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).

12 files changed, 40 insertions, 40 deletions

diff --git a/library/test/src/cli.rs b/library/test/src/cli.rs
index b39701a3d42..000f5fa3f58 100644
--- a/library/test/src/cli.rs
+++ b/library/test/src/cli.rs
@@ -149,7 +149,7 @@ fn optgroups() -> getopts::Options {
 }
 
 fn usage(binary: &str, options: &getopts::Options) {
-    let message = format!("Usage: {} [OPTIONS] [FILTERS...]", binary);
+    let message = format!("Usage: {binary} [OPTIONS] [FILTERS...]");
     println!(
         r#"{usage}
 
@@ -360,7 +360,7 @@ fn get_shuffle_seed(matches: &getopts::Matches, allow_unstable: bool) -> OptPart
         shuffle_seed = match env::var("RUST_TEST_SHUFFLE_SEED") {
             Ok(val) => match val.parse::<u64>() {
                 Ok(n) => Some(n),
-                Err(_) => panic!("RUST_TEST_SHUFFLE_SEED is `{}`, should be a number.", val),
+                Err(_) => panic!("RUST_TEST_SHUFFLE_SEED is `{val}`, should be a number."),
             },
             Err(_) => None,
         };
diff --git a/library/test/src/console.rs b/library/test/src/console.rs
index 22fcd77dccc..c7e8507113e 100644
--- a/library/test/src/console.rs
+++ b/library/test/src/console.rs
@@ -114,11 +114,11 @@ impl ConsoleTestState {
                 match *result {
                     TestResult::TrOk => "ok".to_owned(),
                     TestResult::TrFailed => "failed".to_owned(),
-                    TestResult::TrFailedMsg(ref msg) => format!("failed: {}", msg),
+                    TestResult::TrFailedMsg(ref msg) => format!("failed: {msg}"),
                     TestResult::TrIgnored => {
                         #[cfg(not(bootstrap))]
                         if let Some(msg) = ignore_message {
-                            format!("ignored, {}", msg)
+                            format!("ignored, {msg}")
                         } else {
                             "ignored".to_owned()
                         }
@@ -132,7 +132,7 @@ impl ConsoleTestState {
             )
         })?;
         if let Some(exec_time) = exec_time {
-            self.write_log(|| format!(" <{}>", exec_time))?;
+            self.write_log(|| format!(" <{exec_time}>"))?;
         }
         self.write_log(|| "\n")
     }
@@ -171,14 +171,14 @@ pub fn list_tests_console(opts: &TestOpts, tests: Vec<TestDescAndFn>) -> io::Res
             }
         };
 
-        writeln!(output, "{}: {}", name, fntype)?;
-        st.write_log(|| format!("{} {}\n", fntype, name))?;
+        writeln!(output, "{name}: {fntype}")?;
+        st.write_log(|| format!("{fntype} {name}\n"))?;
     }
 
     fn plural(count: u32, s: &str) -> String {
         match count {
-            1 => format!("{} {}", 1, s),
-            n => format!("{} {}s", n, s),
+            1 => format!("1 {s}"),
+            n => format!("{n} {s}s"),
         }
     }
 
@@ -218,7 +218,7 @@ fn handle_test_result(st: &mut ConsoleTestState, completed_test: CompletedTest)
         TestResult::TrFailedMsg(msg) => {
             st.failed += 1;
             let mut stdout = stdout;
-            stdout.extend_from_slice(format!("note: {}", msg).as_bytes());
+            stdout.extend_from_slice(format!("note: {msg}").as_bytes());
             st.failures.push((test, stdout));
         }
         TestResult::TrTimedFail => {
diff --git a/library/test/src/formatters/junit.rs b/library/test/src/formatters/junit.rs
index 54e9860ab54..e6fb4f5707b 100644
--- a/library/test/src/formatters/junit.rs
+++ b/library/test/src/formatters/junit.rs
@@ -97,7 +97,7 @@ impl<T: Write> OutputFormatter for JunitFormatter<T> {
                         test_name,
                         duration.as_secs_f64()
                     ))?;
-                    self.write_message(&*format!("<failure message=\"{}\" type=\"assert\"/>", m))?;
+                    self.write_message(&*format!("<failure message=\"{m}\" type=\"assert\"/>"))?;
                     self.write_message("</testcase>")?;
                 }
 
diff --git a/library/test/src/formatters/pretty.rs b/library/test/src/formatters/pretty.rs
index 041df5216d7..f55d390aa56 100644
--- a/library/test/src/formatters/pretty.rs
+++ b/library/test/src/formatters/pretty.rs
@@ -96,7 +96,7 @@ impl<T: Write> PrettyFormatter<T> {
         exec_time: Option<&time::TestExecTime>,
     ) -> io::Result<()> {
         if let (Some(opts), Some(time)) = (self.time_options, exec_time) {
-            let time_str = format!(" <{}>", time);
+            let time_str = format!(" <{time}>");
 
             let color = if self.use_color {
                 if opts.is_critical(desc, time) {
@@ -124,7 +124,7 @@ impl<T: Write> PrettyFormatter<T> {
         inputs: &Vec<(TestDesc, Vec<u8>)>,
         results_type: &str,
     ) -> io::Result<()> {
-        let results_out_str = format!("\n{}:\n", results_type);
+        let results_out_str = format!("\n{results_type}:\n");
 
         self.write_plain(&results_out_str)?;
 
@@ -147,7 +147,7 @@ impl<T: Write> PrettyFormatter<T> {
         self.write_plain(&results_out_str)?;
         results.sort();
         for name in &results {
-            self.write_plain(&format!("    {}\n", name))?;
+            self.write_plain(&format!("    {name}\n"))?;
         }
         Ok(())
     }
@@ -167,9 +167,9 @@ impl<T: Write> PrettyFormatter<T> {
     fn write_test_name(&mut self, desc: &TestDesc) -> io::Result<()> {
         let name = desc.padded_name(self.max_name_len, desc.name.padding());
         if let Some(test_mode) = desc.test_mode() {
-            self.write_plain(&format!("test {} - {} ... ", name, test_mode))?;
+            self.write_plain(&format!("test {name} - {test_mode} ... "))?;
         } else {
-            self.write_plain(&format!("test {} ... ", name))?;
+            self.write_plain(&format!("test {name} ... "))?;
         }
 
         Ok(())
@@ -180,11 +180,11 @@ impl<T: Write> OutputFormatter for PrettyFormatter<T> {
     fn write_run_start(&mut self, test_count: usize, shuffle_seed: Option<u64>) -> io::Result<()> {
         let noun = if test_count != 1 { "tests" } else { "test" };
         let shuffle_seed_msg = if let Some(shuffle_seed) = shuffle_seed {
-            format!(" (shuffle seed: {})", shuffle_seed)
+            format!(" (shuffle seed: {shuffle_seed})")
         } else {
             String::new()
         };
-        self.write_plain(&format!("\nrunning {} {}{}\n", test_count, noun, shuffle_seed_msg))
+        self.write_plain(&format!("\nrunning {test_count} {noun}{shuffle_seed_msg}\n"))
     }
 
     fn write_test_start(&mut self, desc: &TestDesc) -> io::Result<()> {
@@ -266,7 +266,7 @@ impl<T: Write> OutputFormatter for PrettyFormatter<T> {
         self.write_plain(&s)?;
 
         if let Some(ref exec_time) = state.exec_time {
-            let time_str = format!("; finished in {}", exec_time);
+            let time_str = format!("; finished in {exec_time}");
             self.write_plain(&time_str)?;
         }
 
diff --git a/library/test/src/formatters/terse.rs b/library/test/src/formatters/terse.rs
index 12aca7cd9a4..fb40f86b42e 100644
--- a/library/test/src/formatters/terse.rs
+++ b/library/test/src/formatters/terse.rs
@@ -122,7 +122,7 @@ impl<T: Write> TerseFormatter<T> {
         self.write_plain("\nsuccesses:\n")?;
         successes.sort();
         for name in &successes {
-            self.write_plain(&format!("    {}\n", name))?;
+            self.write_plain(&format!("    {name}\n"))?;
         }
         Ok(())
     }
@@ -148,7 +148,7 @@ impl<T: Write> TerseFormatter<T> {
         self.write_plain("\nfailures:\n")?;
         failures.sort();
         for name in &failures {
-            self.write_plain(&format!("    {}\n", name))?;
+            self.write_plain(&format!("    {name}\n"))?;
         }
         Ok(())
     }
@@ -156,9 +156,9 @@ impl<T: Write> TerseFormatter<T> {
     fn write_test_name(&mut self, desc: &TestDesc) -> io::Result<()> {
         let name = desc.padded_name(self.max_name_len, desc.name.padding());
         if let Some(test_mode) = desc.test_mode() {
-            self.write_plain(&format!("test {} - {} ... ", name, test_mode))?;
+            self.write_plain(&format!("test {name} - {test_mode} ... "))?;
         } else {
-            self.write_plain(&format!("test {} ... ", name))?;
+            self.write_plain(&format!("test {name} ... "))?;
         }
 
         Ok(())
@@ -170,11 +170,11 @@ impl<T: Write> OutputFormatter for TerseFormatter<T> {
         self.total_test_count = test_count;
         let noun = if test_count != 1 { "tests" } else { "test" };
         let shuffle_seed_msg = if let Some(shuffle_seed) = shuffle_seed {
-            format!(" (shuffle seed: {})", shuffle_seed)
+            format!(" (shuffle seed: {shuffle_seed})")
         } else {
             String::new()
         };
-        self.write_plain(&format!("\nrunning {} {}{}\n", test_count, noun, shuffle_seed_msg))
+        self.write_plain(&format!("\nrunning {test_count} {noun}{shuffle_seed_msg}\n"))
     }
 
     fn write_test_start(&mut self, desc: &TestDesc) -> io::Result<()> {
@@ -247,7 +247,7 @@ impl<T: Write> OutputFormatter for TerseFormatter<T> {
         self.write_plain(&s)?;
 
         if let Some(ref exec_time) = state.exec_time {
-            let time_str = format!("; finished in {}", exec_time);
+            let time_str = format!("; finished in {exec_time}");
             self.write_plain(&time_str)?;
         }
 
diff --git a/library/test/src/helpers/concurrency.rs b/library/test/src/helpers/concurrency.rs
index e25f524ec05..eb211157371 100644
--- a/library/test/src/helpers/concurrency.rs
+++ b/library/test/src/helpers/concurrency.rs
@@ -6,7 +6,7 @@ pub fn get_concurrency() -> usize {
     if let Ok(value) = env::var("RUST_TEST_THREADS") {
         match value.parse::<NonZeroUsize>().ok() {
             Some(n) => n.get(),
-            _ => panic!("RUST_TEST_THREADS is `{}`, should be a positive integer.", value),
+            _ => panic!("RUST_TEST_THREADS is `{value}`, should be a positive integer."),
         }
     } else {
         thread::available_parallelism().map(|n| n.get()).unwrap_or(1)
diff --git a/library/test/src/helpers/exit_code.rs b/library/test/src/helpers/exit_code.rs
index 50bb260762a..f762f88819d 100644
--- a/library/test/src/helpers/exit_code.rs
+++ b/library/test/src/helpers/exit_code.rs
@@ -13,7 +13,7 @@ pub fn get_exit_code(status: ExitStatus) -> Result<i32, String> {
     match status.code() {
         Some(code) => Ok(code),
         None => match status.signal() {
-            Some(signal) => Err(format!("child process exited with signal {}", signal)),
+            Some(signal) => Err(format!("child process exited with signal {signal}")),
             None => Err("child process exited with unknown signal".into()),
         },
     }
diff --git a/library/test/src/lib.rs b/library/test/src/lib.rs
index 8fc2b4ed748..088e3a23ea4 100644
--- a/library/test/src/lib.rs
+++ b/library/test/src/lib.rs
@@ -99,7 +99,7 @@ pub fn test_main(args: &[String], tests: Vec<TestDescAndFn>, options: Option<Opt
     let mut opts = match cli::parse_opts(args) {
         Some(Ok(o)) => o,
         Some(Err(msg)) => {
-            eprintln!("error: {}", msg);
+            eprintln!("error: {msg}");
             process::exit(ERROR_EXIT_CODE);
         }
         None => return,
@@ -109,7 +109,7 @@ pub fn test_main(args: &[String], tests: Vec<TestDescAndFn>, options: Option<Opt
     }
     if opts.list {
         if let Err(e) = console::list_tests_console(&opts, tests) {
-            eprintln!("error: io error when listing tests: {:?}", e);
+            eprintln!("error: io error when listing tests: {e:?}");
             process::exit(ERROR_EXIT_CODE);
         }
     } else {
@@ -117,7 +117,7 @@ pub fn test_main(args: &[String], tests: Vec<TestDescAndFn>, options: Option<Opt
             Ok(true) => {}
             Ok(false) => process::exit(ERROR_EXIT_CODE),
             Err(e) => {
-                eprintln!("error: io error when listing tests: {:?}", e);
+                eprintln!("error: io error when listing tests: {e:?}");
                 process::exit(ERROR_EXIT_CODE);
             }
         }
@@ -153,7 +153,7 @@ pub fn test_main_static_abort(tests: &[&TestDescAndFn]) {
             .filter(|test| test.desc.name.as_slice() == name)
             .map(make_owned_test)
             .next()
-            .unwrap_or_else(|| panic!("couldn't find a test with the provided name '{}'", name));
+            .unwrap_or_else(|| panic!("couldn't find a test with the provided name '{name}'"));
         let TestDescAndFn { desc, testfn } = test;
         let testfn = match testfn {
             StaticTestFn(f) => f,
@@ -524,7 +524,7 @@ pub fn run_test(
                     Arc::get_mut(&mut runtest).unwrap().get_mut().unwrap().take().unwrap()();
                     None
                 }
-                Err(e) => panic!("failed to spawn thread to run test: {}", e),
+                Err(e) => panic!("failed to spawn thread to run test: {e}"),
             }
         } else {
             runtest();
@@ -678,7 +678,7 @@ fn run_test_in_spawned_subprocess(desc: TestDesc, testfn: Box<dyn FnOnce() + Sen
         // We don't support serializing TrFailedMsg, so just
         // print the message out to stderr.
         if let TrFailedMsg(msg) = &test_result {
-            eprintln!("{}", msg);
+            eprintln!("{msg}");
         }
 
         if let Some(info) = panic_info {
diff --git a/library/test/src/term/terminfo/parm.rs b/library/test/src/term/terminfo/parm.rs
index 0d37eb7359d..0756c8374aa 100644
--- a/library/test/src/term/terminfo/parm.rs
+++ b/library/test/src/term/terminfo/parm.rs
@@ -268,7 +268,7 @@ pub(crate) fn expand(
                     },
                     'e' => state = SeekIfEnd(0),
                     ';' => (),
-                    _ => return Err(format!("unrecognized format option {}", cur)),
+                    _ => return Err(format!("unrecognized format option {cur}")),
                 }
             }
             PushParam => {
diff --git a/library/test/src/term/terminfo/parm/tests.rs b/library/test/src/term/terminfo/parm/tests.rs
index 256d1aaf446..c738f3ba04f 100644
--- a/library/test/src/term/terminfo/parm/tests.rs
+++ b/library/test/src/term/terminfo/parm/tests.rs
@@ -78,15 +78,15 @@ fn test_push_bad_param() {
 fn test_comparison_ops() {
     let v = [('<', [1u8, 0u8, 0u8]), ('=', [0u8, 1u8, 0u8]), ('>', [0u8, 0u8, 1u8])];
     for &(op, bs) in v.iter() {
-        let s = format!("%{{1}}%{{2}}%{}%d", op);
+        let s = format!("%{{1}}%{{2}}%{op}%d");
         let res = expand(s.as_bytes(), &[], &mut Variables::new());
         assert!(res.is_ok(), "{}", res.unwrap_err());
         assert_eq!(res.unwrap(), vec![b'0' + bs[0]]);
-        let s = format!("%{{1}}%{{1}}%{}%d", op);
+        let s = format!("%{{1}}%{{1}}%{op}%d");
         let res = expand(s.as_bytes(), &[], &mut Variables::new());
         assert!(res.is_ok(), "{}", res.unwrap_err());
         assert_eq!(res.unwrap(), vec![b'0' + bs[1]]);
-        let s = format!("%{{2}}%{{1}}%{}%d", op);
+        let s = format!("%{{2}}%{{1}}%{op}%d");
         let res = expand(s.as_bytes(), &[], &mut Variables::new());
         assert!(res.is_ok(), "{}", res.unwrap_err());
         assert_eq!(res.unwrap(), vec![b'0' + bs[2]]);
diff --git a/library/test/src/term/terminfo/parser/compiled.rs b/library/test/src/term/terminfo/parser/compiled.rs
index b24f3f8b05e..5d40b7988b5 100644
--- a/library/test/src/term/terminfo/parser/compiled.rs
+++ b/library/test/src/term/terminfo/parser/compiled.rs
@@ -198,7 +198,7 @@ pub(crate) fn parse(file: &mut dyn io::Read, longnames: bool) -> Result<TermInfo
     let extended = match magic {
         0o0432 => false,
         0o01036 => true,
-        _ => return Err(format!("invalid magic number, found {:o}", magic)),
+        _ => return Err(format!("invalid magic number, found {magic:o}")),
     };
 
     // According to the spec, these fields must be >= -1 where -1 means that the feature is not
diff --git a/library/test/src/test_result.rs b/library/test/src/test_result.rs
index 8c216a1e0e7..7f44d6e3d0f 100644
--- a/library/test/src/test_result.rs
+++ b/library/test/src/test_result.rs
@@ -89,7 +89,7 @@ pub fn get_result_from_exit_code(
     let result = match code {
         TR_OK => TestResult::TrOk,
         TR_FAILED => TestResult::TrFailed,
-        _ => TestResult::TrFailedMsg(format!("got unexpected return code {}", code)),
+        _ => TestResult::TrFailedMsg(format!("got unexpected return code {code}")),
     };
 
     // If test is already failed (or allowed to fail), do not change the result.