Remove unneeded fn main blocks from docs

src/liballoc/boxed.rs

@@ -29,10 +29,8 @@
 //!     Nil,
 //! }
 //!
-//! fn main() {
 //! let list: List<i32> = List::Cons(1, Box::new(List::Cons(2, Box::new(List::Nil))));
 //! println!("{:?}", list);
-//! }
 //! ```
 //!
 //! This will print `Cons(1, Cons(2, Nil))`.
@@ -375,14 +373,12 @@ impl<T: ?Sized> Box<T> {
     /// ```
     /// #![feature(box_into_raw_non_null)]
     ///
-    /// fn main() {
     /// let x = Box::new(5);
     /// let ptr = Box::into_raw_non_null(x);
     ///
     /// // Clean up the memory by converting the NonNull pointer back
     /// // into a Box and letting the Box be dropped.
     /// let x = unsafe { Box::from_raw(ptr.as_ptr()) };
-    /// }
     /// ```
     #[unstable(feature = "box_into_raw_non_null", issue = "47336")]
     #[inline]
@@ -428,23 +424,19 @@ impl<T: ?Sized> Box<T> {
     /// Simple usage:
     ///
     /// ```
-    /// fn main() {
     /// let x = Box::new(41);
     /// let static_ref: &'static mut usize = Box::leak(x);
     /// *static_ref += 1;
     /// assert_eq!(*static_ref, 42);
-    /// }
     /// ```
     ///
     /// Unsized data:
     ///
     /// ```
-    /// fn main() {
     /// let x = vec![1, 2, 3].into_boxed_slice();
     /// let static_ref = Box::leak(x);
     /// static_ref[0] = 4;
     /// assert_eq!(*static_ref, [4, 2, 3]);
-    /// }
     /// ```
     #[stable(feature = "box_leak", since = "1.26.0")]
     #[inline]
@@ -780,11 +772,9 @@ impl Box<dyn Any> {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// let my_string = "Hello World".to_string();
     /// print_if_string(Box::new(my_string));
     /// print_if_string(Box::new(0i8));
-    /// }
     /// ```
     pub fn downcast<T: Any>(self) -> Result<Box<T>, Box<dyn Any>> {
         if self.is::<T>() {
@@ -814,11 +804,9 @@ impl Box<dyn Any + Send> {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// let my_string = "Hello World".to_string();
     /// print_if_string(Box::new(my_string));
     /// print_if_string(Box::new(0i8));
-    /// }
     /// ```
     pub fn downcast<T: Any>(self) -> Result<Box<T>, Box<dyn Any + Send>> {
         <Box<dyn Any>>::downcast(self).map_err(|s| unsafe {

src/liballoc/collections/btree/map.rs

@@ -2226,14 +2226,12 @@ impl<'a, K: Ord, V: Default> Entry<'a, K, V> {
     /// # Examples
     ///
     /// ```
-    /// # fn main() {
     /// use std::collections::BTreeMap;
     ///
     /// let mut map: BTreeMap<&str, Option<usize>> = BTreeMap::new();
     /// map.entry("poneyland").or_default();
     ///
     /// assert_eq!(map["poneyland"], None);
-    /// # }
     /// ```
     pub fn or_default(self) -> &'a mut V {
         match self {

src/liballoc/rc.rs

@@ -861,11 +861,9 @@ impl Rc<dyn Any> {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// let my_string = "Hello World".to_string();
     /// print_if_string(Rc::new(my_string));
     /// print_if_string(Rc::new(0i8));
-    /// }
     /// ```
     pub fn downcast<T: Any>(self) -> Result<Rc<T>, Rc<dyn Any>> {
         if (*self).is::<T>() {

src/liballoc/slice.rs

@@ -412,20 +412,15 @@ impl<T> [T] {
     ///
     /// ```
     /// #![feature(repeat_generic_slice)]
-    ///
-    /// fn main() {
     /// assert_eq!([1, 2].repeat(3), vec![1, 2, 1, 2, 1, 2]);
-    /// }
     /// ```
     ///
     /// A panic upon overflow:
     ///
     /// ```should_panic
     /// #![feature(repeat_generic_slice)]
-    /// fn main() {
     /// // this will panic at runtime
     /// b"0123456789abcdef".repeat(usize::max_value());
-    /// }
     /// ```
     #[unstable(feature = "repeat_generic_slice",
                reason = "it's on str, why not on slice?",

src/liballoc/str.rs

@@ -500,10 +500,8 @@ impl str {
     /// A panic upon overflow:
     ///
     /// ```should_panic
-    /// fn main() {
     /// // this will panic at runtime
     /// "0123456789abcdef".repeat(usize::max_value());
-    /// }
     /// ```
     #[stable(feature = "repeat_str", since = "1.16.0")]
     pub fn repeat(&self, n: usize) -> String {

src/liballoc/string.rs

@@ -164,10 +164,8 @@ use crate::vec::Vec;
 ///
 /// fn example_func<A: TraitExample>(example_arg: A) {}
 ///
-/// fn main() {
 /// let example_string = String::from("example_string");
 /// example_func(&example_string);
-/// }
 /// ```
 ///
 /// There are two options that would work instead. The first would be to

src/liballoc/sync.rs

@@ -1244,11 +1244,9 @@ impl Arc<dyn Any + Send + Sync> {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// let my_string = "Hello World".to_string();
     /// print_if_string(Arc::new(my_string));
     /// print_if_string(Arc::new(0i8));
-    /// }
     /// ```
     pub fn downcast<T>(self) -> Result<Arc<T>, Self>
     where

src/liballoc/vec.rs

@@ -389,7 +389,6 @@ impl<T> Vec<T> {
     /// use std::ptr;
     /// use std::mem;
     ///
-    /// fn main() {
     /// let mut v = vec![1, 2, 3];
     ///
     /// // Pull out the various important pieces of information about `v`
@@ -411,7 +410,6 @@ impl<T> Vec<T> {
     ///     let rebuilt = Vec::from_raw_parts(p, len, cap);
     ///     assert_eq!(rebuilt, [4, 5, 6]);
     /// }
-    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Vec<T> {
@@ -1391,12 +1389,10 @@ impl<T> Vec<T> {
     /// ```
     /// #![feature(vec_leak)]
     ///
-    /// fn main() {
     /// let x = vec![1, 2, 3];
     /// let static_ref: &'static mut [usize] = Vec::leak(x);
     /// static_ref[0] += 1;
     /// assert_eq!(static_ref, &[2, 2, 3]);
-    /// }
     /// ```
     #[unstable(feature = "vec_leak", issue = "62195")]
     #[inline]

src/libcore/any.rs

@@ -87,10 +87,8 @@ pub trait Any: 'static {
     ///     TypeId::of::<String>() == s.type_id()
     /// }
     ///
-    /// fn main() {
     /// assert_eq!(is_string(&0), false);
     /// assert_eq!(is_string(&"cookie monster".to_string()), true);
-    /// }
     /// ```
     #[stable(feature = "get_type_id", since = "1.34.0")]
     fn type_id(&self) -> TypeId;
@@ -145,10 +143,8 @@ impl dyn Any {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// is_string(&0);
     /// is_string(&"cookie monster".to_string());
-    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -179,10 +175,8 @@ impl dyn Any {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// print_if_string(&0);
     /// print_if_string(&"cookie monster".to_string());
-    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -210,7 +204,6 @@ impl dyn Any {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// let mut x = 10u32;
     /// let mut s = "starlord".to_string();
     ///
@@ -219,7 +212,6 @@ impl dyn Any {
     ///
     /// assert_eq!(x, 42);
     /// assert_eq!(&s, "starlord");
-    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -250,10 +242,8 @@ impl dyn Any+Send {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// is_string(&0);
     /// is_string(&"cookie monster".to_string());
-    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -276,10 +266,8 @@ impl dyn Any+Send {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// print_if_string(&0);
     /// print_if_string(&"cookie monster".to_string());
-    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -300,7 +288,6 @@ impl dyn Any+Send {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// let mut x = 10u32;
     /// let mut s = "starlord".to_string();
     ///
@@ -309,7 +296,6 @@ impl dyn Any+Send {
     ///
     /// assert_eq!(x, 42);
     /// assert_eq!(&s, "starlord");
-    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -334,10 +320,8 @@ impl dyn Any+Send+Sync {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// is_string(&0);
     /// is_string(&"cookie monster".to_string());
-    /// }
     /// ```
     #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
     #[inline]
@@ -360,10 +344,8 @@ impl dyn Any+Send+Sync {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// print_if_string(&0);
     /// print_if_string(&"cookie monster".to_string());
-    /// }
     /// ```
     #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
     #[inline]
@@ -384,7 +366,6 @@ impl dyn Any+Send+Sync {
     ///     }
     /// }
     ///
-    /// fn main() {
     /// let mut x = 10u32;
     /// let mut s = "starlord".to_string();
     ///
@@ -393,7 +374,6 @@ impl dyn Any+Send+Sync {
     ///
     /// assert_eq!(x, 42);
     /// assert_eq!(&s, "starlord");
-    /// }
     /// ```
     #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
     #[inline]
@@ -437,10 +417,8 @@ impl TypeId {
     ///     TypeId::of::<String>() == TypeId::of::<T>()
     /// }
     ///
-    /// fn main() {
     /// assert_eq!(is_string(&0), false);
     /// assert_eq!(is_string(&"cookie monster".to_string()), true);
-    /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature="const_type_id")]

src/libcore/char/convert.rs

@@ -111,11 +111,9 @@ impl From<char> for u32 {
     /// ```
     /// use std::mem;
     ///
-    /// fn main() {
     /// let c = 'c';
     /// let u = u32::from(c);
     /// assert!(4 == mem::size_of_val(&u))
-    /// }
     /// ```
     #[inline]
     fn from(c: char) -> Self {
@@ -150,11 +148,9 @@ impl From<u8> for char {
     /// ```
     /// use std::mem;
     ///
-    /// fn main() {
     /// let u = 32 as u8;
     /// let c = char::from(u);
     /// assert!(4 == mem::size_of_val(&c))
-    /// }
     /// ```
     #[inline]
     fn from(i: u8) -> Self {