Reword E0044 and message for !Send types

 - Reword E0044 help.
 - Change error message for types that don't implement `Send`

Author: estebank

src/libcore/marker.rs

@@ -343,7 +343,10 @@ pub trait Copy : Clone {
 /// [transmute]: ../../std/mem/fn.transmute.html
 #[stable(feature = "rust1", since = "1.0.0")]
 #[lang = "sync"]
-#[rustc_on_unimplemented = "`{Self}` cannot be shared between threads safely"]
+#[rustc_on_unimplemented(
+    message="`{Self}` cannot be shared between threads safely",
+    label="`{Self}` cannot be shared between threads safely"
+)]
 pub unsafe auto trait Sync {
     // Empty
 }

src/librustc_typeck/check/mod.rs

@@ -1222,9 +1222,10 @@ pub fn check_item_type<'a,'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, it: &'tcx hir::Item
                 if !generics.types.is_empty() {
                     let mut err = struct_span_err!(tcx.sess, item.span, E0044,
                         "foreign items may not have type parameters");
-                    span_help!(&mut err, item.span,
-                        "consider using specialization instead of \
-                        type parameters");
+                    // FIXME: once we start storing spans for type arguments, turn this into a
+                    // suggestion.
+                    err.help("use specialization instead of type parameters by replacing them \
+                              with concrete types like `u32`");
                     err.emit();
                 }
 

src/test/compile-fail/builtin-superkinds-double-superkind.rs

@@ -13,9 +13,11 @@
 
 trait Foo : Send+Sync { }
 
-impl <T: Sync+'static> Foo for (T,) { } //~ ERROR `T: std::marker::Send` is not satisfied
+impl <T: Sync+'static> Foo for (T,) { }
+//~^ ERROR the trait bound `T: std::marker::Send` is not satisfied in `(T,)` [E0277]
 
-impl <T: Send> Foo for (T,T) { } //~ ERROR `T: std::marker::Sync` is not satisfied
+impl <T: Send> Foo for (T,T) { }
+//~^ ERROR `T` cannot be shared between threads safely [E0277]
 
 impl <T: Send+Sync> Foo for (T,T,T) { } // (ok)
 

src/test/compile-fail/closure-bounds-subtype.rs

@@ -21,7 +21,7 @@ fn give_any<F>(f: F) where F: FnOnce() {
 
 fn give_owned<F>(f: F) where F: FnOnce() + Send {
     take_any(f);
-    take_const_owned(f); //~ ERROR `F: std::marker::Sync` is not satisfied
+    take_const_owned(f); //~ ERROR `F` cannot be shared between threads safely [E0277]
 }
 
 fn main() {}

src/test/compile-fail/extern-types-not-sync-send.rs

@@ -21,7 +21,7 @@ fn assert_send<T: ?Sized + Send>() { }
 
 fn main() {
     assert_sync::<A>();
-    //~^ ERROR the trait bound `A: std::marker::Sync` is not satisfied
+    //~^ ERROR `A` cannot be shared between threads safely [E0277]
 
     assert_send::<A>();
     //~^ ERROR the trait bound `A: std::marker::Send` is not satisfied

src/test/compile-fail/issue-16538.rs

@@ -21,7 +21,7 @@ mod Y {
 }
 
 static foo: *const Y::X = Y::foo(Y::x as *const Y::X);
-//~^ ERROR `*const usize: std::marker::Sync` is not satisfied
+//~^ ERROR `*const usize` cannot be shared between threads safely [E0277]
 //~| ERROR cannot refer to other statics by value, use the address-of operator or a constant instead
 //~| ERROR E0015
 

src/test/compile-fail/issue-17718-static-sync.rs

@@ -17,6 +17,6 @@ impl !Sync for Foo {}
 
 static FOO: usize = 3;
 static BAR: Foo = Foo;
-//~^ ERROR: `Foo: std::marker::Sync` is not satisfied
+//~^ ERROR: `Foo` cannot be shared between threads safely [E0277]
 
 fn main() {}

src/test/compile-fail/issue-43733-2.rs

@@ -33,7 +33,7 @@ impl<T> Key<T> {
 use std::thread::__FastLocalKeyInner as Key;
 
 static __KEY: Key<()> = Key::new();
-//~^ ERROR `std::cell::UnsafeCell<std::option::Option<()>>: std::marker::Sync` is not satisfied
-//~| ERROR `std::cell::Cell<bool>: std::marker::Sync` is not satisfied
+//~^ ERROR `std::cell::UnsafeCell<std::option::Option<()>>` cannot be shared between threads
+//~| ERROR `std::cell::Cell<bool>` cannot be shared between threads safely [E0277]
 
 fn main() {}

src/test/compile-fail/issue-7364.rs

@@ -15,6 +15,6 @@ use std::cell::RefCell;
 // Regression test for issue 7364
 static boxed: Box<RefCell<isize>> = box RefCell::new(0);
 //~^ ERROR allocations are not allowed in statics
-//~| ERROR `std::cell::RefCell<isize>: std::marker::Sync` is not satisfied
+//~| ERROR `std::cell::RefCell<isize>` cannot be shared between threads safely [E0277]
 
 fn main() { }

src/test/compile-fail/kindck-send-object.rs

@@ -20,7 +20,7 @@ trait Message : Send { }
 
 fn object_ref_with_static_bound_not_ok() {
     assert_send::<&'static (Dummy+'static)>();
-    //~^ ERROR : std::marker::Sync` is not satisfied
+    //~^ ERROR `Dummy + 'static` cannot be shared between threads safely [E0277]
 }
 
 fn box_object_with_no_bound_not_ok<'a>() {