add back variance testing mechanism

make it work for traits etc uniformly

src/librustc_typeck/lib.rs

@@ -318,6 +318,11 @@ pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>)
           coherence::check_coherence(tcx));
     })?;
 
+    tcx.sess.track_errors(|| {
+        time(time_passes, "variance testing", ||
+             variance::test::test_variance(tcx));
+    })?;
+
     time(time_passes, "wf checking", || check::check_wf_new(tcx))?;
 
     time(time_passes, "item-types checking", || check::check_item_types(tcx))?;

src/librustc_typeck/variance/mod.rs

@@ -29,6 +29,9 @@ mod constraints;
 /// Code to solve constraints and write out the results.
 mod solve;
 
+/// Code to write unit tests of variance.
+pub mod test;
+
 /// Code for transforming variances.
 mod xform;
 
@@ -89,3 +92,4 @@ fn variances_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_def_id: DefId)
         }
     }
 }
+

src/librustc_typeck/variance/solve.rs

@@ -128,16 +128,6 @@ impl<'a, 'tcx> SolveContext<'a, 'tcx> {
 
             let item_def_id = tcx.hir.local_def_id(item_id);
 
-            // For unit testing: check for a special "rustc_variance"
-            // attribute and report an error with various results if found.
-            if tcx.has_attr(item_def_id, "rustc_variance") {
-                span_err!(tcx.sess,
-                          tcx.hir.span(item_id),
-                          E0208,
-                          "{:?}",
-                          item_variances);
-            }
-
             map.insert(item_def_id, Rc::new(item_variances));
         }
 

src/librustc_typeck/variance/test.rs

@@ -0,0 +1,41 @@
+// Copyright 2013 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.
+
+use rustc::hir;
+use rustc::hir::itemlikevisit::ItemLikeVisitor;
+use rustc::ty::TyCtxt;
+
+pub fn test_variance<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
+    tcx.hir.krate().visit_all_item_likes(&mut VarianceTest { tcx });
+}
+
+struct VarianceTest<'a, 'tcx: 'a> {
+    tcx: TyCtxt<'a, 'tcx, 'tcx>
+}
+
+impl<'a, 'tcx> ItemLikeVisitor<'tcx> for VarianceTest<'a, 'tcx> {
+    fn visit_item(&mut self, item: &'tcx hir::Item) {
+        let item_def_id = self.tcx.hir.local_def_id(item.id);
+
+        // For unit testing: check for a special "rustc_variance"
+        // attribute and report an error with various results if found.
+        if self.tcx.has_attr(item_def_id, "rustc_variance") {
+            let item_variances = self.tcx.variances_of(item_def_id);
+            span_err!(self.tcx.sess,
+                      item.span,
+                      E0208,
+                      "{:?}",
+                      item_variances);
+        }
+    }
+
+    fn visit_trait_item(&mut self, _: &'tcx hir::TraitItem) { }
+    fn visit_impl_item(&mut self, _: &'tcx hir::ImplItem) { }
+}

src/test/compile-fail/variance-regions-direct.rs

@@ -60,7 +60,6 @@ struct Test6<'a, 'b:'a> { //~ ERROR [-, o]
 
 #[rustc_variance]
 struct Test7<'a> { //~ ERROR [*]
-    //~^ ERROR parameter `'a` is never used
     x: isize
 }
 

src/test/compile-fail/variance-regions-indirect.rs

@@ -16,7 +16,6 @@
 
 #[rustc_variance]
 enum Base<'a, 'b, 'c:'b, 'd> { //~ ERROR [+, -, o, *]
-    //~^ ERROR parameter `'d` is never used
     Test8A(extern "Rust" fn(&'a isize)),
     Test8B(&'b [isize]),
     Test8C(&'b mut &'c str),
@@ -24,19 +23,16 @@ enum Base<'a, 'b, 'c:'b, 'd> { //~ ERROR [+, -, o, *]
 
 #[rustc_variance]
 struct Derived1<'w, 'x:'y, 'y, 'z> { //~ ERROR [*, o, -, +]
-    //~^ ERROR parameter `'w` is never used
     f: Base<'z, 'y, 'x, 'w>
 }
 
 #[rustc_variance] // Combine - and + to yield o
 struct Derived2<'a, 'b:'a, 'c> { //~ ERROR [o, o, *]
-    //~^ ERROR parameter `'c` is never used
     f: Base<'a, 'a, 'b, 'c>
 }
 
 #[rustc_variance] // Combine + and o to yield o (just pay attention to 'a here)
 struct Derived3<'a:'b, 'b, 'c> { //~ ERROR [o, -, *]
-    //~^ ERROR parameter `'c` is never used
     f: Base<'a, 'b, 'a, 'c>
 }
 

src/test/compile-fail/variance-trait-bounds.rs

@@ -30,8 +30,7 @@ struct TestStruct<U,T:Setter<U>> { //~ ERROR [+, +]
 }
 
 #[rustc_variance]
-enum TestEnum<U,T:Setter<U>> {//~ ERROR [*, +]
-    //~^ ERROR parameter `U` is never used
+enum TestEnum<U,T:Setter<U>> { //~ ERROR [*, +]
     Foo(T)
 }
 
@@ -51,13 +50,11 @@ trait TestTrait3<U> { //~ ERROR [o, o]
 
 #[rustc_variance]
 struct TestContraStruct<U,T:Setter<U>> { //~ ERROR [*, +]
-    //~^ ERROR parameter `U` is never used
     t: T
 }
 
 #[rustc_variance]
 struct TestBox<U,T:Getter<U>+Setter<U>> { //~ ERROR [*, +]
-    //~^ ERROR parameter `U` is never used
     t: T
 }