Rename fail! to panic!

rust-lang/rfcs#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]

Author: steveklabnik

src/compiletest/compiletest.rs

@@ -41,7 +41,7 @@ pub fn main() {
     let config = parse_config(args);
 
     if config.valgrind_path.is_none() && config.force_valgrind {
-        fail!("Can't find Valgrind to run Valgrind tests");
+        panic!("Can't find Valgrind to run Valgrind tests");
     }
 
     log_config(&config);
@@ -94,20 +94,20 @@ pub fn parse_config(args: Vec<String> ) -> Config {
         let message = format!("Usage: {} [OPTIONS] [TESTNAME...]", argv0);
         println!("{}", getopts::usage(message.as_slice(), groups.as_slice()));
         println!("");
-        fail!()
+        panic!()
     }
 
     let matches =
         &match getopts::getopts(args_.as_slice(), groups.as_slice()) {
           Ok(m) => m,
-          Err(f) => fail!("{}", f)
+          Err(f) => panic!("{}", f)
         };
 
     if matches.opt_present("h") || matches.opt_present("help") {
         let message = format!("Usage: {} [OPTIONS]  [TESTNAME...]", argv0);
         println!("{}", getopts::usage(message.as_slice(), groups.as_slice()));
         println!("");
-        fail!()
+        panic!()
     }
 
     fn opt_path(m: &getopts::Matches, nm: &str) -> Path {
@@ -120,7 +120,7 @@ pub fn parse_config(args: Vec<String> ) -> Config {
             Ok(re) => Some(re),
             Err(e) => {
                 println!("failed to parse filter /{}/: {}", s, e);
-                fail!()
+                panic!()
             }
         }
     } else {
@@ -263,7 +263,7 @@ pub fn run_tests(config: &Config) {
     let res = test::run_tests_console(&opts, tests.into_iter().collect());
     match res {
         Ok(true) => {}
-        Ok(false) => fail!("Some tests failed"),
+        Ok(false) => panic!("Some tests failed"),
         Err(e) => {
             println!("I/O failure during tests: {}", e);
         }

src/compiletest/header.rs

@@ -305,7 +305,7 @@ fn parse_exec_env(line: &str) -> Option<(String, String)> {
               let end = strs.pop().unwrap();
               (strs.pop().unwrap(), end)
           }
-          n => fail!("Expected 1 or 2 strings, not {}", n)
+          n => panic!("Expected 1 or 2 strings, not {}", n)
         }
     })
 }
@@ -350,7 +350,7 @@ pub fn gdb_version_to_int(version_string: &str) -> int {
     let components: Vec<&str> = version_string.trim().split('.').collect();
 
     if components.len() != 2 {
-        fail!("{}", error_string);
+        panic!("{}", error_string);
     }
 
     let major: int = FromStr::from_str(components[0]).expect(error_string);