auto merge of #17894 : steveklabnik/rust/fail_to_panic, r=aturon

This in-progress PR implements https://github.com/rust-lang/rust/issues/17489.

I made the code changes in this commit, next is to go through alllllllll the documentation and fix various things.

- Rename column headings as appropriate, `# Panics` for panic conditions and `# Errors` for `Result`s.
- clean up usage of words like 'fail' in error messages

Anything else to add to the list, @aturon ? I think I should leave the actual functions with names like `slice_or_fail` alone, since you'll get to those in your conventions work?

I'm submitting just the code bits now so that we can see it separately, and I also don't want to have to keep re-building rust over and over again if I don't have to 😉 

Listing all the bits so I can remember as I go:

- [x] compiler-rt
- [x] compiletest
- [x] doc
- [x] driver
- [x] etc
- [x] grammar
- [x] jemalloc
- [x] liballoc
- [x] libarena
- [x] libbacktrace
- [x] libcollections
- [x] libcore
- [x] libcoretest
- [x] libdebug
- [x] libflate
- [x] libfmt_macros
- [x] libfourcc
- [x] libgetopts
- [x] libglob
- [x] libgraphviz
- [x] libgreen
- [x] libhexfloat
- [x] liblibc
- [x] liblog
- [x] libnative
- [x] libnum
- [x] librand
- [x] librbml
- [x] libregex
- [x] libregex_macros
- [x] librlibc
- [x] librustc
- [x] librustc_back
- [x] librustc_llvm
- [x] librustdoc
- [x] librustrt
- [x] libsemver
- [x] libserialize
- [x] libstd
- [x] libsync
- [x] libsyntax
- [x] libterm
- [x] libtest
- [x] libtime
- [x] libunicode
- [x] liburl
- [x] libuuid
- [x] llvm
- [x] rt
- [x] test

src/libregex/compile.rs

@@ -240,13 +240,13 @@ impl<'r> Compiler<'r> {
     /// Sets the left and right locations of a `Split` instruction at index
     /// `i` to `pc1` and `pc2`, respectively.
     /// If the instruction at index `i` isn't a `Split` instruction, then
-    /// `fail!` is called.
+    /// `panic!` is called.
     #[inline]
     fn set_split(&mut self, i: InstIdx, pc1: InstIdx, pc2: InstIdx) {
         let split = self.insts.get_mut(i);
         match *split {
             Split(_, _) => *split = Split(pc1, pc2),
-            _ => fail!("BUG: Invalid split index."),
+            _ => panic!("BUG: Invalid split index."),
         }
     }
 
@@ -260,13 +260,13 @@ impl<'r> Compiler<'r> {
 
     /// Sets the location of a `Jump` instruction at index `i` to `pc`.
     /// If the instruction at index `i` isn't a `Jump` instruction, then
-    /// `fail!` is called.
+    /// `panic!` is called.
     #[inline]
     fn set_jump(&mut self, i: InstIdx, pc: InstIdx) {
         let jmp = self.insts.get_mut(i);
         match *jmp {
             Jump(_) => *jmp = Jump(pc),
-            _ => fail!("BUG: Invalid jump index."),
+            _ => panic!("BUG: Invalid jump index."),
         }
     }
 }

src/libregex/lib.rs

@@ -31,7 +31,7 @@
 //! use regex::Regex;
 //! let re = match Regex::new(r"^\d{4}-\d{2}-\d{2}$") {
 //!     Ok(re) => re,
-//!     Err(err) => fail!("{}", err),
+//!     Err(err) => panic!("{}", err),
 //! };
 //! assert_eq!(re.is_match("2014-01-01"), true);
 //! ```

src/libregex/parse.rs

@@ -117,7 +117,7 @@ impl BuildAst {
     fn flags(&self) -> Flags {
         match *self {
             Paren(flags, _, _) => flags,
-            _ => fail!("Cannot get flags from {}", self),
+            _ => panic!("Cannot get flags from {}", self),
         }
     }
 
@@ -125,7 +125,7 @@ impl BuildAst {
         match *self {
             Paren(_, 0, _) => None,
             Paren(_, c, _) => Some(c),
-            _ => fail!("Cannot get capture group from {}", self),
+            _ => panic!("Cannot get capture group from {}", self),
         }
     }
 
@@ -139,7 +139,7 @@ impl BuildAst {
                     Some(name.clone())
                 }
             }
-            _ => fail!("Cannot get capture name from {}", self),
+            _ => panic!("Cannot get capture name from {}", self),
         }
     }
 
@@ -153,7 +153,7 @@ impl BuildAst {
     fn unwrap(self) -> Result<Ast, Error> {
         match self {
             Expr(x) => Ok(x),
-            _ => fail!("Tried to unwrap non-AST item: {}", self),
+            _ => panic!("Tried to unwrap non-AST item: {}", self),
         }
     }
 }
@@ -321,7 +321,7 @@ impl<'a> Parser<'a> {
         }
         let rep: Repeater = match c {
             '?' => ZeroOne, '*' => ZeroMore, '+' => OneMore,
-            _ => fail!("Not a valid repeater operator."),
+            _ => panic!("Not a valid repeater operator."),
         };
 
         match self.peek(1) {
@@ -389,7 +389,7 @@ impl<'a> Parser<'a> {
                             continue
                         }
                         Some(ast) =>
-                            fail!("Expected Class AST but got '{}'", ast),
+                            panic!("Expected Class AST but got '{}'", ast),
                         // Just drop down and try to add as a regular character.
                         None => {},
                     },
@@ -404,7 +404,7 @@ impl<'a> Parser<'a> {
                             return self.err(
                                 "\\A, \\z, \\b and \\B are not valid escape \
                                  sequences inside a character class."),
-                        ast => fail!("Unexpected AST item '{}'", ast),
+                        ast => panic!("Unexpected AST item '{}'", ast),
                     }
                 }
                 ']' if ranges.len() > 0 || alts.len() > 0 => {

src/libregex/re.rs

@@ -76,7 +76,7 @@ pub fn is_match(regex: &str, text: &str) -> Result<bool, parse::Error> {
 /// # use regex::Regex;
 /// let re = match Regex::new("[0-9]{3}-[0-9]{3}-[0-9]{4}") {
 ///     Ok(re) => re,
-///     Err(err) => fail!("{}", err),
+///     Err(err) => panic!("{}", err),
 /// };
 /// assert_eq!(re.find("phone: 111-222-3333"), Some((7, 19)));
 /// ```

src/libregex/test/bench.rs

@@ -15,7 +15,7 @@ use stdtest::Bencher;
 use regex::{Regex, NoExpand};
 
 fn bench_assert_match(b: &mut Bencher, re: Regex, text: &str) {
-    b.iter(|| if !re.is_match(text) { fail!("no match") });
+    b.iter(|| if !re.is_match(text) { panic!("no match") });
 }
 
 #[bench]
@@ -143,7 +143,7 @@ macro_rules! throughput(
         fn $name(b: &mut Bencher) {
             let text = gen_text($size);
             b.bytes = $size;
-            b.iter(|| if $regex.is_match(text.as_slice()) { fail!("match") });
+            b.iter(|| if $regex.is_match(text.as_slice()) { panic!("match") });
         }
     );
 )

src/libregex/test/mod.rs

@@ -30,7 +30,7 @@ macro_rules! regex(
     ($re:expr) => (
         match ::regex::Regex::new($re) {
             Ok(re) => re,
-            Err(err) => fail!("{}", err),
+            Err(err) => panic!("{}", err),
         }
     );
 )

src/libregex/test/tests.rs

@@ -99,7 +99,7 @@ macro_rules! noparse(
             let re = $re;
             match Regex::new(re) {
                 Err(_) => {},
-                Ok(_) => fail!("Regex '{}' should cause a parse error.", re),
+                Ok(_) => panic!("Regex '{}' should cause a parse error.", re),
             }
         }
     );
@@ -161,7 +161,7 @@ macro_rules! mat(
                 sgot = sgot[0..sexpect.len()]
             }
             if sexpect != sgot {
-                fail!("For RE '{}' against '{}', expected '{}' but got '{}'",
+                panic!("For RE '{}' against '{}', expected '{}' but got '{}'",
                       $re, text, sexpect, sgot);
             }
         }