enable `rust_2018_idioms` for doctests

Signed-off-by: ozkanonur <work@onurozkan.dev>

9 files changed, 41 insertions, 46 deletions

diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index bcca8d924cd..5c5a4fd0e3f 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -115,7 +115,7 @@
 //!     let shared_map: Rc<RefCell<_>> = Rc::new(RefCell::new(HashMap::new()));
 //!     // Create a new block to limit the scope of the dynamic borrow
 //!     {
-//!         let mut map: RefMut<_> = shared_map.borrow_mut();
+//!         let mut map: RefMut<'_, _> = shared_map.borrow_mut();
 //!         map.insert("africa", 92388);
 //!         map.insert("kyoto", 11837);
 //!         map.insert("piccadilly", 11826);
@@ -1435,8 +1435,8 @@ impl<'b, T: ?Sized> Ref<'b, T> {
     /// use std::cell::{RefCell, Ref};
     ///
     /// let c = RefCell::new((5, 'b'));
-    /// let b1: Ref<(u32, char)> = c.borrow();
-    /// let b2: Ref<u32> = Ref::map(b1, |t| &t.0);
+    /// let b1: Ref<'_, (u32, char)> = c.borrow();
+    /// let b2: Ref<'_, u32> = Ref::map(b1, |t| &t.0);
     /// assert_eq!(*b2, 5)
     /// ```
     #[stable(feature = "cell_map", since = "1.8.0")]
@@ -1464,8 +1464,8 @@ impl<'b, T: ?Sized> Ref<'b, T> {
     /// use std::cell::{RefCell, Ref};
     ///
     /// let c = RefCell::new(vec![1, 2, 3]);
-    /// let b1: Ref<Vec<u32>> = c.borrow();
-    /// let b2: Result<Ref<u32>, _> = Ref::filter_map(b1, |v| v.get(1));
+    /// let b1: Ref<'_, Vec<u32>> = c.borrow();
+    /// let b2: Result<Ref<'_, u32>, _> = Ref::filter_map(b1, |v| v.get(1));
     /// assert_eq!(*b2.unwrap(), 2);
     /// ```
     #[stable(feature = "cell_filter_map", since = "1.63.0")]
@@ -1577,8 +1577,8 @@ impl<'b, T: ?Sized> RefMut<'b, T> {
     ///
     /// let c = RefCell::new((5, 'b'));
     /// {
-    ///     let b1: RefMut<(u32, char)> = c.borrow_mut();
-    ///     let mut b2: RefMut<u32> = RefMut::map(b1, |t| &mut t.0);
+    ///     let b1: RefMut<'_, (u32, char)> = c.borrow_mut();
+    ///     let mut b2: RefMut<'_, u32> = RefMut::map(b1, |t| &mut t.0);
     ///     assert_eq!(*b2, 5);
     ///     *b2 = 42;
     /// }
@@ -1612,8 +1612,8 @@ impl<'b, T: ?Sized> RefMut<'b, T> {
     /// let c = RefCell::new(vec![1, 2, 3]);
     ///
     /// {
-    ///     let b1: RefMut<Vec<u32>> = c.borrow_mut();
-    ///     let mut b2: Result<RefMut<u32>, _> = RefMut::filter_map(b1, |v| v.get_mut(1));
+    ///     let b1: RefMut<'_, Vec<u32>> = c.borrow_mut();
+    ///     let mut b2: Result<RefMut<'_, u32>, _> = RefMut::filter_map(b1, |v| v.get_mut(1));
     ///
     ///     if let Ok(mut b2) = b2 {
     ///         *b2 += 2;
diff --git a/library/core/src/fmt/builders.rs b/library/core/src/fmt/builders.rs
index d1c6b67b278..36f49d51ca6 100644
--- a/library/core/src/fmt/builders.rs
+++ b/library/core/src/fmt/builders.rs
@@ -60,7 +60,7 @@ impl fmt::Write for PadAdapter<'_, '_> {
 /// }
 ///
 /// impl fmt::Debug for Foo {
-///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
 ///         fmt.debug_struct("Foo")
 ///            .field("bar", &self.bar)
 ///            .field("baz", &self.baz)
@@ -249,7 +249,7 @@ impl<'a, 'b: 'a> DebugStruct<'a, 'b> {
 /// struct Foo(i32, String);
 ///
 /// impl fmt::Debug for Foo {
-///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
 ///         fmt.debug_tuple("Foo")
 ///            .field(&self.0)
 ///            .field(&self.1)
@@ -418,7 +418,7 @@ impl<'a, 'b: 'a> DebugInner<'a, 'b> {
 /// struct Foo(Vec<i32>);
 ///
 /// impl fmt::Debug for Foo {
-///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
 ///         fmt.debug_set().entries(self.0.iter()).finish()
 ///     }
 /// }
@@ -548,7 +548,7 @@ impl<'a, 'b: 'a> DebugSet<'a, 'b> {
 /// struct Foo(Vec<i32>);
 ///
 /// impl fmt::Debug for Foo {
-///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
 ///         fmt.debug_list().entries(self.0.iter()).finish()
 ///     }
 /// }
@@ -678,7 +678,7 @@ impl<'a, 'b: 'a> DebugList<'a, 'b> {
 /// struct Foo(Vec<(String, i32)>);
 ///
 /// impl fmt::Debug for Foo {
-///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
 ///         fmt.debug_map().entries(self.0.iter().map(|&(ref k, ref v)| (k, v))).finish()
 ///     }
 /// }
diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index a901ae72669..2138fafeaaf 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -534,7 +534,7 @@ impl<'a> Arguments<'a> {
     ///
     /// fn write_str(_: &str) { /* ... */ }
     ///
-    /// fn write_fmt(args: &Arguments) {
+    /// fn write_fmt(args: &Arguments<'_>) {
     ///     if let Some(s) = args.as_str() {
     ///         write_str(s)
     ///     } else {
@@ -1381,7 +1381,7 @@ impl<'a> Formatter<'a> {
     /// }
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         // We need to remove "-" from the number output.
     ///         let tmp = self.nb.abs().to_string();
     ///
@@ -1481,7 +1481,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo;
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         formatter.pad("Foo")
     ///     }
     /// }
@@ -1663,7 +1663,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo;
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         formatter.write_str("Foo")
     ///         // This is equivalent to:
     ///         // write!(formatter, "Foo")
@@ -1688,7 +1688,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo(i32);
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         formatter.write_fmt(format_args!("Foo {}", self.0))
     ///     }
     /// }
@@ -1723,7 +1723,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo;
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         let c = formatter.fill();
     ///         if let Some(width) = formatter.width() {
     ///             for _ in 0..width {
@@ -1751,14 +1751,12 @@ impl<'a> Formatter<'a> {
     /// # Examples
     ///
     /// ```
-    /// extern crate core;
-    ///
     /// use std::fmt::{self, Alignment};
     ///
     /// struct Foo;
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         let s = if let Some(s) = formatter.align() {
     ///             match s {
     ///                 Alignment::Left    => "left",
@@ -1798,7 +1796,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo(i32);
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         if let Some(width) = formatter.width() {
     ///             // If we received a width, we use it
     ///             write!(formatter, "{:width$}", format!("Foo({})", self.0), width = width)
@@ -1829,7 +1827,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo(f32);
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         if let Some(precision) = formatter.precision() {
     ///             // If we received a precision, we use it.
     ///             write!(formatter, "Foo({1:.*})", precision, self.0)
@@ -1859,7 +1857,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo(i32);
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         if formatter.sign_plus() {
     ///             write!(formatter,
     ///                    "Foo({}{})",
@@ -1891,7 +1889,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo(i32);
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         if formatter.sign_minus() {
     ///             // You want a minus sign? Have one!
     ///             write!(formatter, "-Foo({})", self.0)
@@ -1920,7 +1918,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo(i32);
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         if formatter.alternate() {
     ///             write!(formatter, "Foo({})", self.0)
     ///         } else {
@@ -1948,7 +1946,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo(i32);
     ///
     /// impl fmt::Display for Foo {
-    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         assert!(formatter.sign_aware_zero_pad());
     ///         assert_eq!(formatter.width(), Some(4));
     ///         // We ignore the formatter's options.
@@ -1992,7 +1990,7 @@ impl<'a> Formatter<'a> {
     /// }
     ///
     /// impl fmt::Debug for Foo {
-    ///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         fmt.debug_struct("Foo")
     ///             .field("bar", &self.bar)
     ///             .field("baz", &self.baz)
@@ -2150,7 +2148,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo<T>(i32, String, PhantomData<T>);
     ///
     /// impl<T> fmt::Debug for Foo<T> {
-    ///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         fmt.debug_tuple("Foo")
     ///             .field(&self.0)
     ///             .field(&self.1)
@@ -2282,7 +2280,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo(Vec<i32>);
     ///
     /// impl fmt::Debug for Foo {
-    ///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         fmt.debug_list().entries(self.0.iter()).finish()
     ///     }
     /// }
@@ -2305,7 +2303,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo(Vec<i32>);
     ///
     /// impl fmt::Debug for Foo {
-    ///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         fmt.debug_set().entries(self.0.iter()).finish()
     ///     }
     /// }
@@ -2321,14 +2319,14 @@ impl<'a> Formatter<'a> {
     /// ```rust
     /// use std::fmt;
     ///
-    /// struct Arm<'a, L: 'a, R: 'a>(&'a (L, R));
-    /// struct Table<'a, K: 'a, V: 'a>(&'a [(K, V)], V);
+    /// struct Arm<'a, L, R>(&'a (L, R));
+    /// struct Table<'a, K, V>(&'a [(K, V)], V);
     ///
     /// impl<'a, L, R> fmt::Debug for Arm<'a, L, R>
     /// where
     ///     L: 'a + fmt::Debug, R: 'a + fmt::Debug
     /// {
-    ///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         L::fmt(&(self.0).0, fmt)?;
     ///         fmt.write_str(" => ")?;
     ///         R::fmt(&(self.0).1, fmt)
@@ -2339,7 +2337,7 @@ impl<'a> Formatter<'a> {
     /// where
     ///     K: 'a + fmt::Debug, V: 'a + fmt::Debug
     /// {
-    ///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         fmt.debug_set()
     ///         .entries(self.0.iter().map(Arm))
     ///         .entry(&Arm(&(format_args!("_"), &self.1)))
@@ -2363,7 +2361,7 @@ impl<'a> Formatter<'a> {
     /// struct Foo(Vec<(String, i32)>);
     ///
     /// impl fmt::Debug for Foo {
-    ///     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         fmt.debug_map().entries(self.0.iter().map(|&(ref k, ref v)| (k, v))).finish()
     ///     }
     /// }
diff --git a/library/core/src/intrinsics/mir.rs b/library/core/src/intrinsics/mir.rs
index 45498a54b25..b4639c07c35 100644
--- a/library/core/src/intrinsics/mir.rs
+++ b/library/core/src/intrinsics/mir.rs
@@ -15,7 +15,6 @@
 //! ```rust
 //! #![feature(core_intrinsics, custom_mir)]
 //!
-//! extern crate core;
 //! use core::intrinsics::mir::*;
 //!
 //! #[custom_mir(dialect = "built")]
@@ -65,7 +64,6 @@
 //! ```rust
 //! #![feature(core_intrinsics, custom_mir)]
 //!
-//! extern crate core;
 //! use core::intrinsics::mir::*;
 //!
 //! #[custom_mir(dialect = "built")]
@@ -317,7 +315,6 @@ define!(
     /// ```rust
     /// #![feature(custom_mir, core_intrinsics)]
     ///
-    /// extern crate core;
     /// use core::intrinsics::mir::*;
     ///
     /// #[custom_mir(dialect = "built")]
diff --git a/library/core/src/iter/adapters/chain.rs b/library/core/src/iter/adapters/chain.rs
index 2046b70c9c6..9fae9f6744c 100644
--- a/library/core/src/iter/adapters/chain.rs
+++ b/library/core/src/iter/adapters/chain.rs
@@ -15,7 +15,7 @@ use crate::ops::Try;
 ///
 /// let a1 = [1, 2, 3];
 /// let a2 = [4, 5, 6];
-/// let iter: Chain<Iter<_>, Iter<_>> = a1.iter().chain(a2.iter());
+/// let iter: Chain<Iter<'_, _>, Iter<'_, _>> = a1.iter().chain(a2.iter());
 /// ```
 #[derive(Clone, Debug)]
 #[must_use = "iterators are lazy and do nothing unless consumed"]
diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index 7c93c93b4a0..b24882ddb17 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs
@@ -498,7 +498,6 @@ macro_rules! r#try {
 /// In a `no_std` setup you are responsible for the implementation details of the components.
 ///
 /// ```no_run
-/// # extern crate core;
 /// use core::fmt::Write;
 ///
 /// struct Example;
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index e85c0c0a688..c25a2a8bd15 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -591,7 +591,7 @@ impl<T: ?Sized> !Sync for *mut T {}
 /// use std::marker::PhantomData;
 ///
 /// # #[allow(dead_code)]
-/// struct Slice<'a, T: 'a> {
+/// struct Slice<'a, T> {
 ///     start: *const T,
 ///     end: *const T,
 ///     phantom: PhantomData<&'a T>,
@@ -607,7 +607,7 @@ impl<T: ?Sized> !Sync for *mut T {}
 /// ```
 /// # #![allow(dead_code)]
 /// # use std::marker::PhantomData;
-/// # struct Slice<'a, T: 'a> {
+/// # struct Slice<'a, T> {
 /// #     start: *const T,
 /// #     end: *const T,
 /// #     phantom: PhantomData<&'a T>,
diff --git a/library/core/src/ops/arith.rs b/library/core/src/ops/arith.rs
index 1501dc4e38b..840c8cd2fe8 100644
--- a/library/core/src/ops/arith.rs
+++ b/library/core/src/ops/arith.rs
@@ -517,7 +517,7 @@ div_impl_float! { f32 f64 }
 /// use std::ops::Rem;
 ///
 /// #[derive(PartialEq, Debug)]
-/// struct SplitSlice<'a, T: 'a> {
+/// struct SplitSlice<'a, T> {
 ///     slice: &'a [T],
 /// }
 ///
diff --git a/library/core/src/primitive_docs.rs b/library/core/src/primitive_docs.rs
index 3df990e5dd9..b8230042875 100644
--- a/library/core/src/primitive_docs.rs
+++ b/library/core/src/primitive_docs.rs
@@ -555,6 +555,7 @@ impl Copy for () {
 ///
 /// ```
 /// # #![feature(rustc_private)]
+/// #[allow(unused_extern_crates)]
 /// extern crate libc;
 ///
 /// use std::mem;