Auto merge of rust-lang#94845 - Dylan-DPC:rollup-3phylaq, r=Dylan-DPC

Rollup of 5 pull requests

Successful merges:

 - rust-lang#93283 (Fix for localized windows editions in testcase fn read_link() Issue#93211)
 - rust-lang#94592 (Fallback to top-level config.toml if not present in current directory, and remove fallback for env vars and CLI flags)
 - rust-lang#94776 (Optimize ascii::escape_default)
 - rust-lang#94840 (update `replace_bound_vars_with_placeholders` doc comment)
 - rust-lang#94842 (Remove unnecessary try_opt for operations that cannot fail)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_infer/src/infer/higher_ranked/mod.rs

@@ -58,14 +58,11 @@ impl<'a, 'tcx> CombineFields<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
- /// Replaces all regions (resp. types) bound by `binder` with placeholder
- /// regions (resp. types) and return a map indicating which bound-region
- /// placeholder region. This is the first step of checking subtyping
- /// when higher-ranked things are involved.
+ /// Replaces all bound variables (lifetimes, types, and constants) bound by
+ /// `binder` with placeholder variables.
  ///
- /// **Important:** You have to be careful to not leak these placeholders,
- /// for more information about how placeholders and HRTBs work, see
- /// the [rustc dev guide].
+ /// This is the first step of checking subtyping when higher-ranked things are involved.
+ /// For more details visit the relevant sections of the [rustc dev guide].
  ///
  /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
  pub fn replace_bound_vars_with_placeholders<T>(&self, binder: ty::Binder<'tcx, T>) -> T

library/core/src/ascii.rs

@@ -98,22 +98,20 @@ pub fn escape_default(c: u8) -> EscapeDefault {
  b'\'' => ([b'\\', b'\'', 0, 0], 2),
  b'"' => ([b'\\', b'"', 0, 0], 2),
  b'\x20'..=b'\x7e' => ([c, 0, 0, 0], 1),
- _ => ([b'\\', b'x', hexify(c >> 4), hexify(c & 0xf)], 4),
+ _ => {
+ let hex_digits: &[u8; 16] = b"0123456789abcdef";
+ ([b'\\', b'x', hex_digits[(c >> 4) as usize], hex_digits[(c & 0xf) as usize]], 4)
+ }
  };
 
  return EscapeDefault { range: 0..len, data };
-
- fn hexify(b: u8) -> u8 {
- match b {
- 0..=9 => b'0' + b,
- _ => b'a' + b - 10,
- }
- }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Iterator for EscapeDefault {
  type Item = u8;
+
+ #[inline]
  fn next(&mut self) -> Option<u8> {
  self.range.next().map(|i| self.data[i as usize])
  }

library/core/src/num/int_macros.rs

@@ -2166,15 +2166,17 @@ macro_rules! int_impl {
 
  let r = try_opt!(self.checked_rem(rhs));
  let m = if (r > 0 && rhs < 0) || (r < 0 && rhs > 0) {
- try_opt!(r.checked_add(rhs))
+ // r + rhs cannot overflow because they have opposite signs
+ r + rhs
  } else {
  r
  };
 
  if m == 0 {
  Some(self)
  } else {
- self.checked_add(try_opt!(rhs.checked_sub(m)))
+ // rhs - m cannot overflow because m has the same sign as rhs
+ self.checked_add(rhs - m)
  }
  }
 

library/core/src/num/uint_macros.rs

@@ -2119,7 +2119,8 @@ macro_rules! uint_impl {
  pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self> {
  match try_opt!(self.checked_rem(rhs)) {
  0 => Some(self),
- r => self.checked_add(try_opt!(rhs.checked_sub(r)))
+ // rhs - r cannot overflow because r is smaller than rhs
+ r => self.checked_add(rhs - r)
  }
  }
 

library/std/src/fs/tests.rs

@@ -1,5 +1,6 @@
 use crate::io::prelude::*;
 
+use crate::env;
 use crate::fs::{self, File, OpenOptions};
 use crate::io::{ErrorKind, SeekFrom};
 use crate::path::Path;
@@ -906,7 +907,14 @@ fn read_link() {
  // junction
  assert_eq!(check!(fs::read_link(r"C:\Users\Default User")), Path::new(r"C:\Users\Default"));
  // junction with special permissions
- assert_eq!(check!(fs::read_link(r"C:\Documents and Settings\")), Path::new(r"C:\Users"));
+ // Since not all localized windows versions contain the folder "Documents and Settings" in english,
+ // we will briefly check, if it exists and otherwise skip the test. Except during CI we will always execute the test.
+ if Path::new(r"C:\Documents and Settings\").exists() || env::var_os("CI").is_some() {
+ assert_eq!(
+ check!(fs::read_link(r"C:\Documents and Settings\")),
+ Path::new(r"C:\Users")
+ );
+ }
  }
  let tmpdir = tmpdir();
  let link = tmpdir.join("link");

src/bootstrap/bootstrap.py

@@ -1233,16 +1233,18 @@ def bootstrap(help_triggered):
  build.verbose = args.verbose
  build.clean = args.clean
 
- # Read from `--config`, then `RUST_BOOTSTRAP_CONFIG`, then fallback to `config.toml` (if it
- # exists).
+ # Read from `--config`, then `RUST_BOOTSTRAP_CONFIG`, then `./config.toml`,
+ # then `config.toml` in the root directory.
  toml_path = args.config or os.getenv('RUST_BOOTSTRAP_CONFIG')
- if not toml_path and os.path.exists('config.toml'):
+ using_default_path = toml_path is None
+ if using_default_path:
  toml_path = 'config.toml'
-
- if toml_path:
  if not os.path.exists(toml_path):
  toml_path = os.path.join(build.rust_root, toml_path)
 
+ # Give a hard error if `--config` or `RUST_BOOTSTRAP_CONFIG` are set to a missing path,
+ # but not if `config.toml` hasn't been created.
+ if not using_default_path or os.path.exists(toml_path):
  with open(toml_path) as config:
  build.config_toml = config.read()
 

src/bootstrap/config.rs

@@ -647,7 +647,8 @@ impl Config {
  let get_toml = |file: &Path| {
  use std::process;
 
- let contents = t!(fs::read_to_string(file), "`include` config not found");
+ let contents =
+ t!(fs::read_to_string(file), format!("config file {} not found", file.display()));
  match toml::from_str(&contents) {
  Ok(table) => table,
  Err(err) => {
@@ -657,14 +658,24 @@ impl Config {
  }
  };
 
- // check --config first, then `$RUST_BOOTSTRAP_CONFIG` first, then `config.toml`
+ // Read from `--config`, then `RUST_BOOTSTRAP_CONFIG`, then `./config.toml`, then `config.toml` in the root directory.
  let toml_path = flags
  .config
  .clone()
- .or_else(|| env::var_os("RUST_BOOTSTRAP_CONFIG").map(PathBuf::from))
- .unwrap_or_else(|| PathBuf::from("config.toml"));
- let mut toml =
- if toml_path.exists() { get_toml(&toml_path) } else { TomlConfig::default() };
+ .or_else(|| env::var_os("RUST_BOOTSTRAP_CONFIG").map(PathBuf::from));
+ let using_default_path = toml_path.is_none();
+ let mut toml_path = toml_path.unwrap_or_else(|| PathBuf::from("config.toml"));
+ if using_default_path && !toml_path.exists() {
+ toml_path = config.src.join(toml_path);
+ }
+
+ // Give a hard error if `--config` or `RUST_BOOTSTRAP_CONFIG` are set to a missing path,
+ // but not if `config.toml` hasn't been created.
+ let mut toml = if !using_default_path || toml_path.exists() {
+ get_toml(&toml_path)
+ } else {
+ TomlConfig::default()
+ };
 
  if let Some(include) = &toml.profile {
  let mut include_path = config.src.clone();