Fix tracing-macros::dbg

…and the `factorial` example.

tracing-macros/Cargo.toml

@@ -17,11 +17,10 @@ keywords = ["logging", "tracing"]
 license = "MIT"
 
 [dependencies]
-tracing = "0.1.18"
+tracing = "0.1.20"
 
 [dev-dependencies]
-tracing-log = "0.1"
-env_logger = "0.7"
+tracing-subscriber = "0.2"
 
 [badges]
 maintenance = { status = "experimental" }

tracing-macros/examples/factorial.rs

@@ -12,9 +12,7 @@ fn factorial(n: u32) -> u32 {
 }
 
 fn main() {
-    env_logger::Builder::new().parse_filters("trace").init();
-    #[allow(deprecated)]
-    let subscriber = tracing_log::TraceLogger::new();
+    let subscriber = tracing_subscriber::fmt().finish();
 
     tracing::subscriber::with_default(subscriber, || dbg!(factorial(4)));
 }

tracing-macros/src/lib.rs

@@ -29,6 +29,7 @@ macro_rules! dbg {
         use tracing::{
             callsite,
             field::{debug, Value},
+            subscriber::Interest,
             Event, Id, Subscriber,
         };
         let callsite = tracing::callsite! {
@@ -39,7 +40,7 @@ macro_rules! dbg {
             fields: value,
         };
         let val = $ex;
-        if callsite.is_enabled() {
+        if callsite.is_enabled(Interest::always()) {
             let meta = callsite.metadata();
             let fields = meta.fields();
             let key = meta
@@ -49,7 +50,7 @@ macro_rules! dbg {
                 .expect("trace_dbg event must have one field");
             Event::dispatch(
                 meta,
-                &fields.value_set(&[(&key, Some(&debug(&val) as &Value))]),
+                &fields.value_set(&[(&key, Some(&debug(&val) as &dyn Value))]),
             );
         }
         val