Auto merge of rust-lang#78421 - JohnTitor:rollup-bq2d7fo, r=JohnTitor

Rollup of 16 pull requests

Successful merges:

 - rust-lang#76635 (Add [T]::as_chunks(_mut))
 - rust-lang#77703 (add system-llvm-libunwind config option)
 - rust-lang#78219 (Prefer to use `print_def_path`)
 - rust-lang#78298 (Add test for bad NLL higher-ranked subtype)
 - rust-lang#78332 (Update description for error E0308)
 - rust-lang#78342 (Use check-pass in single-use-lifetime ui tests)
 - rust-lang#78347 (Add lexicographical comparison doc)
 - rust-lang#78348 (Make some functions private that don't have to be public)
 - rust-lang#78349 (Use its own `TypeckResults` to avoid ICE)
 - rust-lang#78375 (Use ? in core/std macros)
 - rust-lang#78377 (Fix typo in debug statement)
 - rust-lang#78388 (Add some regression tests)
 - rust-lang#78394 (fix(docs): typo in BufWriter documentation)
 - rust-lang#78396 (Add compiler support for LLVM's x86_64 ERMSB feature)
 - rust-lang#78405 (Fix typo in lint description)
 - rust-lang#78412 (Improve formatting of hash collections docs)

Failed merges:

r? `@ghost`

Author: bors

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -63,6 +63,7 @@ const X86_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
     ("bmi1", None),
     ("bmi2", None),
     ("cmpxchg16b", Some(sym::cmpxchg16b_target_feature)),
+    ("ermsb", Some(sym::ermsb_target_feature)),
     ("f16c", Some(sym::f16c_target_feature)),
     ("fma", None),
     ("fxsr", None),

compiler/rustc_error_codes/src/error_codes/E0308.md

@@ -1,18 +1,26 @@
 Expected type did not match the received type.
 
-Erroneous code example:
+Erroneous code examples:
 
 ```compile_fail,E0308
-let x: i32 = "I am not a number!";
-//     ~~~   ~~~~~~~~~~~~~~~~~~~~
-//      |             |
-//      |    initializing expression;
-//      |    compiler infers type `&str`
-//      |
-//    type `i32` assigned to variable `x`
+fn plus_one(x: i32) -> i32 {
+    x + 1
+}
+
+plus_one("Not a number");
+//       ^^^^^^^^^^^^^^ expected `i32`, found `&str`
+
+if "Not a bool" {
+// ^^^^^^^^^^^^ expected `bool`, found `&str`
+}
+
+let x: f32 = "Not a float";
+//     ---   ^^^^^^^^^^^^^ expected `f32`, found `&str`
+//     |
+//     expected due to this
 ```
 
-This error occurs when the compiler is unable to infer the concrete type of a
-variable. It can occur in several cases, the most common being a mismatch
-between two types: the type the author explicitly assigned, and the type the
-compiler inferred.
+This error occurs when an expression was used in a place where the compiler
+expected an expression of a different type. It can occur in several cases, the
+most common being when calling a function and passing an argument which has a
+different type than the matching type in the function declaration.

compiler/rustc_feature/src/active.rs

@@ -243,6 +243,7 @@ declare_features! (
     (active, rtm_target_feature, "1.35.0", Some(44839), None),
     (active, f16c_target_feature, "1.36.0", Some(44839), None),
     (active, riscv_target_feature, "1.45.0", Some(44839), None),
+    (active, ermsb_target_feature, "1.49.0", Some(44839), None),
 
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates (target features)

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -658,7 +658,7 @@ pub trait PrettyPrinter<'tcx>:
                         let span = self.tcx().hir().span(hir_id);
                         p!(write("@{}", self.tcx().sess.source_map().span_to_string(span)));
                     } else {
-                        p!(write("@{}", self.tcx().def_path_str(did)));
+                        p!(write("@"), print_def_path(did, substs));
                     }
                 } else {
                     p!(print_def_path(did, substs));
@@ -694,7 +694,7 @@ pub trait PrettyPrinter<'tcx>:
                             p!(write("@{}", self.tcx().sess.source_map().span_to_string(span)));
                         }
                     } else {
-                        p!(write("@{}", self.tcx().def_path_str(did)));
+                        p!(write("@"), print_def_path(did, substs));
                     }
                 } else {
                     p!(print_def_path(did, substs));

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -231,7 +231,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         let arm_end_blocks: Vec<_> = arm_candidates
             .into_iter()
             .map(|(arm, candidate)| {
-                debug!("lowering arm {:?}\ncanidate = {:?}", arm, candidate);
+                debug!("lowering arm {:?}\ncandidate = {:?}", arm, candidate);
 
                 let arm_source_info = self.source_info(arm.span);
                 let arm_scope = (arm.scope, arm_source_info);

compiler/rustc_save_analysis/src/lib.rs

@@ -630,9 +630,14 @@ impl<'tcx> SaveContext<'tcx> {
             })
             | Node::Ty(&hir::Ty { kind: hir::TyKind::Path(ref qpath), .. }) => match qpath {
                 hir::QPath::Resolved(_, path) => path.res,
-                hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
-                    .maybe_typeck_results
-                    .map_or(Res::Err, |typeck_results| typeck_results.qpath_res(qpath, hir_id)),
+                hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => {
+                    // #75962: `self.typeck_results` may be different from the `hir_id`'s result.
+                    if self.tcx.has_typeck_results(hir_id.owner.to_def_id()) {
+                        self.tcx.typeck(hir_id.owner).qpath_res(qpath, hir_id)
+                    } else {
+                        Res::Err
+                    }
+                }
             },
 
             Node::Binding(&hir::Pat {

compiler/rustc_save_analysis/src/sig.rs

@@ -262,7 +262,7 @@ impl<'hir> Sig for hir::Ty<'hir> {
                 } else {
                     let start = offset + prefix.len() + 5;
                     let end = start + name.len();
-                    // FIXME should put the proper path in there, not elipses.
+                    // FIXME should put the proper path in there, not ellipsis.
                     Ok(Signature {
                         text: prefix + "...::" + &name,
                         defs: vec![],
@@ -272,7 +272,7 @@ impl<'hir> Sig for hir::Ty<'hir> {
             }
             hir::TyKind::Path(hir::QPath::TypeRelative(ty, segment)) => {
                 let nested_ty = ty.make(offset + 1, id, scx)?;
-                let prefix = format!("<{}>::", nested_ty.text,);
+                let prefix = format!("<{}>::", nested_ty.text);
 
                 let name = path_segment_to_string(segment);
                 let res = scx.get_path_res(id.ok_or("Missing id for Path")?);
@@ -551,7 +551,7 @@ impl<'hir> Sig for hir::Item<'hir> {
                 // FIXME where clause
             }
             hir::ItemKind::ForeignMod(_) => Err("extern mod"),
-            hir::ItemKind::GlobalAsm(_) => Err("glboal asm"),
+            hir::ItemKind::GlobalAsm(_) => Err("global asm"),
             hir::ItemKind::ExternCrate(_) => Err("extern crate"),
             hir::ItemKind::OpaqueTy(..) => Err("opaque type"),
             // FIXME should implement this (e.g., pub use).

compiler/rustc_session/src/lint/builtin.rs

@@ -2648,7 +2648,7 @@ declare_lint! {
 }
 
 declare_lint! {
-    /// The `uninhabited_static` lint detects uninhbaited statics.
+    /// The `uninhabited_static` lint detects uninhabited statics.
     ///
     /// ### Example
     ///

compiler/rustc_span/src/symbol.rs

@@ -467,6 +467,7 @@ symbols! {
         encode,
         env,
         eq,
+        ermsb_target_feature,
         err,
         exact_div,
         except,

compiler/rustc_typeck/src/collect.rs

@@ -2409,6 +2409,7 @@ fn from_target_feature(
                 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
                 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
                 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
+                Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
                 Some(name) => bug!("unknown target feature gate {}", name),
                 None => true,
             };

config.toml.example

@@ -527,7 +527,8 @@ changelog-seen = 2
 #test-compare-mode = false
 
 # Use LLVM libunwind as the implementation for Rust's unwinder.
-#llvm-libunwind = false
+# Accepted values are 'in-tree' (formerly true), 'system' or 'no' (formerly false).
+#llvm-libunwind = 'no'
 
 # Enable Windows Control Flow Guard checks in the standard library.
 # This only applies from stage 1 onwards, and only for Windows targets.

library/alloc/src/vec.rs

@@ -2566,7 +2566,7 @@ __impl_slice_eq1! { [const N: usize] Vec<A>, &[B; N], #[stable(feature = "rust1"
 //__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &[B; N], }
 //__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &mut [B; N], }
 
-/// Implements comparison of vectors, lexicographically.
+/// Implements comparison of vectors, [lexicographically](core::cmp::Ord#lexicographical-comparison).
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: PartialOrd> PartialOrd for Vec<T> {
     #[inline]
@@ -2578,7 +2578,7 @@ impl<T: PartialOrd> PartialOrd for Vec<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Eq> Eq for Vec<T> {}
 
-/// Implements ordering of vectors, lexicographically.
+/// Implements ordering of vectors, [lexicographically](core::cmp::Ord#lexicographical-comparison).
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Ord> Ord for Vec<T> {
     #[inline]

library/core/src/array/mod.rs

@@ -344,7 +344,7 @@ impl<T: PartialOrd, const N: usize> PartialOrd for [T; N] {
     }
 }
 
-/// Implements comparison of arrays lexicographically.
+/// Implements comparison of arrays [lexicographically](Ord#lexicographical-comparison).
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Ord, const N: usize> Ord for [T; N] {
     #[inline]

library/core/src/cmp.rs

@@ -506,9 +506,19 @@ impl<T: Ord> Ord for Reverse<T> {
 /// ## Derivable
 ///
 /// This trait can be used with `#[derive]`. When `derive`d on structs, it will produce a
-/// lexicographic ordering based on the top-to-bottom declaration order of the struct's members.
+/// [lexicographic](https://en.wikipedia.org/wiki/Lexicographic_order) ordering based on the top-to-bottom declaration order of the struct's members.
 /// When `derive`d on enums, variants are ordered by their top-to-bottom discriminant order.
 ///
+/// ## Lexicographical comparison
+///
+/// Lexicographical comparison is an operation with the following properties:
+///  - Two sequences are compared element by element.
+///  - The first mismatching element defines which sequence is lexicographically less or greater than the other.
+///  - If one sequence is a prefix of another, the shorter sequence is lexicographically less than the other.
+///  - If two sequence have equivalent elements and are of the same length, then the sequences are lexicographically equal.
+///  - An empty sequence is lexicographically less than any non-empty sequence.
+///  - Two empty sequences are lexicographically equal.
+///
 /// ## How can I implement `Ord`?
 ///
 /// `Ord` requires that the type also be [`PartialOrd`] and [`Eq`] (which requires [`PartialEq`]).

library/core/src/iter/traits/iterator.rs

@@ -2851,7 +2851,7 @@ pub trait Iterator {
         Product::product(self)
     }
 
-    /// Lexicographically compares the elements of this [`Iterator`] with those
+    /// [Lexicographically](Ord#lexicographical-comparison) compares the elements of this [`Iterator`] with those
     /// of another.
     ///
     /// # Examples
@@ -2873,7 +2873,7 @@ pub trait Iterator {
         self.cmp_by(other, |x, y| x.cmp(&y))
     }
 
-    /// Lexicographically compares the elements of this [`Iterator`] with those
+    /// [Lexicographically](Ord#lexicographical-comparison) compares the elements of this [`Iterator`] with those
     /// of another with respect to the specified comparison function.
     ///
     /// # Examples
@@ -2925,7 +2925,7 @@ pub trait Iterator {
         }
     }
 
-    /// Lexicographically compares the elements of this [`Iterator`] with those
+    /// [Lexicographically](Ord#lexicographical-comparison) compares the elements of this [`Iterator`] with those
     /// of another.
     ///
     /// # Examples
@@ -2949,7 +2949,7 @@ pub trait Iterator {
         self.partial_cmp_by(other, |x, y| x.partial_cmp(&y))
     }
 
-    /// Lexicographically compares the elements of this [`Iterator`] with those
+    /// [Lexicographically](Ord#lexicographical-comparison) compares the elements of this [`Iterator`] with those
     /// of another with respect to the specified comparison function.
     ///
     /// # Examples
@@ -3089,7 +3089,7 @@ pub trait Iterator {
         !self.eq(other)
     }
 
-    /// Determines if the elements of this [`Iterator`] are lexicographically
+    /// Determines if the elements of this [`Iterator`] are [lexicographically](Ord#lexicographical-comparison)
     /// less than those of another.
     ///
     /// # Examples
@@ -3110,7 +3110,7 @@ pub trait Iterator {
         self.partial_cmp(other) == Some(Ordering::Less)
     }
 
-    /// Determines if the elements of this [`Iterator`] are lexicographically
+    /// Determines if the elements of this [`Iterator`] are [lexicographically](Ord#lexicographical-comparison)
     /// less or equal to those of another.
     ///
     /// # Examples
@@ -3131,7 +3131,7 @@ pub trait Iterator {
         matches!(self.partial_cmp(other), Some(Ordering::Less | Ordering::Equal))
     }
 
-    /// Determines if the elements of this [`Iterator`] are lexicographically
+    /// Determines if the elements of this [`Iterator`] are [lexicographically](Ord#lexicographical-comparison)
     /// greater than those of another.
     ///
     /// # Examples
@@ -3152,7 +3152,7 @@ pub trait Iterator {
         self.partial_cmp(other) == Some(Ordering::Greater)
     }
 
-    /// Determines if the elements of this [`Iterator`] are lexicographically
+    /// Determines if the elements of this [`Iterator`] are [lexicographically](Ord#lexicographical-comparison)
     /// greater than or equal to those of another.
     ///
     /// # Examples