Auto merge of #57428 - alexreg:associated_type_bounds, r=nikomatsakis,Centril

Implementation of RFC 2289 (associated_type_bounds)

This PR implements the [`asociated_type_bounds` feature](https://github.com/rust-lang/rfcs/blob/master/text/2289-associated-type-bounds.md).

Associated type bounds are implemented in:
   - function/method arguments and return types
   - structs, enums, unions
   - associated items in traits
   - type aliases
   - type parameter defaults
   - trait objects
   - let bindings

CC @nikomatsakis @centril

2 files changed, 4 insertions, 6 deletions

diff --git a/src/libsyntax_ext/deriving/generic/mod.rs b/src/libsyntax_ext/deriving/generic/mod.rs
index 7e3082a87d9..ffec667aba5 100644
--- a/src/libsyntax_ext/deriving/generic/mod.rs
+++ b/src/libsyntax_ext/deriving/generic/mod.rs
@@ -922,8 +922,7 @@ impl<'a> MethodDef<'a> {
                      arg_types: Vec<(Ident, P<ast::Ty>)>,
                      body: P<Expr>)
                      -> ast::ImplItem {
-
-        // create the generics that aren't for Self
+        // Create the generics that aren't for `Self`.
         let fn_generics = self.generics.to_generics(cx, trait_.span, type_ident, generics);
 
         let args = {
diff --git a/src/libsyntax_ext/proc_macro_decls.rs b/src/libsyntax_ext/proc_macro_decls.rs
index 5b8f4f35f2d..de8b689396f 100644
--- a/src/libsyntax_ext/proc_macro_decls.rs
+++ b/src/libsyntax_ext/proc_macro_decls.rs
@@ -245,8 +245,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
         // First up, make sure we're checking a bare function. If we're not then
         // we're just not interested in this item.
         //
-        // If we find one, try to locate a `#[proc_macro_derive]` attribute on
-        // it.
+        // If we find one, try to locate a `#[proc_macro_derive]` attribute on it.
         let is_fn = match item.node {
             ast::ItemKind::Fn(..) => true,
             _ => false,
@@ -259,7 +258,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
                 if let Some(prev_attr) = found_attr {
                     let msg = if attr.path.segments[0].ident.name ==
                                  prev_attr.path.segments[0].ident.name {
-                        format!("Only one `#[{}]` attribute is allowed on any given function",
+                        format!("only one `#[{}]` attribute is allowed on any given function",
                                 attr.path)
                     } else {
                         format!("`#[{}]` and `#[{}]` attributes cannot both be applied \
@@ -267,7 +266,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
                     };
 
                     self.handler.struct_span_err(attr.span, &msg)
-                        .span_note(prev_attr.span, "Previous attribute here")
+                        .span_note(prev_attr.span, "previous attribute here")
                         .emit();
 
                     return;