feat(kv): Use now-stable kv feature of log crate

Which means updating to 0.4.21

Cargo.toml

@@ -52,10 +52,10 @@ color = ["dep:anstream", "dep:anstyle"]
 auto-color = ["color", "anstream/auto"]
 humantime = ["dep:humantime"]
 regex = ["env_filter/regex"]
-unstable-kv = ["log/kv_unstable"]
+unstable-kv = ["log/kv"]
 
 [dependencies]
-log = { version = "0.4.8", features = ["std"] }
+log = { version = "0.4.21", features = ["std"] }
 env_filter = { version = "0.1.0", path = "crates/env_filter", default-features = false }
 humantime = { version = "2.0.0", optional = true }
 anstream = { version = "0.6.11", default-features = false, features = ["wincon"], optional = true }

src/fmt/kv.rs

@@ -5,7 +5,7 @@ use super::WriteStyle;
 use super::{Formatter, StyledValue};
 #[cfg(feature = "color")]
 use anstyle::Style;
-use log::kv::{source::Source, Error, Key, Value, Visitor};
+use log::kv::{Error, Key, Source, Value, VisitSource};
 
 /// Format function for serializing key/value pairs
 ///
@@ -35,22 +35,20 @@ pub fn hidden_kv_format(_formatter: &mut Formatter, _fields: &dyn Source) -> io:
 /// For example: `ip=127.0.0.1 port=123456 path=/example`
 pub fn default_kv_format(formatter: &mut Formatter, fields: &dyn Source) -> io::Result<()> {
     fields
-        .visit(&mut DefaultVisitor(formatter))
+        .visit(&mut DefaultVisitSource(formatter))
         .map_err(|e| io::Error::new(io::ErrorKind::Other, e))
 }
 
-struct DefaultVisitor<'a>(&'a mut Formatter);
+struct DefaultVisitSource<'a>(&'a mut Formatter);
 
-impl<'a, 'kvs> Visitor<'kvs> for DefaultVisitor<'a> {
+impl<'a, 'kvs> VisitSource<'kvs> for DefaultVisitSource<'a> {
     fn visit_pair(&mut self, key: Key, value: Value<'kvs>) -> Result<(), Error> {
-        // TODO: add styling
-        // tracing-subscriber uses italic for the key and dimmed for the =
         write!(self.0, " {}={}", self.style_key(key), value)?;
         Ok(())
     }
 }
 
-impl DefaultVisitor<'_> {
+impl DefaultVisitSource<'_> {
     fn style_key<'k>(&self, text: Key<'k>) -> StyledValue<Key<'k>> {
         #[cfg(feature = "color")]
         {

src/fmt/mod.rs

@@ -40,10 +40,13 @@
 //! function that is called by the default format with [`Builder::format_key_values`].
 //!
 //! ```
+//! # #[cfg(feature= "unstable-kv")]
+//! # {
 //! use log::info;
 //! env_logger::init();
 //! info!(x="45"; "Some message");
 //! info!(x="12"; "Another message {x}", x="12");
+//! # }
 //! ```
 //!
 //! See <https://docs.rs/log/latest/log/#structured-logging>.

src/logger.rs

@@ -326,7 +326,7 @@ impl Builder {
     #[cfg(feature = "unstable-kv")]
     pub fn format_key_values<F: 'static>(&mut self, format: F) -> &mut Self
     where
-        F: Fn(&mut Formatter, &dyn log::kv::source::Source) -> io::Result<()> + Sync + Send,
+        F: Fn(&mut Formatter, &dyn log::kv::Source) -> io::Result<()> + Sync + Send,
     {
         self.format.kv_format = Some(Box::new(format));
         self