Auto merge of #67964 - JohnTitor:rollup-pu5kosl, r=JohnTitor

Rollup of 13 pull requests

Successful merges:

 - #67566 (Add an unstable conversion from thread ID to u64)
 - #67671 (Account for `type X = impl Trait;` in lifetime suggestion)
 - #67727 (Stabilise vec::remove_item)
 - #67877 (Omit underscore constants from rustdoc)
 - #67880 (Handle multiple error fix suggestions carefuly)
 - #67898 (Improve hygiene of `newtype_index`)
 - #67908 (rustdoc: HTML escape const values)
 - #67909 (Fix ICE in const pretty printing and resolve FIXME)
 - #67929 (Formatting an example for method Vec.retain)
 - #67934 (Clean up E0178 explanation)
 - #67936 (fire "non_camel_case_types" for associated types)
 - #67943 (Missing module std in example.)
 - #67962 (Update books)

Failed merges:

r? @ghost

src/liballoc/tests/lib.rs

@@ -11,7 +11,6 @@
 #![feature(associated_type_bounds)]
 #![feature(binary_heap_into_iter_sorted)]
 #![feature(binary_heap_drain_sorted)]
-#![feature(vec_remove_item)]
 
 use std::collections::hash_map::DefaultHasher;
 use std::hash::{Hash, Hasher};

src/liballoc/vec.rs

@@ -1054,7 +1054,7 @@ impl<T> Vec<T> {
     ///
     /// ```
     /// let mut vec = vec![1, 2, 3, 4];
-    /// vec.retain(|&x| x%2 == 0);
+    /// vec.retain(|&x| x % 2 == 0);
     /// assert_eq!(vec, [2, 4]);
     /// ```
     ///
@@ -1696,14 +1696,13 @@ impl<T> Vec<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(vec_remove_item)]
     /// let mut vec = vec![1, 2, 3, 1];
     ///
     /// vec.remove_item(&1);
     ///
     /// assert_eq!(vec, vec![2, 3, 1]);
     /// ```
-    #[unstable(feature = "vec_remove_item", reason = "recently added", issue = "40062")]
+    #[stable(feature = "vec_remove_item", since = "1.42.0")]
     pub fn remove_item<V>(&mut self, item: &V) -> Option<T>
     where
         T: PartialEq<V>,

src/librustc/dep_graph/serialized.rs

@@ -2,7 +2,7 @@
 
 use crate::dep_graph::DepNode;
 use crate::ich::Fingerprint;
-use rustc_index::vec::{Idx, IndexVec};
+use rustc_index::vec::IndexVec;
 
 rustc_index::newtype_index! {
     pub struct SerializedDepNodeIndex { .. }

src/librustc/lib.rs

@@ -50,7 +50,6 @@
 #![feature(thread_local)]
 #![feature(trace_macros)]
 #![feature(trusted_len)]
-#![feature(vec_remove_item)]
 #![feature(stmt_expr_attributes)]
 #![feature(integer_atomics)]
 #![feature(test)]

src/librustc/middle/region.rs

@@ -14,7 +14,6 @@ use rustc_hir::Node;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_index::vec::Idx;
 use rustc_macros::HashStable;
 use rustc_span::{Span, DUMMY_SP};
 

src/librustc/ty/print/obsolete.rs

@@ -166,19 +166,12 @@ impl DefPathBasedNames<'tcx> {
     }
 
     // Pushes the the name of the specified const to the provided string.
-    // If `debug` is true, usually-unprintable consts (such as `Infer`) will be printed,
-    // as well as the unprintable types of constants (see `push_type_name` for more details).
-    pub fn push_const_name(&self, c: &Const<'tcx>, output: &mut String, debug: bool) {
-        if let ty::ConstKind::Value(_) = c.val {
-            // FIXME(const_generics): we could probably do a better job here.
-            write!(output, "{:?}", c).unwrap()
-        } else if debug {
-            write!(output, "{:?}", c).unwrap()
-        } else {
-            bug!("DefPathBasedNames: trying to create const name for unexpected const: {:?}", c,);
-        }
+    // If `debug` is true, the unprintable types of constants will be printed with `fmt::Debug`
+    // (see `push_type_name` for more details).
+    pub fn push_const_name(&self, ct: &Const<'tcx>, output: &mut String, debug: bool) {
+        write!(output, "{}", ct).unwrap();
         output.push_str(": ");
-        self.push_type_name(c.ty, output, debug);
+        self.push_type_name(ct.ty, output, debug);
     }
 
     pub fn push_def_path(&self, def_id: DefId, output: &mut String) {

src/librustc_error_codes/error_codes/E0178.md

@@ -1,16 +1,27 @@
-In types, the `+` type operator has low precedence, so it is often necessary
-to use parentheses.
+The `+` type operator was used in an ambiguous context.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0178
 trait Foo {}
 
 struct Bar<'a> {
-    w: &'a Foo + Copy,   // error, use &'a (Foo + Copy)
-    x: &'a Foo + 'a,     // error, use &'a (Foo + 'a)
-    y: &'a mut Foo + 'a, // error, use &'a mut (Foo + 'a)
-    z: fn() -> Foo + 'a, // error, use fn() -> (Foo + 'a)
+    x: &'a Foo + 'a,     // error!
+    y: &'a mut Foo + 'a, // error!
+    z: fn() -> Foo + 'a, // error!
+}
+```
+
+In types, the `+` type operator has low precedence, so it is often necessary
+to use parentheses:
+
+```
+trait Foo {}
+
+struct Bar<'a> {
+    x: &'a (Foo + 'a),     // ok!
+    y: &'a mut (Foo + 'a), // ok!
+    z: fn() -> (Foo + 'a), // ok!
 }
 ```
 

src/librustc_errors/emitter.rs

@@ -1530,7 +1530,7 @@ impl EmitterWriter {
 
             // This offset and the ones below need to be signed to account for replacement code
             // that is shorter than the original code.
-            let mut offset: isize = 0;
+            let mut offsets: Vec<(usize, isize)> = Vec::new();
             // Only show an underline in the suggestions if the suggestion is not the
             // entirety of the code being shown and the displayed code is not multiline.
             if show_underline {
@@ -1550,12 +1550,19 @@ impl EmitterWriter {
                         .map(|ch| unicode_width::UnicodeWidthChar::width(ch).unwrap_or(1))
                         .sum();
 
+                    let offset: isize = offsets
+                        .iter()
+                        .filter_map(
+                            |(start, v)| if span_start_pos <= *start { None } else { Some(v) },
+                        )
+                        .sum();
                     let underline_start = (span_start_pos + start) as isize + offset;
                     let underline_end = (span_start_pos + start + sub_len) as isize + offset;
+                    assert!(underline_start >= 0 && underline_end >= 0);
                     for p in underline_start..underline_end {
                         buffer.putc(
                             row_num,
-                            max_line_num_len + 3 + p as usize,
+                            ((max_line_num_len + 3) as isize + p) as usize,
                             '^',
                             Style::UnderlinePrimary,
                         );
@@ -1565,7 +1572,7 @@ impl EmitterWriter {
                         for p in underline_start - 1..underline_start + 1 {
                             buffer.putc(
                                 row_num,
-                                max_line_num_len + 3 + p as usize,
+                                ((max_line_num_len + 3) as isize + p) as usize,
                                 '-',
                                 Style::UnderlineSecondary,
                             );
@@ -1582,8 +1589,9 @@ impl EmitterWriter {
                     // length of the code to be substituted
                     let snippet_len = span_end_pos as isize - span_start_pos as isize;
                     // For multiple substitutions, use the position *after* the previous
-                    // substitutions have happened.
-                    offset += full_sub_len - snippet_len;
+                    // substitutions have happened, only when further substitutions are
+                    // located strictly after.
+                    offsets.push((span_end_pos, full_sub_len - snippet_len));
                 }
                 row_num += 1;
             }

src/librustc_hir/hir_id.rs

@@ -56,7 +56,6 @@ impl fmt::Display for HirId {
 rustc_data_structures::define_id_collections!(HirIdMap, HirIdSet, HirId);
 rustc_data_structures::define_id_collections!(ItemLocalMap, ItemLocalSet, ItemLocalId);
 
-use rustc_index::vec::Idx;
 rustc_index::newtype_index! {
     /// An `ItemLocalId` uniquely identifies something within a given "item-like";
     /// that is, within a `hir::Item`, `hir::TraitItem`, or `hir::ImplItem`. There is no

src/librustc_index/vec.rs

@@ -120,21 +120,21 @@ macro_rules! newtype_index {
         impl $type {
             $v const MAX_AS_U32: u32 = $max;
 
-            $v const MAX: $type = $type::from_u32_const($max);
+            $v const MAX: Self = Self::from_u32_const($max);
 
             #[inline]
             $v fn from_usize(value: usize) -> Self {
                 assert!(value <= ($max as usize));
                 unsafe {
-                    $type::from_u32_unchecked(value as u32)
+                    Self::from_u32_unchecked(value as u32)
                 }
             }
 
             #[inline]
             $v fn from_u32(value: u32) -> Self {
                 assert!(value <= $max);
                 unsafe {
-                    $type::from_u32_unchecked(value)
+                    Self::from_u32_unchecked(value)
                 }
             }
 
@@ -152,13 +152,13 @@ macro_rules! newtype_index {
                 ];
 
                 unsafe {
-                    $type { private: value }
+                    Self { private: value }
                 }
             }
 
             #[inline]
             $v const unsafe fn from_u32_unchecked(value: u32) -> Self {
-                $type { private: value }
+                Self { private: value }
             }
 
             /// Extracts the value of this index as an integer.
@@ -184,14 +184,14 @@ macro_rules! newtype_index {
             type Output = Self;
 
             fn add(self, other: usize) -> Self {
-                Self::new(self.index() + other)
+                Self::from_usize(self.index() + other)
             }
         }
 
-        impl Idx for $type {
+        impl $crate::vec::Idx for $type {
             #[inline]
             fn new(value: usize) -> Self {
-                Self::from(value)
+                Self::from_usize(value)
             }
 
             #[inline]
@@ -204,39 +204,39 @@ macro_rules! newtype_index {
             #[inline]
             fn steps_between(start: &Self, end: &Self) -> Option<usize> {
                 <usize as ::std::iter::Step>::steps_between(
-                    &Idx::index(*start),
-                    &Idx::index(*end),
+                    &Self::index(*start),
+                    &Self::index(*end),
                 )
             }
 
             #[inline]
             fn replace_one(&mut self) -> Self {
-                ::std::mem::replace(self, Self::new(1))
+                ::std::mem::replace(self, Self::from_u32(1))
             }
 
             #[inline]
             fn replace_zero(&mut self) -> Self {
-                ::std::mem::replace(self, Self::new(0))
+                ::std::mem::replace(self, Self::from_u32(0))
             }
 
             #[inline]
             fn add_one(&self) -> Self {
-                Self::new(Idx::index(*self) + 1)
+                Self::from_usize(Self::index(*self) + 1)
             }
 
             #[inline]
             fn sub_one(&self) -> Self {
-                Self::new(Idx::index(*self) - 1)
+                Self::from_usize(Self::index(*self) - 1)
             }
 
             #[inline]
             fn add_usize(&self, u: usize) -> Option<Self> {
-                Idx::index(*self).checked_add(u).map(Self::new)
+                Self::index(*self).checked_add(u).map(Self::from_usize)
             }
 
             #[inline]
             fn sub_usize(&self, u: usize) -> Option<Self> {
-                Idx::index(*self).checked_sub(u).map(Self::new)
+                Self::index(*self).checked_sub(u).map(Self::from_usize)
             }
         }
 
@@ -257,14 +257,14 @@ macro_rules! newtype_index {
         impl From<usize> for $type {
             #[inline]
             fn from(value: usize) -> Self {
-                $type::from_usize(value)
+                Self::from_usize(value)
             }
         }
 
         impl From<u32> for $type {
             #[inline]
             fn from(value: u32) -> Self {
-                $type::from_u32(value)
+                Self::from_u32(value)
             }
         }
 
@@ -409,7 +409,7 @@ macro_rules! newtype_index {
     (@decodable $type:ident) => (
         impl ::rustc_serialize::Decodable for $type {
             fn decode<D: ::rustc_serialize::Decoder>(d: &mut D) -> Result<Self, D::Error> {
-                d.read_u32().map(Self::from)
+                d.read_u32().map(Self::from_u32)
             }
         }
     );
@@ -500,7 +500,7 @@ macro_rules! newtype_index {
                    const $name:ident = $constant:expr,
                    $($tokens:tt)*) => (
         $(#[doc = $doc])*
-        pub const $name: $type = $type::from_u32_const($constant);
+        $v const $name: $type = $type::from_u32_const($constant);
         $crate::newtype_index!(
             @derives      [$($derives,)*]
             @attrs        [$(#[$attrs])*]
@@ -839,3 +839,6 @@ impl<I: Idx> FnMut<(usize,)> for IntoIdx<I> {
         I::new(n)
     }
 }
+
+#[cfg(test)]
+mod tests;

src/librustc_index/vec/tests.rs

@@ -0,0 +1,51 @@
+#![allow(dead_code)]
+newtype_index!(struct MyIdx { MAX = 0xFFFF_FFFA });
+
+#[test]
+fn index_size_is_optimized() {
+    use std::mem::size_of;
+
+    assert_eq!(size_of::<MyIdx>(), 4);
+    // Uses 0xFFFF_FFFB
+    assert_eq!(size_of::<Option<MyIdx>>(), 4);
+    // Uses 0xFFFF_FFFC
+    assert_eq!(size_of::<Option<Option<MyIdx>>>(), 4);
+    // Uses 0xFFFF_FFFD
+    assert_eq!(size_of::<Option<Option<Option<MyIdx>>>>(), 4);
+    // Uses 0xFFFF_FFFE
+    assert_eq!(size_of::<Option<Option<Option<Option<MyIdx>>>>>(), 4);
+    // Uses 0xFFFF_FFFF
+    assert_eq!(size_of::<Option<Option<Option<Option<Option<MyIdx>>>>>>(), 4);
+    // Uses a tag
+    assert_eq!(size_of::<Option<Option<Option<Option<Option<Option<MyIdx>>>>>>>(), 8);
+}
+
+#[test]
+fn range_iterator_iterates_forwards() {
+    let range = MyIdx::from_u32(1)..MyIdx::from_u32(4);
+    assert_eq!(
+        range.collect::<Vec<_>>(),
+        [MyIdx::from_u32(1), MyIdx::from_u32(2), MyIdx::from_u32(3)]
+    );
+}
+
+#[test]
+fn range_iterator_iterates_backwards() {
+    let range = MyIdx::from_u32(1)..MyIdx::from_u32(4);
+    assert_eq!(
+        range.rev().collect::<Vec<_>>(),
+        [MyIdx::from_u32(3), MyIdx::from_u32(2), MyIdx::from_u32(1)]
+    );
+}
+
+#[test]
+fn range_count_is_correct() {
+    let range = MyIdx::from_u32(1)..MyIdx::from_u32(4);
+    assert_eq!(range.count(), 3);
+}
+
+#[test]
+fn range_size_hint_is_correct() {
+    let range = MyIdx::from_u32(1)..MyIdx::from_u32(4);
+    assert_eq!(range.size_hint(), (3, Some(3)));
+}