!()
+}
+
+impl Runtime {
+    #[track_caller]
+    pub fn block_on<F: Future>(&self, mut future: F) -> F::Output {
+        loop {
+            unsafe {
+                Pin::new_unchecked(&mut future).poll(&mut Context::from_waker(waker()));
+            }
+        }
+    }
+}
+
+fn main() {
+    Runtime.block_on(async {
+        StructAsync { callback }.await;
+        //~^ ERROR expected `fn() -> impl Future<Output = ()> {callback}` to be a fn item that returns `Pin<Box<(dyn Future<Output = ()> + 'static)>>`, but it returns `impl Future<Output = ()>`
+        //~| ERROR expected `fn() -> impl Future<Output = ()> {callback}` to be a fn item that returns `Pin<Box<(dyn Future<Output = ()> + 'static)>>`, but it returns `impl Future<Output = ()>`
+        //~| ERROR expected `fn() -> impl Future<Output = ()> {callback}` to be a fn item that returns `Pin<Box<(dyn Future<Output = ()> + 'static)>>`, but it returns `impl Future<Output = ()>`
+    });
+}
diff --git a/src/test/ui/async-await/issue-98634.stderr b/src/test/ui/async-await/issue-98634.stderr
new file mode 100644
index 00000000000..5160e48d88a
--- /dev/null
+++ b/src/test/ui/async-await/issue-98634.stderr
@@ -0,0 +1,60 @@
+error[E0271]: expected `fn() -> impl Future<Output = ()> {callback}` to be a fn item that returns `Pin<Box<(dyn Future<Output = ()> + 'static)>>`, but it returns `impl Future<Output = ()>`
+  --> $DIR/issue-98634.rs:45:23
+   |
+LL |         StructAsync { callback }.await;
+   |                       ^^^^^^^^ expected struct `Pin`, found opaque type
+   |
+note: while checking the return type of the `async fn`
+  --> $DIR/issue-98634.rs:24:21
+   |
+LL | async fn callback() {}
+   |                     ^ checked the `Output` of this `async fn`, found opaque type
+   = note:   expected struct `Pin<Box<(dyn Future<Output = ()> + 'static)>>`
+           found opaque type `impl Future<Output = ()>`
+note: required by a bound in `StructAsync`
+  --> $DIR/issue-98634.rs:9:35
+   |
+LL | pub struct StructAsync<F: Fn() -> Pin<Box<dyn Future<Output = ()>>>> {
+   |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `StructAsync`
+
+error[E0271]: expected `fn() -> impl Future<Output = ()> {callback}` to be a fn item that returns `Pin<Box<(dyn Future<Output = ()> + 'static)>>`, but it returns `impl Future<Output = ()>`
+  --> $DIR/issue-98634.rs:45:9
+   |
+LL |         StructAsync { callback }.await;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^ expected struct `Pin`, found opaque type
+   |
+note: while checking the return type of the `async fn`
+  --> $DIR/issue-98634.rs:24:21
+   |
+LL | async fn callback() {}
+   |                     ^ checked the `Output` of this `async fn`, found opaque type
+   = note:   expected struct `Pin<Box<(dyn Future<Output = ()> + 'static)>>`
+           found opaque type `impl Future<Output = ()>`
+note: required by a bound in `StructAsync`
+  --> $DIR/issue-98634.rs:9:35
+   |
+LL | pub struct StructAsync<F: Fn() -> Pin<Box<dyn Future<Output = ()>>>> {
+   |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `StructAsync`
+
+error[E0271]: expected `fn() -> impl Future<Output = ()> {callback}` to be a fn item that returns `Pin<Box<(dyn Future<Output = ()> + 'static)>>`, but it returns `impl Future<Output = ()>`
+  --> $DIR/issue-98634.rs:45:33
+   |
+LL |         StructAsync { callback }.await;
+   |                                 ^^^^^^ expected struct `Pin`, found opaque type
+   |
+note: while checking the return type of the `async fn`
+  --> $DIR/issue-98634.rs:24:21
+   |
+LL | async fn callback() {}
+   |                     ^ checked the `Output` of this `async fn`, found opaque type
+   = note:   expected struct `Pin<Box<(dyn Future<Output = ()> + 'static)>>`
+           found opaque type `impl Future<Output = ()>`
+note: required by a bound in `StructAsync`
+  --> $DIR/issue-98634.rs:9:35
+   |
+LL | pub struct StructAsync<F: Fn() -> Pin<Box<dyn Future<Output = ()>>>> {
+   |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `StructAsync`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/src/test/ui/generic-associated-types/issue-87258_a.stderr b/src/test/ui/generic-associated-types/issue-87258_a.stderr
index fa0748a280b..eae9bd9b16f 100644
--- a/src/test/ui/generic-associated-types/issue-87258_a.stderr
+++ b/src/test/ui/generic-associated-types/issue-87258_a.stderr
@@ -4,7 +4,7 @@ error: unconstrained opaque type
 LL |     type FooFuture<'a> = impl Trait1;
    |                          ^^^^^^^^^^^
    |
-   = note: `FooFuture` must be used in combination with a concrete type within the same module
+   = note: `FooFuture` must be used in combination with a concrete type within the same impl
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/lint/inline-trait-and-foreign-items.stderr b/src/test/ui/lint/inline-trait-and-foreign-items.stderr
index 27399746bed..2f1fb4c46c0 100644
--- a/src/test/ui/lint/inline-trait-and-foreign-items.stderr
+++ b/src/test/ui/lint/inline-trait-and-foreign-items.stderr
@@ -67,7 +67,7 @@ error: unconstrained opaque type
 LL |     type U = impl Trait;
    |              ^^^^^^^^^^
    |
-   = note: `U` must be used in combination with a concrete type within the same module
+   = note: `U` must be used in combination with a concrete type within the same impl
 
 error: aborting due to 6 previous errors; 2 warnings emitted
 
diff --git a/src/test/ui/lint/no-coverage.stderr b/src/test/ui/lint/no-coverage.stderr
index 8452ccc7a03..404efbeac1e 100644
--- a/src/test/ui/lint/no-coverage.stderr
+++ b/src/test/ui/lint/no-coverage.stderr
@@ -94,7 +94,7 @@ error: unconstrained opaque type
 LL |     type U = impl Trait;
    |              ^^^^^^^^^^
    |
-   = note: `U` must be used in combination with a concrete type within the same module
+   = note: `U` must be used in combination with a concrete type within the same impl
 
 error: aborting due to 7 previous errors; 6 warnings emitted
 
diff --git a/src/test/ui/save-analysis/issue-68621.stderr b/src/test/ui/save-analysis/issue-68621.stderr
index 4a4bf9a6996..4452ee7915b 100644
--- a/src/test/ui/save-analysis/issue-68621.stderr
+++ b/src/test/ui/save-analysis/issue-68621.stderr
@@ -4,7 +4,7 @@ error: unconstrained opaque type
 LL |     type Future = impl Trait;
    |                   ^^^^^^^^^^
    |
-   = note: `Future` must be used in combination with a concrete type within the same module
+   = note: `Future` must be used in combination with a concrete type within the same impl
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/type-alias-impl-trait/issue-101750.rs b/src/test/ui/type-alias-impl-trait/issue-101750.rs
new file mode 100644
index 00000000000..f564f4fa702
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-101750.rs
@@ -0,0 +1,37 @@
+#![feature(type_alias_impl_trait)]
+
+// check-pass
+
+trait Trait {}
+
+type TAIT = impl Trait;
+
+struct Concrete;
+impl Trait for Concrete {}
+
+fn tait() -> TAIT {
+    Concrete
+}
+
+trait OuterTrait {
+    type Item;
+}
+struct Dummy<T> {
+    t: T,
+}
+impl<T> OuterTrait for Dummy<T> {
+    type Item = T;
+}
+
+fn tait_and_impl_trait() -> impl OuterTrait<Item = (TAIT, impl Trait)> {
+    Dummy {
+        t: (tait(), Concrete),
+    }
+}
+
+fn tait_and_dyn_trait() -> impl OuterTrait<Item = (TAIT, Box<dyn Trait>)> {
+    let b: Box<dyn Trait> = Box::new(Concrete);
+    Dummy { t: (tait(), b) }
+}
+
+fn main() {}