Auto merge of #22561 - richo:as_slice-as_str, r=Manishearth

This may not be quite ready to go out, I fixed some docs but suspect I missed a bunch.

I also wound up fixing a bunch of redundant `[]` suffixes, but on closer inspection I don't believe that can land until after a snapshot.

Author: bors

src/doc/style/errors/ergonomics.md

@@ -22,9 +22,9 @@ fn write_info(info: &Info) -> Result<(), IoError> {
     let mut file = File::open_mode(&Path::new("my_best_friends.txt"),
                                    Open, Write);
     // Early return on error
-    try!(file.write_line(format!("name: {}", info.name).as_slice()));
-    try!(file.write_line(format!("age: {}", info.age).as_slice()));
-    try!(file.write_line(format!("rating: {}", info.rating).as_slice()));
+    try!(file.write_line(&format!("name: {}", info.name)));
+    try!(file.write_line(&format!("age: {}", info.age)));
+    try!(file.write_line(&format!("rating: {}", info.rating)));
     return Ok(());
 }
 ```
@@ -44,15 +44,15 @@ fn write_info(info: &Info) -> Result<(), IoError> {
     let mut file = File::open_mode(&Path::new("my_best_friends.txt"),
                                    Open, Write);
     // Early return on error
-    match file.write_line(format!("name: {}", info.name).as_slice()) {
+    match file.write_line(&format!("name: {}", info.name)) {
         Ok(_) => (),
         Err(e) => return Err(e)
     }
-    match file.write_line(format!("age: {}", info.age).as_slice()) {
+    match file.write_line(&format!("age: {}", info.age)) {
         Ok(_) => (),
         Err(e) => return Err(e)
     }
-    return file.write_line(format!("rating: {}", info.rating).as_slice());
+    return file.write_line(&format!("rating: {}", info.rating));
 }
 ```
 

src/libcollections/fmt.rs

@@ -198,7 +198,7 @@
 //!         // for details, and the function `pad` can be used to pad strings.
 //!         let decimals = f.precision().unwrap_or(3);
 //!         let string = f64::to_str_exact(magnitude, decimals);
-//!         f.pad_integral(true, "", string.as_slice())
+//!         f.pad_integral(true, "", &string)
 //!     }
 //! }
 //!

src/libcollections/string.rs

@@ -139,7 +139,7 @@ impl String {
     /// ```rust
     /// let input = b"Hello \xF0\x90\x80World";
     /// let output = String::from_utf8_lossy(input);
-    /// assert_eq!(output.as_slice(), "Hello \u{FFFD}World");
+    /// assert_eq!(output, "Hello \u{FFFD}World");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn from_utf8_lossy<'a>(v: &'a [u8]) -> Cow<'a, str> {
@@ -355,7 +355,7 @@ impl String {
     /// ```
     /// let mut s = String::from_str("foo");
     /// s.push_str("bar");
-    /// assert_eq!(s.as_slice(), "foobar");
+    /// assert_eq!(s, "foobar");
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -450,7 +450,7 @@ impl String {
     /// s.push('1');
     /// s.push('2');
     /// s.push('3');
-    /// assert_eq!(s.as_slice(), "abc123");
+    /// assert_eq!(s, "abc123");
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -503,7 +503,7 @@ impl String {
     /// ```
     /// let mut s = String::from_str("hello");
     /// s.truncate(2);
-    /// assert_eq!(s.as_slice(), "he");
+    /// assert_eq!(s, "he");
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -622,7 +622,7 @@ impl String {
     ///     assert!(vec == &[104, 101, 108, 108, 111]);
     ///     vec.reverse();
     /// }
-    /// assert_eq!(s.as_slice(), "olleh");
+    /// assert_eq!(s, "olleh");
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]

src/libcore/result.rs

@@ -178,13 +178,13 @@
 //! fn write_info(info: &Info) -> Result<(), IoError> {
 //!     let mut file = File::open_mode(&Path::new("my_best_friends.txt"), Open, Write);
 //!     // Early return on error
-//!     if let Err(e) = file.write_line(format!("name: {}", info.name).as_slice()) {
+//!     if let Err(e) = file.write_line(&format!("name: {}", info.name)) {
 //!         return Err(e)
 //!     }
-//!     if let Err(e) = file.write_line(format!("age: {}", info.age).as_slice()) {
+//!     if let Err(e) = file.write_line(&format!("age: {}", info.age)) {
 //!         return Err(e)
 //!     }
-//!     return file.write_line(format!("rating: {}", info.rating).as_slice());
+//!     return file.write_line(&format!("rating: {}", info.rating));
 //! }
 //! ```
 //!
@@ -202,9 +202,9 @@
 //! fn write_info(info: &Info) -> Result<(), IoError> {
 //!     let mut file = File::open_mode(&Path::new("my_best_friends.txt"), Open, Write);
 //!     // Early return on error
-//!     try!(file.write_line(format!("name: {}", info.name).as_slice()));
-//!     try!(file.write_line(format!("age: {}", info.age).as_slice()));
-//!     try!(file.write_line(format!("rating: {}", info.rating).as_slice()));
+//!     try!(file.write_line(&format!("name: {}", info.name)));
+//!     try!(file.write_line(&format!("age: {}", info.age)));
+//!     try!(file.write_line(&format!("rating: {}", info.rating)));
 //!     return Ok(());
 //! }
 //! ```

src/libgetopts/lib.rs

@@ -46,7 +46,7 @@
 //!
 //! fn print_usage(program: &str, opts: &[OptGroup]) {
 //!     let brief = format!("Usage: {} [options]", program);
-//!     print!("{}", usage(brief.as_slice(), opts));
+//!     print!("{}", usage(brief, opts));
 //! }
 //!
 //! fn main() {
@@ -63,17 +63,17 @@
 //!         Err(f) => { panic!(f.to_string()) }
 //!     };
 //!     if matches.opt_present("h") {
-//!         print_usage(program.as_slice(), opts);
+//!         print_usage(program, opts);
 //!         return;
 //!     }
 //!     let output = matches.opt_str("o");
 //!     let input = if !matches.free.is_empty() {
 //!         matches.free[0].clone()
 //!     } else {
-//!         print_usage(program.as_slice(), opts);
+//!         print_usage(program, opts);
 //!         return;
 //!     };
-//!     do_work(input.as_slice(), output);
+//!     do_work(input, output);
 //! }
 //! ```
 

src/librustc/metadata/creader.rs

@@ -493,7 +493,7 @@ impl<'a> CrateReader<'a> {
         };
 
         let dylib = library.dylib.clone();
-        let register = should_link && self.existing_match(info.name.as_slice(),
+        let register = should_link && self.existing_match(&info.name,
                                                           None,
                                                           PathKind::Crate).is_none();
         let metadata = if register {

src/librustc/middle/check_match.rs

@@ -276,7 +276,7 @@ fn check_for_static_nan(cx: &MatchCheckCtxt, pat: &Pat) {
                     let subspan = p.span.lo <= err.span.lo && err.span.hi <= p.span.hi;
                     cx.tcx.sess.span_err(err.span,
                                          &format!("constant evaluation error: {}",
-                                                  err.description().as_slice()));
+                                                  err.description()));
                     if !subspan {
                         cx.tcx.sess.span_note(p.span,
                                               "in pattern here")

src/librustc/middle/const_eval.rs

@@ -204,7 +204,7 @@ pub fn const_expr_to_pat(tcx: &ty::ctxt, expr: &Expr, span: Span) -> P<ast::Pat>
 pub fn eval_const_expr(tcx: &ty::ctxt, e: &Expr) -> const_val {
     match eval_const_expr_partial(tcx, e, None) {
         Ok(r) => r,
-        Err(s) => tcx.sess.span_fatal(s.span, s.description().as_slice())
+        Err(s) => tcx.sess.span_fatal(s.span, &s.description())
     }
 }
 
@@ -665,14 +665,14 @@ pub fn compare_lit_exprs<'tcx>(tcx: &ty::ctxt<'tcx>,
     let a = match eval_const_expr_partial(tcx, a, ty_hint) {
         Ok(a) => a,
         Err(e) => {
-            tcx.sess.span_err(a.span, e.description().as_slice());
+            tcx.sess.span_err(a.span, &e.description());
             return None;
         }
     };
     let b = match eval_const_expr_partial(tcx, b, ty_hint) {
         Ok(b) => b,
         Err(e) => {
-            tcx.sess.span_err(b.span, e.description().as_slice());
+            tcx.sess.span_err(b.span, &e.description());
             return None;
         }
     };

src/librustc/middle/ty.rs

@@ -5485,7 +5485,7 @@ pub fn enum_variants<'tcx>(cx: &ctxt<'tcx>, id: ast::DefId)
                                         Err(err) => {
                                             span_err!(cx.sess, err.span, E0305,
                                                       "constant evaluation error: {}",
-                                                      err.description().as_slice());
+                                                      err.description());
                                         }
                                     }
                                 } else {

src/librustc/util/ppaux.rs

@@ -115,7 +115,7 @@ pub fn explain_region_and_span(cx: &ctxt, region: ty::Region)
             region::CodeExtent::Misc(_) => tag,
             region::CodeExtent::DestructionScope(_) => {
                 new_string = format!("destruction scope surrounding {}", tag);
-                new_string.as_slice()
+                &*new_string
             }
             region::CodeExtent::Remainder(r) => {
                 new_string = format!("block suffix following statement {}",