Use fewer instructions for fail!()

src/librustrt/lib.rs

@@ -33,7 +33,7 @@ extern crate collections;
 #[cfg(test)] #[phase(plugin, link)] extern crate std;
 
 pub use self::util::{Stdio, Stdout, Stderr};
-pub use self::unwind::{begin_unwind, begin_unwind_fmt};
+pub use self::unwind::{begin_unwind, begin_unwind_fmt, begin_unwind_no_time_to_explain};
 
 use core::prelude::*;
 

src/librustrt/unwind.rs

@@ -432,6 +432,11 @@ pub fn begin_unwind<M: Any + Send>(msg: M, file: &'static str, line: uint) -> !
     begin_unwind_inner(box msg, file, line)
 }
 
+/// Unwinding for `fail!()`. Saves passing a string.
+#[inline(never)] #[cold] #[experimental]
+pub fn begin_unwind_no_time_to_explain(file: &'static str, line: uint) -> ! {
+    begin_unwind_inner(box () ("explicit failure"), file, line)
+}
 
 /// The core of the unwinding.
 ///

src/libstd/macros.rs

@@ -39,7 +39,7 @@
 #[macro_export]
 macro_rules! fail(
     () => (
-        fail!("explicit failure")
+        ::std::rt::begin_unwind_no_time_to_explain(file!(), line!())
     );
     ($msg:expr) => (
         ::std::rt::begin_unwind($msg, file!(), line!())

src/libstd/rt/mod.rs

@@ -66,7 +66,8 @@ pub use self::util::{default_sched_threads, min_stack, running_on_valgrind};
 // standard library which work together to create the entire runtime.
 pub use alloc::{heap, libc_heap};
 pub use rustrt::{task, local, mutex, exclusive, stack, args, rtio, thread};
-pub use rustrt::{Stdio, Stdout, Stderr, begin_unwind, begin_unwind_fmt};
+pub use rustrt::{Stdio, Stdout, Stderr};
+pub use rustrt::{begin_unwind, begin_unwind_fmt, begin_unwind_no_time_to_explain};
 pub use rustrt::{bookkeeping, at_exit, unwind, DEFAULT_ERROR_CODE, Runtime};
 
 // Simple backtrace functionality (to print on failure)