Rollup merge of #42324 - seanmonstar:41323-compare_const_impl, r=nikomatsakis

associated_consts: check trait obligations and regionck for associated consts

Closes #41323

r? @nikomatsakis

Author: frewsxcv

Diff for: src/librustc_typeck/check/compare_method.rs

@@ -787,6 +787,14 @@ pub fn compare_const_impl<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
             diag.emit();
         }
 
-        // FIXME(#41323) Check the obligations in the fulfillment context.
+        // Check that all obligations are satisfied by the implementation's
+        // version.
+        if let Err(ref errors) = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx) {
+            infcx.report_fulfillment_errors(errors);
+            return;
+        }
+
+        let fcx = FnCtxt::new(&inh, impl_c_node_id);
+        fcx.regionck_item(impl_c_node_id, impl_c_span, &[]);
     });
 }

Diff for: src/test/compile-fail/associated-const-generic-obligations.rs

@@ -0,0 +1,30 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(associated_consts)]
+
+trait Foo {
+    type Out: Sized;
+}
+
+impl Foo for String {
+    type Out = String;
+}
+
+trait Bar: Foo {
+    const FROM: Self::Out;
+}
+
+impl<T: Foo> Bar for T {
+    const FROM: &'static str = "foo";
+    //~^ ERROR the trait bound `T: Foo` is not satisfied [E0277]
+}
+
+fn main() {}

Diff for: src/test/compile-fail/associated-const-impl-wrong-lifetime.rs

@@ -0,0 +1,27 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(associated_consts)]
+
+trait Foo {
+    const NAME: &'static str;
+}
+
+
+impl<'a> Foo for &'a () {
+//~^ NOTE the lifetime 'a as defined
+    const NAME: &'a str = "unit";
+    //~^ ERROR mismatched types [E0308]
+    //~| NOTE lifetime mismatch
+    //~| NOTE expected type `&'static str`
+    //~| NOTE ...does not necessarily outlive the static lifetime
+}
+
+fn main() {}