Remove E0134 and E0135 error explanation

Author: GuillaumeGomez

src/librustc/diagnostics.rs

@@ -411,42 +411,6 @@ fn main() {
 See also https://doc.rust-lang.org/book/unsafe.html
 "##,
 
-E0134: r##"
-You tried to modify the str type, which isn't allowed. Erroneous code
-example:
-
-```
-let s = "salut";
-let c = &mut s[0..1]; // error: modification of string types is not
-                      //        allowed
-```
-
-I you want to modify an str, please use the String type. Example:
-
-```
-let mut s = "salut";
-let mut c = s[0..1].to_owned(); // ok!
-```
-"##,
-
-E0135: r##"
-You tried to modify the str type, which isn't allowed. Erroneous code
-example:
-
-```
-let s = "salut";
-let c = &mut (*s)[0..1]; // error: modification of string types is not
-                         //        allowed
-```
-
-If you want to modify an str, please use the String type. Example:
-
-```
-let mut s = "salut";
-let mut c = s[0..1].to_owned(); // ok!
-```
-"##,
-
 E0137: r##"
 This error indicates that the compiler found multiple functions with the
 `#[main]` attribute. This is an error because there must be a unique entry

src/librustc_typeck/diagnostics.rs

@@ -1369,23 +1369,30 @@ struct Foo {
 "##,
 
 E0128: r##"
-You declared a type parameter with a default which has the same identifier as
-the type parameter. Erroneous code example:
+Type parameter defaults can only use parameters that occur before them.
+Erroneous code example:
 
 ```
-pub struct Foo<SomeType=SomeType>;
+pub struct Foo<T=U, U=()> {
+    field1: T,
+    filed2: U,
+}
 // error: type parameters with a default cannot use forward declared
 // identifiers
 ```
 
-Please verify that a name clash hasn't been accidentally introduced, and rename
-the type parameter if so. Example:
+Since type parameters are evaluated in-order, you may be able to fix this issue
+by doing:
 
 ```
-pub struct Foo<T=SomeType> {
-    value: T
+pub struct Foo<U=(), T=U> {
+    field1: T,
+    filed2: U,
 }
 ```
+
+Please also verify that this wasn't because of a name-clash and rename the type
+parameter if so.
 "##,
 
 E0130: r##"