Rollup of 6 pull requests

src/liballoc/task.rs

@@ -12,10 +12,12 @@ use crate::sync::Arc;
 /// to the tasks that are executed on that executor.
 ///
 /// This trait is a memory-safe and ergonomic alternative to constructing a
-/// [`RawWaker`]. It supports the common executor design in which the data
-/// used to wake up a task is stored in an [`Arc`]. Some executors (especially
+/// [`RawWaker`]. It supports the common executor design in which the data used
+/// to wake up a task is stored in an [`Arc`][arc]. Some executors (especially
 /// those for embedded systems) cannot use this API, which is why [`RawWaker`]
 /// exists as an alternative for those systems.
+///
+/// [arc]: ../../std/sync/struct.Arc.html
 #[unstable(feature = "wake_trait", issue = "69912")]
 pub trait Wake {
     /// Wake this task.

src/libcore/alloc/mod.rs

@@ -119,7 +119,7 @@ pub enum ReallocPlacement {
 ///
 /// Unlike [`GlobalAlloc`][], zero-sized allocations are allowed in `AllocRef`. If an underlying
 /// allocator does not support this (like jemalloc) or return a null pointer (such as
-/// `libc::malloc`), this case must be caught.
+/// `libc::malloc`), this must be caught by the implementation.
 ///
 /// ### Currently allocated memory
 ///
@@ -157,18 +157,20 @@ pub enum ReallocPlacement {
 /// # Safety
 ///
 /// * Memory blocks returned from an allocator must point to valid memory and retain their validity
-///   until the instance and all of its clones are dropped, and
+///   until the instance and all of its clones are dropped,
 ///
 /// * cloning or moving the allocator must not invalidate memory blocks returned from this
-///   allocator. A cloned allocator must behave like the same allocator.
+///   allocator. A cloned allocator must behave like the same allocator, and
 ///
 /// * any pointer to a memory block which is [*currently allocated*] may be passed to any other
 ///   method of the allocator.
 ///
 /// [*currently allocated*]: #currently-allocated-memory
 #[unstable(feature = "allocator_api", issue = "32838")]
 pub unsafe trait AllocRef {
-    /// On success, returns a memory block meeting the size and alignment guarantees of `layout`.
+    /// Attempts to allocate a block of memory.
+    ///
+    /// On success, returns a [`MemoryBlock`][] meeting the size and alignment guarantees of `layout`.
     ///
     /// The returned block may have a larger size than specified by `layout.size()` and is
     /// initialized as specified by [`init`], all the way up to the returned size of the block.
@@ -190,26 +192,26 @@ pub unsafe trait AllocRef {
     /// [`handle_alloc_error`]: ../../alloc/alloc/fn.handle_alloc_error.html
     fn alloc(&mut self, layout: Layout, init: AllocInit) -> Result<MemoryBlock, AllocErr>;
 
-    /// Deallocates the memory denoted by `memory`.
+    /// Deallocates the memory referenced by `ptr`.
     ///
     /// # Safety
     ///
-    /// * `ptr` must be [*currently allocated*] via this allocator, and
-    /// * `layout` must [*fit*] the `ptr`.
+    /// * `ptr` must denote a block of memory [*currently allocated*] via this allocator, and
+    /// * `layout` must [*fit*] that block of memory.
     ///
     /// [*currently allocated*]: #currently-allocated-memory
     /// [*fit*]: #memory-fitting
     unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout);
 
     /// Attempts to extend the memory block.
     ///
-    /// Returns a new memory block containing a pointer and the actual size of the allocated
-    /// block. The pointer is suitable for holding data described by a new layout with `layout`’s
+    /// Returns a new [`MemoryBlock`][] containing a pointer and the actual size of the allocated
+    /// memory. The pointer is suitable for holding data described by a new layout with `layout`’s
     /// alignment and a size given by `new_size`. To accomplish this, the allocator may extend the
     /// allocation referenced by `ptr` to fit the new layout. If the [`placement`] is
     /// [`InPlace`], the returned pointer is guaranteed to be the same as the passed `ptr`.
     ///
-    /// If `ReallocPlacement::MayMove` is used then ownership of the memory block referenced by `ptr`
+    /// If [`MayMove`] is used then ownership of the memory block referenced by `ptr`
     /// is transferred to this allocator. The memory may or may not be freed, and should be
     /// considered unusable (unless of course it is transferred back to the caller again via the
     /// return value of this method).
@@ -227,17 +229,18 @@ pub unsafe trait AllocRef {
     ///     the size of the `MemoryBlock` returned by the `grow` call.
     ///
     /// [`InPlace`]: ReallocPlacement::InPlace
+    /// [`MayMove`]: ReallocPlacement::MayMove
     /// [`placement`]: ReallocPlacement
     /// [`init`]: AllocInit
     ///
     /// # Safety
     ///
-    /// * `ptr` must be [*currently allocated*] via this allocator,
-    /// * `layout` must [*fit*] the `ptr`. (The `new_size` argument need not fit it.)
+    /// * `ptr` must denote a block of memory [*currently allocated*] via this allocator,
+    /// * `layout` must [*fit*] that block of memory (The `new_size` argument need not fit it.),
     // We can't require that `new_size` is strictly greater than `memory.size` because of ZSTs.
     // An alternative would be
     // * `new_size must be strictly greater than `memory.size` or both are zero
-    /// * `new_size` must be greater than or equal to `layout.size()`
+    /// * `new_size` must be greater than or equal to `layout.size()`, and
     /// * `new_size`, when rounded up to the nearest multiple of `layout.align()`, must not overflow
     ///   (i.e., the rounded value must be less than or equal to `usize::MAX`).
     ///
@@ -289,8 +292,8 @@ pub unsafe trait AllocRef {
 
     /// Attempts to shrink the memory block.
     ///
-    /// Returns a new memory block containing a pointer and the actual size of the allocated
-    /// block. The pointer is suitable for holding data described by a new layout with `layout`’s
+    /// Returns a new [`MemoryBlock`][] containing a pointer and the actual size of the allocated
+    /// memory. The pointer is suitable for holding data described by a new layout with `layout`’s
     /// alignment and a size given by `new_size`. To accomplish this, the allocator may shrink the
     /// allocation referenced by `ptr` to fit the new layout. If the [`placement`] is
     /// [`InPlace`], the returned pointer is guaranteed to be the same as the passed `ptr`.
@@ -310,20 +313,20 @@ pub unsafe trait AllocRef {
     ///
     /// # Safety
     ///
-    /// * `ptr` must be [*currently allocated*] via this allocator,
-    /// * `layout` must [*fit*] the `ptr`. (The `new_size` argument need not fit it.)
+    /// * `ptr` must denote a block of memory [*currently allocated*] via this allocator,
+    /// * `layout` must [*fit*] that block of memory (The `new_size` argument need not fit it.), and
     // We can't require that `new_size` is strictly smaller than `memory.size` because of ZSTs.
     // An alternative would be
     // * `new_size must be strictly smaller than `memory.size` or both are zero
-    /// * `new_size` must be smaller than or equal to `layout.size()`
+    /// * `new_size` must be smaller than or equal to `layout.size()`.
     ///
     /// [*currently allocated*]: #currently-allocated-memory
     /// [*fit*]: #memory-fitting
     ///
     /// # Errors
     ///
     /// Returns `Err` if the new layout does not meet the allocator's size and alignment
-    /// constraints of the allocator, or if growing otherwise fails.
+    /// constraints of the allocator, or if shrinking otherwise fails.
     ///
     /// Implementations are encouraged to return `Err` on memory exhaustion rather than panicking or
     /// aborting, but this is not a strict requirement. (Specifically: it is *legal* to implement

src/libcore/clone.rs

@@ -169,7 +169,8 @@ pub struct AssertParamIsCopy<T: Copy + ?Sized> {
 /// Implementations of `Clone` for primitive types.
 ///
 /// Implementations that cannot be described in Rust
-/// are implemented in `SelectionContext::copy_clone_conditions()` in librustc_middle.
+/// are implemented in `traits::SelectionContext::copy_clone_conditions()`
+/// in `rustc_trait_selection`.
 mod impls {
 
     use super::Clone;

src/libcore/marker.rs

@@ -759,7 +759,8 @@ impl<T: ?Sized> Unpin for *mut T {}
 /// Implementations of `Copy` for primitive types.
 ///
 /// Implementations that cannot be described in Rust
-/// are implemented in `SelectionContext::copy_clone_conditions()` in librustc_middle.
+/// are implemented in `traits::SelectionContext::copy_clone_conditions()`
+/// in `rustc_trait_selection`.
 mod copy_impls {
 
     use super::Copy;

src/libcore/raw.rs

@@ -6,7 +6,8 @@
 //! They can be used as targets of transmutes in unsafe code for manipulating
 //! the raw representations directly.
 //!
-//! Their definition should always match the ABI defined in `rustc_target::abi`.
+//! Their definition should always match the ABI defined in
+//! `rustc_middle::ty::layout`.
 
 /// The representation of a trait object like `&SomeTrait`.
 ///

src/librustc_infer/infer/lexical_region_resolve/graphviz.rs

@@ -1,5 +1,5 @@
 //! This module provides linkage between libgraphviz traits and
-//! `rustc_middle::middle::typeck::infer::region_constraints`, generating a
+//! `rustc_trait_selection::infer::region_constraints`, generating a
 //! rendering of the graph represented by the list of `Constraint`
 //! instances (which make up the edges of the graph), as well as the
 //! origin for each constraint (which are attached to the labels on

src/librustc_mir/borrow_check/region_infer/mod.rs

@@ -202,7 +202,7 @@ pub(crate) enum Cause {
 ///
 /// For more information about this translation, see
 /// `InferCtxt::process_registered_region_obligations` and
-/// `InferCtxt::type_must_outlive` in `rustc_middle::infer::outlives`.
+/// `InferCtxt::type_must_outlive` in `rustc_infer::infer::InferCtxt`.
 #[derive(Clone, Debug)]
 pub struct TypeTest<'tcx> {
     /// The type `T` that must outlive the region.

src/librustc_mir/borrow_check/type_check/mod.rs

@@ -1053,7 +1053,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     /// regions which are extracted and stored as having occurred at
     /// `locations`.
     ///
-    /// **Any `rustc_middle::infer` operations that might generate region
+    /// **Any `rustc_infer::infer` operations that might generate region
     /// constraints should occur within this method so that those
     /// constraints can be properly localized!**
     fn fully_perform_op<R>(

src/librustc_parse/parser/stmt.rs

@@ -165,9 +165,9 @@ impl<'a> Parser<'a> {
                     // Rewind to before attempting to parse the type and continue parsing.
                     let parser_snapshot_after_type = self.clone();
                     mem::replace(self, parser_snapshot_before_type);
-
-                    let snippet = self.span_to_snippet(pat.span).unwrap();
-                    err.span_label(pat.span, format!("while parsing the type for `{}`", snippet));
+                    if let Ok(snip) = self.span_to_snippet(pat.span) {
+                        err.span_label(pat.span, format!("while parsing the type for `{}`", snip));
+                    }
                     (Some((parser_snapshot_after_type, colon_sp, err)), None)
                 }
             }

src/librustc_passes/region.rs

@@ -27,8 +27,8 @@ pub struct Context {
     /// of the innermost fn body. Each fn forms its own disjoint tree
     /// in the region hierarchy. These fn bodies are themselves
     /// arranged into a tree. See the "Modeling closures" section of
-    /// the README in `infer::region_constraints` for more
-    /// details.
+    /// the README in `rustc_trait_selection::infer::region_constraints`
+    /// for more details.
     root_id: Option<hir::ItemLocalId>,
 
     /// The scope that contains any new variables declared, plus its depth in

src/librustc_passes/stability.rs

@@ -438,7 +438,7 @@ fn new_index(tcx: TyCtxt<'tcx>) -> Index<'tcx> {
         // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
         // a parent stability annotation which indicates that this is private
         // with the `rustc_private` feature. This is intended for use when
-        // compiling librustc_middle crates themselves so we can leverage crates.io
+        // compiling `librustc_*` crates themselves so we can leverage crates.io
         // while maintaining the invariant that all sysroot crates are unstable
         // by default and are unable to be used.
         if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {

src/librustc_session/filesearch.rs

@@ -143,8 +143,8 @@ fn find_libdir(sysroot: &Path) -> Cow<'static, str> {
     // FIXME: This is a quick hack to make the rustc binary able to locate
     // Rust libraries in Linux environments where libraries might be installed
     // to lib64/lib32. This would be more foolproof by basing the sysroot off
-    // of the directory where librustc_middle is located, rather than where the rustc
-    // binary is.
+    // of the directory where `librustc_driver` is located, rather than
+    // where the rustc binary is.
     // If --libdir is set during configuration to the value other than
     // "lib" (i.e., non-default), this value is used (see issue #16552).
 

src/librustc_session/lint.rs

@@ -195,7 +195,7 @@ pub enum BuiltinLintDiagnostics {
 }
 
 /// Lints that are buffered up early on in the `Session` before the
-/// `LintLevels` is calculated. These are later passed to `librustc_middle`.
+/// `LintLevels` is calculated.
 #[derive(PartialEq)]
 pub struct BufferedEarlyLint {
     /// The span of code that we are linting on.
@@ -207,7 +207,8 @@ pub struct BufferedEarlyLint {
     /// The `NodeId` of the AST node that generated the lint.
     pub node_id: NodeId,
 
-    /// A lint Id that can be passed to `rustc_session::lint::Lint::from_parser_lint_id`.
+    /// A lint Id that can be passed to
+    /// `rustc_lint::early::EarlyContextAndPass::check_id`.
     pub lint_id: LintId,
 
     /// Customization of the `DiagnosticBuilder<'_>` for the lint.

src/librustc_trait_selection/traits/error_reporting/mod.rs

@@ -65,7 +65,7 @@ pub trait InferCtxtExt<'tcx> {
     /// returns a span and `ArgKind` information that describes the
     /// arguments it expects. This can be supplied to
     /// `report_arg_count_mismatch`.
-    fn get_fn_like_arguments(&self, node: Node<'_>) -> (Span, Vec<ArgKind>);
+    fn get_fn_like_arguments(&self, node: Node<'_>) -> Option<(Span, Vec<ArgKind>)>;
 
     /// Reports an error when the number of arguments needed by a
     /// trait match doesn't match the number that the expression
@@ -611,10 +611,10 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                     )
                 } else {
                     let (closure_span, found) = found_did
-                        .and_then(|did| self.tcx.hir().get_if_local(did))
-                        .map(|node| {
-                            let (found_span, found) = self.get_fn_like_arguments(node);
-                            (Some(found_span), found)
+                        .and_then(|did| {
+                            let node = self.tcx.hir().get_if_local(did)?;
+                            let (found_span, found) = self.get_fn_like_arguments(node)?;
+                            Some((Some(found_span), found))
                         })
                         .unwrap_or((found_span, found));
 
@@ -672,43 +672,38 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
     /// returns a span and `ArgKind` information that describes the
     /// arguments it expects. This can be supplied to
     /// `report_arg_count_mismatch`.
-    fn get_fn_like_arguments(&self, node: Node<'_>) -> (Span, Vec<ArgKind>) {
-        match node {
+    fn get_fn_like_arguments(&self, node: Node<'_>) -> Option<(Span, Vec<ArgKind>)> {
+        let sm = self.tcx.sess.source_map();
+        let hir = self.tcx.hir();
+        Some(match node {
             Node::Expr(&hir::Expr {
                 kind: hir::ExprKind::Closure(_, ref _decl, id, span, _),
                 ..
             }) => (
-                self.tcx.sess.source_map().guess_head_span(span),
-                self.tcx
-                    .hir()
-                    .body(id)
+                sm.guess_head_span(span),
+                hir.body(id)
                     .params
                     .iter()
                     .map(|arg| {
                         if let hir::Pat { kind: hir::PatKind::Tuple(ref args, _), span, .. } =
                             *arg.pat
                         {
-                            ArgKind::Tuple(
+                            Some(ArgKind::Tuple(
                                 Some(span),
                                 args.iter()
                                     .map(|pat| {
-                                        let snippet = self
-                                            .tcx
-                                            .sess
-                                            .source_map()
-                                            .span_to_snippet(pat.span)
-                                            .unwrap();
-                                        (snippet, "_".to_owned())
+                                        sm.span_to_snippet(pat.span)
+                                            .ok()
+                                            .map(|snippet| (snippet, "_".to_owned()))
                                     })
-                                    .collect::<Vec<_>>(),
-                            )
+                                    .collect::<Option<Vec<_>>>()?,
+                            ))
                         } else {
-                            let name =
-                                self.tcx.sess.source_map().span_to_snippet(arg.pat.span).unwrap();
-                            ArgKind::Arg(name, "_".to_owned())
+                            let name = sm.span_to_snippet(arg.pat.span).ok()?;
+                            Some(ArgKind::Arg(name, "_".to_owned()))
                         }
                     })
-                    .collect::<Vec<ArgKind>>(),
+                    .collect::<Option<Vec<ArgKind>>>()?,
             ),
             Node::Item(&hir::Item { span, kind: hir::ItemKind::Fn(ref sig, ..), .. })
             | Node::ImplItem(&hir::ImplItem {
@@ -721,7 +716,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 kind: hir::TraitItemKind::Fn(ref sig, _),
                 ..
             }) => (
-                self.tcx.sess.source_map().guess_head_span(span),
+                sm.guess_head_span(span),
                 sig.decl
                     .inputs
                     .iter()
@@ -735,16 +730,12 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                     .collect::<Vec<ArgKind>>(),
             ),
             Node::Ctor(ref variant_data) => {
-                let span = variant_data
-                    .ctor_hir_id()
-                    .map(|hir_id| self.tcx.hir().span(hir_id))
-                    .unwrap_or(DUMMY_SP);
-                let span = self.tcx.sess.source_map().guess_head_span(span);
-
+                let span = variant_data.ctor_hir_id().map(|id| hir.span(id)).unwrap_or(DUMMY_SP);
+                let span = sm.guess_head_span(span);
                 (span, vec![ArgKind::empty(); variant_data.fields().len()])
             }
             _ => panic!("non-FnLike node found: {:?}", node),
-        }
+        })
     }
 
     /// Reports an error when the number of arguments needed by a