Add must use annotation to Span as in tokio-rs#3234.

Author: raldone01

tracing-mock/tests/span_ancestry.rs

@@ -22,7 +22,7 @@ fn contextual_parent() {
 
     with_default(collector, || {
         let _guard = tracing::info_span!("contextual parent").entered();
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -45,7 +45,7 @@ fn contextual_parent_wrong_name() {
 
     with_default(collector, || {
         let _guard = tracing::info_span!("another parent").entered();
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -70,7 +70,7 @@ fn contextual_parent_wrong_id() {
     with_default(collector, || {
         let _span = tracing::info_span!("contextual parent");
         let _guard = tracing::info_span!("another parent").entered();
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -94,7 +94,7 @@ fn contextual_parent_wrong_level() {
 
     with_default(collector, || {
         let _guard = tracing::debug_span!("contextual parent").entered();
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -111,7 +111,7 @@ fn expect_contextual_parent_actual_contextual_root() {
     let (collector, handle) = collector::mock().new_span(span).run_with_handle();
 
     with_default(collector, || {
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -132,7 +132,7 @@ fn expect_contextual_parent_actual_explicit_parent() {
 
     with_default(collector, || {
         let span = tracing::info_span!("explicit parent");
-        tracing::info_span!(parent: span.id(), "span");
+        let _ = tracing::info_span!(parent: span.id(), "span");
     });
 
     handle.assert_finished();
@@ -153,7 +153,7 @@ fn expect_contextual_parent_actual_explicit_root() {
 
     with_default(collector, || {
         let _guard = tracing::info_span!("contextual parent").entered();
-        tracing::info_span!(parent: None, "span");
+        let _ = tracing::info_span!(parent: None, "span");
     });
 
     handle.assert_finished();
@@ -168,7 +168,7 @@ fn contextual_root() {
     let (collector, handle) = collector::mock().new_span(span).run_with_handle();
 
     with_default(collector, || {
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -188,7 +188,7 @@ fn expect_contextual_root_actual_contextual_parent() {
 
     with_default(collector, || {
         let _guard = tracing::info_span!("contextual parent").entered();
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -208,7 +208,7 @@ fn expect_contextual_root_actual_explicit_parent() {
 
     with_default(collector, || {
         let span = tracing::info_span!("explicit parent");
-        tracing::info_span!(parent: span.id(), "span");
+        let _ = tracing::info_span!(parent: span.id(), "span");
     });
 
     handle.assert_finished();
@@ -228,7 +228,7 @@ fn expect_contextual_root_actual_explicit_root() {
 
     with_default(collector, || {
         let _guard = tracing::info_span!("contextual parent").entered();
-        tracing::info_span!(parent: None, "span");
+        let _ = tracing::info_span!(parent: None, "span");
     });
 
     handle.assert_finished();
@@ -247,7 +247,7 @@ fn explicit_parent() {
 
     with_default(collector, || {
         let span = tracing::info_span!("explicit parent");
-        tracing::info_span!(parent: span.id(), "span");
+        let _ = tracing::info_span!(parent: span.id(), "span");
     });
 
     handle.assert_finished();
@@ -270,7 +270,7 @@ fn explicit_parent_wrong_name() {
 
     with_default(collector, || {
         let span = tracing::info_span!("another parent");
-        tracing::info_span!(parent: span.id(), "span");
+        let _ = tracing::info_span!(parent: span.id(), "span");
     });
 
     handle.assert_finished();
@@ -294,7 +294,7 @@ fn explicit_parent_wrong_id() {
     with_default(collector, || {
         let _span = tracing::info_span!("explicit parent");
         let another_span = tracing::info_span!("another parent");
-        tracing::info_span!(parent: another_span.id(), "span");
+        let _ = tracing::info_span!(parent: another_span.id(), "span");
     });
 
     handle.assert_finished();
@@ -316,7 +316,7 @@ fn explicit_parent_wrong_level() {
 
     with_default(collector, || {
         let span = tracing::debug_span!("explicit parent");
-        tracing::info_span!(parent: span.id(), "span");
+        let _ = tracing::info_span!(parent: span.id(), "span");
     });
 
     handle.assert_finished();
@@ -337,7 +337,7 @@ fn expect_explicit_parent_actual_contextual_parent() {
 
     with_default(collector, || {
         let _guard = tracing::info_span!("contextual parent").entered();
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -354,7 +354,7 @@ fn expect_explicit_parent_actual_contextual_root() {
     let (collector, handle) = collector::mock().new_span(span).run_with_handle();
 
     with_default(collector, || {
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -375,7 +375,7 @@ fn expect_explicit_parent_actual_explicit_root() {
 
     with_default(collector, || {
         let _guard = tracing::info_span!("contextual parent").entered();
-        tracing::info_span!(parent: None, "span");
+        let _ = tracing::info_span!(parent: None, "span");
     });
 
     handle.assert_finished();
@@ -395,7 +395,7 @@ fn explicit_root() {
 
     with_default(collector, || {
         let _guard = tracing::info_span!("contextual parent").entered();
-        tracing::info_span!(parent: None, "span");
+        let _ = tracing::info_span!(parent: None, "span");
     });
 
     handle.assert_finished();
@@ -415,7 +415,7 @@ fn expect_explicit_root_actual_contextual_parent() {
 
     with_default(collector, || {
         let _guard = tracing::info_span!("contextual parent").entered();
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -431,7 +431,7 @@ fn expect_explicit_root_actual_contextual_root() {
     let (collector, handle) = collector::mock().new_span(span).run_with_handle();
 
     with_default(collector, || {
-        tracing::info_span!("span");
+        let _ = tracing::info_span!("span");
     });
 
     handle.assert_finished();
@@ -451,7 +451,7 @@ fn expect_explicit_root_actual_explicit_parent() {
 
     with_default(collector, || {
         let span = tracing::info_span!("explicit parent");
-        tracing::info_span!(parent: span.id(), "span");
+        let _ = tracing::info_span!(parent: span.id(), "span");
     });
 
     handle.assert_finished();
@@ -466,7 +466,7 @@ fn explicit_and_contextual_root_is_explicit() {
     let (collector, handle) = collector::mock().new_span(span).run_with_handle();
 
     with_default(collector, || {
-        tracing::info_span!(parent: None, "span");
+        let _ = tracing::info_span!(parent: None, "span");
     });
 
     handle.assert_finished();

tracing-subscriber/tests/env_filter/main.rs

@@ -53,8 +53,8 @@ fn same_name_spans() {
         .run_with_handle();
     let subscriber = subscriber.with(filter);
     with_default(subscriber, || {
-        tracing::trace_span!("foo", bar = 1);
-        tracing::trace_span!("foo", baz = 1);
+        let _ = tracing::trace_span!("foo", bar = 1);
+        let _ = tracing::trace_span!("foo", baz = 1);
     });
 
     finished.assert_finished();
@@ -343,9 +343,9 @@ fn more_specific_dynamic_filter_more_verbose() {
     let subscriber = collector.with(filter);
 
     with_default(subscriber, || {
-        tracing::info_span!("enabled info");
-        tracing::debug_span!("disabled debug");
-        tracing::debug_span!("enabled debug", hello = &4_u64);
+        let _ = tracing::info_span!("enabled info");
+        let _ = tracing::debug_span!("disabled debug");
+        let _ = tracing::debug_span!("enabled debug", hello = &4_u64);
 
         // .only() doesn't work when we don't enter/exit spans
         tracing::info!("marker");
@@ -391,10 +391,10 @@ fn more_specific_dynamic_filter_less_verbose() {
     let subscriber = collector.with(filter);
 
     with_default(subscriber, || {
-        tracing::info_span!("enabled info");
-        tracing::warn_span!("enabled hello=100 warn", hello = &100_u64);
-        tracing::info_span!("disabled hello=4 info", hello = &4_u64);
-        tracing::warn_span!("enabled hello=4 warn", hello = &4_u64);
+        let _ = tracing::info_span!("enabled info");
+        let _ = tracing::warn_span!("enabled hello=100 warn", hello = &100_u64);
+        let _ = tracing::info_span!("disabled hello=4 info", hello = &4_u64);
+        let _ = tracing::warn_span!("enabled hello=4 warn", hello = &4_u64);
 
         // .only() doesn't work when we don't enter/exit spans
         tracing::info!("marker");

tracing-subscriber/tests/env_filter/per_subscriber.rs

@@ -52,8 +52,8 @@ fn same_name_spans() {
         .with(subscriber.with_filter(filter))
         .set_default();
 
-    tracing::trace_span!("foo", bar = 1);
-    tracing::trace_span!("foo", baz = 1);
+    let _ = tracing::trace_span!("foo", bar = 1);
+    let _ = tracing::trace_span!("foo", baz = 1);
 
     handle.assert_finished();
 }

tracing-subscriber/tests/same_len_filters.rs

@@ -73,8 +73,8 @@ fn same_num_fields_and_name_len() {
         .run_with_handle();
     let subscriber = subscriber.with(filter);
     with_default(subscriber, || {
-        tracing::trace_span!("foo", bar = 1);
-        tracing::trace_span!("baz", boz = 1);
+        let _ = tracing::trace_span!("foo", bar = 1);
+        let _ = tracing::trace_span!("baz", boz = 1);
     });
 
     finished.assert_finished();

tracing-subscriber/tests/subscriber_filters/main.rs

@@ -71,9 +71,9 @@ fn basic_subscriber_filters_spans() {
         .with(info_subscriber.with_filter(LevelFilter::INFO))
         .set_default();
 
-    tracing::trace_span!("hello trace");
-    tracing::debug_span!("hello debug");
-    tracing::info_span!("hello info");
+    let _ = tracing::trace_span!("hello trace");
+    let _ = tracing::debug_span!("hello debug");
+    let _ = tracing::info_span!("hello info");
 
     trace_handle.assert_finished();
     debug_handle.assert_finished();

tracing/src/span.rs

@@ -328,6 +328,7 @@ pub trait AsId: crate::sealed::Sealed {
 /// span will silently do nothing. Thus, the handle can be used in the same
 /// manner regardless of whether or not the trace is currently being collected.
 #[derive(Clone)]
+#[must_use = "Once a span has been created, it should be entered."]
 pub struct Span {
     /// A handle used to enter the span when it is not executing.
     ///

tracing/tests/macro_imports.rs

@@ -3,21 +3,21 @@ use tracing::Level;
 #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 #[test]
 fn prefixed_span_macros() {
-    tracing::span!(Level::DEBUG, "foo");
-    tracing::trace_span!("foo");
-    tracing::debug_span!("foo");
-    tracing::info_span!("foo");
-    tracing::warn_span!("foo");
-    tracing::error_span!("foo");
+    let _ = tracing::span!(Level::DEBUG, "foo");
+    let _ = tracing::trace_span!("foo");
+    let _ = tracing::debug_span!("foo");
+    let _ = tracing::info_span!("foo");
+    let _ = tracing::warn_span!("foo");
+    let _ = tracing::error_span!("foo");
 }
 
 #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 #[test]
 fn prefixed_event_macros() {
-    tracing::event!(Level::DEBUG, "foo");
-    tracing::trace!("foo");
-    tracing::debug!("foo");
-    tracing::info!("foo");
-    tracing::warn!("foo");
-    tracing::error!("foo");
+    let _ = tracing::event!(Level::DEBUG, "foo");
+    let _ = tracing::trace!("foo");
+    let _ = tracing::debug!("foo");
+    let _ = tracing::info!("foo");
+    let _ = tracing::warn!("foo");
+    let _ = tracing::error!("foo");
 }