auto merge of #18694 : nikomatsakis/rust/issue-18208-method-dispatch-2, r=nrc

This is a pretty major refactoring of the method dispatch infrastructure. It is intended to avoid gross inefficiencies and enable caching and other optimizations (e.g. #17995), though it itself doesn't seem to execute particularly faster yet. It also solves some cases where we were failing to resolve methods that we theoretically should have succeeded with.

Fixes #18674.

cc #18208

Author: bors

src/librustc/lib.rs

@@ -29,7 +29,7 @@ This API is completely unstable and subject to change.
       html_root_url = "http://doc.rust-lang.org/nightly/")]
 
 #![feature(default_type_params, globs, if_let, import_shadowing, macro_rules, phase, quote)]
-#![feature(slicing_syntax, struct_variant, unsafe_destructor)]
+#![feature(slicing_syntax, struct_variant, tuple_indexing, unsafe_destructor)]
 #![feature(rustc_diagnostic_macros)]
 
 extern crate arena;

src/librustc/middle/traits/mod.rs

@@ -276,6 +276,16 @@ pub fn overlapping_impls(infcx: &InferCtxt,
     coherence::impl_can_satisfy(infcx, impl2_def_id, impl1_def_id)
 }
 
+pub fn impl_obligations(tcx: &ty::ctxt,
+                        cause: ObligationCause,
+                        impl_def_id: ast::DefId,
+                        impl_substs: &subst::Substs)
+                        -> subst::VecPerParamSpace<Obligation>
+{
+    let impl_generics = ty::lookup_item_type(tcx, impl_def_id).generics;
+    obligations_for_generics(tcx, cause, &impl_generics, impl_substs)
+}
+
 pub fn obligations_for_generics(tcx: &ty::ctxt,
                                 cause: ObligationCause,
                                 generics: &ty::Generics,

src/librustc/middle/traits/select.rs

@@ -1709,7 +1709,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 closure_type.sig.binder_id,
                 &closure_type.sig,
                 |br| self.infcx.next_region_var(
-                         infer::LateBoundRegion(obligation.cause.span, br)));
+                         infer::LateBoundRegion(obligation.cause.span, br,
+                                                infer::FnCall)));
 
         let arguments_tuple = new_signature.inputs[0];
         let trait_ref = Rc::new(ty::TraitRef {

src/librustc/middle/ty.rs

@@ -1111,7 +1111,8 @@ impl CLike for BuiltinBound {
 
 #[deriving(Clone, PartialEq, Eq, Hash)]
 pub struct TyVid {
-    pub index: uint
+    pub index: uint,
+    pub counter: uint,
 }
 
 #[deriving(Clone, PartialEq, Eq, Hash)]
@@ -1167,7 +1168,7 @@ impl cmp::PartialEq for InferRegion {
 
 impl fmt::Show for TyVid {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result{
-        write!(f, "_#{}t", self.index)
+        write!(f, "_#{}/{}t", self.index, self.counter)
     }
 }
 
@@ -3485,43 +3486,45 @@ pub fn adjust_ty(cx: &ctxt,
                         }
                     }
 
-                    match adj.autoref {
-                        None => adjusted_ty,
-                        Some(ref autoref) => adjust_for_autoref(cx, span, adjusted_ty, autoref)
-                    }
+                    adjust_ty_for_autoref(cx, span, adjusted_ty, adj.autoref.as_ref())
                 }
             }
         }
         None => unadjusted_ty
     };
+}
 
-    fn adjust_for_autoref(cx: &ctxt,
-                          span: Span,
-                          ty: ty::t,
-                          autoref: &AutoRef) -> ty::t{
-        match *autoref {
-            AutoPtr(r, m, ref a) => {
-                let adjusted_ty = match a {
-                    &Some(box ref a) => adjust_for_autoref(cx, span, ty, a),
-                    &None => ty
-                };
-                mk_rptr(cx, r, mt {
-                    ty: adjusted_ty,
-                    mutbl: m
-                })
-            }
+pub fn adjust_ty_for_autoref(cx: &ctxt,
+                             span: Span,
+                             ty: ty::t,
+                             autoref: Option<&AutoRef>)
+                             -> ty::t
+{
+    match autoref {
+        None => ty,
 
-            AutoUnsafe(m, ref a) => {
-                let adjusted_ty = match a {
-                    &Some(box ref a) => adjust_for_autoref(cx, span, ty, a),
-                    &None => ty
-                };
-                mk_ptr(cx, mt {ty: adjusted_ty, mutbl: m})
-            }
+        Some(&AutoPtr(r, m, ref a)) => {
+            let adjusted_ty = match a {
+                &Some(box ref a) => adjust_ty_for_autoref(cx, span, ty, Some(a)),
+                &None => ty
+            };
+            mk_rptr(cx, r, mt {
+                ty: adjusted_ty,
+                mutbl: m
+            })
+        }
 
-            AutoUnsize(ref k) => unsize_ty(cx, ty, k, span),
-            AutoUnsizeUniq(ref k) => ty::mk_uniq(cx, unsize_ty(cx, ty, k, span)),
+        Some(&AutoUnsafe(m, ref a)) => {
+            let adjusted_ty = match a {
+                &Some(box ref a) => adjust_ty_for_autoref(cx, span, ty, Some(a)),
+                &None => ty
+            };
+            mk_ptr(cx, mt {ty: adjusted_ty, mutbl: m})
         }
+
+        Some(&AutoUnsize(ref k)) => unsize_ty(cx, ty, k, span),
+
+        Some(&AutoUnsizeUniq(ref k)) => ty::mk_uniq(cx, unsize_ty(cx, ty, k, span)),
     }
 }