Use implicit capture syntax in format_args

This updates the standard library's documentation to use the new syntax. The
documentation is worthwhile to update as it should be more idiomatic
(particularly for features like this, which are nice for users to get acquainted
with). The general codebase is likely more hassle than benefit to update: it'll
hurt git blame, and generally updates can be done by folks updating the code if
(and when) that makes things more readable with the new format.

A few places in the compiler and library code are updated (mostly just due to
already having been done when this commit was first authored).

5 files changed, 6 insertions, 6 deletions

diff --git a/library/std/src/sys_common/backtrace.rs b/library/std/src/sys_common/backtrace.rs
index b0b55592f6f..31164afdc7b 100644
--- a/library/std/src/sys_common/backtrace.rs
+++ b/library/std/src/sys_common/backtrace.rs
@@ -174,7 +174,7 @@ pub fn output_filename(
         if let Some(cwd) = cwd {
             if let Ok(stripped) = file.strip_prefix(&cwd) {
                 if let Some(s) = stripped.to_str() {
-                    return write!(fmt, ".{}{}", path::MAIN_SEPARATOR, s);
+                    return write!(fmt, ".{}{s}", path::MAIN_SEPARATOR);
                 }
             }
         }
diff --git a/library/std/src/sys_common/net/tests.rs b/library/std/src/sys_common/net/tests.rs
index 7d45621e09a..ac75d9ebfc8 100644
--- a/library/std/src/sys_common/net/tests.rs
+++ b/library/std/src/sys_common/net/tests.rs
@@ -6,7 +6,7 @@ fn no_lookup_host_duplicates() {
     let mut addrs = HashMap::new();
     let lh = match LookupHost::try_from(("localhost", 0)) {
         Ok(lh) => lh,
-        Err(e) => panic!("couldn't resolve `localhost': {}", e),
+        Err(e) => panic!("couldn't resolve `localhost': {e}"),
     };
     for sa in lh {
         *addrs.entry(sa).or_insert(0) += 1;
diff --git a/library/std/src/sys_common/thread_parker/generic.rs b/library/std/src/sys_common/thread_parker/generic.rs
index d99e901bb5f..ffb61200e15 100644
--- a/library/std/src/sys_common/thread_parker/generic.rs
+++ b/library/std/src/sys_common/thread_parker/generic.rs
@@ -84,7 +84,7 @@ impl Parker {
         match self.state.swap(EMPTY, SeqCst) {
             NOTIFIED => {} // got a notification, hurray!
             PARKED => {}   // no notification, alas
-            n => panic!("inconsistent park_timeout state: {}", n),
+            n => panic!("inconsistent park_timeout state: {n}"),
         }
     }
 
diff --git a/library/std/src/sys_common/wtf8.rs b/library/std/src/sys_common/wtf8.rs
index 7a6e6246357..10ef6662115 100644
--- a/library/std/src/sys_common/wtf8.rs
+++ b/library/std/src/sys_common/wtf8.rs
@@ -830,7 +830,7 @@ pub unsafe fn slice_unchecked(s: &Wtf8, begin: usize, end: usize) -> &Wtf8 {
 #[inline(never)]
 pub fn slice_error_fail(s: &Wtf8, begin: usize, end: usize) -> ! {
     assert!(begin <= end);
-    panic!("index {} and/or {} in `{:?}` do not lie on character boundary", begin, end, s);
+    panic!("index {begin} and/or {end} in `{s:?}` do not lie on character boundary");
 }
 
 /// Iterator for the code points of a WTF-8 string.
diff --git a/library/std/src/sys_common/wtf8/tests.rs b/library/std/src/sys_common/wtf8/tests.rs
index 1bafbaa6939..931996791fb 100644
--- a/library/std/src/sys_common/wtf8/tests.rs
+++ b/library/std/src/sys_common/wtf8/tests.rs
@@ -266,7 +266,7 @@ fn wtf8buf_extend() {
 fn wtf8buf_show() {
     let mut string = Wtf8Buf::from_str("a\té \u{7f}💩\r");
     string.push(CodePoint::from_u32(0xD800).unwrap());
-    assert_eq!(format!("{:?}", string), "\"a\\té \\u{7f}\u{1f4a9}\\r\\u{d800}\"");
+    assert_eq!(format!("{string:?}"), "\"a\\té \\u{7f}\u{1f4a9}\\r\\u{d800}\"");
 }
 
 #[test]
@@ -278,7 +278,7 @@ fn wtf8buf_as_slice() {
 fn wtf8buf_show_str() {
     let text = "a\té 💩\r";
     let string = Wtf8Buf::from_str(text);
-    assert_eq!(format!("{:?}", text), format!("{:?}", string));
+    assert_eq!(format!("{text:?}"), format!("{string:?}"));
 }
 
 #[test]