subscriber: remove space when timestamps are disabled

tracing-subscriber/src/fmt/fmt_subscriber.rs

@@ -1006,7 +1006,7 @@ mod test {
         });
         let actual = sanitize_timings(make_writer.get_string());
         assert_eq!(
-            " span1{x=42}: tracing_subscriber::fmt::fmt_subscriber::test: close\n",
+            "span1{x=42}: tracing_subscriber::fmt::fmt_subscriber::test: close\n",
             actual.as_str()
         );
     }

tracing-subscriber/src/fmt/format/mod.rs

@@ -1,5 +1,5 @@
 //! Formatters for logging `tracing` events.
-use super::time::{self, FormatTime, SystemTime};
+use super::time::{FormatTime, SystemTime};
 use crate::{
     field::{MakeOutput, MakeVisitor, RecordFields, VisitFmt, VisitOutput},
     fmt::fmt_subscriber::FmtContext,
@@ -253,6 +253,7 @@ pub struct Format<F = Full, T = SystemTime> {
     format: F,
     pub(crate) timer: T,
     pub(crate) ansi: bool,
+    pub(crate) display_timestamp: bool,
     pub(crate) display_target: bool,
     pub(crate) display_level: bool,
     pub(crate) display_thread_id: bool,
@@ -265,6 +266,7 @@ impl Default for Format<Full, SystemTime> {
             format: Full,
             timer: SystemTime,
             ansi: true,
+            display_timestamp: true,
             display_target: true,
             display_level: true,
             display_thread_id: false,
@@ -283,6 +285,7 @@ impl<F, T> Format<F, T> {
             timer: self.timer,
             ansi: self.ansi,
             display_target: false,
+            display_timestamp: self.display_timestamp,
             display_level: self.display_level,
             display_thread_id: self.display_thread_id,
             display_thread_name: self.display_thread_name,
@@ -319,6 +322,7 @@ impl<F, T> Format<F, T> {
             timer: self.timer,
             ansi: self.ansi,
             display_target: self.display_target,
+            display_timestamp: self.display_timestamp,
             display_level: self.display_level,
             display_thread_id: self.display_thread_id,
             display_thread_name: self.display_thread_name,
@@ -348,6 +352,7 @@ impl<F, T> Format<F, T> {
             timer: self.timer,
             ansi: self.ansi,
             display_target: self.display_target,
+            display_timestamp: self.display_timestamp,
             display_level: self.display_level,
             display_thread_id: self.display_thread_id,
             display_thread_name: self.display_thread_name,
@@ -370,6 +375,7 @@ impl<F, T> Format<F, T> {
             timer,
             ansi: self.ansi,
             display_target: self.display_target,
+            display_timestamp: self.display_timestamp,
             display_level: self.display_level,
             display_thread_id: self.display_thread_id,
             display_thread_name: self.display_thread_name,
@@ -382,6 +388,7 @@ impl<F, T> Format<F, T> {
             format: self.format,
             timer: (),
             ansi: self.ansi,
+            display_timestamp: false,
             display_target: self.display_target,
             display_level: self.display_level,
             display_thread_id: self.display_thread_id,
@@ -452,6 +459,34 @@ impl<F, T> Format<F, T> {
 
         Ok(())
     }
+
+    #[inline]
+    fn format_timestamp(&self, writer: &mut dyn fmt::Write) -> fmt::Result
+    where
+        T: FormatTime,
+    {
+        // If timestamps are disabled, do nothing.
+        if !self.display_timestamp {
+            return Ok(());
+        }
+
+        // If ANSI color codes are enabled, format the timestamp with ANSI
+        // colors.
+        #[cfg(feature = "ansi")]
+        {
+            if self.ansi {
+                let style = Style::new().dimmed();
+                write!(writer, "{}", style.prefix())?;
+                self.timer.format_time(writer)?;
+                write!(writer, "{} ", style.suffix())?;
+                return Ok(());
+            }
+        }
+
+        // Otherwise, just format the timestamp without ANSI formatting.
+        self.timer.format_time(writer)?;
+        writer.write_char(' ')
+    }
 }
 
 #[cfg(feature = "json")]
@@ -513,11 +548,8 @@ where
         let meta = normalized_meta.as_ref().unwrap_or_else(|| event.metadata());
         #[cfg(not(feature = "tracing-log"))]
         let meta = event.metadata();
-        #[cfg(feature = "ansi")]
-        time::write(&self.timer, writer, self.ansi)?;
-        #[cfg(not(feature = "ansi"))]
-        time::write(&self.timer, writer)?;
 
+        self.format_timestamp(writer)?;
         self.format_level(*meta.level(), writer)?;
 
         if self.display_thread_name {
@@ -576,11 +608,8 @@ where
         let meta = normalized_meta.as_ref().unwrap_or_else(|| event.metadata());
         #[cfg(not(feature = "tracing-log"))]
         let meta = event.metadata();
-        #[cfg(feature = "ansi")]
-        time::write(&self.timer, writer, self.ansi)?;
-        #[cfg(not(feature = "ansi"))]
-        time::write(&self.timer, writer)?;
 
+        self.format_timestamp(writer)?;
         self.format_level(*meta.level(), writer)?;
 
         if self.display_thread_name {
@@ -1239,6 +1268,22 @@ pub(super) mod test {
         }
     }
 
+    #[test]
+    fn disable_everything() {
+        // This test reproduces https://github.com/tokio-rs/tracing/issues/1354
+        let make_writer = MockMakeWriter::default();
+        let subscriber = crate::fmt::Collector::builder()
+            .with_writer(make_writer.clone())
+            .without_time()
+            .with_level(false)
+            .with_target(false)
+            .with_thread_ids(false)
+            .with_thread_names(false);
+        #[cfg(feature = "ansi")]
+        let subscriber = subscriber.with_ansi(false);
+        run_test(subscriber, make_writer, "hello\n")
+    }
+
     #[cfg(feature = "ansi")]
     #[test]
     fn with_ansi_true() {

tracing-subscriber/src/fmt/format/pretty.rs

@@ -107,7 +107,8 @@ where
         #[cfg(not(feature = "tracing-log"))]
         let meta = event.metadata();
         write!(writer, "  ")?;
-        time::write(&self.timer, writer, self.ansi)?;
+
+        self.format_timestamp(writer)?;
 
         let style = if self.display_level && self.ansi {
             Pretty::style_for(meta.level())

tracing-subscriber/src/fmt/time/mod.rs

@@ -1,6 +1,4 @@
 //! Formatters for event timestamps.
-#[cfg(feature = "ansi")]
-use ansi_term::Style;
 use std::fmt;
 use std::time::Instant;
 
@@ -244,31 +242,3 @@ impl FormatTime for ChronoLocal {
         }
     }
 }
-
-#[inline(always)]
-#[cfg(feature = "ansi")]
-pub(crate) fn write<T>(timer: T, writer: &mut dyn fmt::Write, with_ansi: bool) -> fmt::Result
-where
-    T: FormatTime,
-{
-    if with_ansi {
-        let style = Style::new().dimmed();
-        write!(writer, "{}", style.prefix())?;
-        timer.format_time(writer)?;
-        write!(writer, "{}", style.suffix())?;
-    } else {
-        timer.format_time(writer)?;
-    }
-    writer.write_char(' ')?;
-    Ok(())
-}
-
-#[inline(always)]
-#[cfg(not(feature = "ansi"))]
-pub(crate) fn write<T>(timer: T, writer: &mut dyn fmt::Write) -> fmt::Result
-where
-    T: FormatTime,
-{
-    timer.format_time(writer)?;
-    write!(writer, " ")
-}