Rename fail! to panic!

https://github.com/rust-lang/rfcs/pull/221

The current terminology of "task failure" often causes problems when
writing or speaking about code. You often want to talk about the
possibility of an operation that returns a Result "failing", but cannot
because of the ambiguity with task failure. Instead, you have to speak
of "the failing case" or "when the operation does not succeed" or other
circumlocutions.

Likewise, we use a "Failure" header in rustdoc to describe when
operations may fail the task, but it would often be helpful to separate
out a section describing the "Err-producing" case.

We have been steadily moving away from task failure and toward Result as
an error-handling mechanism, so we should optimize our terminology
accordingly: Result-producing functions should be easy to describe.

To update your code, rename any call to `fail!` to `panic!` instead.
Assuming you have not created your own macro named `panic!`, this
will work on UNIX based systems:

    grep -lZR 'fail!' . | xargs -0 -l sed -i -e 's/fail!/panic!/g'

You can of course also do this by hand.

[breaking-change]

1 files changed, 10 insertions, 10 deletions

diff --git a/src/libcore/macros.rs b/src/libcore/macros.rs
index 17fcf025457..9ba67bb2e47 100644
--- a/src/libcore/macros.rs
+++ b/src/libcore/macros.rs
@@ -10,15 +10,15 @@
 
 #![macro_escape]
 
-/// Entry point of failure, for details, see std::macros
+/// Entry point of task panic, for details, see std::macros
 #[macro_export]
-macro_rules! fail(
+macro_rules! panic(
     () => (
-        fail!("{}", "explicit failure")
+        panic!("{}", "explicit panic")
     );
     ($msg:expr) => ({
         static _MSG_FILE_LINE: (&'static str, &'static str, uint) = ($msg, file!(), line!());
-        ::core::failure::fail(&_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
@@ -31,7 +31,7 @@ macro_rules! fail(
         // 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 fail!()
+        // 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
@@ -40,7 +40,7 @@ macro_rules! fail(
         #[inline(always)]
         fn _run_fmt(fmt: &::std::fmt::Arguments) -> ! {
             static _FILE_LINE: (&'static str, uint) = (file!(), line!());
-            ::core::failure::fail_fmt(fmt, &_FILE_LINE)
+            ::core::panicking::panic_fmt(fmt, &_FILE_LINE)
         }
         format_args!(_run_fmt, $fmt, $($arg)*)
     });
@@ -51,12 +51,12 @@ macro_rules! fail(
 macro_rules! assert(
     ($cond:expr) => (
         if !$cond {
-            fail!(concat!("assertion failed: ", stringify!($cond)))
+            panic!(concat!("assertion failed: ", stringify!($cond)))
         }
     );
     ($cond:expr, $($arg:tt)*) => (
         if !$cond {
-            fail!($($arg)*)
+            panic!($($arg)*)
         }
     );
 )
@@ -78,7 +78,7 @@ macro_rules! assert_eq(
         let c1 = $cond1;
         let c2 = $cond2;
         if c1 != c2 || c2 != c1 {
-            fail!("expressions not equal, left: {}, right: {}", c1, c2);
+            panic!("expressions not equal, left: {}, right: {}", c1, c2);
         }
     })
 )
@@ -130,4 +130,4 @@ macro_rules! write(
 )
 
 #[macro_export]
-macro_rules! unreachable( () => (fail!("unreachable code")) )
+macro_rules! unreachable( () => (panic!("unreachable code")) )