Auto merge of #70734 - Dylan-DPC:rollup-xmncatq, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - #70696 (Extend #69020 test to include reversed operand order.)
 - #70706 (Minor cleanup in rustdoc --check-theme)
 - #70725 (Avoid `.unwrap()`s on `.span_to_snippet(...)`s)
 - #70728 (Minor doc improvements on `AllocRef`)
 - #70730 (Fix link in task::Wake docs)
 - #70731 (Minor follow-up after renaming librustc(_middle))

Failed merges:

r? @ghost

Author: bors

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

src/librustc_trait_selection/traits/error_reporting/suggestions.rs

@@ -732,12 +732,13 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 true
             };
 
+        let sm = self.tcx.sess.source_map();
         let (snippet, last_ty) =
             if let (true, hir::TyKind::TraitObject(..), Ok(snippet), true, Some(last_ty)) = (
                 // Verify that we're dealing with a return `dyn Trait`
                 ret_ty.span.overlaps(span),
                 &ret_ty.kind,
-                self.tcx.sess.source_map().span_to_snippet(ret_ty.span),
+                sm.span_to_snippet(ret_ty.span),
                 // If any of the return types does not conform to the trait, then we can't
                 // suggest `impl Trait` nor trait objects, it is a type mismatch error.
                 all_returns_conform_to_trait,
@@ -775,26 +776,23 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             if is_object_safe {
                 // Suggest `-> Box<dyn Trait>` and `Box::new(returned_value)`.
                 // Get all the return values and collect their span and suggestion.
-                let mut suggestions = visitor
+                if let Some(mut suggestions) = visitor
                     .returns
                     .iter()
                     .map(|expr| {
-                        (
-                            expr.span,
-                            format!(
-                                "Box::new({})",
-                                self.tcx.sess.source_map().span_to_snippet(expr.span).unwrap()
-                            ),
-                        )
+                        let snip = sm.span_to_snippet(expr.span).ok()?;
+                        Some((expr.span, format!("Box::new({})", snip)))
                     })
-                    .collect::<Vec<_>>();
-                // Add the suggestion for the return type.
-                suggestions.push((ret_ty.span, format!("Box<dyn {}>", trait_obj)));
-                err.multipart_suggestion(
-                    "return a boxed trait object instead",
-                    suggestions,
-                    Applicability::MaybeIncorrect,
-                );
+                    .collect::<Option<Vec<_>>>()
+                {
+                    // Add the suggestion for the return type.
+                    suggestions.push((ret_ty.span, format!("Box<dyn {}>", trait_obj)));
+                    err.multipart_suggestion(
+                        "return a boxed trait object instead",
+                        suggestions,
+                        Applicability::MaybeIncorrect,
+                    );
+                }
             } else {
                 // This is currently not possible to trigger because E0038 takes precedence, but
                 // leave it in for completeness in case anything changes in an earlier stage.

src/librustc_trait_selection/traits/project.rs

@@ -1010,7 +1010,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                 // type.
                 //
                 // NOTE: This should be kept in sync with the similar code in
-                // `rustc_middle::ty::instance::resolve_associated_item()`.
+                // `rustc_ty::instance::resolve_associated_item()`.
                 let node_item =
                     assoc_ty_def(selcx, impl_data.impl_def_id, obligation.predicate.item_def_id)
                         .map_err(|ErrorReported| ())?;

src/librustc_traits/implied_outlives_bounds.rs

@@ -1,5 +1,6 @@
 //! Provider for the `implied_outlives_bounds` query.
-//! Do not call this query directory. See [`rustc_middle::traits::query::implied_outlives_bounds`].
+//! Do not call this query directory. See
+//! [`rustc_trait_selection::traits::query::type_op::implied_outlives_bounds`].
 
 use rustc_hir as hir;
 use rustc_infer::infer::canonical::{self, Canonical};

src/librustc_ty/instance.rs

@@ -118,7 +118,7 @@ fn resolve_associated_item<'tcx>(
             // Since this is a trait item, we need to see if the item is either a trait default item
             // or a specialization because we can't resolve those unless we can `Reveal::All`.
             // NOTE: This should be kept in sync with the similar code in
-            // `rustc_middle::traits::project::assemble_candidates_from_impls()`.
+            // `rustc_trait_selection::traits::project::assemble_candidates_from_impls()`.
             let eligible = if leaf_def.is_final() {
                 // Non-specializable items are always projectable.
                 true

src/librustc_typeck/check/closure.rs

@@ -432,18 +432,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         body: &hir::Body<'_>,
         expected_sig: ExpectedSig<'tcx>,
     ) -> ClosureSignatures<'tcx> {
-        let expr_map_node = self.tcx.hir().get_if_local(expr_def_id).unwrap();
+        let hir = self.tcx.hir();
+        let expr_map_node = hir.get_if_local(expr_def_id).unwrap();
         let expected_args: Vec<_> = expected_sig
             .sig
             .inputs()
             .iter()
             .map(|ty| ArgKind::from_expected_ty(ty, None))
             .collect();
-        let (closure_span, found_args) = self.get_fn_like_arguments(expr_map_node);
-        let expected_span = expected_sig.cause_span.unwrap_or(closure_span);
+        let (closure_span, found_args) = match self.get_fn_like_arguments(expr_map_node) {
+            Some((sp, args)) => (Some(sp), args),
+            None => (None, Vec::new()),
+        };
+        let expected_span =
+            expected_sig.cause_span.unwrap_or_else(|| hir.span_if_local(expr_def_id).unwrap());
         self.report_arg_count_mismatch(
             expected_span,
-            Some(closure_span),
+            closure_span,
             expected_args,
             found_args,
             true,

src/librustc_typeck/check/op.rs

@@ -481,7 +481,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 
     /// If one of the types is an uncalled function and calling it would yield the other type,
-    /// suggest calling the function. Returns whether a suggestion was given.
+    /// suggest calling the function. Returns `true` if suggestion would apply (even if not given).
     fn add_type_neq_err_label(
         &self,
         err: &mut rustc_errors::DiagnosticBuilder<'_>,
@@ -514,24 +514,20 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .lookup_op_method(fn_sig.output(), &[other_ty], Op::Binary(op, is_assign))
                 .is_ok()
             {
-                let (variable_snippet, applicability) = if !fn_sig.inputs().is_empty() {
-                    (
-                        format!("{}( /* arguments */ )", source_map.span_to_snippet(span).unwrap()),
-                        Applicability::HasPlaceholders,
-                    )
-                } else {
-                    (
-                        format!("{}()", source_map.span_to_snippet(span).unwrap()),
-                        Applicability::MaybeIncorrect,
-                    )
-                };
+                if let Ok(snippet) = source_map.span_to_snippet(span) {
+                    let (variable_snippet, applicability) = if !fn_sig.inputs().is_empty() {
+                        (format!("{}( /* arguments */ )", snippet), Applicability::HasPlaceholders)
+                    } else {
+                        (format!("{}()", snippet), Applicability::MaybeIncorrect)
+                    };
 
-                err.span_suggestion(
-                    span,
-                    "you might have forgotten to call this function",
-                    variable_snippet,
-                    applicability,
-                );
+                    err.span_suggestion(
+                        span,
+                        "you might have forgotten to call this function",
+                        variable_snippet,
+                        applicability,
+                    );
+                }
                 return true;
             }
         }

src/librustdoc/theme.rs

@@ -8,18 +8,6 @@ use rustc_errors::Handler;
 #[cfg(test)]
 mod tests;
 
-macro_rules! try_something {
-    ($e:expr, $diag:expr, $out:expr) => {{
-        match $e {
-            Ok(c) => c,
-            Err(e) => {
-                $diag.struct_err(&e.to_string()).emit();
-                return $out;
-            }
-        }
-    }};
-}
-
 #[derive(Debug, Clone, Eq)]
 pub struct CssPath {
     pub name: String,
@@ -265,7 +253,13 @@ pub fn test_theme_against<P: AsRef<Path>>(
     against: &CssPath,
     diag: &Handler,
 ) -> (bool, Vec<String>) {
-    let data = try_something!(fs::read(f), diag, (false, vec![]));
+    let data = match fs::read(f) {
+        Ok(c) => c,
+        Err(e) => {
+            diag.struct_err(&e.to_string()).emit();
+            return (false, vec![]);
+        }
+    };
 
     let paths = load_css_paths(&data);
     let mut ret = vec![];

src/libstd/alloc.rs

@@ -289,10 +289,10 @@ pub fn rust_oom(layout: Layout) -> ! {
 pub mod __default_lib_allocator {
     use super::{GlobalAlloc, Layout, System};
     // These magic symbol names are used as a fallback for implementing the
-    // `__rust_alloc` etc symbols (see `src/liballoc/alloc.rs) when there is
+    // `__rust_alloc` etc symbols (see `src/liballoc/alloc.rs`) when there is
     // no `#[global_allocator]` attribute.
 
-    // for symbol names src/librustc_middle/middle/allocator.rs
+    // for symbol names src/librustc_ast/expand/allocator.rs
     // for signatures src/librustc_allocator/lib.rs
 
     // linkage directives are provided as part of the current compiler allocator

src/test/ui/associated-const/issue-69020-assoc-const-arith-overflow.noopt.stderr

@@ -0,0 +1,54 @@
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:29:22
+   |
+LL |     const NEG: i32 = -i32::MIN + T::NEG;
+   |                      ^^^^^^^^^ attempt to negate with overflow
+   |
+   = note: `#[deny(arithmetic_overflow)]` on by default
+
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:31:35
+   |
+LL |     const NEG_REV: i32 = T::NEG + (-i32::MIN);
+   |                                   ^^^^^^^^^^^ attempt to negate with overflow
+
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:34:22
+   |
+LL |     const ADD: i32 = (i32::MAX+1) + T::ADD;
+   |                      ^^^^^^^^^^^^ attempt to add with overflow
+
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:36:36
+   |
+LL |     const ADD_REV: i32 =  T::ADD + (i32::MAX+1);
+   |                                    ^^^^^^^^^^^^ attempt to add with overflow
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:39:22
+   |
+LL |     const DIV: i32 = (1/0) + T::DIV;
+   |                      ^^^^^ attempt to divide by zero
+   |
+   = note: `#[deny(unconditional_panic)]` on by default
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:41:35
+   |
+LL |     const DIV_REV: i32 = T::DIV + (1/0);
+   |                                   ^^^^^ attempt to divide by zero
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:44:22
+   |
+LL |     const OOB: i32 = [1][1] + T::OOB;
+   |                      ^^^^^^ index out of bounds: the len is 1 but the index is 1
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:46:35
+   |
+LL |     const OOB_REV: i32 = T::OOB + [1][1];
+   |                                   ^^^^^^ index out of bounds: the len is 1 but the index is 1
+
+error: aborting due to 8 previous errors
+

src/test/ui/associated-const/issue-69020-assoc-const-arith-overflow.opt.stderr

@@ -0,0 +1,54 @@
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:29:22
+   |
+LL |     const NEG: i32 = -i32::MIN + T::NEG;
+   |                      ^^^^^^^^^ attempt to negate with overflow
+   |
+   = note: `#[deny(arithmetic_overflow)]` on by default
+
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:31:35
+   |
+LL |     const NEG_REV: i32 = T::NEG + (-i32::MIN);
+   |                                   ^^^^^^^^^^^ attempt to negate with overflow
+
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:34:22
+   |
+LL |     const ADD: i32 = (i32::MAX+1) + T::ADD;
+   |                      ^^^^^^^^^^^^ attempt to add with overflow
+
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:36:36
+   |
+LL |     const ADD_REV: i32 =  T::ADD + (i32::MAX+1);
+   |                                    ^^^^^^^^^^^^ attempt to add with overflow
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:39:22
+   |
+LL |     const DIV: i32 = (1/0) + T::DIV;
+   |                      ^^^^^ attempt to divide by zero
+   |
+   = note: `#[deny(unconditional_panic)]` on by default
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:41:35
+   |
+LL |     const DIV_REV: i32 = T::DIV + (1/0);
+   |                                   ^^^^^ attempt to divide by zero
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:44:22
+   |
+LL |     const OOB: i32 = [1][1] + T::OOB;
+   |                      ^^^^^^ index out of bounds: the len is 1 but the index is 1
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:46:35
+   |
+LL |     const OOB_REV: i32 = T::OOB + [1][1];
+   |                                   ^^^^^^ index out of bounds: the len is 1 but the index is 1
+
+error: aborting due to 8 previous errors
+

src/test/ui/associated-const/issue-69020-assoc-const-arith-overflow.opt_with_overflow_checks.stderr

@@ -0,0 +1,54 @@
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:29:22
+   |
+LL |     const NEG: i32 = -i32::MIN + T::NEG;
+   |                      ^^^^^^^^^ attempt to negate with overflow
+   |
+   = note: `#[deny(arithmetic_overflow)]` on by default
+
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:31:35
+   |
+LL |     const NEG_REV: i32 = T::NEG + (-i32::MIN);
+   |                                   ^^^^^^^^^^^ attempt to negate with overflow
+
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:34:22
+   |
+LL |     const ADD: i32 = (i32::MAX+1) + T::ADD;
+   |                      ^^^^^^^^^^^^ attempt to add with overflow
+
+error: this arithmetic operation will overflow
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:36:36
+   |
+LL |     const ADD_REV: i32 =  T::ADD + (i32::MAX+1);
+   |                                    ^^^^^^^^^^^^ attempt to add with overflow
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:39:22
+   |
+LL |     const DIV: i32 = (1/0) + T::DIV;
+   |                      ^^^^^ attempt to divide by zero
+   |
+   = note: `#[deny(unconditional_panic)]` on by default
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:41:35
+   |
+LL |     const DIV_REV: i32 = T::DIV + (1/0);
+   |                                   ^^^^^ attempt to divide by zero
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:44:22
+   |
+LL |     const OOB: i32 = [1][1] + T::OOB;
+   |                      ^^^^^^ index out of bounds: the len is 1 but the index is 1
+
+error: this operation will panic at runtime
+  --> $DIR/issue-69020-assoc-const-arith-overflow.rs:46:35
+   |
+LL |     const OOB_REV: i32 = T::OOB + [1][1];
+   |                                   ^^^^^^ index out of bounds: the len is 1 but the index is 1
+
+error: aborting due to 8 previous errors
+

src/test/ui/consts/issue-69020.rs renamed to src/test/ui/associated-const/issue-69020-assoc-const-arith-overflow.rs

@@ -9,21 +9,40 @@ use std::i32;
 
 pub trait Foo {
     const NEG: i32;
+    const NEG_REV: i32;
+
     const ADD: i32;
+    const ADD_REV: i32;
+
     const DIV: i32;
+    const DIV_REV: i32;
+
     const OOB: i32;
+    const OOB_REV: i32;
 }
 
-// These constants cannot be evaluated already (they depend on `T::N`), so
-// they can just be linted like normal run-time code.  But codegen works
-// a bit different in const context, so this test makes sure that we still catch overflow.
+// These constants cannot be evaluated already (they depend on `T::N`), so they can just be linted
+// like normal run-time code. But codegen works a bit different in const context, so this test
+// makes sure that we still catch overflow. Also make sure we emit the same lints if we reverse the
+// operands (so that the generic operand comes first).
 impl<T: Foo> Foo for Vec<T> {
     const NEG: i32 = -i32::MIN + T::NEG;
     //~^ ERROR arithmetic operation will overflow
+    const NEG_REV: i32 = T::NEG + (-i32::MIN);
+    //~^ ERROR arithmetic operation will overflow
+
     const ADD: i32 = (i32::MAX+1) + T::ADD;
     //~^ ERROR arithmetic operation will overflow
+    const ADD_REV: i32 =  T::ADD + (i32::MAX+1);
+    //~^ ERROR arithmetic operation will overflow
+
     const DIV: i32 = (1/0) + T::DIV;
     //~^ ERROR operation will panic
+    const DIV_REV: i32 = T::DIV + (1/0);
+    //~^ ERROR operation will panic
+
     const OOB: i32 = [1][1] + T::OOB;
     //~^ ERROR operation will panic
+    const OOB_REV: i32 = T::OOB + [1][1];
+    //~^ ERROR operation will panic
 }

src/test/ui/consts/issue-69020.noopt.stderr

@@ -0,0 +1,10 @@
+fn a() -> i32 {
+    3
+}
+
+pub fn main() {
+    assert_eq!(a, 0);
+    //~^ ERROR binary operation `==` cannot
+    //~| ERROR mismatched types
+    //~| ERROR doesn't implement
+}

src/test/ui/consts/issue-69020.opt.stderr

@@ -0,0 +1,41 @@
+error[E0369]: binary operation `==` cannot be applied to type `fn() -> i32 {a}`
+  --> $DIR/issue-70724-add_type_neq_err_label-unwrap.rs:6:5
+   |
+LL |     assert_eq!(a, 0);
+   |     ^^^^^^^^^^^^^^^^^
+   |     |
+   |     fn() -> i32 {a}
+   |     {integer}
+   |     help: you might have forgotten to call this function: `*left_val()`
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0308]: mismatched types
+  --> $DIR/issue-70724-add_type_neq_err_label-unwrap.rs:6:5
+   |
+LL |     assert_eq!(a, 0);
+   |     ^^^^^^^^^^^^^^^^^ expected fn item, found integer
+   |
+   = note: expected fn item `fn() -> i32 {a}`
+                 found type `i32`
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: `fn() -> i32 {a}` doesn't implement `std::fmt::Debug`
+  --> $DIR/issue-70724-add_type_neq_err_label-unwrap.rs:6:5
+   |
+LL | fn a() -> i32 {
+   |    - consider calling this function
+...
+LL |     assert_eq!(a, 0);
+   |     ^^^^^^^^^^^^^^^^^ `fn() -> i32 {a}` cannot be formatted using `{:?}` because it doesn't implement `std::fmt::Debug`
+   |
+   = help: the trait `std::fmt::Debug` is not implemented for `fn() -> i32 {a}`
+   = help: use parentheses to call the function: `a()`
+   = note: required because of the requirements on the impl of `std::fmt::Debug` for `&fn() -> i32 {a}`
+   = note: required by `std::fmt::Debug::fmt`
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0277, E0308, E0369.
+For more information about an error, try `rustc --explain E0277`.