Merge from rust-lang/rust

4 files changed, 48 insertions, 9 deletions

diff --git a/compiler/rustc_error_codes/src/error_codes/E0229.md b/compiler/rustc_error_codes/src/error_codes/E0229.md
index a8fab057d43..f4a983cb9ef 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0229.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0229.md
@@ -1,5 +1,4 @@
-An associated type binding was done outside of the type parameter declaration
-and `where` clause.
+An associated item constraint was written in an unexpected context.
 
 Erroneous code example:
 
@@ -16,12 +15,12 @@ impl Foo for isize {
     fn boo(&self) -> usize { 42 }
 }
 
-fn baz<I>(x: &<I as Foo<A=Bar>>::A) {}
-// error: associated type bindings are not allowed here
+fn baz<I>(x: &<I as Foo<A = Bar>>::A) {}
+// error: associated item constraint are not allowed here
 ```
 
-To solve this error, please move the type bindings in the type parameter
-declaration:
+To solve this error, please move the associated item constraints to the type
+parameter declaration:
 
 ```
 # struct Bar;
@@ -29,7 +28,7 @@ declaration:
 fn baz<I: Foo<A=Bar>>(x: &<I as Foo>::A) {} // ok!
 ```
 
-Or in the `where` clause:
+Or into the where-clause:
 
 ```
 # struct Bar;
diff --git a/compiler/rustc_error_codes/src/error_codes/E0582.md b/compiler/rustc_error_codes/src/error_codes/E0582.md
index e50cc60ea33..b2cdb509c95 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0582.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0582.md
@@ -27,6 +27,40 @@ fn bar<F, G>(t: F, u: G)
 fn main() { }
 ```
 
+This error also includes the use of associated types with lifetime parameters.
+```compile_fail,E0582
+trait Foo {
+    type Assoc<'a>;
+}
+
+struct Bar<X, F>
+where
+    X: Foo,
+    F: for<'a> Fn(X::Assoc<'a>) -> &'a i32
+{
+    x: X,
+    f: F
+}
+```
+The latter scenario encounters this error because `Foo::Assoc<'a>` could be
+implemented by a type that does not use the `'a` parameter, so there is no
+guarentee that `X::Assoc<'a>` actually uses `'a`.
+
+To fix this we can pass a dummy parameter:
+```
+# trait Foo {
+#     type Assoc<'a>;
+# }
+struct Bar<X, F>
+where
+    X: Foo,
+    F: for<'a> Fn(X::Assoc<'a>, /* dummy */ &'a ()) -> &'a i32
+{
+    x: X,
+    f: F
+}
+```
+
 Note: The examples above used to be (erroneously) accepted by the
 compiler, but this was since corrected. See [issue #33685] for more
 details.
diff --git a/compiler/rustc_error_codes/src/error_codes/E0792.md b/compiler/rustc_error_codes/src/error_codes/E0792.md
index bad2b5abfe4..5e3dcc4aa72 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0792.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0792.md
@@ -39,6 +39,8 @@ type Foo<T> = impl std::fmt::Debug;
 fn foo<U>() -> Foo<U> {
     5u32
 }
+
+fn main() {}
 ```
 
 This means that no matter the generic parameter to `foo`,
@@ -57,4 +59,6 @@ type Foo<T: Debug> = impl Debug;
 fn foo<U: Debug>() -> Foo<U> {
     Vec::<U>::new()
 }
+
+fn main() {}
 ```
diff --git a/compiler/rustc_error_codes/src/lib.rs b/compiler/rustc_error_codes/src/lib.rs
index f4a33a05c1b..d13d5e1bca2 100644
--- a/compiler/rustc_error_codes/src/lib.rs
+++ b/compiler/rustc_error_codes/src/lib.rs
@@ -1,10 +1,12 @@
 //! This library is used to gather all error codes into one place, to make
 //! their maintenance easier.
 
+// tidy-alphabetical-start
 #![allow(internal_features)]
-#![feature(rustdoc_internals)]
-#![doc(rust_logo)]
 #![deny(rustdoc::invalid_codeblock_attributes)]
+#![doc(rust_logo)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 // This higher-order macro defines the error codes that are in use. It is used
 // in the `rustc_errors` crate. Removed error codes are listed in the comment