Add a logging panic handler

.travis.yml

@@ -7,18 +7,20 @@ rust:
   - nightly
 script:
   - cargo build --verbose
+  - ([ $TRAVIS_RUST_VERSION != nightly ] || cargo build --verbose --features nightly)
   - cargo test --verbose
   - cargo test --verbose --manifest-path env/Cargo.toml
   - cargo run --verbose --manifest-path tests/max_level_features/Cargo.toml
   - cargo run --verbose --manifest-path tests/max_level_features/Cargo.toml --release
-  - cargo doc --manifest-path env/Cargo.toml
+  - ([ $TRAVIS_RUST_VERSION != nightly ] || cargo doc --no-deps --features nightly)
+  - CARGO_TARGET_DIR=target cargo doc --no-deps --manifest-path env/Cargo.toml
 after_success: |
   [ $TRAVIS_BRANCH = master ] &&
   [ $TRAVIS_PULL_REQUEST = false ] &&
   [ $TRAVIS_RUST_VERSION = nightly ] &&
-  echo '<meta http-equiv=refresh content=0;url=log/index.html>' > env/target/doc/index.html &&
+  echo '<meta http-equiv=refresh content=0;url=log/index.html>' > target/doc/index.html &&
   pip install ghp-import --user $USER &&
-  $HOME/.local/bin/ghp-import -n env/target/doc &&
+  $HOME/.local/bin/ghp-import -n target/doc &&
   git push -qf https://${TOKEN}@github.com/${TRAVIS_REPO_SLUG}.git gh-pages
 env:
   global:

Cargo.toml

@@ -33,3 +33,5 @@ release_max_level_warn  = []
 release_max_level_info  = []
 release_max_level_debug = []
 release_max_level_trace = []
+
+nightly = []

src/lib.rs

@@ -148,6 +148,7 @@
        html_favicon_url = "https://www.rust-lang.org/favicon.ico",
        html_root_url = "https://doc.rust-lang.org/log/")]
 #![warn(missing_docs)]
+#![cfg_attr(feature = "nightly", feature(panic_handler))]
 
 extern crate libc;
 
@@ -159,6 +160,7 @@ use std::mem;
 use std::ops::Deref;
 use std::str::FromStr;
 use std::sync::atomic::{AtomicUsize, ATOMIC_USIZE_INIT, Ordering};
+#[macro_use]
 mod macros;
 
 // The setup here is a bit weird to make at_exit work.
@@ -620,6 +622,49 @@ impl error::Error for SetLoggerError {
     fn description(&self) -> &str { "set_logger() called multiple times" }
 }
 
+/// Registers a panic handler which logs at the error level.
+///
+/// The format is the same as the default panic handler. The reporting module is
+/// `log::panic`.
+///
+/// Requires the `nightly` feature.
+#[cfg(feature = "nightly")]
+pub fn log_panics() {
+    std::panic::set_handler(panic::log);
+}
+
+// inner module so that the reporting module is log::panic instead of log
+#[cfg(feature = "nightly")]
+mod panic {
+    use std::panic::PanicInfo;
+    use std::thread;
+
+    pub fn log(info: &PanicInfo) {
+        let thread = thread::current();
+        let thread = thread.name().unwrap_or("<unnamed>");
+
+        let msg = match info.payload().downcast_ref::<&'static str>() {
+            Some(s) => *s,
+            None => match info.payload().downcast_ref::<String>() {
+                Some(s) => &s[..],
+                None => "Box<Any>",
+            }
+        };
+
+        match info.location() {
+            Some(location) => {
+                error!("thread '{}' panicked at '{}': {}:{}",
+                       thread,
+                       msg,
+                       location.file(),
+                       location.line())
+            }
+            None => error!("thread '{}' panicked at '{}'", thread, msg),
+        }
+    }
+}
+
+
 struct LoggerGuard(usize);
 
 impl Drop for LoggerGuard {