Rollup of 7 pull requests

.mailmap

@@ -5,7 +5,6 @@
 # email addresses.
 #
 
-Aaron Power <theaaronepower@gmail.com> Erin Power <xampprocky@gmail.com>
 Aaron Todd <github@opprobrio.us>
 Abhishek Chanda <abhishek.becs@gmail.com> Abhishek Chanda <abhishek@cloudscaling.com>
 Adolfo Ochagavía <aochagavia92@gmail.com>
@@ -84,6 +83,8 @@ Eric Holk <eric.holk@gmail.com> <eholk@mozilla.com>
 Eric Holmes <eric@ejholmes.net>
 Eric Reed <ecreed@cs.washington.edu> <ereed@mozilla.com>
 Erick Tryzelaar <erick.tryzelaar@gmail.com> <etryzelaar@iqt.org>
+Erin Power <xampprocky@gmail.com> <theaaronepower@gmail.com>
+Erin Power <xampprocky@gmail.com> <Aaronepower@users.noreply.github.com>
 Esteban Küber <esteban@kuber.com.ar> <esteban@commure.com>
 Esteban Küber <esteban@kuber.com.ar> <estebank@users.noreply.github.com>
 Esteban Küber <esteban@kuber.com.ar> <github@kuber.com.ar>

src/bootstrap/toolstate.rs

@@ -443,7 +443,7 @@ fn change_toolstate(
         if new_state != state {
             eprintln!("The state of `{}` has changed from `{}` to `{}`", tool, state, new_state);
             if new_state < state {
-                if !["rustc-guide", "miri", "embedded-book"].contains(&tool.as_str()) {
+                if !NIGHTLY_TOOLS.iter().any(|(name, _path)| name == tool) {
                     regressed = true;
                 }
             }

src/libcore/iter/adapters/mod.rs

@@ -1894,9 +1894,7 @@ where
             let to_skip = self.n;
             self.n = 0;
             // nth(n) skips n+1
-            if self.iter.nth(to_skip - 1).is_none() {
-                return None;
-            }
+            self.iter.nth(to_skip - 1)?;
         }
         self.iter.nth(n)
     }
@@ -1916,9 +1914,7 @@ where
     fn last(mut self) -> Option<I::Item> {
         if self.n > 0 {
             // nth(n) skips n+1
-            if self.iter.nth(self.n - 1).is_none() {
-                return None;
-            }
+            self.iter.nth(self.n - 1)?;
         }
         self.iter.last()
     }

src/librustc/hir/map/mod.rs

@@ -338,9 +338,8 @@ impl<'hir> Map<'hir> {
             Node::Variant(_) => DefKind::Variant,
             Node::Ctor(variant_data) => {
                 // FIXME(eddyb) is this even possible, if we have a `Node::Ctor`?
-                if variant_data.ctor_hir_id().is_none() {
-                    return None;
-                }
+                variant_data.ctor_hir_id()?;
+
                 let ctor_of = match self.find(self.get_parent_node(hir_id)) {
                     Some(Node::Item(..)) => def::CtorOf::Struct,
                     Some(Node::Variant(..)) => def::CtorOf::Variant,

src/librustc/ty/instance.rs

@@ -115,9 +115,7 @@ impl<'tcx> Instance<'tcx> {
         }
 
         // If this a non-generic instance, it cannot be a shared monomorphization.
-        if self.substs.non_erasable_generics().next().is_none() {
-            return None;
-        }
+        self.substs.non_erasable_generics().next()?;
 
         match self.def {
             InstanceDef::Item(def_id) => tcx

src/librustc_error_codes/error_codes.rs

@@ -395,6 +395,7 @@ E0714: include_str!("./error_codes/E0714.md"),
 E0715: include_str!("./error_codes/E0715.md"),
 E0716: include_str!("./error_codes/E0716.md"),
 E0718: include_str!("./error_codes/E0718.md"),
+E0719: include_str!("./error_codes/E0719.md"),
 E0720: include_str!("./error_codes/E0720.md"),
 E0723: include_str!("./error_codes/E0723.md"),
 E0725: include_str!("./error_codes/E0725.md"),
@@ -605,7 +606,6 @@ E0748: include_str!("./error_codes/E0748.md"),
     E0710, // an unknown tool name found in scoped lint
     E0711, // a feature has been declared with conflicting stability attributes
     E0717, // rustc_promotable without stability attribute
-    E0719, // duplicate values for associated type binding
 //  E0721, // `await` keyword
     E0722, // Malformed `#[optimize]` attribute
     E0724, // `#[ffi_returns_twice]` is only allowed in foreign functions

src/librustc_error_codes/error_codes/E0378.md

@@ -1,10 +1,28 @@
+The `DispatchFromDyn` trait was implemented on something which is not a pointer
+or a newtype wrapper around a pointer.
+
+Erroneous code example:
+
+```compile-fail,E0378
+#![feature(dispatch_from_dyn)]
+use std::ops::DispatchFromDyn;
+
+struct WrapperExtraField<T> {
+    ptr: T,
+    extra_stuff: i32,
+}
+
+impl<T, U> DispatchFromDyn<WrapperExtraField<U>> for WrapperExtraField<T>
+where
+    T: DispatchFromDyn<U>,
+{}
+```
+
 The `DispatchFromDyn` trait currently can only be implemented for
 builtin pointer types and structs that are newtype wrappers around them
 — that is, the struct must have only one field (except for`PhantomData`),
 and that field must itself implement `DispatchFromDyn`.
 
-Examples:
-
 ```
 #![feature(dispatch_from_dyn, unsize)]
 use std::{
@@ -20,6 +38,8 @@ where
 {}
 ```
 
+Another example:
+
 ```
 #![feature(dispatch_from_dyn)]
 use std::{
@@ -37,21 +57,3 @@ where
     T: DispatchFromDyn<U>,
 {}
 ```
-
-Example of illegal `DispatchFromDyn` implementation
-(illegal because of extra field)
-
-```compile-fail,E0378
-#![feature(dispatch_from_dyn)]
-use std::ops::DispatchFromDyn;
-
-struct WrapperExtraField<T> {
-    ptr: T,
-    extra_stuff: i32,
-}
-
-impl<T, U> DispatchFromDyn<WrapperExtraField<U>> for WrapperExtraField<T>
-where
-    T: DispatchFromDyn<U>,
-{}
-```

src/librustc_error_codes/error_codes/E0719.md

@@ -0,0 +1,35 @@
+The value for an associated type has already been specified.
+
+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 }
+```
+
+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

src/librustc_incremental/persist/work_product.rs

@@ -13,9 +13,7 @@ pub fn copy_cgu_workproducts_to_incr_comp_cache_dir(
     files: &[(WorkProductFileKind, PathBuf)],
 ) -> Option<(WorkProductId, WorkProduct)> {
     debug!("copy_cgu_workproducts_to_incr_comp_cache_dir({:?},{:?})", cgu_name, files);
-    if sess.opts.incremental.is_none() {
-        return None;
-    }
+    sess.opts.incremental.as_ref()?;
 
     let saved_files = files
         .iter()

src/librustc_resolve/imports.rs

@@ -1252,7 +1252,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
         // this may resolve to either a value or a type, but for documentation
         // purposes it's good enough to just favor one over the other.
         self.r.per_ns(|this, ns| {
-            if let Some(binding) = source_bindings[ns].get().ok() {
+            if let Ok(binding) = source_bindings[ns].get() {
                 this.import_res_map.entry(directive.id).or_default()[ns] = Some(binding.res());
             }
         });
@@ -1293,7 +1293,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
         let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
 
         self.r.per_ns(|this, ns| {
-            if let Some(binding) = source_bindings[ns].get().ok() {
+            if let Ok(binding) = source_bindings[ns].get() {
                 if binding.res() == Res::Err {
                     return;
                 }

src/librustc_traits/chalk_context/mod.rs

@@ -112,9 +112,7 @@ impl context::AggregateOps<ChalkArenas<'tcx>> for ChalkContext<'tcx> {
 
         debug!("make_solution(root_goal = {:?})", root_goal);
 
-        if simplified_answers.peek_answer().is_none() {
-            return None;
-        }
+        simplified_answers.peek_answer()?;
 
         let SimplifiedAnswer { subst: constrained_subst, ambiguous } =
             simplified_answers.next_answer().unwrap();

src/libstd/net/addr.rs

@@ -901,7 +901,7 @@ impl ToSocketAddrs for str {
     type Iter = vec::IntoIter<SocketAddr>;
     fn to_socket_addrs(&self) -> io::Result<vec::IntoIter<SocketAddr>> {
         // try to parse as a regular SocketAddr first
-        if let Some(addr) = self.parse().ok() {
+        if let Ok(addr) = self.parse() {
             return Ok(vec![addr].into_iter());
         }
 

src/test/ui/associated-type-bounds/duplicate.stderr

@@ -728,3 +728,4 @@ LL | type TADyn3 = dyn Iterator<Item: 'static, Item: 'static>;
 
 error: aborting due to 96 previous errors
 
+For more information about this error, try `rustc --explain E0719`.

src/test/ui/error-codes/E0719.stderr

@@ -16,3 +16,4 @@ LL | fn test() -> Box<dyn Iterator<Item = (), Item = Unit>> {
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0719`.