Auto merge of #66691 - dtolnay:fmt0, r=sfackler

Format libcore with rustfmt

I am interested in whether we can begin cautious incremental progress on #66688 and assess along the way whether we can keep the disruption sufficiently small.

This PR applies rustfmt with default settings to files in src/libcore *that are not involved in any currently open PR* to minimize merge conflicts. The list of files involved in open PRs was determined by querying GitHub's GraphQL API  [with this script](https://gist.github.com/dtolnay/aa9c34993dc051a4f344d1b10e4487e8).

With the list of files from the script in `outstanding_files`, the relevant commands were:

```console
$ find src/libcore -name '*.rs' | xargs rustfmt --edition=2018
$ rg libcore outstanding_files | xargs git checkout --
```

Repeating this process several months apart should get us coverage of most of the rest of libcore.

src/libcore/ascii.rs

@@ -12,8 +12,8 @@
 #![stable(feature = "core_ascii", since = "1.26.0")]
 
 use crate::fmt;
-use crate::ops::Range;
 use crate::iter::FusedIterator;
+use crate::ops::Range;
 use crate::str::from_utf8_unchecked;
 
 /// An iterator over the escaped version of a byte.
@@ -100,15 +100,15 @@ pub fn escape_default(c: u8) -> EscapeDefault {
         b'\\' => ([b'\\', b'\\', 0, 0], 2),
         b'\'' => ([b'\\', b'\'', 0, 0], 2),
         b'"' => ([b'\\', b'"', 0, 0], 2),
-        b'\x20' ..= b'\x7e' => ([c, 0, 0, 0], 1),
+        b'\x20'..=b'\x7e' => ([c, 0, 0, 0], 1),
         _ => ([b'\\', b'x', hexify(c >> 4), hexify(c & 0xf)], 4),
     };
 
     return EscapeDefault { range: 0..len, data };
 
     fn hexify(b: u8) -> u8 {
         match b {
-            0 ..= 9 => b'0' + b,
+            0..=9 => b'0' + b,
             _ => b'a' + b - 10,
         }
     }
@@ -117,9 +117,15 @@ pub fn escape_default(c: u8) -> EscapeDefault {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Iterator for EscapeDefault {
     type Item = u8;
-    fn next(&mut self) -> Option<u8> { self.range.next().map(|i| self.data[i]) }
-    fn size_hint(&self) -> (usize, Option<usize>) { self.range.size_hint() }
-    fn last(mut self) -> Option<u8> { self.next_back() }
+    fn next(&mut self) -> Option<u8> {
+        self.range.next().map(|i| self.data[i])
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.range.size_hint()
+    }
+    fn last(mut self) -> Option<u8> {
+        self.next_back()
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl DoubleEndedIterator for EscapeDefault {

src/libcore/char/convert.rs

@@ -158,7 +158,6 @@ impl From<u8> for char {
     }
 }
 
-
 /// An error which can be returned when parsing a char.
 #[stable(feature = "char_from_str", since = "1.20.0")]
 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -167,16 +166,16 @@ pub struct ParseCharError {
 }
 
 impl ParseCharError {
-    #[unstable(feature = "char_error_internals",
-               reason = "this method should not be available publicly",
-               issue = "0")]
+    #[unstable(
+        feature = "char_error_internals",
+        reason = "this method should not be available publicly",
+        issue = "0"
+    )]
     #[doc(hidden)]
     pub fn __description(&self) -> &str {
         match self.kind {
-            CharErrorKind::EmptyString => {
-                "cannot parse char from empty string"
-            },
-            CharErrorKind::TooManyChars => "too many characters in string"
+            CharErrorKind::EmptyString => "cannot parse char from empty string",
+            CharErrorKind::TooManyChars => "too many characters in string",
         }
     }
 }
@@ -194,7 +193,6 @@ impl fmt::Display for ParseCharError {
     }
 }
 
-
 #[stable(feature = "char_from_str", since = "1.20.0")]
 impl FromStr for char {
     type Err = ParseCharError;
@@ -203,18 +201,13 @@ impl FromStr for char {
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         let mut chars = s.chars();
         match (chars.next(), chars.next()) {
-            (None, _) => {
-                Err(ParseCharError { kind: CharErrorKind::EmptyString })
-            },
+            (None, _) => Err(ParseCharError { kind: CharErrorKind::EmptyString }),
             (Some(c), None) => Ok(c),
-            _ => {
-                Err(ParseCharError { kind: CharErrorKind::TooManyChars })
-            }
+            _ => Err(ParseCharError { kind: CharErrorKind::TooManyChars }),
         }
     }
 }
 
-
 #[stable(feature = "try_from", since = "1.34.0")]
 impl TryFrom<u32> for char {
     type Error = CharTryFromError;
@@ -304,11 +297,7 @@ pub fn from_digit(num: u32, radix: u32) -> Option<char> {
     }
     if num < radix {
         let num = num as u8;
-        if num < 10 {
-            Some((b'0' + num) as char)
-        } else {
-            Some((b'a' + num - 10) as char)
-        }
+        if num < 10 { Some((b'0' + num) as char) } else { Some((b'a' + num - 10) as char) }
     } else {
         None
     }

src/libcore/char/decode.rs

@@ -8,7 +8,8 @@ use super::from_u32_unchecked;
 #[stable(feature = "decode_utf16", since = "1.9.0")]
 #[derive(Clone, Debug)]
 pub struct DecodeUtf16<I>
-    where I: Iterator<Item = u16>
+where
+    I: Iterator<Item = u16>,
 {
     iter: I,
     buf: Option<u16>,
@@ -70,10 +71,7 @@ pub struct DecodeUtf16Error {
 #[stable(feature = "decode_utf16", since = "1.9.0")]
 #[inline]
 pub fn decode_utf16<I: IntoIterator<Item = u16>>(iter: I) -> DecodeUtf16<I::IntoIter> {
-    DecodeUtf16 {
-        iter: iter.into_iter(),
-        buf: None,
-    }
+    DecodeUtf16 { iter: iter.into_iter(), buf: None }
 }
 
 #[stable(feature = "decode_utf16", since = "1.9.0")]
@@ -83,7 +81,7 @@ impl<I: Iterator<Item = u16>> Iterator for DecodeUtf16<I> {
     fn next(&mut self) -> Option<Result<char, DecodeUtf16Error>> {
         let u = match self.buf.take() {
             Some(buf) => buf,
-            None => self.iter.next()?
+            None => self.iter.next()?,
         };
 
         if u < 0xD800 || 0xDFFF < u {

src/libcore/char/methods.rs

@@ -130,11 +130,7 @@ impl char {
             }
         };
 
-        if val < radix {
-            Some(val)
-        } else {
-            None
-        }
+        if val < radix { Some(val) } else { None }
     }
 
     /// Returns an iterator that yields the hexadecimal Unicode escape of a
@@ -950,11 +946,7 @@ impl char {
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_uppercase(&self) -> char {
-        if self.is_ascii() {
-            (*self as u8).to_ascii_uppercase() as char
-        } else {
-            *self
-        }
+        if self.is_ascii() { (*self as u8).to_ascii_uppercase() as char } else { *self }
     }
 
     /// Makes a copy of the value in its ASCII lower case equivalent.
@@ -982,11 +974,7 @@ impl char {
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_lowercase(&self) -> char {
-        if self.is_ascii() {
-            (*self as u8).to_ascii_lowercase() as char
-        } else {
-            *self
-        }
+        if self.is_ascii() { (*self as u8).to_ascii_lowercase() as char } else { *self }
     }
 
     /// Checks that two values are an ASCII case-insensitive match.

src/libcore/char/mod.rs

@@ -24,14 +24,14 @@ mod decode;
 mod methods;
 
 // stable re-exports
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use self::convert::{from_u32, from_digit};
 #[stable(feature = "char_from_unchecked", since = "1.5.0")]
 pub use self::convert::from_u32_unchecked;
-#[stable(feature = "char_from_str", since = "1.20.0")]
-pub use self::convert::ParseCharError;
 #[stable(feature = "try_from", since = "1.34.0")]
 pub use self::convert::CharTryFromError;
+#[stable(feature = "char_from_str", since = "1.20.0")]
+pub use self::convert::ParseCharError;
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use self::convert::{from_digit, from_u32};
 #[stable(feature = "decode_utf16", since = "1.9.0")]
 pub use self::decode::{decode_utf16, DecodeUtf16, DecodeUtf16Error};
 
@@ -45,13 +45,13 @@ use crate::fmt::{self, Write};
 use crate::iter::FusedIterator;
 
 // UTF-8 ranges and tags for encoding characters
-const TAG_CONT: u8     = 0b1000_0000;
-const TAG_TWO_B: u8    = 0b1100_0000;
-const TAG_THREE_B: u8  = 0b1110_0000;
-const TAG_FOUR_B: u8   = 0b1111_0000;
-const MAX_ONE_B: u32   =     0x80;
-const MAX_TWO_B: u32   =    0x800;
-const MAX_THREE_B: u32 =  0x10000;
+const TAG_CONT: u8 = 0b1000_0000;
+const TAG_TWO_B: u8 = 0b1100_0000;
+const TAG_THREE_B: u8 = 0b1110_0000;
+const TAG_FOUR_B: u8 = 0b1111_0000;
+const MAX_ONE_B: u32 = 0x80;
+const MAX_TWO_B: u32 = 0x800;
+const MAX_THREE_B: u32 = 0x10000;
 
 /*
     Lu  Uppercase_Letter        an uppercase letter
@@ -190,11 +190,11 @@ impl Iterator for EscapeUnicode {
         match self.state {
             EscapeUnicodeState::Done => None,
 
-            EscapeUnicodeState::RightBrace |
-            EscapeUnicodeState::Value |
-            EscapeUnicodeState::LeftBrace |
-            EscapeUnicodeState::Type |
-            EscapeUnicodeState::Backslash => Some('}'),
+            EscapeUnicodeState::RightBrace
+            | EscapeUnicodeState::Value
+            | EscapeUnicodeState::LeftBrace
+            | EscapeUnicodeState::Type
+            | EscapeUnicodeState::Backslash => Some('}'),
         }
     }
 }
@@ -204,14 +204,15 @@ impl ExactSizeIterator for EscapeUnicode {
     #[inline]
     fn len(&self) -> usize {
         // The match is a single memory access with no branching
-        self.hex_digit_idx + match self.state {
-            EscapeUnicodeState::Done => 0,
-            EscapeUnicodeState::RightBrace => 1,
-            EscapeUnicodeState::Value => 2,
-            EscapeUnicodeState::LeftBrace => 3,
-            EscapeUnicodeState::Type => 4,
-            EscapeUnicodeState::Backslash => 5,
-        }
+        self.hex_digit_idx
+            + match self.state {
+                EscapeUnicodeState::Done => 0,
+                EscapeUnicodeState::RightBrace => 1,
+                EscapeUnicodeState::Value => 2,
+                EscapeUnicodeState::LeftBrace => 3,
+                EscapeUnicodeState::Type => 4,
+                EscapeUnicodeState::Backslash => 5,
+            }
     }
 }
 
@@ -238,7 +239,7 @@ impl fmt::Display for EscapeUnicode {
 #[derive(Clone, Debug)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct EscapeDefault {
-    state: EscapeDefaultState
+    state: EscapeDefaultState,
 }
 
 #[derive(Clone, Debug)]
@@ -284,24 +285,20 @@ impl Iterator for EscapeDefault {
             EscapeDefaultState::Backslash(c) if n == 0 => {
                 self.state = EscapeDefaultState::Char(c);
                 Some('\\')
-            },
+            }
             EscapeDefaultState::Backslash(c) if n == 1 => {
                 self.state = EscapeDefaultState::Done;
                 Some(c)
-            },
+            }
             EscapeDefaultState::Backslash(_) => {
                 self.state = EscapeDefaultState::Done;
                 None
-            },
+            }
             EscapeDefaultState::Char(c) => {
                 self.state = EscapeDefaultState::Done;
 
-                if n == 0 {
-                    Some(c)
-                } else {
-                    None
-                }
-            },
+                if n == 0 { Some(c) } else { None }
+            }
             EscapeDefaultState::Done => None,
             EscapeDefaultState::Unicode(ref mut i) => i.nth(n),
         }
@@ -355,12 +352,16 @@ pub struct EscapeDebug(EscapeDefault);
 #[stable(feature = "char_escape_debug", since = "1.20.0")]
 impl Iterator for EscapeDebug {
     type Item = char;
-    fn next(&mut self) -> Option<char> { self.0.next() }
-    fn size_hint(&self) -> (usize, Option<usize>) { self.0.size_hint() }
+    fn next(&mut self) -> Option<char> {
+        self.0.next()
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.0.size_hint()
+    }
 }
 
 #[stable(feature = "char_escape_debug", since = "1.20.0")]
-impl ExactSizeIterator for EscapeDebug { }
+impl ExactSizeIterator for EscapeDebug {}
 
 #[stable(feature = "fused", since = "1.26.0")]
 impl FusedIterator for EscapeDebug {}
@@ -440,7 +441,7 @@ impl CaseMappingIter {
     fn new(chars: [char; 3]) -> CaseMappingIter {
         if chars[2] == '\0' {
             if chars[1] == '\0' {
-                CaseMappingIter::One(chars[0])  // Including if chars[0] == '\0'
+                CaseMappingIter::One(chars[0]) // Including if chars[0] == '\0'
             } else {
                 CaseMappingIter::Two(chars[0], chars[1])
             }
@@ -493,9 +494,7 @@ impl fmt::Display for CaseMappingIter {
                 f.write_char(b)?;
                 f.write_char(c)
             }
-            CaseMappingIter::One(c) => {
-                f.write_char(c)
-            }
+            CaseMappingIter::One(c) => f.write_char(c),
             CaseMappingIter::Zero => Ok(()),
         }
     }