Check lifetime parameters when we do check for supertrait impls. Fixes #14050.

Author: nikomatsakis

src/librustc/middle/typeck/check/vtable.rs

@@ -733,7 +733,8 @@ pub fn early_resolve_expr(ex: &ast::Expr, fcx: &FnCtxt, is_early: bool) {
 pub fn resolve_impl(tcx: &ty::ctxt,
                     impl_item: &ast::Item,
                     impl_generics: &ty::Generics,
-                    impl_trait_ref: &ty::TraitRef) {
+                    impl_trait_ref: &ty::TraitRef)
+{
     let param_env = ty::construct_parameter_environment(
         tcx,
         None,
@@ -774,6 +775,7 @@ pub fn resolve_impl(tcx: &ty::ctxt,
         lookup_vtables_for_param(&vcx, impl_item.span, None,
                                  &param_bounds, t, false);
 
+    infcx.resolve_regions_and_report_errors();
 
     let res = impl_res {
         trait_vtables: vtbls,

src/test/compile-fail/trait-impl-of-supertrait-has-wrong-lifetime-parameters.rs

@@ -0,0 +1,41 @@
+// Copyright 2014 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.
+
+// Check that when we test the supertrait we ensure consistent use of
+// lifetime parameters. In this case, implementing T2<'a,'b> requires
+// an impl of T1<'a>, but we have an impl of T1<'b>.
+
+trait T1<'x> {
+    fn x(&self) -> &'x int;
+}
+
+trait T2<'x, 'y> : T1<'x> {
+    fn y(&self) -> &'y int;
+}
+
+struct S<'a, 'b> {
+    a: &'a int,
+    b: &'b int
+}
+
+impl<'a,'b> T1<'b> for S<'a, 'b> {
+    fn x(&self) -> &'b int {
+        self.b
+    }
+}
+
+impl<'a,'b> T2<'a, 'b> for S<'a, 'b> { //~ ERROR cannot infer an appropriate lifetime
+    fn y(&self) -> &'b int {
+        self.b
+    }
+}
+
+pub fn main() {
+}