2 files changed, 15 insertions, 14 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0608.md b/compiler/rustc_error_codes/src/error_codes/E0608.md
index d0ebc3a26f0..3c29484f575 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0608.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0608.md
@@ -1,5 +1,5 @@
-An attempt to use index on a type which doesn't implement the `std::ops::Index`
-trait was performed.
+Attempted to index a value whose type doesn't implement the
+`std::ops::Index` trait.
 
 Erroneous code example:
 
@@ -7,8 +7,8 @@ Erroneous code example:
 0u8[2]; // error: cannot index into a value of type `u8`
 ```
 
-To be able to index into a type it needs to implement the `std::ops::Index`
-trait. Example:
+Only values with types that implement the `std::ops::Index` trait
+can be indexed with square brackets. Example:
 
 ```
 let v: Vec<u8> = vec![0, 1, 2, 3];
@@ -16,3 +16,10 @@ let v: Vec<u8> = vec![0, 1, 2, 3];
 // The `Vec` type implements the `Index` trait so you can do:
 println!("{}", v[2]);
 ```
+
+Tuples and structs are indexed with dot (`.`), not with brackets (`[]`),
+and tuple element names are their positions:
+```ignore(pseudo code)
+// this (pseudo code) expression is true for any tuple:
+tuple == (tuple.0, tuple.1, ...)
+```
diff --git a/compiler/rustc_error_codes/src/error_codes/E0719.md b/compiler/rustc_error_codes/src/error_codes/E0719.md
index cd981db1058..6aec38b42a3 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0719.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0719.md
@@ -1,4 +1,4 @@
-An associated type value was specified more than once.
+An associated item was specified more than once in a trait object.
 
 Erroneous code example:
 
@@ -7,21 +7,15 @@ trait FooTrait {}
 trait BarTrait {}
 
 // error: associated type `Item` in trait `Iterator` is specified twice
-struct Foo<T: Iterator<Item: FooTrait, Item: BarTrait>> { f: T }
+type Foo = dyn Iterator<Item = u32, Item = u32>;
 ```
 
-`Item` in trait `Iterator` cannot be specified multiple times for struct `Foo`.
-To fix this, create a new trait that is a combination of the desired traits and
-specify the associated type with the new trait.
+To fix this, remove the duplicate specifier:
 
 Corrected example:
 
 ```
-trait FooTrait {}
-trait BarTrait {}
-trait FooBarTrait: FooTrait + BarTrait {}
-
-struct Foo<T: Iterator<Item: FooBarTrait>> { f: T } // ok!
+type Foo = dyn Iterator<Item = u32>; // ok!
 ```
 
 For more information about associated types, see [the book][bk-at]. For more