Test fixes and rebase conflicts

This commit switches over the backtrace infrastructure from piggy-backing off
the RUST_LOG environment variable to using the RUST_BACKTRACE environment
variable (logging is now disabled in libstd).

2 files changed, 21 insertions, 3 deletions

diff --git a/src/libstd/rt/backtrace.rs b/src/libstd/rt/backtrace.rs
index 831f6c73e35..bc75a98e085 100644
--- a/src/libstd/rt/backtrace.rs
+++ b/src/libstd/rt/backtrace.rs
@@ -16,15 +16,31 @@ use from_str::from_str;
 use io::{IoResult, Writer};
 use iter::Iterator;
 use option::{Some, None};
+use os;
 use result::{Ok, Err};
 use str::StrSlice;
+use sync::atomics;
 
 pub use self::imp::write;
 
-// This function is defined in this module so that the way to enable logging of
-// backtraces has the word 'backtrace' in it: std::rt::backtrace.
+// For now logging is turned off by default, and this function checks to see
+// whether the magical environment variable is present to see if it's turned on.
 pub fn log_enabled() -> bool {
-    log_enabled!(::logging::DEBUG)
+    static mut ENABLED: atomics::AtomicInt = atomics::INIT_ATOMIC_INT;
+    unsafe {
+        match ENABLED.load(atomics::SeqCst) {
+            1 => return false,
+            2 => return true,
+            _ => {}
+        }
+    }
+
+    let val = match os::getenv("RUST_BACKTRACE") {
+        Some(..) => 2,
+        None => 1,
+    };
+    unsafe { ENABLED.store(val, atomics::SeqCst); }
+    val == 2
 }
 
 #[cfg(target_word_size = "64")] static HEX_WIDTH: uint = 18;
diff --git a/src/libstd/rt/unwind.rs b/src/libstd/rt/unwind.rs
index 3a06075ce48..7f54b8b3320 100644
--- a/src/libstd/rt/unwind.rs
+++ b/src/libstd/rt/unwind.rs
@@ -398,6 +398,8 @@ fn begin_unwind_inner(msg: ~Any, file: &'static str, line: uint) -> ! {
                 if backtrace::log_enabled() {
                     let mut err = ::rt::util::Stderr;
                     let _err = backtrace::write(&mut err);
+                } else {
+                    rterrln!("run with `RUST_BACKTRACE=1` to see a backtrace");
                 }
                 unsafe { intrinsics::abort() }
             }