---

yaml
---
r: 107694
b: refs/heads/dist-snap
c: b4bb8c0
h: refs/heads/master
v: v3

Author: huonw

[refs]

@@ -6,7 +6,7 @@ refs/heads/try: f64fdf524a434f0e5cd0bc91d09c144723f3c90d
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
 refs/heads/try2: 147ecfdd8221e4a4d4e090486829a06da1e0ca3c
-refs/heads/dist-snap: e5abe669831a59c48faa85e88ed8859b6dc63f49
+refs/heads/dist-snap: b4bb8c0f4ee1234e9d84aa7cb1a9ad691a509212
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596
 refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503
 refs/heads/try3: 9387340aab40a73e8424c48fd42f0c521a4875c0

branches/dist-snap/src/libstd/macros.rs

@@ -48,8 +48,18 @@ macro_rules! fail(
         ::std::rt::begin_unwind($msg, file!(), line!())
     );
     ($fmt:expr, $($arg:tt)*) => (
-        ::std::rt::begin_unwind(format!($fmt, $($arg)*), file!(), line!())
-    )
+        {
+            // a closure can't have return type !, so we need a full
+            // function to pass to format_args!, *and* we need the
+            // file and line numbers right here; so an inner bare fn
+            // is our only choice.
+            #[inline]
+            fn run_fmt(fmt: &::std::fmt::Arguments) -> ! {
+                ::std::rt::begin_unwind_fmt(fmt, file!(), line!())
+            }
+            format_args!(run_fmt, $fmt, $($arg)*)
+        }
+        )
 )
 
 #[macro_export]

branches/dist-snap/src/libstd/rt/mod.rs

@@ -69,7 +69,7 @@ use self::task::{Task, BlockedTask};
 pub use self::util::default_sched_threads;
 
 // Export unwinding facilities used by the failure macros
-pub use self::unwind::{begin_unwind, begin_unwind_raw};
+pub use self::unwind::{begin_unwind, begin_unwind_raw, begin_unwind_fmt};
 
 // FIXME: these probably shouldn't be public...
 #[doc(hidden)]

branches/dist-snap/src/libstd/rt/unwind.rs

@@ -58,6 +58,7 @@
 use any::{Any, AnyRefExt};
 use c_str::CString;
 use cast;
+use fmt;
 use kinds::Send;
 use option::{Some, None, Option};
 use prelude::drop;
@@ -382,6 +383,17 @@ pub fn begin_unwind_raw(msg: *u8, file: *u8, line: uint) -> ! {
     begin_unwind(msg, file, line as uint)
 }
 
+/// The entry point for unwinding with a formatted message.
+///
+/// This is designed to reduce the amount of code required at the call
+/// site as much as possible (so that `fail!()` has as low an implact
+/// on (e.g.) the inlining of other functions as possible), by moving
+/// the actual formatting into this shared place.
+#[inline(never)] #[cold]
+pub fn begin_unwind_fmt(msg: &fmt::Arguments, file: &'static str, line: uint) -> ! {
+    begin_unwind_inner(~fmt::format(msg), file, line)
+}
+
 /// This is the entry point of unwinding for fail!() and assert!().
 #[inline(never)] #[cold] // avoid code bloat at the call sites as much as possible
 pub fn begin_unwind<M: Any + Send>(msg: M, file: &'static str, line: uint) -> ! {