Say what traits that function items impl by default.

Also more links in call-expr.md.

Author: Havvy

src/expressions/call-expr.md

@@ -10,12 +10,12 @@
 A _call expression_ consists of an expression followed by a parenthesized
 expression-list. It invokes a function, providing zero or more input variables.
 If the function eventually returns, then the expression completes. For
-[non-function types](types.html#function-item-types), the expression f(...) uses the
-method on one of the `std::ops::Fn`, `std::ops::FnMut` or `std::ops::FnOnce`
-traits, which differ in whether they take the type by reference, mutable
-reference, or take ownership respectively. An automatic borrow will be taken if
-needed. Rust will also automatically dereference `f` as required. Some examples
-of call expressions:
+[non-function types](types.html#function-item-types), the expression f(...) uses
+the method on one of the [`std::ops::Fn`], [`std::ops::FnMut`] or
+[`std::ops::FnOnce`] traits, which differ in whether they take the type by
+reference, mutable reference, or take ownership respectively. An automatic
+borrow will be taken if needed. Rust will also automatically dereference `f` as
+required. Some examples of call expressions:
 
 ```rust
 # fn add(x: i32, y: i32) -> i32 { 0 }
@@ -93,6 +93,9 @@ fn main() {
 
 Refer to [RFC 132] for further details and motivations.
 
+[`std::ops::Fn`]: ../std/ops/trait.Fn.html
+[`std::ops::FnMut`]: ../std/ops/trait.FnMut.html
+[`std::ops::FnOnce`]: ../std/ops/trait.FnOnce.html
 [RFC 132]: https://github.com/rust-lang/rfcs/blob/master/text/0132-ufcs.md
 
 [_Expression_]: expressions.html

src/types.md

@@ -338,6 +338,9 @@ let foo_ptr_2 = if want_i32 {
 };
 ```
 
+All function items implement [Fn], [FnMut], [FnOnce], [Copy], [Clone], [Send], 
+and [Sync].
+
 ## Function pointer types
 
 Function pointer types, written using the `fn` keyword, refer to a function
@@ -575,6 +578,13 @@ impl Printable for String {
 
 The notation `&self` is a shorthand for `self: &Self`.
 
+[Fn]: ../std/ops/trait.Fn.html
+[FnMut]: ../std/ops/trait.FnMut.html
+[FnOnce]: ../std/ops/trait.FnOnce.html
+[Copy]: special-types-and-traits.html#copy
+[Clone]: special-types-and-traits.html#clone
+[Send]: special-types-and-traits.html#send
+[Sync]: special-types-and-traits.html#sync
 [dynamically sized types]: dynamically-sized-types.html
 [RFC 599]: https://github.com/rust-lang/rfcs/blob/master/text/0599-default-object-bound.md
 [RFC 1156]: https://github.com/rust-lang/rfcs/blob/master/text/1156-adjust-default-object-bounds.md