Filter out log fields from messages

Author: Oliver Scherer

examples/basic.stdout

@@ -34,7 +34,7 @@
 1:main│ │┌┘basic::conn peer_addr="8.8.8.8", port=18230
 1:main│ ├┘basic::server host="localhost", port=8080
 1:main│ ├─ms WARN basic internal error
-1:main│ ├─ms ERROR log this is a log message, log.target="basic", log.module_path="basic", log.file="examples/basic.rs", log.line=63
+1:main│ ├─ms ERROR basic this is a log message
 1:main│ ├─ms INFO basic exit
 1:main│┌┘basic::server host="localhost", port=8080
 1:main├┘basic::hierarchical-example version=0.1

src/format.rs

@@ -189,14 +189,19 @@ pub struct FmtEvent<'a> {
 impl<'a> Visit for FmtEvent<'a> {
     fn record_debug(&mut self, field: &Field, value: &dyn fmt::Debug) {
         let buf = &mut self.bufs.current_buf;
-        write!(buf, "{comma} ", comma = if self.comma { "," } else { "" },).unwrap();
-        let name = field.name();
-        if name == "message" {
-            write!(buf, "{:?}", value).unwrap();
-            self.comma = true;
-        } else {
-            write!(buf, "{}={:?}", name, value).unwrap();
-            self.comma = true;
+        let comma = if self.comma { "," } else { "" };
+        match field.name() {
+            "message" => {
+                write!(buf, "{} {:?}", comma, value).unwrap();
+                self.comma = true;
+            }
+            // Skip fields that are actually log metadata that have already been handled
+            #[cfg(feature = "tracing-log")]
+            name if name.starts_with("log.") => {}
+            name => {
+                write!(buf, "{} {}={:?}", comma, name, value).unwrap();
+                self.comma = true;
+            }
         }
     }
 }

src/lib.rs

@@ -13,6 +13,8 @@ use tracing::{
     span::{Attributes, Id},
     Event, Subscriber,
 };
+#[cfg(feature = "tracing-log")]
+use tracing_log::NormalizeEvent;
 use tracing_subscriber::{
     fmt::MakeWriter,
     layer::{Context, Layer},
@@ -351,7 +353,15 @@ where
             )
             .expect("Unable to write to buffer");
         }
-        let level = event.metadata().level();
+
+        #[cfg(feature = "tracing-log")]
+        let normalized_meta = event.normalized_metadata();
+        #[cfg(feature = "tracing-log")]
+        let metadata = normalized_meta.as_ref().unwrap_or_else(|| event.metadata());
+        #[cfg(not(feature = "tracing-log"))]
+        let metadata = event.metadata();
+
+        let level = metadata.level();
         let level = if self.config.ansi {
             ColorLevel(level).to_string()
         } else {
@@ -360,7 +370,7 @@ where
         write!(&mut event_buf, "{level}", level = level).expect("Unable to write to buffer");
 
         if self.config.targets {
-            let target = event.metadata().target();
+            let target = metadata.target();
             write!(
                 &mut event_buf,
                 " {}",