Auto merge of #10329 - Manishearth:skip-backtrace, r=asajeffrey

Skip printing the backtrace for RecvError/SendError

We currently get tons of useless backtraces clogging up the output when we have a panic cascade. This adds a handler that outputs a single line when a thread panics due to a sender or receiver hanging up, since this is almost always due to a panic cascade.

We could add a commandline arg that gets us back the old behavior, though I'm not sure if this is necessary.

r? @asajeffrey

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components/util/opts.rs

@@ -198,6 +198,9 @@ pub struct Opts {
 
     // Which rendering API to use.
     pub render_api: RenderApi,
+
+    // don't skip any backtraces on panic
+    pub full_backtraces: bool,
 }
 
 fn print_usage(app: &str, opts: &Options) {
@@ -285,6 +288,9 @@ pub struct DebugOptions {
     /// Use multisample antialiasing in WebRender.
     pub use_msaa: bool,
 
+    // don't skip any backtraces on panic
+    pub full_backtraces: bool,
+
 }
 
 
@@ -319,6 +325,7 @@ impl DebugOptions {
                 "disable-vsync" => debug_options.disable_vsync = true,
                 "wr-stats" => debug_options.webrender_stats = true,
                 "msaa" => debug_options.use_msaa = true,
+                "full-backtraces" => debug_options.full_backtraces = true,
                 "" => {},
                 _ => return Err(option)
             };
@@ -365,6 +372,7 @@ pub fn print_debug_usage(app: &str) -> ! {
                  "Disable vsync mode in the compositor to allow profiling at more than monitor refresh rate");
     print_option("wr-stats", "Show WebRender profiler on screen.");
     print_option("msaa", "Use multisample antialiasing in WebRender.");
+    print_option("full-backtraces", "Print full backtraces for all errors");
 
     println!("");
 
@@ -506,6 +514,7 @@ pub fn default_opts() -> Opts {
         use_msaa: false,
         render_api: DEFAULT_RENDER_API,
         profile_dir: None,
+        full_backtraces: false,
     }
 }
 
@@ -791,6 +800,7 @@ pub fn from_cmdline_args(args: &[String]) -> ArgumentParsingResult {
         webrender_stats: debug_options.webrender_stats,
         use_msaa: debug_options.use_msaa,
         profile_dir: opt_match.opt_str("profile-dir"),
+        full_backtraces: debug_options.full_backtraces,
     };
 
     set_defaults(opts);