Auto merge of rust-lang#138031 - workingjubilee:rollup-5bsotpz, r=workingjubilee

Rollup of 15 pull requests

Successful merges:

 - rust-lang#137829 (Stabilize [T]::split_off... methods)
 - rust-lang#137850 (Stabilize `box_uninit_write`)
 - rust-lang#137912 (Do not recover missing lifetime with random in-scope lifetime)
 - rust-lang#137913 (Allow struct field default values to reference struct's generics)
 - rust-lang#137923 (Simplify `<Postorder as Iterator>::size_hint`)
 - rust-lang#137949 (Update MSVC INSTALL.md instructions to recommend VS 2022 + recent Windows 10/11 SDK)
 - rust-lang#137963 (Add ``dyn`` keyword to `E0373` examples)
 - rust-lang#137975 (Remove unused `PpMode::needs_hir`)
 - rust-lang#137981 (rustdoc search: increase strictness of typechecking)
 - rust-lang#137986 (Fix some typos)
 - rust-lang#137991 (Add `avr-none` to SUMMARY.md and platform-support.md)
 - rust-lang#137993 (Remove obsolete comment from DeduceReadOnly)
 - rust-lang#137996 (Revert "compiler/rustc_data_structures/src/sync/worker_local.rs: delete "unsafe impl Sync"")
 - rust-lang#138019 (Pretty-print `#[deprecated]` attribute in HIR.)
 - rust-lang#138026 (Make CrateItem::body() function return an option)

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

Author: bors

CONTRIBUTING.md

@@ -18,7 +18,7 @@ For submodules, changes need to be made against the repository corresponding the
 submodule, and not the main `rust-lang/rust` repository.
 
 For subtrees, prefer sending a PR against the subtree's repository if it does
-not need to be made against the main `rust-lang/rust` repostory (e.g. a
+not need to be made against the main `rust-lang/rust` repository (e.g. a
 rustc-dev-guide change that does not accompany a compiler change).
 
 ## About the [rustc-dev-guide]

INSTALL.md

@@ -210,9 +210,13 @@ itself back on after some time).
 
 ### MSVC
 
-MSVC builds of Rust additionally require an installation of Visual Studio 2017
-(or later) so `rustc` can use its linker. The simplest way is to get
-[Visual Studio], check the "C++ build tools" and "Windows 10 SDK" workload.
+MSVC builds of Rust additionally requires an installation of:
+
+- Visual Studio 2022 (or later) build tools so `rustc` can use its linker. Older
+  Visual Studio versions such as 2019 *may* work but aren't actively tested.
+- A recent Windows 10 or 11 SDK.
+
+The simplest way is to get [Visual Studio], check the "C++ build tools".
 
 [Visual Studio]: https://visualstudio.microsoft.com/downloads/
 

compiler/rustc_data_structures/src/sync/worker_local.rs

@@ -106,6 +106,12 @@ pub struct WorkerLocal<T> {
     registry: Registry,
 }
 
+// This is safe because the `deref` call will return a reference to a `T` unique to each thread
+// or it will panic for threads without an associated local. So there isn't a need for `T` to do
+// it's own synchronization. The `verify` method on `RegistryId` has an issue where the id
+// can be reused, but `WorkerLocal` has a reference to `Registry` which will prevent any reuse.
+unsafe impl<T: Send> Sync for WorkerLocal<T> {}
+
 impl<T> WorkerLocal<T> {
     /// Creates a new worker local where the `initial` closure computes the
     /// value this worker local should take for each thread in the registry.
@@ -132,11 +138,6 @@ impl<T> Deref for WorkerLocal<T> {
     fn deref(&self) -> &T {
         // This is safe because `verify` will only return values less than
         // `self.registry.thread_limit` which is the size of the `self.locals` array.
-
-        // The `deref` call will return a reference to a `T` unique to each thread
-        // or it will panic for threads without an associated local. So there isn't a need for `T` to do
-        // it's own synchronization. The `verify` method on `RegistryId` has an issue where the id
-        // can be reused, but `WorkerLocal` has a reference to `Registry` which will prevent any reuse.
         unsafe { &self.locals.get_unchecked(self.registry.id().verify()).0 }
     }
 }

compiler/rustc_error_codes/src/error_codes/E0373.md

@@ -3,7 +3,7 @@ A captured variable in a closure may not live long enough.
 Erroneous code example:
 
 ```compile_fail,E0373
-fn foo() -> Box<Fn(u32) -> u32> {
+fn foo() -> Box<dyn Fn(u32) -> u32> {
     let x = 0u32;
     Box::new(|y| x + y)
 }
@@ -42,7 +42,7 @@ This approach moves (or copies, where possible) data into the closure, rather
 than taking references to it. For example:
 
 ```
-fn foo() -> Box<Fn(u32) -> u32> {
+fn foo() -> Box<dyn Fn(u32) -> u32> {
     let x = 0u32;
     Box::new(move |y| x + y)
 }

compiler/rustc_hir_analysis/src/collect/generics_of.rs

@@ -187,6 +187,8 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
                         Some(parent_did)
                     }
                     Node::TyPat(_) => Some(parent_did),
+                    // Field default values inherit the ADT's generics.
+                    Node::Field(_) => Some(parent_did),
                     _ => None,
                 }
             }

compiler/rustc_hir_pretty/src/lib.rs

@@ -117,6 +117,80 @@ impl<'a> State<'a> {
                 ));
                 self.hardbreak()
             }
+            hir::Attribute::Parsed(AttributeKind::Deprecation { deprecation, .. }) => {
+                self.word("#[deprecated");
+
+                // There are three possible forms here:
+                // 1. a form with explicit components like
+                //    `#[deprecated(since = "1.2.3", note = "some note", suggestion = "something")]`
+                //    where each component may be present or absent.
+                // 2. `#[deprecated = "message"]`
+                // 3. `#[deprecated]`
+                //
+                // Let's figure out which we need.
+                // If there's a `since` or `suggestion` value, we're definitely in form 1.
+                if matches!(
+                    deprecation.since,
+                    rustc_attr_parsing::DeprecatedSince::RustcVersion(..)
+                        | rustc_attr_parsing::DeprecatedSince::Future
+                        | rustc_attr_parsing::DeprecatedSince::NonStandard(..)
+                ) || deprecation.suggestion.is_some()
+                {
+                    self.word("(");
+                    let mut use_comma = false;
+
+                    match &deprecation.since {
+                        rustc_attr_parsing::DeprecatedSince::RustcVersion(rustc_version) => {
+                            self.word("since = \"");
+                            self.word(format!(
+                                "{}.{}.{}",
+                                rustc_version.major, rustc_version.minor, rustc_version.patch
+                            ));
+                            self.word("\"");
+                            use_comma = true;
+                        }
+                        rustc_attr_parsing::DeprecatedSince::Future => {
+                            self.word("since = \"future\"");
+                            use_comma = true;
+                        }
+                        rustc_attr_parsing::DeprecatedSince::NonStandard(symbol) => {
+                            self.word("since = \"");
+                            self.word(symbol.to_ident_string());
+                            self.word("\"");
+                            use_comma = true;
+                        }
+                        _ => {}
+                    }
+
+                    if let Some(note) = &deprecation.note {
+                        if use_comma {
+                            self.word(", ");
+                        }
+                        self.word("note = \"");
+                        self.word(note.to_ident_string());
+                        self.word("\"");
+                        use_comma = true;
+                    }
+
+                    if let Some(suggestion) = &deprecation.suggestion {
+                        if use_comma {
+                            self.word(", ");
+                        }
+                        self.word("suggestion = \"");
+                        self.word(suggestion.to_ident_string());
+                        self.word("\"");
+                    }
+                } else if let Some(note) = &deprecation.note {
+                    // We're in form 2: `#[deprecated = "message"]`.
+                    self.word(" = \"");
+                    self.word(note.to_ident_string());
+                    self.word("\"");
+                } else {
+                    // We're in form 3: `#[deprecated]`. Nothing to do here.
+                }
+
+                self.word("]");
+            }
             hir::Attribute::Parsed(pa) => {
                 self.word("#[attr=\"");
                 pa.print_attribute(self);

compiler/rustc_middle/src/mir/traversal.rs

@@ -23,19 +23,13 @@ pub struct Preorder<'a, 'tcx> {
     body: &'a Body<'tcx>,
     visited: DenseBitSet<BasicBlock>,
     worklist: Vec<BasicBlock>,
-    root_is_start_block: bool,
 }
 
 impl<'a, 'tcx> Preorder<'a, 'tcx> {
     pub fn new(body: &'a Body<'tcx>, root: BasicBlock) -> Preorder<'a, 'tcx> {
         let worklist = vec![root];
 
-        Preorder {
-            body,
-            visited: DenseBitSet::new_empty(body.basic_blocks.len()),
-            worklist,
-            root_is_start_block: root == START_BLOCK,
-        }
+        Preorder { body, visited: DenseBitSet::new_empty(body.basic_blocks.len()), worklist }
     }
 }
 
@@ -71,15 +65,11 @@ impl<'a, 'tcx> Iterator for Preorder<'a, 'tcx> {
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        // All the blocks, minus the number of blocks we've visited.
-        let upper = self.body.basic_blocks.len() - self.visited.count();
+        // The worklist might be only things already visited.
+        let lower = 0;
 
-        let lower = if self.root_is_start_block {
-            // We will visit all remaining blocks exactly once.
-            upper
-        } else {
-            self.worklist.len()
-        };
+        // This is extremely loose, but it's not worth a popcnt loop to do better.
+        let upper = self.body.basic_blocks.len();
 
         (lower, Some(upper))
     }
@@ -108,7 +98,6 @@ pub struct Postorder<'a, 'tcx> {
     basic_blocks: &'a IndexSlice<BasicBlock, BasicBlockData<'tcx>>,
     visited: DenseBitSet<BasicBlock>,
     visit_stack: Vec<(BasicBlock, Successors<'a>)>,
-    root_is_start_block: bool,
     /// A non-empty `extra` allows for a precise calculation of the successors.
     extra: Option<(TyCtxt<'tcx>, Instance<'tcx>)>,
 }
@@ -123,7 +112,6 @@ impl<'a, 'tcx> Postorder<'a, 'tcx> {
             basic_blocks,
             visited: DenseBitSet::new_empty(basic_blocks.len()),
             visit_stack: Vec::new(),
-            root_is_start_block: root == START_BLOCK,
             extra,
         };
 
@@ -211,16 +199,13 @@ impl<'tcx> Iterator for Postorder<'_, 'tcx> {
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        // All the blocks, minus the number of blocks we've visited.
-        let upper = self.basic_blocks.len() - self.visited.count();
-
-        let lower = if self.root_is_start_block {
-            // We will visit all remaining blocks exactly once.
-            upper
-        } else {
-            self.visit_stack.len()
-        };
+        // These bounds are not at all tight, but that's fine.
+        // It's not worth a popcnt loop in `DenseBitSet` to improve the upper,
+        // and in mono-reachable we can't be precise anyway.
+        // Leaning on amortized growth is fine.
 
+        let lower = self.visit_stack.len();
+        let upper = self.basic_blocks.len();
         (lower, Some(upper))
     }
 }

compiler/rustc_mir_transform/src/deduce_param_attrs.rs

@@ -80,35 +80,6 @@ impl<'tcx> Visitor<'tcx> for DeduceReadOnly {
         // `f` passes. Note that function arguments are the only situation in which this problem can
         // arise: every other use of `move` in MIR doesn't actually write to the value it moves
         // from.
-        //
-        // Anyway, right now this situation doesn't actually arise in practice. Instead, the MIR for
-        // that function looks like this:
-        //
-        //      fn f(_1: BigStruct) -> () {
-        //          let mut _0: ();
-        //          let mut _2: BigStruct;
-        //          bb0: {
-        //              _2 = move _1;
-        //              _0 = g(move _2) -> bb1;
-        //          }
-        //          ...
-        //      }
-        //
-        // Because of that extra move that MIR construction inserts, `x` (i.e. `_1`) can *in
-        // practice* safely be marked `readonly`.
-        //
-        // To handle the possibility that other optimizations (for example, destination propagation)
-        // might someday generate MIR like the first example above, we panic upon seeing an argument
-        // to *our* function that is directly moved into *another* function as an argument. Having
-        // eliminated that problematic case, we can safely treat moves as copies in this analysis.
-        //
-        // In the future, if MIR optimizations cause arguments of a caller to be directly moved into
-        // the argument of a callee, we can just add that argument to `mutated_args` instead of
-        // panicking.
-        //
-        // Note that, because the problematic MIR is never actually generated, we can't add a test
-        // case for this.
-
         if let TerminatorKind::Call { ref args, .. } = terminator.kind {
             for arg in args {
                 if let Operand::Move(place) = arg.node {

compiler/rustc_resolve/src/late.rs

@@ -78,6 +78,7 @@ struct IsNeverPattern;
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 enum AnonConstKind {
     EnumDiscriminant,
+    FieldDefaultValue,
     InlineConst,
     ConstArg(IsRepeatExpr),
 }
@@ -1406,7 +1407,7 @@ impl<'ra: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'_, 'ast, 'r
         visit_opt!(self, visit_ident, ident);
         try_visit!(self.visit_ty(ty));
         if let Some(v) = &default {
-            self.resolve_anon_const(v, AnonConstKind::ConstArg(IsRepeatExpr::No));
+            self.resolve_anon_const(v, AnonConstKind::FieldDefaultValue);
         }
     }
 }
@@ -4659,6 +4660,7 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
             AnonConstKind::EnumDiscriminant => {
                 ConstantHasGenerics::No(NoConstantGenericsReason::IsEnumDiscriminant)
             }
+            AnonConstKind::FieldDefaultValue => ConstantHasGenerics::Yes,
             AnonConstKind::InlineConst => ConstantHasGenerics::Yes,
             AnonConstKind::ConstArg(_) => {
                 if self.r.tcx.features().generic_const_exprs() || is_trivial_const_arg {

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -3515,12 +3515,6 @@ impl<'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                         }
                     }
                 }
-
-                // Record as using the suggested resolution.
-                let (_, (_, res)) = in_scope_lifetimes[0];
-                for &lt in &lifetime_refs {
-                    self.r.lifetimes_res_map.insert(lt.id, res);
-                }
             }
             _ => {
                 let lifetime_spans: Vec<_> =