Auto merge of #72464 - RalfJung:rollup-xhm7w7u, r=RalfJung

Rollup of 7 pull requests

Successful merges:

 - #71829 (Fix suggestion to borrow in struct)
 - #72123 (Stabilize process_set_argv0 feature for Unix)
 - #72235 (Clean up E0590 explanation)
 - #72345 (Clean up E0593 explanation)
 - #72376 ([self-profling] Record the cgu name when doing codegen for a module)
 - #72399 (Add fast-path optimization for Ipv4Addr::fmt)
 - #72435 (rustllvm: Fix warnings about unused function parameters)

Failed merges:

r? @ghost

3 files changed, 18 insertions, 11 deletions

diff --git a/src/libstd/net/ip.rs b/src/libstd/net/ip.rs
index edc28033c9b..6e2478b8308 100644
--- a/src/libstd/net/ip.rs
+++ b/src/libstd/net/ip.rs
@@ -856,16 +856,23 @@ impl From<Ipv6Addr> for IpAddr {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Display for Ipv4Addr {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        const IPV4_BUF_LEN: usize = 15; // Long enough for the longest possible IPv4 address
-        let mut buf = [0u8; IPV4_BUF_LEN];
-        let mut buf_slice = &mut buf[..];
         let octets = self.octets();
-        // Note: The call to write should never fail, hence the unwrap
-        write!(buf_slice, "{}.{}.{}.{}", octets[0], octets[1], octets[2], octets[3]).unwrap();
-        let len = IPV4_BUF_LEN - buf_slice.len();
-        // This unsafe is OK because we know what is being written to the buffer
-        let buf = unsafe { crate::str::from_utf8_unchecked(&buf[..len]) };
-        fmt.pad(buf)
+        // Fast Path: if there's no alignment stuff, write directly to the buffer
+        if fmt.precision().is_none() && fmt.width().is_none() {
+            write!(fmt, "{}.{}.{}.{}", octets[0], octets[1], octets[2], octets[3])
+        } else {
+            const IPV4_BUF_LEN: usize = 15; // Long enough for the longest possible IPv4 address
+            let mut buf = [0u8; IPV4_BUF_LEN];
+            let mut buf_slice = &mut buf[..];
+
+            // Note: The call to write should never fail, hence the unwrap
+            write!(buf_slice, "{}.{}.{}.{}", octets[0], octets[1], octets[2], octets[3]).unwrap();
+            let len = IPV4_BUF_LEN - buf_slice.len();
+
+            // This unsafe is OK because we know what is being written to the buffer
+            let buf = unsafe { crate::str::from_utf8_unchecked(&buf[..len]) };
+            fmt.pad(buf)
+        }
     }
 }
 
diff --git a/src/libstd/sys/unix/ext/process.rs b/src/libstd/sys/unix/ext/process.rs
index fa8670b4aec..048ce24d6ba 100644
--- a/src/libstd/sys/unix/ext/process.rs
+++ b/src/libstd/sys/unix/ext/process.rs
@@ -111,7 +111,7 @@ pub trait CommandExt {
     ///
     /// Set the first process argument, `argv[0]`, to something other than the
     /// default executable path.
-    #[unstable(feature = "process_set_argv0", issue = "66510")]
+    #[stable(feature = "process_set_argv0", since = "1.45.0")]
     fn arg0<S>(&mut self, arg: S) -> &mut process::Command
     where
         S: AsRef<OsStr>;
diff --git a/src/libstd/sys/vxworks/ext/process.rs b/src/libstd/sys/vxworks/ext/process.rs
index 31e691dd136..c3710f4b912 100644
--- a/src/libstd/sys/vxworks/ext/process.rs
+++ b/src/libstd/sys/vxworks/ext/process.rs
@@ -111,7 +111,7 @@ pub trait CommandExt {
     ///
     /// Set the first process argument, `argv[0]`, to something other than the
     /// default executable path.
-    #[unstable(feature = "process_set_argv0", issue = "66510")]
+    #[stable(feature = "process_set_argv0", since = "1.45.0")]
     fn arg0<S>(&mut self, arg: S) -> &mut process::Command
     where
         S: AsRef<OsStr>;