Issue #5656: Make &self not mean "&'self self"

Fixes #5656.
Fixes #5541.

Author: nikomatsakis

src/librustc/middle/kind.rs

@@ -16,7 +16,7 @@ use middle::liveness;
 use middle::pat_util;
 use middle::ty;
 use middle::typeck;
-use util::ppaux::{Repr, ty_to_str, tys_to_str};
+use util::ppaux::{Repr, ty_to_str};
 
 use syntax::ast::*;
 use syntax::attr::attrs_contains_name;

src/librustc/middle/region.rs

@@ -544,10 +544,6 @@ pub struct DetermineRpCtxt {
     // see long discussion on region_is_relevant().
     anon_implies_rp: bool,
 
-    // true when we are not within an &self method.
-    // see long discussion on region_is_relevant().
-    self_implies_rp: bool,
-
     // encodes the context of the current type; invariant if
     // mutable, covariant otherwise
     ambient_variance: region_variance,
@@ -689,7 +685,7 @@ pub impl DetermineRpCtxt {
                 false
             }
             Some(ref l) if l.ident == special_idents::self_ => {
-                self.self_implies_rp
+                true
             }
             Some(_) => {
                 false
@@ -700,23 +696,18 @@ pub impl DetermineRpCtxt {
     fn with(@mut self,
             item_id: ast::node_id,
             anon_implies_rp: bool,
-            self_implies_rp: bool,
             f: &fn()) {
         let old_item_id = self.item_id;
         let old_anon_implies_rp = self.anon_implies_rp;
-        let old_self_implies_rp = self.self_implies_rp;
         self.item_id = item_id;
         self.anon_implies_rp = anon_implies_rp;
-        self.self_implies_rp = self_implies_rp;
-        debug!("with_item_id(%d, %b, %b)",
+        debug!("with_item_id(%d, %b)",
                item_id,
-               anon_implies_rp,
-               self_implies_rp);
+               anon_implies_rp);
         let _i = ::util::common::indenter();
         f();
         self.item_id = old_item_id;
         self.anon_implies_rp = old_anon_implies_rp;
-        self.self_implies_rp = old_self_implies_rp;
     }
 
     fn with_ambient_variance(@mut self, variance: region_variance, f: &fn()) {
@@ -730,7 +721,7 @@ pub impl DetermineRpCtxt {
 pub fn determine_rp_in_item(item: @ast::item,
                             &&cx: @mut DetermineRpCtxt,
                             visitor: visit::vt<@mut DetermineRpCtxt>) {
-    do cx.with(item.id, true, true) {
+    do cx.with(item.id, true) {
         visit::visit_item(item, cx, visitor);
     }
 }
@@ -742,12 +733,7 @@ pub fn determine_rp_in_fn(fk: &visit::fn_kind,
                           _: ast::node_id,
                           &&cx: @mut DetermineRpCtxt,
                           visitor: visit::vt<@mut DetermineRpCtxt>) {
-    let self_implies_rp = match fk {
-        &visit::fk_method(_, _, m) => !m.self_ty.node.is_borrowed(),
-        _ => true
-    };
-
-    do cx.with(cx.item_id, false, self_implies_rp) {
+    do cx.with(cx.item_id, false) {
         do cx.with_ambient_variance(rv_contravariant) {
             for decl.inputs.each |a| {
                 (visitor.visit_ty)(a.ty, cx, visitor);
@@ -763,7 +749,7 @@ pub fn determine_rp_in_fn(fk: &visit::fn_kind,
 pub fn determine_rp_in_ty_method(ty_m: &ast::ty_method,
                                  &&cx: @mut DetermineRpCtxt,
                                  visitor: visit::vt<@mut DetermineRpCtxt>) {
-    do cx.with(cx.item_id, false, !ty_m.self_ty.node.is_borrowed()) {
+    do cx.with(cx.item_id, false) {
         visit::visit_ty_method(ty_m, cx, visitor);
     }
 }
@@ -868,7 +854,7 @@ pub fn determine_rp_in_ty(ty: @ast::Ty,
       ast::ty_bare_fn(@ast::TyBareFn {decl: ref decl, _}) => {
         // fn() binds the & region, so do not consider &T types that
         // appear *inside* a fn() type to affect the enclosing item:
-        do cx.with(cx.item_id, false, true) {
+        do cx.with(cx.item_id, false) {
             // parameters are contravariant
             do cx.with_ambient_variance(rv_contravariant) {
                 for decl.inputs.each |a| {
@@ -929,7 +915,6 @@ pub fn determine_rp_in_crate(sess: Session,
         worklist: ~[],
         item_id: 0,
         anon_implies_rp: false,
-        self_implies_rp: true,
         ambient_variance: rv_covariant
     };
 

src/librustc/middle/subst.rs

@@ -62,22 +62,7 @@ impl EffectfulSubst for ty::t {
             _ => {
                 ty::fold_regions_and_ty(
                     tcx, *self,
-                    |r| match r {
-                        ty::re_bound(ty::br_self) => {
-                            match substs.self_r {
-                                None => {
-                                    tcx.sess.bug(
-                                        fmt!("ty::subst: \
-                                              Reference to self region when \
-                                              given substs with no self region, \
-                                              ty = %s",
-                                             self.repr(tcx)));
-                                }
-                                Some(self_r) => self_r
-                            }
-                        }
-                        _ => r
-                    },
+                    |r| r.subst(tcx, substs),
                     |t| t.effectfulSubst(tcx, substs),
                     |t| t.effectfulSubst(tcx, substs))
             }
@@ -118,7 +103,7 @@ impl Subst for ty::TraitRef {
 impl Subst for ty::substs {
     fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::substs {
         ty::substs {
-            self_r: self.self_r,
+            self_r: self.self_r.subst(tcx, substs),
             self_ty: self.self_ty.map(|typ| typ.subst(tcx, substs)),
             tps: self.tps.map(|typ| typ.subst(tcx, substs))
         }
@@ -166,6 +151,34 @@ impl Subst for ty::Generics {
     }
 }
 
+impl Subst for ty::Region {
+    fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::Region {
+        // Note: This routine only handles the self region, because it
+        // is only concerned with substitutions of regions that appear
+        // in types. Region substitution of the bound regions that
+        // appear in a function signature is done using the
+        // specialized routine
+        // `middle::typeck::check::regionmanip::replace_bound_regions_in_fn_sig()`.
+        // As we transition to the new region syntax this distinction
+        // will most likely disappear.
+        match self {
+            &ty::re_bound(ty::br_self) => {
+                match substs.self_r {
+                    None => {
+                        tcx.sess.bug(
+                            fmt!("ty::Region#subst(): \
+                                  Reference to self region when \
+                                  given substs with no self region: %s",
+                                 substs.repr(tcx)));
+                    }
+                    Some(self_r) => self_r
+                }
+            }
+            _ => *self
+        }
+    }
+}
+
 impl Subst for ty::ty_param_bounds_and_ty {
     fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::ty_param_bounds_and_ty {
         ty::ty_param_bounds_and_ty {

src/librustc/middle/ty.rs

@@ -24,8 +24,7 @@ use middle::subst::Subst;
 use middle::typeck;
 use middle;
 use util::ppaux::{note_and_explain_region, bound_region_to_str};
-use util::ppaux::{region_to_str, vstore_to_str};
-use util::ppaux::{trait_store_to_str, ty_to_str, tys_to_str};
+use util::ppaux::{trait_store_to_str, ty_to_str, vstore_to_str};
 use util::ppaux::Repr;
 use util::common::{indenter};