Rollup merge of rust-lang#66900 - GuillaumeGomez:clean-up-err-codes, r=Dylan-DPC

Clean up error codes

r? @Dylan-DPC

Author: RalfJung

src/librustc_error_codes/error_codes/E0092.md

@@ -1,4 +1,5 @@
-You tried to declare an undefined atomic operation function.
+An undefined atomic operation function was declared.
+
 Erroneous code example:
 
 ```compile_fail,E0092
@@ -11,8 +12,8 @@ extern "rust-intrinsic" {
 ```
 
 Please check you didn't make a mistake in the function's name. All intrinsic
-functions are defined in librustc_codegen_llvm/intrinsic.rs and in
-libcore/intrinsics.rs in the Rust source code. Example:
+functions are defined in `librustc_codegen_llvm/intrinsic.rs` and in
+`libcore/intrinsics.rs` in the Rust source code. Example:
 
 ```
 #![feature(intrinsics)]

src/librustc_error_codes/error_codes/E0093.md

@@ -1,4 +1,6 @@
-You declared an unknown intrinsic function. Erroneous code example:
+An unknown intrinsic function was declared.
+
+Erroneous code example:
 
 ```compile_fail,E0093
 #![feature(intrinsics)]
@@ -15,8 +17,8 @@ fn main() {
 ```
 
 Please check you didn't make a mistake in the function's name. All intrinsic
-functions are defined in librustc_codegen_llvm/intrinsic.rs and in
-libcore/intrinsics.rs in the Rust source code. Example:
+functions are defined in `librustc_codegen_llvm/intrinsic.rs` and in
+`libcore/intrinsics.rs` in the Rust source code. Example:
 
 ```
 #![feature(intrinsics)]

src/librustc_error_codes/error_codes/E0094.md

@@ -1,4 +1,5 @@
-You gave an invalid number of type parameters to an intrinsic function.
+An invalid number of type parameters was given to an intrinsic function.
+
 Erroneous code example:
 
 ```compile_fail,E0094

src/librustc_error_codes/error_codes/E0106.md

@@ -2,7 +2,7 @@ This error indicates that a lifetime is missing from a type. If it is an error
 inside a function signature, the problem may be with failing to adhere to the
 lifetime elision rules (see below).
 
-Here are some simple examples of where you'll run into this error:
+Erroneous code examples:
 
 ```compile_fail,E0106
 struct Foo1 { x: &bool }
@@ -27,7 +27,7 @@ function signatures which allows you to leave out lifetimes in certain cases.
 For more background on lifetime elision see [the book][book-le].
 
 The lifetime elision rules require that any function signature with an elided
-output lifetime must either have
+output lifetime must either have:
 
  - exactly one input lifetime
  - or, multiple input lifetimes, but the function must also be a method with a

src/librustc_error_codes/error_codes/E0107.md

@@ -1,4 +1,6 @@
-This error means that an incorrect number of generic arguments were provided:
+An incorrect number of generic arguments were provided.
+
+Erroneous code example:
 
 ```compile_fail,E0107
 struct Foo<T> { x: T }
@@ -9,19 +11,34 @@ struct Baz<S, T> { x: Foo<S, T> } // error: wrong number of type arguments:
                                   //        expected 1, found 2
 
 fn foo<T, U>(x: T, y: U) {}
+fn f() {}
 
 fn main() {
     let x: bool = true;
     foo::<bool>(x);                 // error: wrong number of type arguments:
                                     //        expected 2, found 1
     foo::<bool, i32, i32>(x, 2, 4); // error: wrong number of type arguments:
                                     //        expected 2, found 3
+    f::<'static>();                 // error: wrong number of lifetime arguments
+                                    //        expected 0, found 1
 }
+```
+
+When using/declaring an item with generic arguments, you must provide the exact
+same number:
+
+```
+struct Foo<T> { x: T }
+
+struct Bar<T> { x: Foo<T> }               // ok!
+struct Baz<S, T> { x: Foo<S>, y: Foo<T> } // ok!
 
+fn foo<T, U>(x: T, y: U) {}
 fn f() {}
 
 fn main() {
-    f::<'static>(); // error: wrong number of lifetime arguments:
-                    //        expected 0, found 1
+    let x: bool = true;
+    foo::<bool, u32>(x, 12);              // ok!
+    f();                                  // ok!
 }
 ```