Auto merge of rust-lang#105918 - matthiaskrgr:rollup-mmazd62, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#105801 (Realistic `Path::as_mut_os_str` doctest)
 - rust-lang#105860 (Add long error docs for `E0460` and `E0457`)
 - rust-lang#105895 (Test that we don't add a new kind of breaking change with TAITs)
 - rust-lang#105902 (docs: improve pin docs)
 - rust-lang#105910 (Update books)
 - rust-lang#105913 (rustdoc: remove width-limiter from source pages, stop overriding CSS)
 - rust-lang#105915 (Revert "Replace usage of `ResumeTy` in async lowering with `Context`")

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_ast_lowering/src/expr.rs

@@ -16,7 +16,7 @@ use rustc_hir::def::Res;
 use rustc_hir::definitions::DefPathData;
 use rustc_session::errors::report_lit_error;
 use rustc_span::source_map::{respan, DesugaringKind, Span, Spanned};
-use rustc_span::symbol::{kw, sym, Ident};
+use rustc_span::symbol::{sym, Ident};
 use rustc_span::DUMMY_SP;
 use thin_vec::thin_vec;
 
@@ -596,38 +596,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ) -> hir::ExprKind<'hir> {
         let output = ret_ty.unwrap_or_else(|| hir::FnRetTy::DefaultReturn(self.lower_span(span)));
 
-        // Resume argument type, which should be `&mut Context<'_>`.
-        // NOTE: Using the `'static` lifetime here is technically cheating.
-        // The `Future::poll` argument really is `&'a mut Context<'b>`, but we cannot
-        // express the fact that we are not storing it across yield-points yet,
-        // and we would thus run into lifetime errors.
-        // See <https://github.com/rust-lang/rust/issues/68923>.
-        // Our lowering makes sure we are not mis-using the `_task_context` input type
-        // in the sense that we are indeed not using it across yield points. We
-        // get a fresh `&mut Context` for each resume / call of `Future::poll`.
-        // This "cheating" was previously done with a `ResumeTy` that contained a raw
-        // pointer, and a `get_context` accessor that pulled the `Context` lifetimes
-        // out of thin air.
-        let context_lifetime_ident = Ident::with_dummy_span(kw::StaticLifetime);
-        let context_lifetime = self.arena.alloc(hir::Lifetime {
-            hir_id: self.next_id(),
-            ident: context_lifetime_ident,
-            res: hir::LifetimeName::Static,
-        });
-        let context_path =
-            hir::QPath::LangItem(hir::LangItem::Context, self.lower_span(span), None);
-        let context_ty = hir::MutTy {
-            ty: self.arena.alloc(hir::Ty {
-                hir_id: self.next_id(),
-                kind: hir::TyKind::Path(context_path),
-                span: self.lower_span(span),
-            }),
-            mutbl: hir::Mutability::Mut,
-        };
+        // Resume argument type: `ResumeTy`
+        let unstable_span =
+            self.mark_span_with_reason(DesugaringKind::Async, span, self.allow_gen_future.clone());
+        let resume_ty = hir::QPath::LangItem(hir::LangItem::ResumeTy, unstable_span, None);
         let input_ty = hir::Ty {
             hir_id: self.next_id(),
-            kind: hir::TyKind::Rptr(context_lifetime, context_ty),
-            span: self.lower_span(span),
+            kind: hir::TyKind::Path(resume_ty),
+            span: unstable_span,
         };
 
         // The closure/generator `FnDecl` takes a single (resume) argument of type `input_ty`.
@@ -686,9 +662,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
             .map_or(false, |attrs| attrs.into_iter().any(|attr| attr.has_name(sym::track_caller)));
 
         let hir_id = self.lower_node_id(closure_node_id);
-        let unstable_span =
-            self.mark_span_with_reason(DesugaringKind::Async, span, self.allow_gen_future.clone());
         if track_caller {
+            let unstable_span = self.mark_span_with_reason(
+                DesugaringKind::Async,
+                span,
+                self.allow_gen_future.clone(),
+            );
             self.lower_attrs(
                 hir_id,
                 &[Attribute {
@@ -731,7 +710,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ///     mut __awaitee => loop {
     ///         match unsafe { ::std::future::Future::poll(
     ///             <::std::pin::Pin>::new_unchecked(&mut __awaitee),
-    ///             task_context,
+    ///             ::std::future::get_context(task_context),
     ///         ) } {
     ///             ::std::task::Poll::Ready(result) => break result,
     ///             ::std::task::Poll::Pending => {}
@@ -772,7 +751,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // unsafe {
         //     ::std::future::Future::poll(
         //         ::std::pin::Pin::new_unchecked(&mut __awaitee),
-        //         task_context,
+        //         ::std::future::get_context(task_context),
         //     )
         // }
         let poll_expr = {
@@ -790,10 +769,16 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 arena_vec![self; ref_mut_awaitee],
                 Some(expr_hir_id),
             );
+            let get_context = self.expr_call_lang_item_fn_mut(
+                gen_future_span,
+                hir::LangItem::GetContext,
+                arena_vec![self; task_context],
+                Some(expr_hir_id),
+            );
             let call = self.expr_call_lang_item_fn(
                 span,
                 hir::LangItem::FuturePoll,
-                arena_vec![self; new_unchecked, task_context],
+                arena_vec![self; new_unchecked, get_context],
                 Some(expr_hir_id),
             );
             self.arena.alloc(self.expr_unsafe(call))

compiler/rustc_error_codes/src/error_codes.rs

@@ -239,8 +239,10 @@ E0452: include_str!("./error_codes/E0452.md"),
 E0453: include_str!("./error_codes/E0453.md"),
 E0454: include_str!("./error_codes/E0454.md"),
 E0455: include_str!("./error_codes/E0455.md"),
+E0457: include_str!("./error_codes/E0457.md"),
 E0458: include_str!("./error_codes/E0458.md"),
 E0459: include_str!("./error_codes/E0459.md"),
+E0460: include_str!("./error_codes/E0460.md"),
 E0463: include_str!("./error_codes/E0463.md"),
 E0464: include_str!("./error_codes/E0464.md"),
 E0466: include_str!("./error_codes/E0466.md"),
@@ -592,8 +594,6 @@ E0791: include_str!("./error_codes/E0791.md"),
 //  E0421, // merged into 531
 //  E0427, // merged into 530
 //  E0456, // plugin `..` is not available for triple `..`
-    E0457, // plugin `..` only found in rlib format, but must be available...
-    E0460, // found possibly newer version of crate `..`
     E0461, // couldn't find crate `..` with expected target triple ..
     E0462, // found staticlib `..` instead of rlib or dylib
     E0465, // multiple .. candidates for `..` found

compiler/rustc_error_codes/src/error_codes/E0457.md

@@ -0,0 +1,36 @@
+Plugin `..` only found in rlib format, but must be available in dylib format.
+
+Erroronous code example:
+
+`rlib-plugin.rs`
+```ignore (needs-linkage-with-other-tests)
+#![crate_type = "rlib"]
+#![feature(rustc_private)]
+
+extern crate rustc_middle;
+extern crate rustc_driver;
+
+use rustc_driver::plugin::Registry;
+
+#[no_mangle]
+fn __rustc_plugin_registrar(_: &mut Registry) {}
+```
+
+`main.rs`
+```ignore (needs-linkage-with-other-tests)
+#![feature(plugin)]
+#![plugin(rlib_plugin)] // error: plugin `rlib_plugin` only found in rlib
+                        //        format, but must be available in dylib
+
+fn main() {}
+```
+
+The compiler exposes a plugin interface to allow altering the compile process
+(adding lints, etc). Plugins must be defined in their own crates (similar to
+[proc-macro](../reference/procedural-macros.html) isolation) and then compiled
+and linked to another crate. Plugin crates *must* be compiled to the
+dynamically-linked dylib format, and not the statically-linked rlib format.
+Learn more about different output types in
+[this section](../reference/linkage.html) of the Rust reference.
+
+This error is easily fixed by recompiling the plugin crate in the dylib format.

compiler/rustc_error_codes/src/error_codes/E0460.md

@@ -0,0 +1,71 @@
+Found possibly newer version of crate `..` which `..` depends on.
+
+Consider these erroneous files:
+
+`a1.rs`
+```ignore (needs-linkage-with-other-tests)
+#![crate_name = "a"]
+
+pub fn foo<T>() {}
+```
+
+`a2.rs`
+```ignore (needs-linkage-with-other-tests)
+#![crate_name = "a"]
+
+pub fn foo<T>() {
+    println!("foo<T>()");
+}
+```
+
+`b.rs`
+```ignore (needs-linkage-with-other-tests)
+#![crate_name = "b"]
+
+extern crate a; // linked with `a1.rs`
+
+pub fn foo() {
+    a::foo::<isize>();
+}
+```
+
+`main.rs`
+```ignore (needs-linkage-with-other-tests)
+extern crate a; // linked with `a2.rs`
+extern crate b; // error: found possibly newer version of crate `a` which `b`
+                //        depends on
+
+fn main() {}
+```
+
+The dependency graph of this program can be represented as follows:
+```text
+    crate `main`
+         |
+         +-------------+
+         |             |
+         |             v
+depends: |         crate `b`
+ `a` v1  |             |
+         |             | depends:
+         |             |  `a` v2
+         v             |
+      crate `a` <------+
+```
+
+Crate `main` depends on crate `a` (version 1) and crate `b` which in turn
+depends on crate `a` (version 2); this discrepancy in versions cannot be
+reconciled. This difference in versions typically occurs when one crate is
+compiled and linked, then updated and linked to another crate. The crate
+"version" is a SVH (Strict Version Hash) of the crate in an
+implementation-specific way. Note that this error can *only* occur when
+directly compiling and linking with `rustc`; [Cargo] automatically resolves
+dependencies, without using the compiler's own dependency management that
+causes this issue.
+
+This error can be fixed by:
+ * Using [Cargo], the Rust package manager, automatically fixing this issue.
+ * Recompiling crate `a` so that both crate `b` and `main` have a uniform
+   version to depend on.
+
+[Cargo]: ../cargo/index.html

compiler/rustc_hir/src/lang_items.rs

@@ -286,9 +286,10 @@ language_item_table! {
 
     // FIXME(swatinem): the following lang items are used for async lowering and
     // should become obsolete eventually.
+    ResumeTy,                sym::ResumeTy,            resume_ty,                  Target::Struct,         GenericRequirement::None;
     IdentityFuture,          sym::identity_future,     identity_future_fn,         Target::Fn,             GenericRequirement::None;
+    GetContext,              sym::get_context,         get_context_fn,             Target::Fn,             GenericRequirement::None;
 
-    Context,                 sym::Context,             context,                    Target::Struct,         GenericRequirement::None;
     FuturePoll,              sym::poll,                future_poll_fn,             Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
 
     FromFrom,                sym::from,                from_fn,                    Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;

compiler/rustc_span/src/symbol.rs

@@ -164,7 +164,6 @@ symbols! {
         Capture,
         Center,
         Clone,
-        Context,
         Continue,
         Copy,
         Count,
@@ -264,6 +263,7 @@ symbols! {
         Relaxed,
         Release,
         Result,
+        ResumeTy,
         Return,
         Right,
         Rust,
@@ -753,6 +753,7 @@ symbols! {
         generic_associated_types_extended,
         generic_const_exprs,
         generic_param_attrs,
+        get_context,
         global_allocator,
         global_asm,
         globs,

library/core/src/future/mod.rs

@@ -44,7 +44,7 @@ pub use poll_fn::{poll_fn, PollFn};
 ///    non-Send/Sync as well, and we don't want that.
 ///
 /// It also simplifies the HIR lowering of `.await`.
-// FIXME(swatinem): This type can be removed when bumping the bootstrap compiler
+#[cfg_attr(not(bootstrap), lang = "ResumeTy")]
 #[doc(hidden)]
 #[unstable(feature = "gen_future", issue = "50547")]
 #[derive(Debug, Copy, Clone)]
@@ -61,7 +61,6 @@ unsafe impl Sync for ResumeTy {}
 /// This function returns a `GenFuture` underneath, but hides it in `impl Trait` to give
 /// better error messages (`impl Future` rather than `GenFuture<[closure.....]>`).
 // This is `const` to avoid extra errors after we recover from `const async fn`
-// FIXME(swatinem): This fn can be removed when bumping the bootstrap compiler
 #[cfg_attr(bootstrap, lang = "from_generator")]
 #[doc(hidden)]
 #[unstable(feature = "gen_future", issue = "50547")]
@@ -103,8 +102,7 @@ where
     GenFuture(gen)
 }
 
-// FIXME(swatinem): This fn can be removed when bumping the bootstrap compiler
-#[cfg_attr(bootstrap, lang = "get_context")]
+#[lang = "get_context"]
 #[doc(hidden)]
 #[unstable(feature = "gen_future", issue = "50547")]
 #[must_use]
@@ -115,10 +113,6 @@ pub unsafe fn get_context<'a, 'b>(cx: ResumeTy) -> &'a mut Context<'b> {
     unsafe { &mut *cx.0.as_ptr().cast() }
 }
 
-// FIXME(swatinem): This fn is currently needed to work around shortcomings
-// in type and lifetime inference.
-// See the comment at the bottom of `LoweringContext::make_async_expr` and
-// <https://github.com/rust-lang/rust/issues/104826>.
 #[cfg_attr(not(bootstrap), lang = "identity_future")]
 #[doc(hidden)]
 #[unstable(feature = "gen_future", issue = "50547")]

library/core/src/pin.rs

@@ -485,6 +485,16 @@ impl<P: Deref<Target: Unpin>> Pin<P> {
     ///
     /// Unlike `Pin::new_unchecked`, this method is safe because the pointer
     /// `P` dereferences to an [`Unpin`] type, which cancels the pinning guarantees.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::pin::Pin;
+    ///
+    /// let mut val: u8 = 5;
+    /// // We can pin the value, since it doesn't care about being moved
+    /// let mut pinned: Pin<&mut u8> = Pin::new(&mut val);
+    /// ```
     #[inline(always)]
     #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
     #[stable(feature = "pin", since = "1.33.0")]
@@ -496,8 +506,20 @@ impl<P: Deref<Target: Unpin>> Pin<P> {
 
     /// Unwraps this `Pin<P>` returning the underlying pointer.
     ///
-    /// This requires that the data inside this `Pin` is [`Unpin`] so that we
+    /// This requires that the data inside this `Pin` implements [`Unpin`] so that we
     /// can ignore the pinning invariants when unwrapping it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::pin::Pin;
+    ///
+    /// let mut val: u8 = 5;
+    /// let pinned: Pin<&mut u8> = Pin::new(&mut val);
+    /// // Unwrap the pin to get a reference to the value
+    /// let r = Pin::into_inner(pinned);
+    /// assert_eq!(*r, 5);
+    /// ```
     #[inline(always)]
     #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
     #[stable(feature = "pin_into_inner", since = "1.39.0")]
@@ -707,6 +729,18 @@ impl<P: DerefMut> Pin<P> {
     ///
     /// This overwrites pinned data, but that is okay: its destructor gets
     /// run before being overwritten, so no pinning guarantee is violated.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use std::pin::Pin;
+    ///
+    /// let mut val: u8 = 5;
+    /// let mut pinned: Pin<&mut u8> = Pin::new(&mut val);
+    /// println!("{}", pinned); // 5
+    /// pinned.as_mut().set(10);
+    /// println!("{}", pinned); // 10
+    /// ```
     #[stable(feature = "pin", since = "1.33.0")]
     #[inline(always)]
     pub fn set(&mut self, value: P::Target)

library/core/src/task/wake.rs

@@ -174,7 +174,6 @@ impl RawWakerVTable {
 /// Currently, `Context` only serves to provide access to a [`&Waker`](Waker)
 /// which can be used to wake the current task.
 #[stable(feature = "futures_api", since = "1.36.0")]
-#[cfg_attr(not(bootstrap), lang = "Context")]
 pub struct Context<'a> {
     waker: &'a Waker,
     // Ensure we future-proof against variance changes by forcing

library/std/src/path.rs

@@ -2039,12 +2039,12 @@ impl Path {
     /// #![feature(path_as_mut_os_str)]
     /// use std::path::{Path, PathBuf};
     ///
-    /// let mut path = PathBuf::from("/Foo.TXT").into_boxed_path();
+    /// let mut path = PathBuf::from("Foo.TXT");
     ///
-    /// assert_ne!(&*path, Path::new("/foo.txt"));
+    /// assert_ne!(path, Path::new("foo.txt"));
     ///
     /// path.as_mut_os_str().make_ascii_lowercase();
-    /// assert_eq!(&*path, Path::new("/foo.txt"));
+    /// assert_eq!(path, Path::new("foo.txt"));
     /// ```
     #[unstable(feature = "path_as_mut_os_str", issue = "105021")]
     #[must_use]