Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 35 insertions, 0 deletions

diff --git a/compiler/rustc_error_codes/src/error_codes/E0719.md b/compiler/rustc_error_codes/src/error_codes/E0719.md
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+An associated type value was specified more than once.
+
+Erroneous code example:
+
+```compile_fail,E0719
+#![feature(associated_type_bounds)]
+
+trait FooTrait {}
+trait BarTrait {}
+
+// error: associated type `Item` in trait `Iterator` is specified twice
+struct Foo<T: Iterator<Item: FooTrait, Item: BarTrait>> { f: T }
+```
+
+`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.
+
+Corrected example:
+
+```
+#![feature(associated_type_bounds)]
+
+trait FooTrait {}
+trait BarTrait {}
+trait FooBarTrait: FooTrait + BarTrait {}
+
+struct Foo<T: Iterator<Item: FooBarTrait>> { f: T } // ok!
+```
+
+For more information about associated types, see [the book][bk-at]. For more
+information on associated type bounds, see [RFC 2289][rfc-2289].
+
+[bk-at]: https://doc.rust-lang.org/book/ch19-03-advanced-traits.html#specifying-placeholder-types-in-trait-definitions-with-associated-types
+[rfc-2289]: https://rust-lang.github.io/rfcs/2289-associated-type-bounds.html