Make Level and LevelFilter Copy

This makes both structs easier to use because you no longer have to
worry about borrow errors while working with them. There's no downside
to making them `Copy` since both are wrappers around a `usize`.

Ideally, this would make `Metadata::Level` return `Level` instead of
`&Level`. However that's a breaking change, so I didn't make it here.

Author: jyn514

tracing-core/src/metadata.rs

@@ -94,7 +94,7 @@ pub struct Metadata<'a> {
 pub struct Kind(KindInner);
 
 /// Describes the level of verbosity of a span or event.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub struct Level(LevelInner);
 
 /// A filter comparable to a verbosity `Level`.
@@ -107,7 +107,7 @@ pub struct Level(LevelInner);
 /// addition of an `OFF` level that completely disables all trace
 /// instrumentation.
 #[repr(transparent)]
-#[derive(Clone, Eq, PartialEq)]
+#[derive(Copy, Clone, Eq, PartialEq)]
 pub struct LevelFilter(Option<Level>);
 
 /// Indicates that a string could not be parsed to a valid level.
@@ -864,7 +864,7 @@ mod tests {
                 // actual repr matches what we expect it to be --- we're testing
                 // that *other* unsafe code is sound using the transmuted value.
                 // We're not going to do anything with it that might be unsound.
-                mem::transmute::<_, usize>(filter.clone())
+                mem::transmute::<_, usize>(filter)
             };
             assert_eq!(expected, repr, "repr changed for {:?}", filter)
         }

tracing-log/src/lib.rs

@@ -310,8 +310,8 @@ lazy_static! {
     static ref ERROR_FIELDS: Fields = Fields::new(ERROR_CS);
 }
 
-fn level_to_cs(level: &Level) -> (&'static dyn Callsite, &'static Fields) {
-    match *level {
+fn level_to_cs(level: Level) -> (&'static dyn Callsite, &'static Fields) {
+    match level {
         Level::TRACE => (TRACE_CS, &*TRACE_FIELDS),
         Level::DEBUG => (DEBUG_CS, &*DEBUG_FIELDS),
         Level::INFO => (INFO_CS, &*INFO_FIELDS),
@@ -415,13 +415,13 @@ impl<'a> NormalizeEvent<'a> for Event<'a> {
     fn normalized_metadata(&'a self) -> Option<Metadata<'a>> {
         let original = self.metadata();
         if self.is_log() {
-            let mut fields = LogVisitor::new_for(self, level_to_cs(original.level()).1);
+            let mut fields = LogVisitor::new_for(self, level_to_cs(*original.level()).1);
             self.record(&mut fields);
 
             Some(Metadata::new(
                 "log event",
                 fields.target.unwrap_or("log"),
-                original.level().clone(),
+                *original.level(),
                 fields.file,
                 fields.line.map(|l| l as u32),
                 fields.module_path,
@@ -434,7 +434,7 @@ impl<'a> NormalizeEvent<'a> for Event<'a> {
     }
 
     fn is_log(&self) -> bool {
-        self.metadata().callsite() == identify_callsite!(level_to_cs(self.metadata().level()).0)
+        self.metadata().callsite() == identify_callsite!(level_to_cs(*self.metadata().level()).0)
     }
 }
 

tracing-log/tests/log_tracer.rs

@@ -39,7 +39,7 @@ impl Subscriber for TestSubscriber {
             event.normalized_metadata().map(|normalized| OwnedMetadata {
                 name: normalized.name().to_string(),
                 target: normalized.target().to_string(),
-                level: normalized.level().clone(),
+                level: *normalized.level(),
                 module_path: normalized.module_path().map(String::from),
                 file: normalized.file().map(String::from),
                 line: normalized.line(),

tracing-subscriber/src/filter/env/directive.rs

@@ -85,7 +85,7 @@ impl Directive {
         Some(StaticDirective {
             target: self.target.clone(),
             field_names,
-            level: self.level.clone(),
+            level: self.level,
         })
     }
 
@@ -119,7 +119,7 @@ impl Directive {
             .ok()?;
         Some(field::CallsiteMatch {
             fields,
-            level: self.level.clone(),
+            level: self.level,
         })
     }
 
@@ -417,9 +417,9 @@ impl<T: Match + Ord> DirectiveSet<T> {
     pub(crate) fn add(&mut self, directive: T) {
         // does this directive enable a more verbose level than the current
         // max? if so, update the max level.
-        let level = directive.level();
-        if *level > self.max_level {
-            self.max_level = level.clone();
+        let level = *directive.level();
+        if level > self.max_level {
+            self.max_level = level;
         }
         // insert the directive into the vec of directives, ordered by
         // specificity (length of target + number of field filters). this
@@ -460,8 +460,8 @@ impl Dynamics {
                     return Some(f);
                 }
                 match base_level {
-                    Some(ref b) if d.level > *b => base_level = Some(d.level.clone()),
-                    None => base_level = Some(d.level.clone()),
+                    Some(ref b) if d.level > *b => base_level = Some(d.level),
+                    None => base_level = Some(d.level),
                     _ => {}
                 }
                 None
@@ -690,7 +690,7 @@ impl CallsiteMatcher {
             .collect();
         SpanMatcher {
             field_matches,
-            base_level: self.base_level.clone(),
+            base_level: self.base_level,
         }
     }
 }
@@ -702,7 +702,7 @@ impl SpanMatcher {
             .iter()
             .filter_map(field::SpanMatch::filter)
             .max()
-            .unwrap_or_else(|| self.base_level.clone())
+            .unwrap_or(self.base_level)
     }
 
     pub(crate) fn record_update(&self, record: &span::Record<'_>) {

tracing-subscriber/src/filter/env/field.rs

@@ -229,7 +229,7 @@ impl CallsiteMatch {
             .collect();
         SpanMatch {
             fields,
-            level: self.level.clone(),
+            level: self.level,
             has_matched: AtomicBool::new(false),
         }
     }
@@ -263,7 +263,7 @@ impl SpanMatch {
     #[inline]
     pub(crate) fn filter(&self) -> Option<LevelFilter> {
         if self.is_matched() {
-            Some(self.level.clone())
+            Some(self.level)
         } else {
             None
         }

tracing/src/macros.rs

@@ -2150,7 +2150,7 @@ macro_rules! fieldset {
 #[macro_export]
 macro_rules! level_to_log {
     ($level:expr) => {
-        match *$level {
+        match $level {
             $crate::Level::ERROR => $crate::log::Level::Error,
             $crate::Level::WARN => $crate::log::Level::Warn,
             $crate::Level::INFO => $crate::log::Level::Info,
@@ -2297,7 +2297,7 @@ macro_rules! __tracing_log {
     (target: $target:expr, $level:expr, $($field:tt)+ ) => {
         $crate::if_log_enabled! {{
             use $crate::log;
-            let level = $crate::level_to_log!(&$level);
+            let level = $crate::level_to_log!($level);
             if level <= log::STATIC_MAX_LEVEL && level <= log::max_level() {
                 let log_meta = log::Metadata::builder()
                     .level(level)

tracing/src/span.rs

@@ -552,7 +552,7 @@ impl Span {
             } else {
                 meta.target()
             };
-            span.log(target, level_to_log!(meta.level()), format_args!("++ {}{}", meta.name(), FmtAttrs(attrs)));
+            span.log(target, level_to_log!(*meta.level()), format_args!("++ {}{}", meta.name(), FmtAttrs(attrs)));
         }}
 
         span
@@ -925,7 +925,7 @@ impl Span {
                 } else {
                     meta.target()
                 };
-                self.log(target, level_to_log!(meta.level()), format_args!("{}{}", meta.name(), FmtValues(&record)));
+                self.log(target, level_to_log!(*meta.level()), format_args!("{}{}", meta.name(), FmtValues(&record)));
             }
         }}
 
@@ -1028,7 +1028,7 @@ impl Span {
     #[inline]
     fn log(&self, target: &str, level: log::Level, message: fmt::Arguments<'_>) {
         if let Some(ref meta) = self.meta {
-            if level_to_log!(meta.level()) <= log::max_level() {
+            if level_to_log!(*meta.level()) <= log::max_level() {
                 let logger = log::logger();
                 let log_meta = log::Metadata::builder().level(level).target(target).build();
                 if logger.enabled(&log_meta) {

tracing/tests/support/subscriber.rs

@@ -200,7 +200,7 @@ where
         }
     }
     fn max_level_hint(&self) -> Option<LevelFilter> {
-        self.max_level.clone()
+        self.max_level
     }
 
     fn record(&self, id: &Id, values: &span::Record<'_>) {