Rollup of 8 pull requests

Cargo.lock

@@ -2492,6 +2492,7 @@ dependencies = [
 name = "panic_abort"
 version = "0.0.0"
 dependencies = [
+ "alloc",
  "cfg-if 0.1.10",
  "compiler_builtins",
  "core",

compiler/rustc_errors/src/json.rs

@@ -493,7 +493,7 @@ impl DiagnosticSpanLine {
         h_end: usize,
     ) -> DiagnosticSpanLine {
         DiagnosticSpanLine {
-            text: sf.get_line(index).map_or(String::new(), |l| l.into_owned()),
+            text: sf.get_line(index).map_or_else(String::new, |l| l.into_owned()),
             highlight_start: h_start,
             highlight_end: h_end,
         }

compiler/rustc_middle/src/ty/instance.rs

@@ -216,9 +216,10 @@ impl<'tcx> InstanceDef<'tcx> {
             // drops of `Option::None` before LTO. We also respect the intent of
             // `#[inline]` on `Drop::drop` implementations.
             return ty.ty_adt_def().map_or(true, |adt_def| {
-                adt_def.destructor(tcx).map_or(adt_def.is_enum(), |dtor| {
-                    tcx.codegen_fn_attrs(dtor.did).requests_inline()
-                })
+                adt_def.destructor(tcx).map_or_else(
+                    || adt_def.is_enum(),
+                    |dtor| tcx.codegen_fn_attrs(dtor.did).requests_inline(),
+                )
             });
         }
         tcx.codegen_fn_attrs(self.def_id()).requests_inline()

compiler/rustc_middle/src/ty/query/on_disk_cache.rs

@@ -525,7 +525,7 @@ impl<'sess> OnDiskCache<'sess> {
     ) {
         let mut current_diagnostics = self.current_diagnostics.borrow_mut();
 
-        let x = current_diagnostics.entry(dep_node_index).or_insert(Vec::new());
+        let x = current_diagnostics.entry(dep_node_index).or_default();
 
         x.extend(Into::<Vec<_>>::into(diagnostics));
     }

compiler/rustc_mir/src/borrow_check/diagnostics/outlives_suggestion.rs

@@ -157,7 +157,7 @@ impl OutlivesSuggestionBuilder {
         debug!("Collected {:?}: {:?}", fr, outlived_fr);
 
         // Add to set of constraints for final help note.
-        self.constraints_to_add.entry(fr).or_insert(Vec::new()).push(outlived_fr);
+        self.constraints_to_add.entry(fr).or_default().push(outlived_fr);
     }
 
     /// Emit an intermediate note on the given `Diagnostic` if the involved regions are

compiler/rustc_parse_format/src/lib.rs

@@ -213,11 +213,13 @@ impl<'a> Iterator for Parser<'a> {
                         Some(String(self.string(pos + 1)))
                     } else {
                         let arg = self.argument();
-                        if let Some(end) = self.must_consume('}') {
-                            let start = self.to_span_index(pos);
-                            let end = self.to_span_index(end + 1);
+                        if let Some(rbrace_byte_idx) = self.must_consume('}') {
+                            let lbrace_inner_offset = self.to_span_index(pos);
+                            let rbrace_inner_offset = self.to_span_index(rbrace_byte_idx);
                             if self.is_literal {
-                                self.arg_places.push(start.to(end));
+                                self.arg_places.push(
+                                    lbrace_inner_offset.to(InnerOffset(rbrace_inner_offset.0 + 1)),
+                                );
                             }
                         }
                         Some(NextArgument(arg))

compiler/rustc_resolve/src/late.rs

@@ -2327,7 +2327,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
 
             ExprKind::Call(ref callee, ref arguments) => {
                 self.resolve_expr(callee, Some(expr));
-                let const_args = self.r.legacy_const_generic_args(callee).unwrap_or(Vec::new());
+                let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
                 for (idx, argument) in arguments.iter().enumerate() {
                     // Constant arguments need to be treated as AnonConst since
                     // that is how they will be later lowered to HIR.

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -184,7 +184,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                         PathResult::Module(ModuleOrUniformRoot::Module(module)) => module.res(),
                         _ => None,
                     }
-                    .map_or(String::new(), |res| format!("{} ", res.descr()));
+                    .map_or_else(String::new, |res| format!("{} ", res.descr()));
                 (mod_prefix, format!("`{}`", Segment::names_to_string(mod_path)))
             };
             (
@@ -1042,10 +1042,10 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                 if let Some(span) = self.def_span(def_id) {
                     err.span_label(span, &format!("`{}` defined here", path_str));
                 }
-                let fields =
-                    self.r.field_names.get(&def_id).map_or("/* fields */".to_string(), |fields| {
-                        vec!["_"; fields.len()].join(", ")
-                    });
+                let fields = self.r.field_names.get(&def_id).map_or_else(
+                    || "/* fields */".to_string(),
+                    |fields| vec!["_"; fields.len()].join(", "),
+                );
                 err.span_suggestion(
                     span,
                     "use the tuple variant pattern syntax instead",

compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs

@@ -163,61 +163,65 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             flags.push((sym::from_desugaring, None));
             flags.push((sym::from_desugaring, Some(format!("{:?}", k))));
         }
-        let generics = self.tcx.generics_of(def_id);
-        let self_ty = trait_ref.self_ty();
-        // This is also included through the generics list as `Self`,
-        // but the parser won't allow you to use it
-        flags.push((sym::_Self, Some(self_ty.to_string())));
-        if let Some(def) = self_ty.ty_adt_def() {
-            // We also want to be able to select self's original
-            // signature with no type arguments resolved
-            flags.push((sym::_Self, Some(self.tcx.type_of(def.did).to_string())));
-        }
 
-        for param in generics.params.iter() {
-            let value = match param.kind {
-                GenericParamDefKind::Type { .. } | GenericParamDefKind::Const { .. } => {
-                    trait_ref.substs[param.index as usize].to_string()
-                }
-                GenericParamDefKind::Lifetime => continue,
-            };
-            let name = param.name;
-            flags.push((name, Some(value)));
-        }
+        // Add all types without trimmed paths.
+        ty::print::with_no_trimmed_paths(|| {
+            let generics = self.tcx.generics_of(def_id);
+            let self_ty = trait_ref.self_ty();
+            // This is also included through the generics list as `Self`,
+            // but the parser won't allow you to use it
+            flags.push((sym::_Self, Some(self_ty.to_string())));
+            if let Some(def) = self_ty.ty_adt_def() {
+                // We also want to be able to select self's original
+                // signature with no type arguments resolved
+                flags.push((sym::_Self, Some(self.tcx.type_of(def.did).to_string())));
+            }
 
-        if let Some(true) = self_ty.ty_adt_def().map(|def| def.did.is_local()) {
-            flags.push((sym::crate_local, None));
-        }
+            for param in generics.params.iter() {
+                let value = match param.kind {
+                    GenericParamDefKind::Type { .. } | GenericParamDefKind::Const { .. } => {
+                        trait_ref.substs[param.index as usize].to_string()
+                    }
+                    GenericParamDefKind::Lifetime => continue,
+                };
+                let name = param.name;
+                flags.push((name, Some(value)));
+            }
 
-        // Allow targeting all integers using `{integral}`, even if the exact type was resolved
-        if self_ty.is_integral() {
-            flags.push((sym::_Self, Some("{integral}".to_owned())));
-        }
+            if let Some(true) = self_ty.ty_adt_def().map(|def| def.did.is_local()) {
+                flags.push((sym::crate_local, None));
+            }
 
-        if let ty::Array(aty, len) = self_ty.kind() {
-            flags.push((sym::_Self, Some("[]".to_owned())));
-            flags.push((sym::_Self, Some(format!("[{}]", aty))));
-            if let Some(def) = aty.ty_adt_def() {
-                // We also want to be able to select the array's type's original
-                // signature with no type arguments resolved
-                let type_string = self.tcx.type_of(def.did).to_string();
-                flags.push((sym::_Self, Some(format!("[{}]", type_string))));
+            // Allow targeting all integers using `{integral}`, even if the exact type was resolved
+            if self_ty.is_integral() {
+                flags.push((sym::_Self, Some("{integral}".to_owned())));
+            }
 
-                let len = len.val.try_to_value().and_then(|v| v.try_to_machine_usize(self.tcx));
-                let string = match len {
-                    Some(n) => format!("[{}; {}]", type_string, n),
-                    None => format!("[{}; _]", type_string),
-                };
-                flags.push((sym::_Self, Some(string)));
+            if let ty::Array(aty, len) = self_ty.kind() {
+                flags.push((sym::_Self, Some("[]".to_owned())));
+                flags.push((sym::_Self, Some(format!("[{}]", aty))));
+                if let Some(def) = aty.ty_adt_def() {
+                    // We also want to be able to select the array's type's original
+                    // signature with no type arguments resolved
+                    let type_string = self.tcx.type_of(def.did).to_string();
+                    flags.push((sym::_Self, Some(format!("[{}]", type_string))));
+
+                    let len = len.val.try_to_value().and_then(|v| v.try_to_machine_usize(self.tcx));
+                    let string = match len {
+                        Some(n) => format!("[{}; {}]", type_string, n),
+                        None => format!("[{}; _]", type_string),
+                    };
+                    flags.push((sym::_Self, Some(string)));
+                }
             }
-        }
-        if let ty::Dynamic(traits, _) = self_ty.kind() {
-            for t in traits.iter() {
-                if let ty::ExistentialPredicate::Trait(trait_ref) = t.skip_binder() {
-                    flags.push((sym::_Self, Some(self.tcx.def_path_str(trait_ref.def_id))))
+            if let ty::Dynamic(traits, _) = self_ty.kind() {
+                for t in traits.iter() {
+                    if let ty::ExistentialPredicate::Trait(trait_ref) = t.skip_binder() {
+                        flags.push((sym::_Self, Some(self.tcx.def_path_str(trait_ref.def_id))))
+                    }
                 }
             }
-        }
+        });
 
         if let Ok(Some(command)) =
             OnUnimplementedDirective::of_item(self.tcx, trait_ref.def_id, def_id)

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

@@ -81,8 +81,8 @@ fn _assert_is_object_safe(_: &dyn Iterator<Item = ()>) {}
     ),
     on(
         _Self = "[]",
-        label = "borrow the array with `&` or call `.iter()` on it to iterate over it",
-        note = "arrays are not iterators, but slices like the following are: `&[1, 2, 3]`"
+        label = "arrays do not yet implement `IntoIterator`; try using `std::array::IntoIter::new(arr)`",
+        note = "see <https://github.com/rust-lang/rust/pull/65819> for more details"
     ),
     on(
         _Self = "{integral}",

library/core/src/num/mod.rs

@@ -2,6 +2,7 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+use crate::ascii;
 use crate::intrinsics;
 use crate::mem;
 use crate::str::FromStr;
@@ -661,6 +662,31 @@ impl u8 {
     pub const fn is_ascii_control(&self) -> bool {
         matches!(*self, b'\0'..=b'\x1F' | b'\x7F')
     }
+
+    /// Returns an iterator that produces an escaped version of a `u8`,
+    /// treating it as an ASCII character.
+    ///
+    /// The behavior is identical to [`ascii::escape_default`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(inherent_ascii_escape)]
+    ///
+    /// assert_eq!("0", b'0'.escape_ascii().to_string());
+    /// assert_eq!("\\t", b'\t'.escape_ascii().to_string());
+    /// assert_eq!("\\r", b'\r'.escape_ascii().to_string());
+    /// assert_eq!("\\n", b'\n'.escape_ascii().to_string());
+    /// assert_eq!("\\'", b'\''.escape_ascii().to_string());
+    /// assert_eq!("\\\"", b'"'.escape_ascii().to_string());
+    /// assert_eq!("\\\\", b'\\'.escape_ascii().to_string());
+    /// assert_eq!("\\x9d", b'\x9d'.escape_ascii().to_string());
+    /// ```
+    #[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+    #[inline]
+    pub fn escape_ascii(&self) -> ascii::EscapeDefault {
+        ascii::escape_default(*self)
+    }
 }
 
 #[lang = "u16"]

library/core/src/slice/ascii.rs

@@ -1,6 +1,10 @@
 //! Operations on ASCII `[u8]`.
 
+use crate::ascii;
+use crate::fmt::{self, Write};
+use crate::iter;
 use crate::mem;
+use crate::ops;
 
 #[lang = "slice_u8"]
 #[cfg(not(test))]
@@ -55,6 +59,95 @@ impl [u8] {
             byte.make_ascii_lowercase();
         }
     }
+
+    /// Returns an iterator that produces an escaped version of this slice,
+    /// treating it as an ASCII string.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(inherent_ascii_escape)]
+    ///
+    /// let s = b"0\t\r\n'\"\\\x9d";
+    /// let escaped = s.escape_ascii().to_string();
+    /// assert_eq!(escaped, "0\\t\\r\\n\\'\\\"\\\\\\x9d");
+    /// ```
+    #[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+    pub fn escape_ascii(&self) -> EscapeAscii<'_> {
+        EscapeAscii { inner: self.iter().flat_map(EscapeByte) }
+    }
+}
+
+impl_fn_for_zst! {
+    #[derive(Clone)]
+    struct EscapeByte impl Fn = |byte: &u8| -> ascii::EscapeDefault {
+        ascii::escape_default(*byte)
+    };
+}
+
+/// An iterator over the escaped version of a byte slice.
+///
+/// This `struct` is created by the [`slice::escape_ascii`] method. See its
+/// documentation for more information.
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+#[derive(Clone)]
+pub struct EscapeAscii<'a> {
+    inner: iter::FlatMap<super::Iter<'a, u8>, ascii::EscapeDefault, EscapeByte>,
+}
+
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> iter::Iterator for EscapeAscii<'a> {
+    type Item = u8;
+    #[inline]
+    fn next(&mut self) -> Option<u8> {
+        self.inner.next()
+    }
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+    #[inline]
+    fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R
+    where
+        Fold: FnMut(Acc, Self::Item) -> R,
+        R: ops::Try<Ok = Acc>,
+    {
+        self.inner.try_fold(init, fold)
+    }
+    #[inline]
+    fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
+    where
+        Fold: FnMut(Acc, Self::Item) -> Acc,
+    {
+        self.inner.fold(init, fold)
+    }
+    #[inline]
+    fn last(mut self) -> Option<u8> {
+        self.next_back()
+    }
+}
+
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> iter::DoubleEndedIterator for EscapeAscii<'a> {
+    fn next_back(&mut self) -> Option<u8> {
+        self.inner.next_back()
+    }
+}
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> iter::ExactSizeIterator for EscapeAscii<'a> {}
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> iter::FusedIterator for EscapeAscii<'a> {}
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> fmt::Display for EscapeAscii<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.clone().try_for_each(|b| f.write_char(b as char))
+    }
+}
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> fmt::Debug for EscapeAscii<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.pad("EscapeAscii { .. }")
+    }
 }
 
 /// Returns `true` if any byte in the word `v` is nonascii (>= 128). Snarfed

library/core/src/slice/mod.rs

@@ -81,6 +81,9 @@ pub use index::SliceIndex;
 #[unstable(feature = "slice_range", issue = "76393")]
 pub use index::range;
 
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+pub use ascii::EscapeAscii;
+
 #[lang = "slice"]
 #[cfg(not(test))]
 impl<T> [T] {

library/panic_abort/Cargo.toml

@@ -13,6 +13,7 @@ bench = false
 doc = false
 
 [dependencies]
+alloc = { path = "../alloc" }
 cfg-if = { version = "0.1.8", features = ['rustc-dep-of-std'] }
 core = { path = "../core" }
 libc = { version = "0.2", default-features = false }