Fix two bugs in HRTB: 1. Categorize early-vs-late bindings on impls when constructing...

Previously, the DeBruijn index for the self type was not being
adjusted to account for the fn binder. This mean that when late-bound
regions were instantiated, you sometimes wind up with two distinct
lifetimes.

Fixes #19537.

diff --git a/src/librustc_typeck/astconv.rs b/src/librustc_typeck/astconv.rs
index 7f1aad8ca77c56f81fb7dae5d1e2113e1b7239e7..790d882f836f5b8230173673db6bdfa020015138 100644 (file)
--- a/src/librustc_typeck/astconv.rs
+++ b/src/librustc_typeck/astconv.rs
@@ -54,6 +54,7 @@
 use middle::subst::{FnSpace, TypeSpace, AssocSpace, SelfSpace, Subst, Substs};
 use middle::subst::{VecPerParamSpace};
 use middle::ty::{mod, Ty};
+use middle::ty_fold;
 use rscope::{mod, UnelidableRscope, RegionScope, SpecificRscope,
              ShiftedRscope, BindingRscope};
 use TypeAndSubsts;
@@ -1062,7 +1063,8 @@ fn ty_of_method_or_bare_fn<'a, 'tcx, AC: AstConv<'tcx>>(
                            opt_self_info: Option<SelfInfo<'a, 'tcx>>,
                            decl: &ast::FnDecl)
                            -> (ty::BareFnTy<'tcx>,
-                               Option<ty::ExplicitSelfCategory>) {
+                               Option<ty::ExplicitSelfCategory>)
+{
     debug!("ty_of_method_or_bare_fn");
 
     // New region names that appear inside of the arguments of the function
@@ -1078,6 +1080,11 @@ fn ty_of_method_or_bare_fn<'a, 'tcx, AC: AstConv<'tcx>>(
     let (self_ty, mut implied_output_region) = match opt_self_info {
         None => (None, None),
         Some(self_info) => {
+            // Shift regions in the self type by 1 to account for the binding
+            // level introduced by the function itself.
+            let untransformed_self_ty =
+                ty_fold::shift_regions(this.tcx(), 1, &self_info.untransformed_self_ty);
+
             // Figure out and record the explicit self category.
             let explicit_self_category =
                 determine_explicit_self_category(this, &rb, &self_info);
@@ -1087,21 +1094,19 @@ fn ty_of_method_or_bare_fn<'a, 'tcx, AC: AstConv<'tcx>>(
                     (None, None)
                 }
                 ty::ByValueExplicitSelfCategory => {
-                    (Some(self_info.untransformed_self_ty), None)
+                    (Some(untransformed_self_ty), None)
                 }
                 ty::ByReferenceExplicitSelfCategory(region, mutability) => {
                     (Some(ty::mk_rptr(this.tcx(),
                                       region,
                                       ty::mt {
-                                        ty: self_info.untransformed_self_ty,
+                                        ty: untransformed_self_ty,
                                         mutbl: mutability
                                       })),
                      Some(region))
                 }
                 ty::ByBoxExplicitSelfCategory => {
-                    (Some(ty::mk_uniq(this.tcx(),
-                                      self_info.untransformed_self_ty)),
-                     None)
+                    (Some(ty::mk_uniq(this.tcx(), untransformed_self_ty)), None)
                 }
             }
         }

diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index 74ac9c480defecc280fecc9305903a370895a168..4ad6dc292a72dea910aa223402e0e04331d8bb64 100644 (file)
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -1055,7 +1055,7 @@ pub fn convert(ccx: &CrateCtxt, it: &ast::Item) {
                       ref selfty,
                       ref impl_items) => {
             // Create generics from the generics specified in the impl head.
-            let ty_generics = ty_generics_for_type(
+            let ty_generics = ty_generics_for_impl(
                     ccx,
                     generics,
                     CreateTypeParametersForAssociatedTypes);
@@ -1655,6 +1655,24 @@ fn ty_generics_for_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
     generics
 }
 
+fn ty_generics_for_impl<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
+                                  generics: &ast::Generics,
+                                  create_type_parameters_for_associated_types:
+                                      CreateTypeParametersForAssociatedTypesFlag)
+                                  -> ty::Generics<'tcx>
+{
+    let early_lifetimes = resolve_lifetime::early_bound_lifetimes(generics);
+    debug!("ty_generics_for_impl: early_lifetimes={}",
+           early_lifetimes);
+    ty_generics(ccx,
+                subst::TypeSpace,
+                early_lifetimes.as_slice(),
+                generics.ty_params.as_slice(),
+                ty::Generics::empty(),
+                &generics.where_clause,
+                create_type_parameters_for_associated_types)
+}
+
 fn ty_generics_for_fn_or_method<'tcx,AC>(
         this: &AC,
         generics: &ast::Generics,

diff --git a/src/test/compile-fail/hrtb-debruijn-in-receiver.rs b/src/test/compile-fail/hrtb-debruijn-in-receiver.rs
new file mode 100644 (file)
index 0000000..2dbd161
--- /dev/null
+++ b/src/test/compile-fail/hrtb-debruijn-in-receiver.rs
@@ -0,0 +1,28 @@
+// 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.
+
+// Test the case where the `Self` type has a bound lifetime that must
+// be adjusted in the fn signature. Issue #19537.
+
+use std::collections::HashMap;
+
+struct Foo<'a> {
+    map: HashMap<uint, &'a str>
+}
+
+impl<'a> Foo<'a> {
+    fn new() -> Foo<'a> { panic!() }
+    fn insert(&'a mut self) { }
+}
+fn main() {
+    let mut foo = Foo::new();
+    foo.insert();
+    foo.insert(); //~ ERROR cannot borrow
+}