libcore: use full path of str in panic! macro

src/libcore/macros.rs

@@ -10,6 +10,8 @@
 
 #![macro_escape]
 
+// NOTE(stage0): Remove macro after a snapshot
+#[cfg(stage0)]
 /// Entry point of task panic, for details, see std::macros
 #[macro_export]
 macro_rules! panic(
@@ -46,6 +48,44 @@ macro_rules! panic(
     });
 )
 
+#[cfg(not(stage0))]  // NOTE(stage0): Remove cfg after a snapshot
+/// Entry point of task panic, for details, see std::macros
+#[macro_export]
+macro_rules! panic(
+    () => (
+        panic!("{}", "explicit panic")
+    );
+    ($msg:expr) => ({
+        static _MSG_FILE_LINE: (&'static ::std::str::str, &'static ::std::str::str, uint) =
+            ($msg, file!(), line!());
+        ::core::panicking::panic(&_MSG_FILE_LINE)
+    });
+    ($fmt:expr, $($arg:tt)*) => ({
+        // 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.
+        //
+        // LLVM doesn't tend to inline this, presumably because begin_unwind_fmt
+        // is #[cold] and #[inline(never)] and because this is flagged as cold
+        // as returning !. We really do want this to be inlined, however,
+        // because it's just a tiny wrapper. Small wins (156K to 149K in size)
+        // were seen when forcing this to be inlined, and that number just goes
+        // up with the number of calls to panic!()
+        //
+        // The leading _'s are to avoid dead code warnings if this is
+        // used inside a dead function. Just `#[allow(dead_code)]` is
+        // insufficient, since the user may have
+        // `#[forbid(dead_code)]` and which cannot be overridden.
+        #[inline(always)]
+        fn _run_fmt(fmt: &::std::fmt::Arguments) -> ! {
+            static _FILE_LINE: (&'static ::std::str::str, uint) = (file!(), line!());
+            ::core::panicking::panic_fmt(fmt, &_FILE_LINE)
+        }
+        format_args!(_run_fmt, $fmt, $($arg)*)
+    });
+)
+
 /// Runtime assertion, for details see std::macros
 #[macro_export]
 macro_rules! assert(