Auto merge of #57568 - Centril:rollup, r=Centril

Rollup of 16 pull requests

Successful merges:

 - #57351 (Don't actually create a full MIR stack frame when not needed)
 - #57353 (Optimise floating point `is_finite` (2x) and `is_infinite` (1.6x).)
 - #57412 (Improve the wording)
 - #57436 (save-analysis: use a fallback when access levels couldn't be computed)
 - #57453 (lldb_batchmode.py: try `import _thread` for Python 3)
 - #57454 (Some cleanups for core::fmt)
 - #57461 (Change `String` to `&'static str` in `ParseResult::Failure`.)
 - #57473 (std: Render large exit codes as hex on Windows)
 - #57474 (save-analysis: Get path def from parent in case there's no def for the path itself.)
 - #57494 (Speed up item_bodies for large match statements involving regions)
 - #57496 (re-do docs for core::cmp)
 - #57508 (rustdoc: Allow inlining of reexported crates and crate items)
 - #57547 (Use `ptr::eq` where applicable)
 - #57557 (resolve: Mark extern crate items as used in more cases)
 - #57560 (hygiene: Do not treat `Self` ctor as a local variable)
 - #57564 (Update the const fn tracking issue to the new metabug)

Failed merges:

r? @ghost

src/doc/unstable-book/src/language-features/const-fn.md

@@ -1,8 +1,8 @@
 # `const_fn`
 
-The tracking issue for this feature is: [#24111]
+The tracking issue for this feature is: [#57563]
 
-[#24111]: https://github.com/rust-lang/rust/issues/24111
+[#57563]: https://github.com/rust-lang/rust/issues/57563
 
 ------------------------
 

src/etc/lldb_batchmode.py

@@ -18,10 +18,15 @@
 import os
 import sys
 import threading
-import thread
 import re
 import time
 
+try:
+    import thread
+except ModuleNotFoundError:
+    # The `thread` module was renamed to `_thread` in Python 3.
+    import _thread as thread
+
 # Set this to True for additional output
 DEBUG_OUTPUT = False
 

src/libcore/cmp.rs

@@ -1,27 +1,22 @@
 //! Functionality for ordering and comparison.
 //!
-//! This module defines both [`PartialOrd`] and [`PartialEq`] traits which are used
-//! by the compiler to implement comparison operators. Rust programs may
-//! implement [`PartialOrd`] to overload the `<`, `<=`, `>`, and `>=` operators,
-//! and may implement [`PartialEq`] to overload the `==` and `!=` operators.
+//! This module contains various tools for ordering and comparing values. In
+//! summary:
 //!
-//! [`PartialOrd`]: trait.PartialOrd.html
-//! [`PartialEq`]: trait.PartialEq.html
+//! * [`Eq`] and [`PartialEq`] are traits that allow you to define total and
+//!   partial equality between values, respectively. Implementing them overloads
+//!   the `==` and `!=` operators.
+//! * [`Ord`] and [`PartialOrd`] are traits that allow you to define total and
+//!   partial orderings between values, respectively. Implementing them overloads
+//!   the `<`, `<=`, `>`, and `>=` operators.
+//! * [`Ordering`][cmp::Ordering] is an enum returned by the
+//!   main functions of [`Ord`] and [`PartialOrd`], and describes an ordering.
+//! * [`Reverse`][cmp::Reverse] is a struct that allows you to easily reverse
+//!   an ordering.
+//! * [`max`][cmp::max] and [`min`][cmp::min] are functions that build off of
+//!   [`Ord`] and allow you to find the maximum or minimum of two values.
 //!
-//! # Examples
-//!
-//! ```
-//! let x: u32 = 0;
-//! let y: u32 = 1;
-//!
-//! // these two lines are equivalent
-//! assert_eq!(x < y, true);
-//! assert_eq!(x.lt(&y), true);
-//!
-//! // these two lines are also equivalent
-//! assert_eq!(x == y, false);
-//! assert_eq!(x.eq(&y), false);
-//! ```
+//! For more details, see the respective documentation of each item in the list.
 
 #![stable(feature = "rust1", since = "1.0.0")]
 

src/libcore/fmt/mod.rs

@@ -191,29 +191,8 @@ pub trait Write {
     /// assert_eq!(&buf, "world");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    fn write_fmt(&mut self, args: Arguments) -> Result {
-        // This Adapter is needed to allow `self` (of type `&mut
-        // Self`) to be cast to a Write (below) without
-        // requiring a `Sized` bound.
-        struct Adapter<'a,T: ?Sized +'a>(&'a mut T);
-
-        impl<T: ?Sized> Write for Adapter<'_, T>
-            where T: Write
-        {
-            fn write_str(&mut self, s: &str) -> Result {
-                self.0.write_str(s)
-            }
-
-            fn write_char(&mut self, c: char) -> Result {
-                self.0.write_char(c)
-            }
-
-            fn write_fmt(&mut self, args: Arguments) -> Result {
-                self.0.write_fmt(args)
-            }
-        }
-
-        write(&mut Adapter(self), args)
+    fn write_fmt(mut self: &mut Self, args: Arguments) -> Result {
+        write(&mut self, args)
     }
 }
 
@@ -268,7 +247,7 @@ struct Void {
 /// family of functions. It contains a function to format the given value. At
 /// compile time it is ensured that the function and the value have the correct
 /// types, and then this struct is used to canonicalize arguments to one type.
-#[derive(Copy)]
+#[derive(Copy, Clone)]
 #[allow(missing_debug_implementations)]
 #[unstable(feature = "fmt_internals", reason = "internal to format_args!",
            issue = "0")]
@@ -278,14 +257,6 @@ pub struct ArgumentV1<'a> {
     formatter: fn(&Void, &mut Formatter) -> Result,
 }
 
-#[unstable(feature = "fmt_internals", reason = "internal to format_args!",
-           issue = "0")]
-impl Clone for ArgumentV1<'_> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-
 impl<'a> ArgumentV1<'a> {
     #[inline(never)]
     fn show_usize(x: &usize, f: &mut Formatter) -> Result {
@@ -1105,7 +1076,7 @@ impl<'a> Formatter<'a> {
                 self.args[i].as_usize()
             }
             rt::v1::Count::NextParam => {
-                self.curarg.next().and_then(|arg| arg.as_usize())
+                self.curarg.next()?.as_usize()
             }
         }
     }
@@ -1171,15 +1142,15 @@ impl<'a> Formatter<'a> {
             sign = Some('+'); width += 1;
         }
 
-        let mut prefixed = false;
-        if self.alternate() {
-            prefixed = true; width += prefix.chars().count();
+        let prefixed = self.alternate();
+        if prefixed {
+            width += prefix.chars().count();
         }
 
         // Writes the sign if it exists, and then the prefix if it was requested
         let write_prefix = |f: &mut Formatter| {
             if let Some(c) = sign {
-                f.buf.write_str(c.encode_utf8(&mut [0; 4]))?;
+                f.buf.write_char(c)?;
             }
             if prefixed { f.buf.write_str(prefix) }
             else { Ok(()) }
@@ -1341,7 +1312,7 @@ impl<'a> Formatter<'a> {
 
                 // remove the sign from the formatted parts
                 formatted.sign = b"";
-                width = if width < sign.len() { 0 } else { width - sign.len() };
+                width = width.saturating_sub(sign.len());
                 align = rt::v1::Alignment::Right;
                 self.fill = '0';
                 self.align = rt::v1::Alignment::Right;

src/libcore/num/f32.rs

@@ -161,6 +161,14 @@ impl f32 {
         self != self
     }
 
+    // FIXME(#50145): `abs` is publicly unavailable in libcore due to
+    // concerns about portability, so this implementation is for
+    // private use internally.
+    #[inline]
+    fn abs_private(self) -> f32 {
+        f32::from_bits(self.to_bits() & 0x7fff_ffff)
+    }
+
     /// Returns `true` if this value is positive infinity or negative infinity and
     /// false otherwise.
     ///
@@ -181,7 +189,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_infinite(self) -> bool {
-        self == INFINITY || self == NEG_INFINITY
+        self.abs_private() == INFINITY
     }
 
     /// Returns `true` if this number is neither infinite nor `NaN`.
@@ -203,7 +211,9 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_finite(self) -> bool {
-        !(self.is_nan() || self.is_infinite())
+        // There's no need to handle NaN separately: if self is NaN,
+        // the comparison is not true, exactly as desired.
+        self.abs_private() < INFINITY
     }
 
     /// Returns `true` if the number is neither zero, infinite,

src/libcore/num/f64.rs

@@ -161,6 +161,14 @@ impl f64 {
         self != self
     }
 
+    // FIXME(#50145): `abs` is publicly unavailable in libcore due to
+    // concerns about portability, so this implementation is for
+    // private use internally.
+    #[inline]
+    fn abs_private(self) -> f64 {
+        f64::from_bits(self.to_bits() & 0x7fff_ffff_ffff_ffff)
+    }
+
     /// Returns `true` if this value is positive infinity or negative infinity and
     /// false otherwise.
     ///
@@ -181,7 +189,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_infinite(self) -> bool {
-        self == INFINITY || self == NEG_INFINITY
+        self.abs_private() == INFINITY
     }
 
     /// Returns `true` if this number is neither infinite nor `NaN`.
@@ -203,7 +211,9 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_finite(self) -> bool {
-        !(self.is_nan() || self.is_infinite())
+        // There's no need to handle NaN separately: if self is NaN,
+        // the comparison is not true, exactly as desired.
+        self.abs_private() < INFINITY
     }
 
     /// Returns `true` if the number is neither zero, infinite,

src/libcore/str/pattern.rs

@@ -425,8 +425,7 @@ impl<'a> Pattern<'a> for char {
     #[inline]
     fn into_searcher(self, haystack: &'a str) -> Self::Searcher {
         let mut utf8_encoded = [0; 4];
-        self.encode_utf8(&mut utf8_encoded);
-        let utf8_size = self.len_utf8();
+        let utf8_size = self.encode_utf8(&mut utf8_encoded).len();
         CharSearcher {
             haystack,
             finger: 0,

src/librustc/infer/lexical_region_resolve/mod.rs

@@ -13,6 +13,7 @@ use rustc_data_structures::graph::implementation::{
     Direction, Graph, NodeIndex, INCOMING, OUTGOING,
 };
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
+use smallvec::SmallVec;
 use std::fmt;
 use std::u32;
 use ty::fold::TypeFoldable;
@@ -190,19 +191,24 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
             match *constraint {
                 Constraint::RegSubVar(a_region, b_vid) => {
                     let b_data = var_values.value_mut(b_vid);
-                    self.expand_node(a_region, b_vid, b_data)
+                    (self.expand_node(a_region, b_vid, b_data), false)
                 }
                 Constraint::VarSubVar(a_vid, b_vid) => match *var_values.value(a_vid) {
-                    VarValue::ErrorValue => false,
+                    VarValue::ErrorValue => (false, false),
                     VarValue::Value(a_region) => {
                         let b_node = var_values.value_mut(b_vid);
-                        self.expand_node(a_region, b_vid, b_node)
+                        let changed = self.expand_node(a_region, b_vid, b_node);
+                        let retain = match *b_node {
+                            VarValue::Value(ReStatic) | VarValue::ErrorValue => false,
+                            _ => true
+                        };
+                        (changed, retain)
                     }
                 },
                 Constraint::RegSubReg(..) | Constraint::VarSubReg(..) => {
                     // These constraints are checked after expansion
                     // is done, in `collect_errors`.
-                    false
+                    (false, false)
                 }
             }
         })
@@ -268,6 +274,13 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
 
     fn lub_concrete_regions(&self, a: Region<'tcx>, b: Region<'tcx>) -> Region<'tcx> {
         let tcx = self.tcx();
+
+        // Equal scopes can show up quite often, if the fixed point
+        // iteration converges slowly, skip them
+        if a == b {
+            return a;
+        }
+
         match (a, b) {
             (&ty::ReClosureBound(..), _)
             | (_, &ty::ReClosureBound(..))
@@ -710,21 +723,23 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
 
     fn iterate_until_fixed_point<F>(&self, tag: &str, mut body: F)
     where
-        F: FnMut(&Constraint<'tcx>, &SubregionOrigin<'tcx>) -> bool,
+        F: FnMut(&Constraint<'tcx>, &SubregionOrigin<'tcx>) -> (bool, bool),
     {
+        let mut constraints: SmallVec<[_; 16]> = self.data.constraints.iter().collect();
         let mut iteration = 0;
         let mut changed = true;
         while changed {
             changed = false;
             iteration += 1;
             debug!("---- {} Iteration {}{}", "#", tag, iteration);
-            for (constraint, origin) in &self.data.constraints {
-                let edge_changed = body(constraint, origin);
+            constraints.retain(|(constraint, origin)| {
+                let (edge_changed, retain) = body(constraint, origin);
                 if edge_changed {
                     debug!("Updated due to constraint {:?}", constraint);
                     changed = true;
                 }
-            }
+                retain
+            });
         }
         debug!("---- {} Complete after {} iteration(s)", tag, iteration);
     }

src/librustc/ty/context.rs

@@ -59,6 +59,7 @@ use std::hash::{Hash, Hasher};
 use std::fmt;
 use std::mem;
 use std::ops::{Deref, Bound};
+use std::ptr;
 use std::iter;
 use std::sync::mpsc;
 use std::sync::Arc;
@@ -168,7 +169,7 @@ impl<'gcx: 'tcx, 'tcx> CtxtInterners<'tcx> {
 
                 // Make sure we don't end up with inference
                 // types/regions in the global interner
-                if local as *const _ as usize == global as *const _ as usize {
+                if ptr::eq(local, global) {
                     bug!("Attempted to intern `{:?}` which contains \
                         inference types/regions in the global type context",
                         &ty_struct);
@@ -1135,9 +1136,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
     /// Returns true if self is the same as self.global_tcx().
     fn is_global(self) -> bool {
-        let local = self.interners as *const _;
-        let global = &self.global_interners as *const _;
-        local as usize == global as usize
+        ptr::eq(self.interners, &self.global_interners)
     }
 
     /// Create a type context and call the closure with a `TyCtxt` reference
@@ -1787,6 +1786,7 @@ pub mod tls {
     use std::fmt;
     use std::mem;
     use std::marker::PhantomData;
+    use std::ptr;
     use syntax_pos;
     use ty::query;
     use errors::{Diagnostic, TRACK_DIAGNOSTICS};
@@ -2021,8 +2021,7 @@ pub mod tls {
     {
         with_context(|context| {
             unsafe {
-                let gcx = tcx.gcx as *const _ as usize;
-                assert!(context.tcx.gcx as *const _ as usize == gcx);
+                assert!(ptr::eq(context.tcx.gcx, tcx.gcx));
                 let context: &ImplicitCtxt<'_, '_, '_> = mem::transmute(context);
                 f(context)
             }
@@ -2040,10 +2039,8 @@ pub mod tls {
     {
         with_context(|context| {
             unsafe {
-                let gcx = tcx.gcx as *const _ as usize;
-                let interners = tcx.interners as *const _ as usize;
-                assert!(context.tcx.gcx as *const _ as usize == gcx);
-                assert!(context.tcx.interners as *const _ as usize == interners);
+                assert!(ptr::eq(context.tcx.gcx, tcx.gcx));
+                assert!(ptr::eq(context.tcx.interners, tcx.interners));
                 let context: &ImplicitCtxt<'_, '_, '_> = mem::transmute(context);
                 f(context)
             }

src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -47,7 +47,7 @@ use syntax_pos::{self, Span, FileName};
 
 impl PartialEq for llvm::Metadata {
     fn eq(&self, other: &Self) -> bool {
-        self as *const _ == other as *const _
+        ptr::eq(self, other)
     }
 }