Rollup of 15 pull requests

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/ich/impls_ty.rs

@@ -302,7 +302,7 @@ impl_stable_hash_for!(struct ty::FieldDef {
 impl_stable_hash_for!(
     impl<'tcx> for enum mir::interpret::ConstValue<'tcx> [ mir::interpret::ConstValue ] {
         Scalar(val),
-        ScalarPair(a, b),
+        Slice(a, b),
         ByRef(id, alloc, offset),
     }
 );

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/mir/interpret/pointer.rs

@@ -76,6 +76,8 @@ pub struct Pointer<Tag=(),Id=AllocId> {
     pub tag: Tag,
 }
 
+static_assert!(POINTER_SIZE: ::std::mem::size_of::<Pointer>() == 16);
+
 /// Produces a `Pointer` which points to the beginning of the Allocation
 impl From<AllocId> for Pointer {
     #[inline(always)]

src/librustc/mir/interpret/value.rs

@@ -22,22 +22,28 @@ pub enum ConstValue<'tcx> {
     /// Not using the enum `Value` to encode that this must not be `Undef`
     Scalar(Scalar),
 
-    /// Used only for *fat pointers* with layout::abi::ScalarPair
+    /// Used only for slices and strings (`&[T]`, `&str`, `*const [T]`, `*mut str`, `Box<str>`, ...)
     ///
-    /// Needed for pattern matching code related to slices and strings.
-    ScalarPair(Scalar, Scalar),
+    /// Empty slices don't necessarily have an address backed by an `AllocId`, thus we also need to
+    /// enable integer pointers. The `Scalar` type covers exactly those two cases. While we could
+    /// create dummy-`AllocId`s, the additional code effort for the conversions doesn't seem worth
+    /// it.
+    Slice(Scalar, u64),
 
     /// An allocation + offset into the allocation.
     /// Invariant: The AllocId matches the allocation.
     ByRef(AllocId, &'tcx Allocation, Size),
 }
 
+#[cfg(target_arch = "x86_64")]
+static_assert!(CONST_SIZE: ::std::mem::size_of::<ConstValue<'static>>() == 40);
+
 impl<'tcx> ConstValue<'tcx> {
     #[inline]
     pub fn try_to_scalar(&self) -> Option<Scalar> {
         match *self {
             ConstValue::ByRef(..) |
-            ConstValue::ScalarPair(..) => None,
+            ConstValue::Slice(..) => None,
             ConstValue::Scalar(val) => Some(val),
         }
     }
@@ -56,17 +62,8 @@ impl<'tcx> ConstValue<'tcx> {
     pub fn new_slice(
         val: Scalar,
         len: u64,
-        cx: &impl HasDataLayout
     ) -> Self {
-        ConstValue::ScalarPair(val, Scalar::Bits {
-            bits: len as u128,
-            size: cx.data_layout().pointer_size.bytes() as u8,
-        })
-    }
-
-    #[inline]
-    pub fn new_dyn_trait(val: Scalar, vtable: Pointer) -> Self {
-        ConstValue::ScalarPair(val, Scalar::Ptr(vtable))
+        ConstValue::Slice(val, len)
     }
 }
 
@@ -90,6 +87,8 @@ pub enum Scalar<Tag=(), Id=AllocId> {
     Ptr(Pointer<Tag, Id>),
 }
 
+static_assert!(SCALAR_SIZE: ::std::mem::size_of::<Scalar>() == 24);
+
 impl<Tag> fmt::Display for Scalar<Tag> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {