From 754b52669ff505b376e0d00b7ba9a0c18db535d1 Mon Sep 17 00:00:00 2001
From: klensy <klensy@users.noreply.github.com>
Date: Sun, 31 Jul 2022 16:44:06 +0300
Subject: [PATCH 1/8] dedupe 'annotate-snippets' crate versions

---
 Cargo.lock                                           | 12 +++---------
 compiler/rustc_errors/Cargo.toml                     |  2 +-
 .../src/annotate_snippet_emitter_writer.rs           |  6 +++++-
 compiler/rustc_macros/Cargo.toml                     |  2 +-
 4 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 058b6198dc425..68c110fa46420 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -82,12 +82,6 @@ dependencies = [
  "url 2.2.2",
 ]
 
-[[package]]
-name = "annotate-snippets"
-version = "0.8.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d78ea013094e5ea606b1c05fe35f1dd7ea1eb1ea259908d040b25bd5ec677ee5"
-
 [[package]]
 name = "annotate-snippets"
 version = "0.9.1"
@@ -3861,7 +3855,7 @@ dependencies = [
 name = "rustc_errors"
 version = "0.0.0"
 dependencies = [
- "annotate-snippets 0.8.0",
+ "annotate-snippets",
  "atty",
  "rustc_data_structures",
  "rustc_error_messages",
@@ -4113,7 +4107,7 @@ dependencies = [
 name = "rustc_macros"
 version = "0.1.0"
 dependencies = [
- "annotate-snippets 0.8.0",
+ "annotate-snippets",
  "fluent-bundle",
  "fluent-syntax",
  "proc-macro2",
@@ -4713,7 +4707,7 @@ dependencies = [
 name = "rustfmt-nightly"
 version = "1.5.1"
 dependencies = [
- "annotate-snippets 0.9.1",
+ "annotate-snippets",
  "anyhow",
  "bytecount",
  "cargo_metadata 0.14.0",
diff --git a/compiler/rustc_errors/Cargo.toml b/compiler/rustc_errors/Cargo.toml
index 7d7e92c522922..36805aa874fe7 100644
--- a/compiler/rustc_errors/Cargo.toml
+++ b/compiler/rustc_errors/Cargo.toml
@@ -18,7 +18,7 @@ rustc_lint_defs = { path = "../rustc_lint_defs" }
 unicode-width = "0.1.4"
 atty = "0.2"
 termcolor = "1.0"
-annotate-snippets = "0.8.0"
+annotate-snippets = "0.9"
 termize = "0.1.1"
 serde = { version = "1.0.125", features = ["derive"] }
 serde_json = "1.0.59"
diff --git a/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs b/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
index 0fcd61d1e58c3..3df562c7edac7 100644
--- a/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
+++ b/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
@@ -183,7 +183,11 @@ impl AnnotateSnippetEmitterWriter {
                     annotation_type: annotation_type_for_level(*level),
                 }),
                 footer: vec![],
-                opt: FormatOptions { color: true, anonymized_line_numbers: self.ui_testing },
+                opt: FormatOptions {
+                    color: true,
+                    anonymized_line_numbers: self.ui_testing,
+                    margin: None,
+                },
                 slices: annotated_files
                     .iter()
                     .map(|(source, line_index, annotations)| {
diff --git a/compiler/rustc_macros/Cargo.toml b/compiler/rustc_macros/Cargo.toml
index 25b3aadc1c527..547c8debb505d 100644
--- a/compiler/rustc_macros/Cargo.toml
+++ b/compiler/rustc_macros/Cargo.toml
@@ -7,7 +7,7 @@ edition = "2021"
 proc-macro = true
 
 [dependencies]
-annotate-snippets = "0.8.0"
+annotate-snippets = "0.9"
 fluent-bundle = "0.15.2"
 fluent-syntax = "0.11"
 synstructure = "0.12.1"

From aac82a9e187d314b770baa4bf1bda7ce3d113d01 Mon Sep 17 00:00:00 2001
From: Chris Denton <christophersdenton@gmail.com>
Date: Thu, 4 Aug 2022 00:20:06 +0100
Subject: [PATCH 2/8] Add visibility modifier to compat macro

---
 library/std/src/sys/windows/compat.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/library/std/src/sys/windows/compat.rs b/library/std/src/sys/windows/compat.rs
index ccc90177a2034..e199bca9f03a0 100644
--- a/library/std/src/sys/windows/compat.rs
+++ b/library/std/src/sys/windows/compat.rs
@@ -151,7 +151,7 @@ impl Module {
 macro_rules! compat_fn_with_fallback {
     (pub static $module:ident: &CStr = $name:expr; $(
         $(#[$meta:meta])*
-        pub fn $symbol:ident($($argname:ident: $argtype:ty),*) -> $rettype:ty $fallback_body:block
+        $vis:vis fn $symbol:ident($($argname:ident: $argtype:ty),*) -> $rettype:ty $fallback_body:block
     )*) => (
         pub static $module: &CStr = $name;
     $(
@@ -208,7 +208,7 @@ macro_rules! compat_fn_with_fallback {
             }
         }
         $(#[$meta])*
-        pub use $symbol::call as $symbol;
+        $vis use $symbol::call as $symbol;
     )*)
 }
 

From c985648593122a6fc8ec146a9ca755b73d0dc788 Mon Sep 17 00:00:00 2001
From: Chris Denton <christophersdenton@gmail.com>
Date: Thu, 4 Aug 2022 01:46:14 +0100
Subject: [PATCH 3/8] Remove Windows function preloading

---
 library/std/src/sys/windows/c.rs             |  18 +-
 library/std/src/sys/windows/compat.rs        | 195 ++++++-------------
 library/std/src/sys/windows/thread_parker.rs |  31 +--
 3 files changed, 86 insertions(+), 158 deletions(-)

diff --git a/library/std/src/sys/windows/c.rs b/library/std/src/sys/windows/c.rs
index 478068c73ba88..c340baf2a4a2a 100644
--- a/library/std/src/sys/windows/c.rs
+++ b/library/std/src/sys/windows/c.rs
@@ -1250,19 +1250,15 @@ compat_fn_with_fallback! {
     }
 }
 
-compat_fn_optional! {
+compat_fn_with_fallback! {
     pub static SYNCH_API: &CStr = ansi_str!("api-ms-win-core-synch-l1-2-0");
-
-    // >= Windows 8 / Server 2012
-    // https://docs.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-waitonaddress
-    pub fn WaitOnAddress(
-        Address: LPVOID,
-        CompareAddress: LPVOID,
-        AddressSize: SIZE_T,
-        dwMilliseconds: DWORD
-    ) -> BOOL;
-    pub fn WakeByAddressSingle(Address: LPVOID) -> ();
+    #[allow(unused)]
+    fn WakeByAddressSingle(Address: LPVOID) -> () {
+        crate::sys::windows::thread_parker::unpark_keyed_event(Address)
+    }
 }
+pub use crate::sys::compat::WaitOnAddress;
+pub use WakeByAddressSingle::call as wake_by_address_single_or_unpark_keyed_event;
 
 compat_fn_with_fallback! {
     pub static NTDLL: &CStr = ansi_str!("ntdll");
diff --git a/library/std/src/sys/windows/compat.rs b/library/std/src/sys/windows/compat.rs
index e199bca9f03a0..ca5b223513498 100644
--- a/library/std/src/sys/windows/compat.rs
+++ b/library/std/src/sys/windows/compat.rs
@@ -7,47 +7,17 @@
 //! `GetModuleHandle` and `GetProcAddress` to look up DLL entry points at
 //! runtime.
 //!
-//! This implementation uses a static initializer to look up the DLL entry
-//! points. The CRT (C runtime) executes static initializers before `main`
-//! is called (for binaries) and before `DllMain` is called (for DLLs).
-//! This is the ideal time to look up DLL imports, because we are guaranteed
-//! that no other threads will attempt to call these entry points. Thus,
-//! we can look up the imports and store them in `static mut` fields
-//! without any synchronization.
+//! This is implemented simply by storing a function pointer in an atomic
+//! and using relaxed ordering to load it. This means that calling it will be no
+//! more expensive then calling any other dynamically imported function.
 //!
-//! This has an additional advantage: Because the DLL import lookup happens
-//! at module initialization, the cost of these lookups is deterministic,
-//! and is removed from the code paths that actually call the DLL imports.
-//! That is, there is no unpredictable "cache miss" that occurs when calling
-//! a DLL import. For applications that benefit from predictable delays,
-//! this is a benefit. This also eliminates the comparison-and-branch
-//! from the hot path.
-//!
-//! Currently, the standard library uses only a small number of dynamic
-//! DLL imports. If this number grows substantially, then the cost of
-//! performing all of the lookups at initialization time might become
-//! substantial.
-//!
-//! The mechanism of registering a static initializer with the CRT is
-//! documented in
-//! [CRT Initialization](https://docs.microsoft.com/en-us/cpp/c-runtime-library/crt-initialization?view=msvc-160).
-//! It works by contributing a global symbol to the `.CRT$XCU` section.
-//! The linker builds a table of all static initializer functions.
-//! The CRT startup code then iterates that table, calling each
-//! initializer function.
-//!
-//! # **WARNING!!*
-//! The environment that a static initializer function runs in is highly
-//! constrained. There are **many** restrictions on what static initializers
-//! can safely do. Static initializer functions **MUST NOT** do any of the
-//! following (this list is not comprehensive):
-//! * touch any other static field that is used by a different static
-//!   initializer, because the order that static initializers run in
-//!   is not defined.
-//! * call `LoadLibrary` or any other function that acquires the DLL
-//!   loader lock.
-//! * call any Rust function or CRT function that touches any static
-//!   (global) state.
+//! The stored function pointer starts out as an importer function which will
+//! swap itself with the real function when it's called for the first time. If
+//! the real function can't be imported then a fallback function is used in its
+//! place. While this is zero cost for the happy path (where the function is
+//! already loaded) it does mean there's some overhead the first time the
+//! function is called. In the worst case, multiple threads may all end up
+//! importing the same function unnecessarily.
 
 use crate::ffi::{c_void, CStr};
 use crate::ptr::NonNull;
@@ -85,39 +55,6 @@ pub(crate) const fn const_cstr_from_bytes(bytes: &'static [u8]) -> &'static CStr
     unsafe { crate::ffi::CStr::from_bytes_with_nul_unchecked(bytes) }
 }
 
-#[used]
-#[link_section = ".CRT$XCU"]
-static INIT_TABLE_ENTRY: unsafe extern "C" fn() = init;
-
-/// This is where the magic preloading of symbols happens.
-///
-/// Note that any functions included here will be unconditionally included in
-/// the final binary, regardless of whether or not they're actually used.
-///
-/// Therefore, this is limited to `compat_fn_optional` functions which must be
-/// preloaded and any functions which may be more time sensitive, even for the first call.
-unsafe extern "C" fn init() {
-    // There is no locking here. This code is executed before main() is entered, and
-    // is guaranteed to be single-threaded.
-    //
-    // DO NOT do anything interesting or complicated in this function! DO NOT call
-    // any Rust functions or CRT functions if those functions touch any global state,
-    // because this function runs during global initialization. For example, DO NOT
-    // do any dynamic allocation, don't call LoadLibrary, etc.
-
-    if let Some(synch) = Module::new(c::SYNCH_API) {
-        // These are optional and so we must manually attempt to load them
-        // before they can be used.
-        c::WaitOnAddress::preload(synch);
-        c::WakeByAddressSingle::preload(synch);
-    }
-
-    if let Some(kernel32) = Module::new(c::KERNEL32) {
-        // Preloading this means getting a precise time will be as fast as possible.
-        c::GetSystemTimePreciseAsFileTime::preload(kernel32);
-    }
-}
-
 /// Represents a loaded module.
 ///
 /// Note that the modules std depends on must not be unloaded.
@@ -196,11 +133,6 @@ macro_rules! compat_fn_with_fallback {
                 $fallback_body
             }
 
-            #[allow(unused)]
-            pub(in crate::sys) fn preload(module: Module) {
-                load_from_module(Some(module));
-            }
-
             #[inline(always)]
             pub unsafe fn call($($argname: $argtype),*) -> $rettype {
                 let func: F = mem::transmute(PTR.load(Ordering::Relaxed));
@@ -212,62 +144,61 @@ macro_rules! compat_fn_with_fallback {
     )*)
 }
 
-/// A function that either exists or doesn't.
+/// Optionally load `WaitOnAddress`.
+/// Unlike the dynamic loading described above, this does not have a fallback.
 ///
-/// NOTE: Optional functions must be preloaded in the `init` function above, or they will always be None.
-macro_rules! compat_fn_optional {
-    (pub static $module:ident: &CStr = $name:expr; $(
-        $(#[$meta:meta])*
-        pub fn $symbol:ident($($argname:ident: $argtype:ty),*) -> $rettype:ty;
-    )*) => (
-        pub static $module: &CStr = $name;
-    $(
-        $(#[$meta])*
-        pub mod $symbol {
-            #[allow(unused_imports)]
-            use super::*;
-            use crate::mem;
-            use crate::sync::atomic::{AtomicPtr, Ordering};
-            use crate::sys::compat::Module;
-            use crate::ptr::{self, NonNull};
-
-            type F = unsafe extern "system" fn($($argtype),*) -> $rettype;
-
-            /// `PTR` will either be `null()` or set to the loaded function.
-            static PTR: AtomicPtr<c_void> = AtomicPtr::new(ptr::null_mut());
-
-            /// Only allow access to the function if it has loaded successfully.
-            #[inline(always)]
-            #[cfg(not(miri))]
-            pub fn option() -> Option<F> {
-                unsafe {
-                    NonNull::new(PTR.load(Ordering::Relaxed)).map(|f| mem::transmute(f))
-                }
-            }
-
-            // Miri does not understand the way we do preloading
-            // therefore load the function here instead.
-            #[cfg(miri)]
-            pub fn option() -> Option<F> {
-                let mut func = NonNull::new(PTR.load(Ordering::Relaxed));
-                if func.is_none() {
-                    unsafe { Module::new($module).map(preload) };
-                    func = NonNull::new(PTR.load(Ordering::Relaxed));
-                }
-                unsafe {
-                    func.map(|f| mem::transmute(f))
-                }
-            }
+/// This is rexported from sys::c. You should prefer to import
+/// from there in case this changes again in the future.
+pub mod WaitOnAddress {
+    use super::*;
+    use crate::mem;
+    use crate::ptr;
+    use crate::sync::atomic::{AtomicBool, AtomicPtr, Ordering};
+    use crate::sys::c;
+
+    static MODULE_NAME: &CStr = ansi_str!("api-ms-win-core-synch-l1-2-0");
+    static SYMBOL_NAME: &CStr = ansi_str!("WaitOnAddress");
+
+    // WaitOnAddress function signature.
+    type F = unsafe extern "system" fn(
+        Address: c::LPVOID,
+        CompareAddress: c::LPVOID,
+        AddressSize: c::SIZE_T,
+        dwMilliseconds: c::DWORD,
+    );
+
+    // A place to store the loaded function atomically.
+    static WAIT_ON_ADDRESS: AtomicPtr<c_void> = AtomicPtr::new(ptr::null_mut());
+
+    // We can skip trying to load again if we already tried.
+    static LOAD_MODULE: AtomicBool = AtomicBool::new(true);
+
+    #[inline(always)]
+    pub fn option() -> Option<F> {
+        let f = WAIT_ON_ADDRESS.load(Ordering::Relaxed);
+        if !f.is_null() { Some(unsafe { mem::transmute(f) }) } else { try_load() }
+    }
 
-            #[allow(unused)]
-            pub(in crate::sys) fn preload(module: Module) {
-                unsafe {
-                    static SYMBOL_NAME: &CStr = ansi_str!(sym $symbol);
-                    if let Some(f) = module.proc_address(SYMBOL_NAME) {
-                        PTR.store(f.as_ptr(), Ordering::Relaxed);
-                    }
-                }
+    #[cold]
+    fn try_load() -> Option<F> {
+        if LOAD_MODULE.load(Ordering::Acquire) {
+            // load the module
+            let mut wait_on_address = None;
+            if let Some(func) = try_load_inner() {
+                WAIT_ON_ADDRESS.store(func.as_ptr(), Ordering::Relaxed);
+                wait_on_address = Some(unsafe { mem::transmute(func) });
             }
+            // Don't try to load the module again even if loading failed.
+            LOAD_MODULE.store(false, Ordering::Release);
+            wait_on_address
+        } else {
+            None
         }
-    )*)
+    }
+
+    // In the future this could be a `try` block but until then I think it's a
+    // little bit cleaner as a separate function.
+    fn try_load_inner() -> Option<NonNull<c_void>> {
+        unsafe { Module::new(MODULE_NAME)?.proc_address(SYMBOL_NAME) }
+    }
 }
diff --git a/library/std/src/sys/windows/thread_parker.rs b/library/std/src/sys/windows/thread_parker.rs
index d876e0f6f3c03..16863c9903ac7 100644
--- a/library/std/src/sys/windows/thread_parker.rs
+++ b/library/std/src/sys/windows/thread_parker.rs
@@ -197,21 +197,9 @@ impl Parker {
         // purpose, to make sure every unpark() has a release-acquire ordering
         // with park().
         if self.state.swap(NOTIFIED, Release) == PARKED {
-            if let Some(wake_by_address_single) = c::WakeByAddressSingle::option() {
-                unsafe {
-                    wake_by_address_single(self.ptr());
-                }
-            } else {
-                // If we run NtReleaseKeyedEvent before the waiting thread runs
-                // NtWaitForKeyedEvent, this (shortly) blocks until we can wake it up.
-                // If the waiting thread wakes up before we run NtReleaseKeyedEvent
-                // (e.g. due to a timeout), this blocks until we do wake up a thread.
-                // To prevent this thread from blocking indefinitely in that case,
-                // park_impl() will, after seeing the state set to NOTIFIED after
-                // waking up, call NtWaitForKeyedEvent again to unblock us.
-                unsafe {
-                    c::NtReleaseKeyedEvent(keyed_event_handle(), self.ptr(), 0, ptr::null_mut());
-                }
+            unsafe {
+                // This calls either WakeByAddressSingle or unpark_keyed_event (see below).
+                c::wake_by_address_single_or_unpark_keyed_event(self.ptr());
             }
         }
     }
@@ -221,6 +209,19 @@ impl Parker {
     }
 }
 
+// This function signature makes it compatible with c::WakeByAddressSingle
+// so that it can be used as a fallback for that function.
+pub unsafe extern "C" fn unpark_keyed_event(address: c::LPVOID) {
+    // If we run NtReleaseKeyedEvent before the waiting thread runs
+    // NtWaitForKeyedEvent, this (shortly) blocks until we can wake it up.
+    // If the waiting thread wakes up before we run NtReleaseKeyedEvent
+    // (e.g. due to a timeout), this blocks until we do wake up a thread.
+    // To prevent this thread from blocking indefinitely in that case,
+    // park_impl() will, after seeing the state set to NOTIFIED after
+    // waking up, call NtWaitForKeyedEvent again to unblock us.
+    c::NtReleaseKeyedEvent(keyed_event_handle(), address, 0, ptr::null_mut());
+}
+
 fn keyed_event_handle() -> c::HANDLE {
     const INVALID: c::HANDLE = ptr::invalid_mut(!0);
     static HANDLE: AtomicPtr<libc::c_void> = AtomicPtr::new(INVALID);

From c62a8ea9df90a14c8c48ccbaffa959ed6ca2a97e Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Thu, 4 Aug 2022 02:55:40 +0000
Subject: [PATCH 4/8] Don't point out return span on every E0308

---
 compiler/rustc_typeck/src/check/coercion.rs   | 23 ++++++++++++++++++-
 compiler/rustc_typeck/src/check/demand.rs     | 22 ------------------
 src/test/ui/closures/issue-84128.stderr       |  5 ----
 .../dont-point-return-on-E0308.rs             | 18 +++++++++++++++
 .../dont-point-return-on-E0308.stderr         | 19 +++++++++++++++
 5 files changed, 59 insertions(+), 28 deletions(-)
 create mode 100644 src/test/ui/mismatched_types/dont-point-return-on-E0308.rs
 create mode 100644 src/test/ui/mismatched_types/dont-point-return-on-E0308.stderr

diff --git a/compiler/rustc_typeck/src/check/coercion.rs b/compiler/rustc_typeck/src/check/coercion.rs
index 2ed5f569b4f3e..b75a2f3edd95a 100644
--- a/compiler/rustc_typeck/src/check/coercion.rs
+++ b/compiler/rustc_typeck/src/check/coercion.rs
@@ -1648,9 +1648,30 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
             );
         }
 
-        if let (Some(sp), Some(fn_output)) = (fcx.ret_coercion_span.get(), fn_output) {
+        let ret_coercion_span = fcx.ret_coercion_span.get();
+
+        if let Some(sp) = ret_coercion_span
+            // If the closure has an explicit return type annotation, or if
+            // the closure's return type has been inferred from outside
+            // requirements (such as an Fn* trait bound), then a type error
+            // may occur at the first return expression we see in the closure
+            // (if it conflicts with the declared return type). Skip adding a
+            // note in this case, since it would be incorrect.
+            && !fcx.return_type_pre_known
+        {
+            err.span_note(
+                sp,
+                &format!(
+                    "return type inferred to be `{}` here",
+                    fcx.resolve_vars_if_possible(expected)
+                ),
+            );
+        }
+
+        if let (Some(sp), Some(fn_output)) = (ret_coercion_span, fn_output) {
             self.add_impl_trait_explanation(&mut err, cause, fcx, expected, sp, fn_output);
         }
+
         err
     }
 
diff --git a/compiler/rustc_typeck/src/check/demand.rs b/compiler/rustc_typeck/src/check/demand.rs
index 4de48dc5ba107..0595b9a73bed5 100644
--- a/compiler/rustc_typeck/src/check/demand.rs
+++ b/compiler/rustc_typeck/src/check/demand.rs
@@ -45,7 +45,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         self.note_type_is_not_clone(err, expected, expr_ty, expr);
         self.note_need_for_fn_pointer(err, expected, expr_ty);
         self.note_internal_mutation_in_method(err, expr, expected, expr_ty);
-        self.report_closure_inferred_return_type(err, expected);
     }
 
     // Requires that the two types unify, and prints an error message if
@@ -1418,25 +1417,4 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             _ => false,
         }
     }
-
-    // Report the type inferred by the return statement.
-    fn report_closure_inferred_return_type(&self, err: &mut Diagnostic, expected: Ty<'tcx>) {
-        if let Some(sp) = self.ret_coercion_span.get()
-            // If the closure has an explicit return type annotation, or if
-            // the closure's return type has been inferred from outside
-            // requirements (such as an Fn* trait bound), then a type error
-            // may occur at the first return expression we see in the closure
-            // (if it conflicts with the declared return type). Skip adding a
-            // note in this case, since it would be incorrect.
-            && !self.return_type_pre_known
-        {
-            err.span_note(
-                sp,
-                &format!(
-                    "return type inferred to be `{}` here",
-                    self.resolve_vars_if_possible(expected)
-                ),
-            );
-        }
-    }
 }
diff --git a/src/test/ui/closures/issue-84128.stderr b/src/test/ui/closures/issue-84128.stderr
index 09c44d261af0c..59607afec8f8d 100644
--- a/src/test/ui/closures/issue-84128.stderr
+++ b/src/test/ui/closures/issue-84128.stderr
@@ -6,11 +6,6 @@ LL |         Foo(())
    |         |
    |         arguments to this struct are incorrect
    |
-note: return type inferred to be `{integer}` here
-  --> $DIR/issue-84128.rs:10:20
-   |
-LL |             return Foo(0);
-   |                    ^^^^^^
 note: tuple struct defined here
   --> $DIR/issue-84128.rs:5:8
    |
diff --git a/src/test/ui/mismatched_types/dont-point-return-on-E0308.rs b/src/test/ui/mismatched_types/dont-point-return-on-E0308.rs
new file mode 100644
index 0000000000000..f2ba610e2d1f6
--- /dev/null
+++ b/src/test/ui/mismatched_types/dont-point-return-on-E0308.rs
@@ -0,0 +1,18 @@
+// edition:2021
+
+async fn f(_: &()) {}
+//~^ NOTE function defined here
+//~| NOTE
+// Second note is the span of the underlined argument, I think...
+
+fn main() {
+    (|| async {
+        Err::<(), ()>(())?;
+        f(());
+        //~^ ERROR mismatched types
+        //~| NOTE arguments to this function are incorrect
+        //~| NOTE expected `&()`, found `()`
+        //~| HELP consider borrowing here
+        Ok::<(), ()>(())
+    })();
+}
diff --git a/src/test/ui/mismatched_types/dont-point-return-on-E0308.stderr b/src/test/ui/mismatched_types/dont-point-return-on-E0308.stderr
new file mode 100644
index 0000000000000..e79ab537b4c0f
--- /dev/null
+++ b/src/test/ui/mismatched_types/dont-point-return-on-E0308.stderr
@@ -0,0 +1,19 @@
+error[E0308]: mismatched types
+  --> $DIR/dont-point-return-on-E0308.rs:10:11
+   |
+LL |         f(());
+   |         - ^^
+   |         | |
+   |         | expected `&()`, found `()`
+   |         | help: consider borrowing here: `&()`
+   |         arguments to this function are incorrect
+   |
+note: function defined here
+  --> $DIR/dont-point-return-on-E0308.rs:3:10
+   |
+LL | async fn f(_: &()) {}
+   |          ^ ------
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.

From 1f463ac40735529abd7343bb8a12a1888bb623df Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Thu, 4 Aug 2022 03:05:57 +0000
Subject: [PATCH 5/8] Resolve vars before emitting coerce error

---
 compiler/rustc_typeck/src/check/coercion.rs   |  3 +-
 src/test/ui/expr/if/if-branch-types.stderr    |  5 ++
 .../ui/expr/if/if-else-type-mismatch.stderr   | 10 +++
 .../type-mismatch-signature-deduction.stderr  |  6 ++
 src/test/ui/impl-trait/equality.stderr        |  7 +-
 ...trait-in-return-position-impl-trait.stderr |  4 +-
 ...type-err-cause-on-impl-trait-return.stderr | 67 +++++++++++++++++--
 .../dont-point-return-on-E0308.stderr         |  2 +-
 .../ui/mismatched_types/issue-84976.stderr    |  5 ++
 src/test/ui/reify-intrinsic.stderr            |  3 +
 .../type-alias-impl-trait/issue-74280.stderr  |  2 +-
 11 files changed, 102 insertions(+), 12 deletions(-)

diff --git a/compiler/rustc_typeck/src/check/coercion.rs b/compiler/rustc_typeck/src/check/coercion.rs
index b75a2f3edd95a..b659eab5ca4c0 100644
--- a/compiler/rustc_typeck/src/check/coercion.rs
+++ b/compiler/rustc_typeck/src/check/coercion.rs
@@ -1478,6 +1478,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
                     // type)
                     (self.final_ty.unwrap_or(self.expected_ty), expression_ty)
                 };
+                let (expected, found) = fcx.resolve_vars_if_possible((expected, found));
 
                 let mut err;
                 let mut unsized_return = false;
@@ -1663,7 +1664,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
                 sp,
                 &format!(
                     "return type inferred to be `{}` here",
-                    fcx.resolve_vars_if_possible(expected)
+                    expected
                 ),
             );
         }
diff --git a/src/test/ui/expr/if/if-branch-types.stderr b/src/test/ui/expr/if/if-branch-types.stderr
index 14f02163a8320..d2bba88211ea8 100644
--- a/src/test/ui/expr/if/if-branch-types.stderr
+++ b/src/test/ui/expr/if/if-branch-types.stderr
@@ -5,6 +5,11 @@ LL |     let x = if true { 10i32 } else { 10u32 };
    |                       -----          ^^^^^ expected `i32`, found `u32`
    |                       |
    |                       expected because of this
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |     let x = if true { 10i32 } else { 10i32 };
+   |                                        ~~~
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/expr/if/if-else-type-mismatch.stderr b/src/test/ui/expr/if/if-else-type-mismatch.stderr
index 9fa190d6c9df3..f1fffdb1e7ef8 100644
--- a/src/test/ui/expr/if/if-else-type-mismatch.stderr
+++ b/src/test/ui/expr/if/if-else-type-mismatch.stderr
@@ -10,6 +10,11 @@ LL | |         2u32
    | |         ^^^^ expected `i32`, found `u32`
 LL | |     };
    | |_____- `if` and `else` have incompatible types
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |         2i32
+   |          ~~~
 
 error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-else-type-mismatch.rs:8:38
@@ -18,6 +23,11 @@ LL |     let _ = if true { 42i32 } else { 42u32 };
    |                       -----          ^^^^^ expected `i32`, found `u32`
    |                       |
    |                       expected because of this
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |     let _ = if true { 42i32 } else { 42i32 };
+   |                                        ~~~
 
 error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-else-type-mismatch.rs:13:9
diff --git a/src/test/ui/generator/type-mismatch-signature-deduction.stderr b/src/test/ui/generator/type-mismatch-signature-deduction.stderr
index 7938fc8097cd2..b98da1ed8be6e 100644
--- a/src/test/ui/generator/type-mismatch-signature-deduction.stderr
+++ b/src/test/ui/generator/type-mismatch-signature-deduction.stderr
@@ -11,6 +11,12 @@ note: return type inferred to be `Result<{integer}, _>` here
    |
 LL |             return Ok(6);
    |                    ^^^^^
+help: try wrapping the expression in a variant of `Result`
+   |
+LL |         Ok(5)
+   |         +++ +
+LL |         Err(5)
+   |         ++++ +
 
 error[E0271]: type mismatch resolving `<[generator@$DIR/type-mismatch-signature-deduction.rs:7:5: 7:7] as Generator>::Return == i32`
   --> $DIR/type-mismatch-signature-deduction.rs:5:13
diff --git a/src/test/ui/impl-trait/equality.stderr b/src/test/ui/impl-trait/equality.stderr
index f14b447b07730..d4a3495515cf1 100644
--- a/src/test/ui/impl-trait/equality.stderr
+++ b/src/test/ui/impl-trait/equality.stderr
@@ -12,10 +12,15 @@ error[E0308]: mismatched types
   --> $DIR/equality.rs:15:5
    |
 LL | fn two(x: bool) -> impl Foo {
-   |                    -------- expected `_` because of return type
+   |                    -------- expected `i32` because of return type
 ...
 LL |     0_u32
    |     ^^^^^ expected `i32`, found `u32`
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |     0_i32
+   |       ~~~
 
 error[E0277]: cannot add `impl Foo` to `u32`
   --> $DIR/equality.rs:24:11
diff --git a/src/test/ui/impl-trait/object-unsafe-trait-in-return-position-impl-trait.stderr b/src/test/ui/impl-trait/object-unsafe-trait-in-return-position-impl-trait.stderr
index 5ca01a593761c..d6f5a1ac25b64 100644
--- a/src/test/ui/impl-trait/object-unsafe-trait-in-return-position-impl-trait.stderr
+++ b/src/test/ui/impl-trait/object-unsafe-trait-in-return-position-impl-trait.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/object-unsafe-trait-in-return-position-impl-trait.rs:36:5
    |
 LL | fn can() -> impl NotObjectSafe {
-   |             ------------------ expected `_` because of return type
+   |             ------------------ expected `A` because of return type
 ...
 LL |     B
    |     ^ expected struct `A`, found struct `B`
@@ -11,7 +11,7 @@ error[E0308]: mismatched types
   --> $DIR/object-unsafe-trait-in-return-position-impl-trait.rs:43:5
    |
 LL | fn cat() -> impl ObjectSafe {
-   |             --------------- expected `_` because of return type
+   |             --------------- expected `A` because of return type
 ...
 LL |     B
    |     ^ expected struct `A`, found struct `B`
diff --git a/src/test/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.stderr b/src/test/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.stderr
index 10510c1754eda..11c1072f02ccc 100644
--- a/src/test/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.stderr
+++ b/src/test/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.stderr
@@ -2,28 +2,43 @@ error[E0308]: mismatched types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:5:5
    |
 LL | fn foo() -> impl std::fmt::Display {
-   |             ---------------------- expected `_` because of return type
+   |             ---------------------- expected `i32` because of return type
 ...
 LL |     1u32
    |     ^^^^ expected `i32`, found `u32`
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |     1i32
+   |      ~~~
 
 error[E0308]: mismatched types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:12:16
    |
 LL | fn bar() -> impl std::fmt::Display {
-   |             ---------------------- expected `_` because of return type
+   |             ---------------------- expected `i32` because of return type
 ...
 LL |         return 1u32;
    |                ^^^^ expected `i32`, found `u32`
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |         return 1i32;
+   |                 ~~~
 
 error[E0308]: mismatched types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:20:9
    |
 LL | fn baz() -> impl std::fmt::Display {
-   |             ---------------------- expected `_` because of return type
+   |             ---------------------- expected `i32` because of return type
 ...
 LL |         1u32
    |         ^^^^ expected `i32`, found `u32`
+   |
+help: you can convert a `u32` to an `i32` and panic if the converted value doesn't fit
+   |
+LL |     }.try_into().unwrap()
+   |      ++++++++++++++++++++
 
 error[E0308]: `if` and `else` have incompatible types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:28:9
@@ -36,36 +51,56 @@ LL | |         1u32
    | |         ^^^^ expected `i32`, found `u32`
 LL | |     }
    | |_____- `if` and `else` have incompatible types
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |         1i32
+   |          ~~~
 
 error[E0308]: mismatched types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:35:14
    |
 LL | fn bat() -> impl std::fmt::Display {
-   |             ---------------------- expected `_` because of return type
+   |             ---------------------- expected `i32` because of return type
 ...
 LL |         _ => 1u32,
    |              ^^^^ expected `i32`, found `u32`
+   |
+help: you can convert a `u32` to an `i32` and panic if the converted value doesn't fit
+   |
+LL |     }.try_into().unwrap()
+   |      ++++++++++++++++++++
 
 error[E0308]: mismatched types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:40:5
    |
 LL |   fn can() -> impl std::fmt::Display {
-   |               ---------------------- expected `_` because of return type
+   |               ---------------------- expected `i32` because of return type
 LL | /     match 13 {
 LL | |         0 => return 0i32,
 LL | |         1 => 1u32,
 LL | |         _ => 2u32,
 LL | |     }
    | |_____^ expected `i32`, found `u32`
+   |
+help: you can convert a `u32` to an `i32` and panic if the converted value doesn't fit
+   |
+LL |     }.try_into().unwrap()
+   |      ++++++++++++++++++++
 
 error[E0308]: mismatched types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:53:13
    |
 LL | fn cat() -> impl std::fmt::Display {
-   |             ---------------------- expected `_` because of return type
+   |             ---------------------- expected `i32` because of return type
 ...
 LL |             1u32
    |             ^^^^ expected `i32`, found `u32`
+   |
+help: you can convert a `u32` to an `i32` and panic if the converted value doesn't fit
+   |
+LL |     }.try_into().unwrap()
+   |      ++++++++++++++++++++
 
 error[E0308]: `match` arms have incompatible types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:61:14
@@ -78,6 +113,11 @@ LL | |         1 => 1u32,
 LL | |         _ => 2u32,
 LL | |     }
    | |_____- `match` arms have incompatible types
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |         1 => 1i32,
+   |               ~~~
 
 error[E0308]: `if` and `else` have incompatible types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:97:9
@@ -90,6 +130,11 @@ LL | |         1u32
    | |         ^^^^ expected `i32`, found `u32`
 LL | |     }
    | |_____- `if` and `else` have incompatible types
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |         1i32
+   |          ~~~
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:66:13
@@ -125,6 +170,11 @@ LL | |         1 => 1u32,
 LL | |         _ => 2u32,
 LL | |     }
    | |_____- `match` arms have incompatible types
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |         1 => 1i32,
+   |               ~~~
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:77:13
@@ -164,6 +214,11 @@ LL | |         1u32
    | |         ^^^^ expected `i32`, found `u32`
 LL | |     }
    | |_____- `if` and `else` have incompatible types
+   |
+help: change the type of the numeric literal from `u32` to `i32`
+   |
+LL |         1i32
+   |          ~~~
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:85:13
diff --git a/src/test/ui/mismatched_types/dont-point-return-on-E0308.stderr b/src/test/ui/mismatched_types/dont-point-return-on-E0308.stderr
index e79ab537b4c0f..13942682d289c 100644
--- a/src/test/ui/mismatched_types/dont-point-return-on-E0308.stderr
+++ b/src/test/ui/mismatched_types/dont-point-return-on-E0308.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/dont-point-return-on-E0308.rs:10:11
+  --> $DIR/dont-point-return-on-E0308.rs:11:11
    |
 LL |         f(());
    |         - ^^
diff --git a/src/test/ui/mismatched_types/issue-84976.stderr b/src/test/ui/mismatched_types/issue-84976.stderr
index f8f2b1f0f5720..9157566e3a79b 100644
--- a/src/test/ui/mismatched_types/issue-84976.stderr
+++ b/src/test/ui/mismatched_types/issue-84976.stderr
@@ -3,6 +3,11 @@ error[E0308]: mismatched types
    |
 LL |     length = { foo(&length) };
    |                ^^^^^^^^^^^^ expected `u32`, found `i32`
+   |
+help: you can convert an `i32` to a `u32` and panic if the converted value doesn't fit
+   |
+LL |     length = { foo(&length).try_into().unwrap() };
+   |                            ++++++++++++++++++++
 
 error[E0308]: mismatched types
   --> $DIR/issue-84976.rs:17:14
diff --git a/src/test/ui/reify-intrinsic.stderr b/src/test/ui/reify-intrinsic.stderr
index 360557fb5201d..f78f1d822bf60 100644
--- a/src/test/ui/reify-intrinsic.stderr
+++ b/src/test/ui/reify-intrinsic.stderr
@@ -23,6 +23,9 @@ LL |         std::intrinsics::unlikely,
    |
    = note: expected fn item `extern "rust-intrinsic" fn(_) -> _ {likely}`
               found fn item `extern "rust-intrinsic" fn(_) -> _ {unlikely}`
+   = note: different `fn` items always have unique types, even if their signatures are the same
+   = help: change the expected type to be function pointer `extern "rust-intrinsic" fn(bool) -> bool`
+   = help: if the expected type is due to type inference, cast the expected `fn` to a function pointer: `likely as extern "rust-intrinsic" fn(bool) -> bool`
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/type-alias-impl-trait/issue-74280.stderr b/src/test/ui/type-alias-impl-trait/issue-74280.stderr
index 5ed29e0ac94ff..66886db6eb946 100644
--- a/src/test/ui/type-alias-impl-trait/issue-74280.stderr
+++ b/src/test/ui/type-alias-impl-trait/issue-74280.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-74280.rs:9:5
    |
 LL | fn test() -> Test {
-   |              ---- expected `_` because of return type
+   |              ---- expected `()` because of return type
 LL |     let y = || -> Test { () };
 LL |     7
    |     ^ expected `()`, found integer

From a0e4c1695854db9bf2f4aae3229026608675307d Mon Sep 17 00:00:00 2001
From: Chris Denton <christophersdenton@gmail.com>
Date: Thu, 4 Aug 2022 12:26:40 +0100
Subject: [PATCH 6/8] Update after code review

---
 library/std/src/sys/windows/c.rs      |  6 ++++++
 library/std/src/sys/windows/compat.rs | 12 ++++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/library/std/src/sys/windows/c.rs b/library/std/src/sys/windows/c.rs
index c340baf2a4a2a..c5a30f8bac86d 100644
--- a/library/std/src/sys/windows/c.rs
+++ b/library/std/src/sys/windows/c.rs
@@ -1254,10 +1254,16 @@ compat_fn_with_fallback! {
     pub static SYNCH_API: &CStr = ansi_str!("api-ms-win-core-synch-l1-2-0");
     #[allow(unused)]
     fn WakeByAddressSingle(Address: LPVOID) -> () {
+        // This fallback is currently tightly coupled to its use in Parker::unpark.
+        //
+        // FIXME: If `WakeByAddressSingle` needs to be used anywhere other than
+        // Parker::unpark then this fallback will be wrong and will need to be decoupled.
         crate::sys::windows::thread_parker::unpark_keyed_event(Address)
     }
 }
 pub use crate::sys::compat::WaitOnAddress;
+// Change exported name of `WakeByAddressSingle` to make the strange fallback
+// behaviour clear.
 pub use WakeByAddressSingle::call as wake_by_address_single_or_unpark_keyed_event;
 
 compat_fn_with_fallback! {
diff --git a/library/std/src/sys/windows/compat.rs b/library/std/src/sys/windows/compat.rs
index ca5b223513498..473544c4d4f7b 100644
--- a/library/std/src/sys/windows/compat.rs
+++ b/library/std/src/sys/windows/compat.rs
@@ -7,14 +7,14 @@
 //! `GetModuleHandle` and `GetProcAddress` to look up DLL entry points at
 //! runtime.
 //!
-//! This is implemented simply by storing a function pointer in an atomic
-//! and using relaxed ordering to load it. This means that calling it will be no
-//! more expensive then calling any other dynamically imported function.
+//! This is implemented simply by storing a function pointer in an atomic.
+//! Loading and calling this function will have little or no overhead
+//! compared with calling any other dynamically imported function.
 //!
 //! The stored function pointer starts out as an importer function which will
 //! swap itself with the real function when it's called for the first time. If
 //! the real function can't be imported then a fallback function is used in its
-//! place. While this is zero cost for the happy path (where the function is
+//! place. While this is low cost for the happy path (where the function is
 //! already loaded) it does mean there's some overhead the first time the
 //! function is called. In the worst case, multiple threads may all end up
 //! importing the same function unnecessarily.
@@ -175,7 +175,7 @@ pub mod WaitOnAddress {
 
     #[inline(always)]
     pub fn option() -> Option<F> {
-        let f = WAIT_ON_ADDRESS.load(Ordering::Relaxed);
+        let f = WAIT_ON_ADDRESS.load(Ordering::Acquire);
         if !f.is_null() { Some(unsafe { mem::transmute(f) }) } else { try_load() }
     }
 
@@ -185,7 +185,7 @@ pub mod WaitOnAddress {
             // load the module
             let mut wait_on_address = None;
             if let Some(func) = try_load_inner() {
-                WAIT_ON_ADDRESS.store(func.as_ptr(), Ordering::Relaxed);
+                WAIT_ON_ADDRESS.store(func.as_ptr(), Ordering::Release);
                 wait_on_address = Some(unsafe { mem::transmute(func) });
             }
             // Don't try to load the module again even if loading failed.

From c195f7c0a432d1d77aed3c490509895add77f93f Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Fri, 5 Aug 2022 17:11:47 +0400
Subject: [PATCH 7/8] Optimize `pointer::as_aligned_to`

---
 library/core/src/ptr/const_ptr.rs | 5 +----
 library/core/src/ptr/mut_ptr.rs   | 5 +----
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index e0655d68d2cfa..2cd6e23c71a3e 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs
@@ -1336,11 +1336,8 @@ impl<T: ?Sized> *const T {
             panic!("is_aligned_to: align is not a power-of-two");
         }
 
-        // SAFETY: `is_power_of_two()` will return `false` for zero.
-        unsafe { core::intrinsics::assume(align != 0) };
-
         // Cast is needed for `T: !Sized`
-        self.cast::<u8>().addr() % align == 0
+        self.cast::<u8>().addr() & align - 1 == 0
     }
 }
 
diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index fc3dd2a9b25a9..56ad5f7658e3d 100644
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -1614,11 +1614,8 @@ impl<T: ?Sized> *mut T {
             panic!("is_aligned_to: align is not a power-of-two");
         }
 
-        // SAFETY: `is_power_of_two()` will return `false` for zero.
-        unsafe { core::intrinsics::assume(align != 0) };
-
         // Cast is needed for `T: !Sized`
-        self.cast::<u8>().addr() % align == 0
+        self.cast::<u8>().addr() & align - 1 == 0
     }
 }
 

From 64d1c91a31c9c7c1b03868e7c62467b352c82325 Mon Sep 17 00:00:00 2001
From: Xavier Noria <fxn@hashref.com>
Date: Fri, 5 Aug 2022 18:45:42 +0200
Subject: [PATCH 8/8] ascii -> ASCII in code comment

---
 library/core/src/str/mod.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
index c4f2e283eb3bc..ee66895a7ed2a 100644
--- a/library/core/src/str/mod.rs
+++ b/library/core/src/str/mod.rs
@@ -2353,7 +2353,7 @@ impl str {
     #[inline]
     pub fn is_ascii(&self) -> bool {
         // We can treat each byte as character here: all multibyte characters
-        // start with a byte that is not in the ascii range, so we will stop
+        // start with a byte that is not in the ASCII range, so we will stop
         // there already.
         self.as_bytes().is_ascii()
     }