std: Deny most warnings in doctests

Allow a few specific ones but otherwise this helps ensure that our examples are
squeaky clean!

Closes #18199

src/libcore/macros.rs

@@ -229,7 +229,6 @@
 /// Iterators:
 ///
 /// ```
-/// # #![feature(core)]
 /// fn divide_by_three(x: u32) -> u32 { // one of the poorest implementations of x/3
 ///     for i in 0.. {
 ///         if 3*i < i { panic!("u32 overflow"); }

src/libstd/collections/hash/set.rs

@@ -304,7 +304,6 @@ fn first<A, B>((a, _): (A, B)) -> A { a }
     /// # Examples
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::collections::HashSet;
     /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
     /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
@@ -335,7 +334,6 @@ pub fn difference<'a>(&'a self, other: &'a HashSet<T, S>) -> Difference<'a, T, S
     /// # Examples
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::collections::HashSet;
     /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
     /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
@@ -362,7 +360,6 @@ pub fn symmetric_difference<'a>(&'a self, other: &'a HashSet<T, S>)
     /// # Examples
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::collections::HashSet;
     /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
     /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
@@ -388,7 +385,6 @@ pub fn intersection<'a>(&'a self, other: &'a HashSet<T, S>) -> Intersection<'a,
     /// # Examples
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::collections::HashSet;
     /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
     /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
@@ -471,7 +467,6 @@ pub fn clear(&mut self) { self.map.clear() }
     /// # Examples
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::collections::HashSet;
     ///
     /// let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
@@ -491,7 +486,6 @@ pub fn contains<Q: ?Sized>(&self, value: &Q) -> bool
     /// # Examples
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::collections::HashSet;
     ///
     /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
@@ -513,7 +507,6 @@ pub fn is_disjoint(&self, other: &HashSet<T, S>) -> bool {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::collections::HashSet;
     ///
     /// let sup: HashSet<_> = [1, 2, 3].iter().cloned().collect();
@@ -535,7 +528,6 @@ pub fn is_subset(&self, other: &HashSet<T, S>) -> bool {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::collections::HashSet;
     ///
     /// let sub: HashSet<_> = [1, 2].iter().cloned().collect();

src/libstd/fs.rs

@@ -96,14 +96,16 @@ pub struct WalkDir {
 
 /// Options and flags which can be used to configure how a file is opened.
 ///
-/// This builder exposes the ability to configure how a `File` is opened and what operations are
-/// permitted on the open file. The `File::open` and `File::create` methods are aliases for
-/// commonly used options using this builder.
+/// This builder exposes the ability to configure how a `File` is opened and
+/// what operations are permitted on the open file. The `File::open` and
+/// `File::create` methods are aliases for commonly used options using this
+/// builder.
 ///
-/// Generally speaking, when using `OpenOptions`, you'll first call `new()`, then chain calls to
-/// methods to set each option, then call `open()`, passing the path of the file you're trying to
-/// open. This will give you a [`io::Result`][result] with a [`File`][file] inside that you can
-/// further operate on.
+/// Generally speaking, when using `OpenOptions`, you'll first call `new()`,
+/// then chain calls to methods to set each option, then call `open()`, passing
+/// the path of the file you're trying to open. This will give you a
+/// [`io::Result`][result] with a [`File`][file] inside that you can further
+/// operate on.
 ///
 /// [result]: ../io/type.Result.html
 /// [file]: struct.File.html
@@ -113,16 +115,15 @@ pub struct WalkDir {
 /// Opening a file to read:
 ///
 /// ```no_run
-/// use std::fs;
 /// use std::fs::OpenOptions;
 ///
 /// let file = OpenOptions::new().read(true).open("foo.txt");
 /// ```
 ///
-/// Opening a file for both reading and writing, as well as creating it if it doesn't exist:
+/// Opening a file for both reading and writing, as well as creating it if it
+/// doesn't exist:
 ///
 /// ```
-/// use std::fs;
 /// use std::fs::OpenOptions;
 ///
 /// let file = OpenOptions::new()
@@ -771,7 +772,9 @@ pub fn rename<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()>
 /// ```no_run
 /// use std::fs;
 ///
-/// fs::copy("foo.txt", "bar.txt");
+/// # fn foo() -> std::io::Result<()> {
+/// try!(fs::copy("foo.txt", "bar.txt"));
+/// # Ok(()) }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<u64> {

src/libstd/io/prelude.rs

@@ -14,6 +14,7 @@
 //! by adding a glob import to the top of I/O heavy modules:
 //!
 //! ```
+//! # #![allow(unused_imports)]
 //! use std::io::prelude::*;
 //! ```
 //!

src/libstd/lib.rs

@@ -103,7 +103,8 @@
        html_favicon_url = "http://www.rust-lang.org/favicon.ico",
        html_root_url = "http://doc.rust-lang.org/nightly/",
        html_playground_url = "http://play.rust-lang.org/")]
-#![doc(test(no_crate_inject))]
+#![doc(test(no_crate_inject, attr(deny(warnings))))]
+#![doc(test(attr(allow(dead_code, deprecated, unused_variables, unused_mut))))]
 
 #![feature(alloc)]
 #![feature(box_syntax)]

src/libstd/net/addr.rs

@@ -281,7 +281,6 @@ fn hash<H: hash::Hasher>(&self, s: &mut H) {
 /// Some examples:
 ///
 /// ```no_run
-/// # #![feature(net)]
 /// use std::net::{SocketAddrV4, TcpStream, UdpSocket, TcpListener, Ipv4Addr};
 ///
 /// fn main() {
@@ -302,7 +301,7 @@ fn hash<H: hash::Hasher>(&self, s: &mut H) {
 ///     let tcp_l = TcpListener::bind("localhost:12345");
 ///
 ///     let mut udp_s = UdpSocket::bind(("127.0.0.1", port)).unwrap();
-///     udp_s.send_to(&[7], (ip, 23451));
+///     udp_s.send_to(&[7], (ip, 23451)).unwrap();
 /// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]

src/libstd/net/tcp.rs

@@ -27,7 +27,6 @@
 /// # Examples
 ///
 /// ```no_run
-/// # #![feature(net)]
 /// use std::io::prelude::*;
 /// use std::net::TcpStream;
 ///
@@ -47,7 +46,6 @@
 /// # Examples
 ///
 /// ```no_run
-/// # #![feature(net)]
 /// use std::net::{TcpListener, TcpStream};
 /// use std::thread;
 ///

src/libstd/net/udp.rs

@@ -27,7 +27,6 @@
 /// # Examples
 ///
 /// ```no_run
-/// # #![feature(net)]
 /// use std::net::UdpSocket;
 ///
 /// # fn foo() -> std::io::Result<()> {

src/libstd/num/f32.rs

@@ -422,7 +422,6 @@ pub fn is_finite(self) -> bool { num::Float::is_finite(self) }
     /// [subnormal][subnormal], or `NaN`.
     ///
     /// ```
-    /// # #![feature(std_misc)]
     /// use std::f32;
     ///
     /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
@@ -856,7 +855,7 @@ pub fn log10(self) -> f32 { num::Float::log10(self) }
     /// Convert radians to degrees.
     ///
     /// ```
-    /// # #![feature(std_misc, core)]
+    /// # #![feature(std_misc)]
     /// use std::f32::{self, consts};
     ///
     /// let angle = consts::PI;
@@ -987,7 +986,6 @@ pub fn min(self, other: f32) -> f32 {
     /// * Else: `self - other`
     ///
     /// ```
-    /// # #![feature(std_misc)]
     /// use std::f32;
     ///
     /// let x = 3.0f32;
@@ -1008,7 +1006,6 @@ pub fn abs_sub(self, other: f32) -> f32 {
     /// Take the cubic root of a number.
     ///
     /// ```
-    /// # #![feature(std_misc)]
     /// use std::f32;
     ///
     /// let x = 8.0f32;
@@ -1210,8 +1207,6 @@ pub fn sin_cos(self) -> (f32, f32) {
     /// number is close to zero.
     ///
     /// ```
-    /// use std::f64;
-    ///
     /// let x = 7.0f64;
     ///
     /// // e^(ln(7)) - 1

src/libstd/num/mod.rs

@@ -280,7 +280,6 @@ pub trait Float
     /// [subnormal][subnormal], or `NaN`.
     ///
     /// ```
-    /// # #![feature(std_misc)]
     /// use std::num::Float;
     /// use std::f32;
     ///
@@ -307,7 +306,6 @@ pub trait Float
     /// predicate instead.
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::{Float, FpCategory};
     /// use std::f32;
     ///
@@ -417,7 +415,6 @@ pub trait Float
     /// number is `Float::nan()`.
     ///
     /// ```
-    /// # #![feature(std_misc)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -441,7 +438,6 @@ pub trait Float
     /// - `Float::nan()` if the number is `Float::nan()`
     ///
     /// ```
-    /// # #![feature(std_misc)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -686,7 +682,6 @@ pub trait Float
     /// Convert radians to degrees.
     ///
     /// ```
-    /// # #![feature(std_misc, core)]
     /// use std::num::Float;
     /// use std::f64::consts;
     ///
@@ -701,7 +696,7 @@ pub trait Float
     /// Convert degrees to radians.
     ///
     /// ```
-    /// # #![feature(std_misc, core)]
+    /// # #![feature(std_misc)]
     /// use std::num::Float;
     /// use std::f64::consts;
     ///
@@ -849,7 +844,6 @@ pub trait Float
     /// Computes the sine of a number (in radians).
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -864,7 +858,6 @@ pub trait Float
     /// Computes the cosine of a number (in radians).
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -879,7 +872,6 @@ pub trait Float
     /// Computes the tangent of a number (in radians).
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -895,7 +887,6 @@ pub trait Float
     /// [-1, 1].
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -913,7 +904,6 @@ pub trait Float
     /// [-1, 1].
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -949,7 +939,6 @@ pub trait Float
     /// * `y < 0`: `arctan(y/x) - pi` -> `(-pi, -pi/2)`
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -975,7 +964,6 @@ pub trait Float
     /// `(sin(x), cos(x))`.
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -1011,7 +999,6 @@ pub trait Float
     /// the operations were performed separately.
     ///
     /// ```
-    /// # #![feature(std_misc, core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -1028,7 +1015,6 @@ pub trait Float
     /// Hyperbolic sine function.
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -1047,7 +1033,6 @@ pub trait Float
     /// Hyperbolic cosine function.
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -1066,7 +1051,6 @@ pub trait Float
     /// Hyperbolic tangent function.
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///
@@ -1113,7 +1097,6 @@ pub trait Float
     /// Inverse hyperbolic tangent function.
     ///
     /// ```
-    /// # #![feature(core)]
     /// use std::num::Float;
     /// use std::f64;
     ///

src/libstd/old_io/mod.rs

@@ -48,7 +48,7 @@
 //! * Read lines from stdin
 //!
 //!     ```rust
-//!     # #![feature(old_io, old_path)]
+//!     # #![feature(old_io)]
 //!     use std::old_io as io;
 //!     use std::old_io::*;
 //!

src/libstd/old_io/net/ip.rs

@@ -414,7 +414,7 @@ fn from_str(s: &str) -> Result<SocketAddr, ParseError> {
 /// Some examples:
 ///
 /// ```rust,no_run
-/// # #![feature(old_io, core, convert)]
+/// # #![feature(old_io)]
 /// # #![allow(unused_must_use)]
 ///
 /// use std::old_io::{TcpStream, TcpListener};

src/libstd/old_io/net/pipe.rs

@@ -191,7 +191,7 @@ impl UnixListener {
     /// let server = Path::new("/path/to/my/socket");
     /// let stream = UnixListener::bind(&server);
     /// for mut client in stream.listen().incoming() {
-    ///     client.write(&[1, 2, 3, 4]);
+    ///     let _ = client.write(&[1, 2, 3, 4]);
     /// }
     /// # }
     /// ```

src/libstd/old_io/process.rs

@@ -367,7 +367,7 @@ pub fn spawn(&self) -> IoResult<Process> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(old_io, core, convert)]
+    /// # #![feature(old_io)]
     /// use std::old_io::Command;
     ///
     /// let output = match Command::new("cat").arg("foot.txt").output() {

src/libstd/old_path/mod.rs

@@ -144,12 +144,10 @@ pub trait GenericPath: Clone + GenericPathUnsafe {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// # #![feature(old_path)]
-    /// use std::old_path::{Path, GenericPath};
-    /// # foo();
-    /// # #[cfg(windows)] fn foo() {}
-    /// # #[cfg(unix)] fn foo() {
+    /// # fn main() {
+    /// use std::old_path::Path;
     /// let path = Path::new("foo/bar");
     /// # }
     /// ```
@@ -170,12 +168,10 @@ fn new<T: BytesContainer>(path: T) -> Self {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```no_run
     /// # #![feature(old_path)]
-    /// use std::old_path::{Path, GenericPath};
-    /// # foo();
-    /// # #[cfg(windows)] fn foo() {}
-    /// # #[cfg(unix)] fn foo() {
+    /// # fn main() {
+    /// use std::old_path::Path;
     /// let x: &[u8] = b"foo\0";
     /// assert!(Path::new_opt(x).is_none());
     /// # }

src/libstd/process.rs

@@ -38,8 +38,6 @@
 /// # Examples
 ///
 /// ```should_panic
-/// # #![feature(process)]
-///
 /// use std::process::Command;
 ///
 /// let output = Command::new("/bin/cat").arg("file.txt").output().unwrap_or_else(|e| {
@@ -267,10 +265,8 @@ pub fn spawn(&mut self) -> io::Result<Child> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(process)]
     /// use std::process::Command;
-    ///
-    /// let output = Command::new("cat").arg("foot.txt").output().unwrap_or_else(|e| {
+    /// let output = Command::new("cat").arg("foo.txt").output().unwrap_or_else(|e| {
     ///     panic!("failed to execute process: {}", e)
     /// });
     ///
@@ -291,7 +287,6 @@ pub fn output(&mut self) -> io::Result<Output> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(process)]
     /// use std::process::Command;
     ///
     /// let status = Command::new("ls").status().unwrap_or_else(|e| {

src/libstd/thread/mod.rs

@@ -99,6 +99,7 @@
 //! `println!` and `panic!` for the child thread:
 //!
 //! ```rust
+//! # #![allow(unused_must_use)]
 //! use std::thread;
 //!
 //! thread::Builder::new().name("child1".to_string()).spawn(move || {