Auto merge of #98180 - notriddle:notriddle/rustdoc-fn, r=petrochenkov,GuillaumeGomez

Improve the function pointer docs

This is #97842 but for function pointers instead of tuples. The concept is basically the same.

* Reduce duplicate impls; show `fn (T₁, T₂, …, Tₙ)` and include a sentence saying that there exists up to twelve of them.
* Show `Copy` and `Clone`.
* Show auto traits like `Send` and `Sync`, and blanket impls like `Any`.

https://notriddle.com/notriddle-rustdoc-test/std/primitive.fn.html

1 files changed, 5 insertions, 5 deletions

diff --git a/compiler/rustc_error_codes/src/error_codes/E0118.md b/compiler/rustc_error_codes/src/error_codes/E0118.md
index 8033aa8384c..cfabae1a634 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0118.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0118.md
@@ -4,7 +4,7 @@ enum, union, or trait object.
 Erroneous code example:
 
 ```compile_fail,E0118
-impl fn(u8) { // error: no nominal type found for inherent implementation
+impl<T> T { // error: no nominal type found for inherent implementation
     fn get_state(&self) -> String {
         // ...
     }
@@ -20,8 +20,8 @@ trait LiveLongAndProsper {
     fn get_state(&self) -> String;
 }
 
-// and now you can implement it on fn(u8)
-impl LiveLongAndProsper for fn(u8) {
+// and now you can implement it on T
+impl<T> LiveLongAndProsper for T {
     fn get_state(&self) -> String {
         "He's dead, Jim!".to_owned()
     }
@@ -33,9 +33,9 @@ For example, `NewType` is a newtype over `Foo` in `struct NewType(Foo)`.
 Example:
 
 ```
-struct TypeWrapper(fn(u8));
+struct TypeWrapper<T>(T);
 
-impl TypeWrapper {
+impl<T> TypeWrapper<T> {
     fn get_state(&self) -> String {
         "Fascinating!".to_owned()
     }