Auto merge of rust-lang#132940 - matthiaskrgr:rollup-f0czmkq, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#132487 (Provide placeholder generics for traits in "no method found for type parameter" suggestions)
 - rust-lang#132627 (cleanup: Remove outdated comment of `thir_body`)
 - rust-lang#132653 (Don't use `maybe_unwrap_block` when checking for macro calls in a block expr)
 - rust-lang#132793 (Update mdbook to 0.4.42)
 - rust-lang#132847 (elem_offset / subslice_range: use addr() instead of 'as usize')
 - rust-lang#132869 (split up the first paragraph of doc comments for better summaries)
 - rust-lang#132929 (Check for null in the `alloc_zeroed` example)
 - rust-lang#132933 (Make sure that we suggest turbofishing the right type arg for never suggestion)

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

Author: bors

compiler/rustc_ast/src/ast.rs

@@ -1194,7 +1194,7 @@ impl Expr {
     ///
     /// Does not ensure that the path resolves to a const param, the caller should check this.
     pub fn is_potential_trivial_const_arg(&self, strip_identity_block: bool) -> bool {
-        let this = if strip_identity_block { self.maybe_unwrap_block().1 } else { self };
+        let this = if strip_identity_block { self.maybe_unwrap_block() } else { self };
 
         if let ExprKind::Path(None, path) = &this.kind
             && path.is_potential_trivial_const_arg()
@@ -1206,14 +1206,41 @@ impl Expr {
     }
 
     /// Returns an expression with (when possible) *one* outter brace removed
-    pub fn maybe_unwrap_block(&self) -> (bool, &Expr) {
+    pub fn maybe_unwrap_block(&self) -> &Expr {
         if let ExprKind::Block(block, None) = &self.kind
             && let [stmt] = block.stmts.as_slice()
             && let StmtKind::Expr(expr) = &stmt.kind
         {
-            (true, expr)
+            expr
         } else {
-            (false, self)
+            self
+        }
+    }
+
+    /// Determines whether this expression is a macro call optionally wrapped in braces . If
+    /// `already_stripped_block` is set then we do not attempt to peel off a layer of braces.
+    ///
+    /// Returns the [`NodeId`] of the macro call and whether a layer of braces has been peeled
+    /// either before, or part of, this function.
+    pub fn optionally_braced_mac_call(
+        &self,
+        already_stripped_block: bool,
+    ) -> Option<(bool, NodeId)> {
+        match &self.kind {
+            ExprKind::Block(block, None)
+                if let [stmt] = &*block.stmts
+                    && !already_stripped_block =>
+            {
+                match &stmt.kind {
+                    StmtKind::MacCall(_) => Some((true, stmt.id)),
+                    StmtKind::Expr(expr) if let ExprKind::MacCall(_) = &expr.kind => {
+                        Some((true, expr.id))
+                    }
+                    _ => None,
+                }
+            }
+            ExprKind::MacCall(_) => Some((already_stripped_block, self.id)),
+            _ => None,
         }
     }
 

compiler/rustc_hir_typeck/src/fallback.rs

@@ -621,7 +621,11 @@ impl<'tcx> AnnotateUnitFallbackVisitor<'_, 'tcx> {
                 .iter()
                 .filter(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_)))
                 .count();
-            for (idx, arg) in args.iter().enumerate() {
+            for (idx, arg) in args
+                .iter()
+                .filter(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_)))
+                .enumerate()
+            {
                 if let Some(ty) = arg.as_type()
                     && let Some(vid) = self.fcx.root_vid(ty)
                     && self.reachable_vids.contains(&vid)

compiler/rustc_hir_typeck/src/lib.rs

@@ -4,6 +4,7 @@
 #![feature(array_windows)]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
+#![feature(iter_intersperse)]
 #![feature(let_chains)]
 #![feature(never_type)]
 #![feature(try_blocks)]

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -3874,22 +3874,52 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 param.name.ident(),
                             ));
                             let bounds_span = hir_generics.bounds_span_for_suggestions(def_id);
+                            let mut applicability = Applicability::MaybeIncorrect;
+                            // Format the path of each suggested candidate, providing placeholders
+                            // for any generic arguments without defaults.
+                            let candidate_strs: Vec<_> = candidates
+                                .iter()
+                                .map(|cand| {
+                                    let cand_path = self.tcx.def_path_str(cand.def_id);
+                                    let cand_params = &self.tcx.generics_of(cand.def_id).own_params;
+                                    let cand_args: String = cand_params
+                                        .iter()
+                                        .skip(1)
+                                        .filter_map(|param| match param.kind {
+                                            ty::GenericParamDefKind::Type {
+                                                has_default: true,
+                                                ..
+                                            }
+                                            | ty::GenericParamDefKind::Const {
+                                                has_default: true,
+                                                ..
+                                            } => None,
+                                            _ => Some(param.name.as_str()),
+                                        })
+                                        .intersperse(", ")
+                                        .collect();
+                                    if cand_args.is_empty() {
+                                        cand_path
+                                    } else {
+                                        applicability = Applicability::HasPlaceholders;
+                                        format!("{cand_path}</* {cand_args} */>")
+                                    }
+                                })
+                                .collect();
+
                             if rcvr_ty.is_ref()
                                 && param.is_impl_trait()
                                 && let Some((bounds_span, _)) = bounds_span
                             {
                                 err.multipart_suggestions(
                                     msg,
-                                    candidates.iter().map(|t| {
+                                    candidate_strs.iter().map(|cand| {
                                         vec![
                                             (param.span.shrink_to_lo(), "(".to_string()),
-                                            (
-                                                bounds_span,
-                                                format!(" + {})", self.tcx.def_path_str(t.def_id)),
-                                            ),
+                                            (bounds_span, format!(" + {cand})")),
                                         ]
                                     }),
-                                    Applicability::MaybeIncorrect,
+                                    applicability,
                                 );
                                 return;
                             }
@@ -3905,16 +3935,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                     (param.span.shrink_to_hi(), Introducer::Colon, None)
                                 };
 
-                            let all_suggs = candidates.iter().map(|cand| {
-                                let suggestion = format!(
-                                    "{} {}",
-                                    match introducer {
-                                        Introducer::Plus => " +",
-                                        Introducer::Colon => ":",
-                                        Introducer::Nothing => "",
-                                    },
-                                    self.tcx.def_path_str(cand.def_id)
-                                );
+                            let all_suggs = candidate_strs.iter().map(|cand| {
+                                let suggestion = format!("{} {cand}", match introducer {
+                                    Introducer::Plus => " +",
+                                    Introducer::Colon => ":",
+                                    Introducer::Nothing => "",
+                                },);
 
                                 let mut suggs = vec![];
 
@@ -3928,11 +3954,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 suggs
                             });
 
-                            err.multipart_suggestions(
-                                msg,
-                                all_suggs,
-                                Applicability::MaybeIncorrect,
-                            );
+                            err.multipart_suggestions(msg, all_suggs, applicability);
 
                             return;
                         }

compiler/rustc_middle/src/query/mod.rs

@@ -463,7 +463,7 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    /// Fetch the THIR for a given body. If typeck for that body failed, returns an empty `Thir`.
+    /// Fetch the THIR for a given body.
     query thir_body(key: LocalDefId) -> Result<(&'tcx Steal<thir::Thir<'tcx>>, thir::ExprId), ErrorGuaranteed> {
         // Perf tests revealed that hashing THIR is inefficient (see #85729).
         no_hash

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -1005,10 +1005,6 @@ pub(crate) fn check_unsafety(tcx: TyCtxt<'_>, def: LocalDefId) {
     // Runs all other queries that depend on THIR.
     tcx.ensure_with_value().mir_built(def);
     let thir = &thir.steal();
-    // If `thir` is empty, a type error occurred, skip this body.
-    if thir.exprs.is_empty() {
-        return;
-    }
 
     let hir_id = tcx.local_def_id_to_hir_id(def);
     let safety_context = tcx.hir().fn_sig_by_hir_id(hir_id).map_or(SafetyContext::Safe, |fn_sig| {

compiler/rustc_resolve/src/def_collector.rs

@@ -130,18 +130,16 @@ impl<'a, 'ra, 'tcx> DefCollector<'a, 'ra, 'tcx> {
         &self,
         anon_const: &'a AnonConst,
     ) -> Option<(PendingAnonConstInfo, NodeId)> {
-        let (block_was_stripped, expr) = anon_const.value.maybe_unwrap_block();
-        match expr {
-            Expr { kind: ExprKind::MacCall(..), id, .. } => Some((
+        anon_const.value.optionally_braced_mac_call(false).map(|(block_was_stripped, id)| {
+            (
                 PendingAnonConstInfo {
                     id: anon_const.id,
                     span: anon_const.value.span,
                     block_was_stripped,
                 },
-                *id,
-            )),
-            _ => None,
-        }
+                id,
+            )
+        })
     }
 
     /// Determines whether the expression `const_arg_sub_expr` is a simple macro call, sometimes
@@ -161,18 +159,11 @@ impl<'a, 'ra, 'tcx> DefCollector<'a, 'ra, 'tcx> {
             panic!("Checking expr is trivial macro call without having entered anon const: `{const_arg_sub_expr:?}`"),
         );
 
-        let (block_was_stripped, expr) = if pending_anon.block_was_stripped {
-            (true, const_arg_sub_expr)
-        } else {
-            const_arg_sub_expr.maybe_unwrap_block()
-        };
-
-        match expr {
-            Expr { kind: ExprKind::MacCall(..), id, .. } => {
-                Some((PendingAnonConstInfo { block_was_stripped, ..pending_anon }, *id))
-            }
-            _ => None,
-        }
+        const_arg_sub_expr.optionally_braced_mac_call(pending_anon.block_was_stripped).map(
+            |(block_was_stripped, id)| {
+                (PendingAnonConstInfo { block_was_stripped, ..pending_anon }, id)
+            },
+        )
     }
 }
 

library/alloc/src/alloc.rs

@@ -155,11 +155,14 @@ pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8
 /// # Examples
 ///
 /// ```
-/// use std::alloc::{alloc_zeroed, dealloc, Layout};
+/// use std::alloc::{alloc_zeroed, dealloc, handle_alloc_error, Layout};
 ///
 /// unsafe {
 ///     let layout = Layout::new::<u16>();
 ///     let ptr = alloc_zeroed(layout);
+///     if ptr.is_null() {
+///         handle_alloc_error(layout);
+///     }
 ///
 ///     assert_eq!(*(ptr as *mut u16), 0);
 ///

library/alloc/src/rc.rs

@@ -2932,7 +2932,9 @@ impl<T, I: iter::TrustedLen<Item = T>> ToRcSlice<T> for I {
 }
 
 /// `Weak` is a version of [`Rc`] that holds a non-owning reference to the
-/// managed allocation. The allocation is accessed by calling [`upgrade`] on the `Weak`
+/// managed allocation.
+///
+/// The allocation is accessed by calling [`upgrade`] on the `Weak`
 /// pointer, which returns an <code>[Option]<[Rc]\<T>></code>.
 ///
 /// Since a `Weak` reference does not count towards ownership, it will not

library/alloc/src/sync.rs

@@ -291,7 +291,9 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
 }
 
 /// `Weak` is a version of [`Arc`] that holds a non-owning reference to the
-/// managed allocation. The allocation is accessed by calling [`upgrade`] on the `Weak`
+/// managed allocation.
+///
+/// The allocation is accessed by calling [`upgrade`] on the `Weak`
 /// pointer, which returns an <code>[Option]<[Arc]\<T>></code>.
 ///
 /// Since a `Weak` reference does not count towards ownership, it will not