Added show-backtrace feature

Cargo.toml

@@ -12,10 +12,11 @@ categories = []
 keywords = []
 
 [features]
-default = ["track-caller", "capture-spantrace"]
+default = ["track-caller", "capture-spantrace", "show-backtrace"]
 capture-spantrace = ["tracing-error", "color-spantrace"]
 issue-url = ["url"]
 track-caller = []
+show-backtrace = []
 
 [dependencies]
 eyre = "0.6.1"

src/writers.rs

@@ -185,13 +185,15 @@ impl fmt::Display for EnvSection<'_> {
         } else {
             lib_verbosity()
         };
+        #[cfg(feature = "show-backtrace")]
         write!(f, "{}", BacktraceOmited(!self.bt_captured))?;
 
         let mut separated = HeaderWriter {
             inner: &mut *f,
             header: &"\n",
             started: false,
         };
+        #[cfg(feature = "show-backtrace")]
         write!(&mut separated.ready(), "{}", SourceSnippets(v))?;
         #[cfg(feature = "capture-spantrace")]
         write!(
@@ -223,8 +225,10 @@ impl fmt::Display for SpanTraceOmited<'_> {
     }
 }
 
+#[cfg(feature = "show-backtrace")]
 struct BacktraceOmited(bool);
 
+#[cfg(feature = "show-backtrace")]
 impl fmt::Display for BacktraceOmited {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // Print some info on how to increase verbosity.
@@ -245,8 +249,10 @@ impl fmt::Display for BacktraceOmited {
     }
 }
 
+#[cfg(feature = "show-backtrace")]
 struct SourceSnippets(Verbosity);
 
+#[cfg(feature = "show-backtrace")]
 impl fmt::Display for SourceSnippets {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         if self.0 <= Verbosity::Medium {