Imported Upstream version 1.2.0+dfsg1

[rustc.git] / src / librustc / middle / infer / glb.rs

diff --git a/src/librustc/middle/infer/glb.rs b/src/librustc/middle/infer/glb.rs
index 5822fb0f2d432fba8d7c3fe10959268c158d3fc4..adfd1a8a7d7945abf088ad564ae2d0836be68604 100644 (file)
--- a/src/librustc/middle/infer/glb.rs
+++ b/src/librustc/middle/infer/glb.rs
@@ -16,7 +16,6 @@ use super::Subtype;
 
 use middle::ty::{self, Ty};
 use middle::ty_relate::{Relate, RelateResult, TypeRelation};
-use util::ppaux::Repr;
 
 /// "Greatest lower bound" (common subtype)
 pub struct Glb<'a, 'tcx: 'a> {
@@ -36,6 +35,16 @@ impl<'a, 'tcx> TypeRelation<'a, 'tcx> for Glb<'a, 'tcx> {
 
     fn a_is_expected(&self) -> bool { self.fields.a_is_expected }
 
+    fn will_change(&mut self, a: bool, b: bool) -> bool {
+        // Hmm, so the result of GLB will still be a LB if one or both
+        // sides change to 'static, but it may no longer be the GLB.
+        // I'm going to go with `a || b` here to be conservative,
+        // since the result of this operation may be affected, though
+        // I think it would mostly be more accepting than before (since the result
+        // would be a bigger region).
+        a || b
+    }
+
     fn relate_with_variance<T:Relate<'a,'tcx>>(&mut self,
                                                variance: ty::Variance,
                                                a: &T,
@@ -55,10 +64,10 @@ impl<'a, 'tcx> TypeRelation<'a, 'tcx> for Glb<'a, 'tcx> {
     }
 
     fn regions(&mut self, a: ty::Region, b: ty::Region) -> RelateResult<'tcx, ty::Region> {
-        debug!("{}.regions({}, {})",
+        debug!("{}.regions({:?}, {:?})",
                self.tag(),
-               a.repr(self.fields.infcx.tcx),
-               b.repr(self.fields.infcx.tcx));
+               a,
+               b);
 
         let origin = Subtype(self.fields.trace.clone());
         Ok(self.fields.infcx.region_vars.glb_regions(origin, a, b))