hir: lower `ImplicitSelf` to resolved `Self` TyQPath's.

10 files changed, 106 insertions, 183 deletions

diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 1cf5e35a095..d1fe19364b4 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -259,7 +259,7 @@ impl<'a> LoweringContext<'a> {
         P(hir::Ty {
             id: t.id,
             node: match t.node {
-                TyKind::Infer | TyKind::ImplicitSelf => hir::TyInfer,
+                TyKind::Infer => hir::TyInfer,
                 TyKind::Slice(ref ty) => hir::TySlice(self.lower_ty(ty)),
                 TyKind::Ptr(ref mt) => hir::TyPtr(self.lower_mt(mt)),
                 TyKind::Rptr(ref region, ref mt) => {
@@ -283,6 +283,16 @@ impl<'a> LoweringContext<'a> {
                 TyKind::Path(ref qself, ref path) => {
                     hir::TyPath(self.lower_qpath(t.id, qself, path, ParamMode::Explicit))
                 }
+                TyKind::ImplicitSelf => {
+                    hir::TyPath(hir::QPath::Resolved(None, P(hir::Path {
+                        def: self.expect_full_def(t.id),
+                        segments: hir_vec![hir::PathSegment {
+                            name: keywords::SelfType.name(),
+                            parameters: hir::PathParameters::none()
+                        }],
+                        span: t.span,
+                    })))
+                }
                 TyKind::ObjectSum(ref ty, ref bounds) => {
                     hir::TyObjectSum(self.lower_ty(ty), self.lower_bounds(bounds))
                 }
@@ -976,7 +986,7 @@ impl<'a> LoweringContext<'a> {
                 ImplItemKind::Const(..) => hir::AssociatedItemKind::Const,
                 ImplItemKind::Type(..) => hir::AssociatedItemKind::Type,
                 ImplItemKind::Method(ref sig, _) => hir::AssociatedItemKind::Method {
-                    has_self: sig.decl.get_self().is_some(),
+                    has_self: sig.decl.has_self(),
                 },
                 ImplItemKind::Macro(..) => unimplemented!(),
             },
@@ -1051,24 +1061,13 @@ impl<'a> LoweringContext<'a> {
     }
 
     fn lower_method_sig(&mut self, sig: &MethodSig) -> hir::MethodSig {
-        let hir_sig = hir::MethodSig {
+        hir::MethodSig {
             generics: self.lower_generics(&sig.generics),
             abi: sig.abi,
             unsafety: self.lower_unsafety(sig.unsafety),
             constness: self.lower_constness(sig.constness),
             decl: self.lower_fn_decl(&sig.decl),
-        };
-        // Check for `self: _` and `self: &_`
-        if let Some(SelfKind::Explicit(..)) = sig.decl.get_self().map(|eself| eself.node) {
-            match hir_sig.decl.get_self().map(|eself| eself.node) {
-                Some(hir::SelfKind::Value(..)) | Some(hir::SelfKind::Region(..)) => {
-                    self.diagnostic().span_err(sig.decl.inputs[0].ty.span,
-                        "the type placeholder `_` is not allowed within types on item signatures");
-                }
-                _ => {}
-            }
         }
-        hir_sig
     }
 
     fn lower_unsafety(&mut self, u: Unsafety) -> hir::Unsafety {
diff --git a/src/librustc/hir/mod.rs b/src/librustc/hir/mod.rs
index 4eee76d466a..d135762ae82 100644
--- a/src/librustc/hir/mod.rs
+++ b/src/librustc/hir/mod.rs
@@ -35,8 +35,8 @@ use hir::def_id::DefId;
 use util::nodemap::{NodeMap, FxHashSet};
 use rustc_data_structures::fnv::FnvHashMap;
 
-use syntax_pos::{mk_sp, Span, ExpnId, DUMMY_SP};
-use syntax::codemap::{self, respan, Spanned};
+use syntax_pos::{Span, ExpnId, DUMMY_SP};
+use syntax::codemap::{self, Spanned};
 use syntax::abi::Abi;
 use syntax::ast::{Name, NodeId, DUMMY_NODE_ID, AsmDialect};
 use syntax::ast::{Attribute, Lit, StrStyle, FloatTy, IntTy, UintTy, MetaItem};
@@ -1234,37 +1234,8 @@ pub struct Arg {
     pub id: NodeId,
 }
 
-/// Alternative representation for `Arg`s describing `self` parameter of methods.
-#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
-pub enum SelfKind {
-    /// `self`, `mut self`
-    Value(Mutability),
-    /// `&'lt self`, `&'lt mut self`
-    Region(Option<Lifetime>, Mutability),
-    /// `self: TYPE`, `mut self: TYPE`
-    Explicit(P<Ty>, Mutability),
-}
-
-pub type ExplicitSelf = Spanned<SelfKind>;
-
 impl Arg {
-    pub fn to_self(&self) -> Option<ExplicitSelf> {
-        if let PatKind::Binding(BindByValue(mutbl), _, name, _) = self.pat.node {
-            if name.node == keywords::SelfValue.name() {
-                return match self.ty.node {
-                    TyInfer => Some(respan(self.pat.span, SelfKind::Value(mutbl))),
-                    TyRptr(lt, MutTy{ref ty, mutbl}) if ty.node == TyInfer => {
-                        Some(respan(self.pat.span, SelfKind::Region(lt, mutbl)))
-                    }
-                    _ => Some(respan(mk_sp(self.pat.span.lo, self.ty.span.hi),
-                                     SelfKind::Explicit(self.ty.clone(), mutbl)))
-                }
-            }
-        }
-        None
-    }
-
-    pub fn is_self(&self) -> bool {
+    fn is_self(&self) -> bool {
         if let PatKind::Binding(_, _, name, _) = self.pat.node {
             name.node == keywords::SelfValue.name()
         } else {
@@ -1282,9 +1253,6 @@ pub struct FnDecl {
 }
 
 impl FnDecl {
-    pub fn get_self(&self) -> Option<ExplicitSelf> {
-        self.inputs.get(0).and_then(Arg::to_self)
-    }
     pub fn has_self(&self) -> bool {
         self.inputs.get(0).map(Arg::is_self).unwrap_or(false)
     }
diff --git a/src/librustc/hir/print.rs b/src/librustc/hir/print.rs
index 100e344d941..eaed62e4dce 100644
--- a/src/librustc/hir/print.rs
+++ b/src/librustc/hir/print.rs
@@ -25,7 +25,7 @@ use syntax_pos::{self, BytePos};
 use errors;
 
 use hir;
-use hir::{Crate, PatKind, RegionTyParamBound, SelfKind, TraitTyParamBound, TraitBoundModifier};
+use hir::{Crate, PatKind, RegionTyParamBound, TraitTyParamBound, TraitBoundModifier};
 
 use std::io::{self, Write, Read};
 
@@ -1954,27 +1954,6 @@ impl<'a> State<'a> {
         self.end() // close enclosing cbox
     }
 
-    fn print_explicit_self(&mut self, explicit_self: &hir::ExplicitSelf) -> io::Result<()> {
-        match explicit_self.node {
-            SelfKind::Value(m) => {
-                self.print_mutability(m)?;
-                word(&mut self.s, "self")
-            }
-            SelfKind::Region(ref lt, m) => {
-                word(&mut self.s, "&")?;
-                self.print_opt_lifetime(lt)?;
-                self.print_mutability(m)?;
-                word(&mut self.s, "self")
-            }
-            SelfKind::Explicit(ref typ, m) => {
-                self.print_mutability(m)?;
-                word(&mut self.s, "self")?;
-                self.word_space(":")?;
-                self.print_type(&typ)
-            }
-        }
-    }
-
     pub fn print_fn(&mut self,
                     decl: &hir::FnDecl,
                     unsafety: hir::Unsafety,
@@ -2185,21 +2164,17 @@ impl<'a> State<'a> {
         match input.ty.node {
             hir::TyInfer if is_closure => self.print_pat(&input.pat)?,
             _ => {
-                if let Some(eself) = input.to_self() {
-                    self.print_explicit_self(&eself)?;
+                let invalid = if let PatKind::Binding(_, _, name, _) = input.pat.node {
+                    name.node == keywords::Invalid.name()
                 } else {
-                    let invalid = if let PatKind::Binding(_, _, name, _) = input.pat.node {
-                        name.node == keywords::Invalid.name()
-                    } else {
-                        false
-                    };
-                    if !invalid {
-                        self.print_pat(&input.pat)?;
-                        word(&mut self.s, ":")?;
-                        space(&mut self.s)?;
-                    }
-                    self.print_type(&input.ty)?;
+                    false
+                };
+                if !invalid {
+                    self.print_pat(&input.pat)?;
+                    word(&mut self.s, ":")?;
+                    space(&mut self.s)?;
                 }
+                self.print_type(&input.ty)?;
             }
         }
         self.end()
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index 2ab10d0446b..180141d674a 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -2127,7 +2127,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
         let (kind, has_self, has_value) = match trait_item.node {
             hir::MethodTraitItem(ref sig, ref body) => {
-                (AssociatedKind::Method, sig.decl.get_self().is_some(),
+                (AssociatedKind::Method, sig.decl.has_self(),
                  body.is_some())
             }
             hir::ConstTraitItem(_, ref value) => {
diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index a0af4c45653..63bcbfeb23d 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -571,6 +571,11 @@ impl<'a, 'tcx> Visitor<'tcx> for Resolver<'a> {
     fn visit_ty(&mut self, ty: &'tcx Ty) {
         if let TyKind::Path(ref qself, ref path) = ty.node {
             self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
+        } else if let TyKind::ImplicitSelf = ty.node {
+            let self_ty = keywords::SelfType.ident();
+            let def = self.resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.span))
+                          .map_or(Def::Err, |d| d.def());
+            self.record_def(ty.id, PathResolution::new(def));
         }
         visit::walk_ty(self, ty);
     }
@@ -741,6 +746,13 @@ impl<'a> LexicalScopeBinding<'a> {
             _ => None,
         }
     }
+
+    fn def(self) -> Def {
+        match self {
+            LexicalScopeBinding::Item(binding) => binding.def(),
+            LexicalScopeBinding::Def(def) => def,
+        }
+    }
 }
 
 #[derive(Clone)]
diff --git a/src/librustc_typeck/astconv.rs b/src/librustc_typeck/astconv.rs
index 598003a3925..7ccb0fffb7d 100644
--- a/src/librustc_typeck/astconv.rs
+++ b/src/librustc_typeck/astconv.rs
@@ -50,7 +50,7 @@
 
 use rustc_const_eval::eval_length;
 use rustc_data_structures::accumulate_vec::AccumulateVec;
-use hir::{self, SelfKind};
+use hir;
 use hir::def::Def;
 use hir::def_id::DefId;
 use hir::print as pprust;
@@ -1743,36 +1743,33 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
         // declaration are bound to that function type.
         let rb = MaybeWithAnonTypes::new(BindingRscope::new(), arg_anon_scope);
 
-        // `implied_output_region` is the region that will be assumed for any
-        // region parameters in the return type. In accordance with the rules for
-        // lifetime elision, we can determine it in two ways. First (determined
-        // here), if self is by-reference, then the implied output region is the
-        // region of the self parameter.
-        let (self_ty, explicit_self) = match (opt_untransformed_self_ty, decl.get_self()) {
-            (Some(untransformed_self_ty), Some(explicit_self)) => {
-                let self_type = self.determine_self_type(&rb, untransformed_self_ty,
-                                                         &explicit_self);
-                (Some(self_type), Some(ExplicitSelf::determine(untransformed_self_ty, self_type)))
-            }
-            _ => (None, None),
-        };
+        let input_tys: Vec<Ty> =
+            decl.inputs.iter().map(|a| self.ty_of_arg(&rb, a, None)).collect();
 
-        // HACK(eddyb) replace the fake self type in the AST with the actual type.
-        let arg_params = if self_ty.is_some() {
-            &decl.inputs[1..]
-        } else {
-            &decl.inputs[..]
+        let has_self = decl.has_self();
+        let explicit_self = match (opt_untransformed_self_ty, has_self) {
+            (Some(untransformed_self_ty), true) => {
+                Some(ExplicitSelf::determine(untransformed_self_ty, input_tys[0]))
+            }
+            _ => None
         };
-        let arg_tys: Vec<Ty> =
-            arg_params.iter().map(|a| self.ty_of_arg(&rb, a, None)).collect();
 
-        // Second, if there was exactly one lifetime (either a substitution or a
-        // reference) in the arguments, then any anonymous regions in the output
-        // have that lifetime.
         let implied_output_region = match explicit_self {
+            // `implied_output_region` is the region that will be assumed for any
+            // region parameters in the return type. In accordance with the rules for
+            // lifetime elision, we can determine it in two ways. First (determined
+            // here), if self is by-reference, then the implied output region is the
+            // region of the self parameter.
             Some(ExplicitSelf::ByReference(region, _)) => Ok(*region),
+
+            // Second, if there was exactly one lifetime (either a substitution or a
+            // reference) in the arguments, then any anonymous regions in the output
+            // have that lifetime.
             _ => {
-                self.find_implied_output_region(&arg_tys,
+                let arg_params = &decl.inputs[has_self as usize..];
+                let arg_tys = &input_tys[has_self as usize..];
+
+                self.find_implied_output_region(arg_tys,
                                                 arg_params.iter()
                                                     .map(|a| pprust::pat_to_string(&a.pat)))
 
@@ -1793,37 +1790,13 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
             unsafety: unsafety,
             abi: abi,
             sig: ty::Binder(self.tcx().mk_fn_sig(
-                self_ty.into_iter().chain(arg_tys),
+                input_tys.into_iter(),
                 output_ty,
                 decl.variadic
             )),
         })
     }
 
-    fn determine_self_type<'a>(&self,
-                               rscope: &RegionScope,
-                               untransformed_self_ty: Ty<'tcx>,
-                               explicit_self: &hir::ExplicitSelf)
-                               -> Ty<'tcx>
-    {
-        match explicit_self.node {
-            SelfKind::Value(..) => untransformed_self_ty,
-            SelfKind::Region(ref lifetime, mutability) => {
-                let region =
-                    self.opt_ast_region_to_region(
-                                             rscope,
-                                             explicit_self.span,
-                                             lifetime);
-                self.tcx().mk_ref(region,
-                    ty::TypeAndMut {
-                        ty: untransformed_self_ty,
-                        mutbl: mutability
-                    })
-            }
-            SelfKind::Explicit(ref ast_type, _) => self.ast_ty_to_ty(rscope, &ast_type)
-        }
-    }
-
     pub fn ty_of_closure(&self,
         unsafety: hir::Unsafety,
         decl: &hir::FnDecl,
diff --git a/src/librustc_typeck/check/compare_method.rs b/src/librustc_typeck/check/compare_method.rs
index 478de167317..1536aa6def7 100644
--- a/src/librustc_typeck/check/compare_method.rs
+++ b/src/librustc_typeck/check/compare_method.rs
@@ -8,14 +8,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use rustc::hir;
+use rustc::hir::{self, ImplItemKind, TraitItem_};
 use rustc::infer::{self, InferOk};
 use rustc::middle::free_region::FreeRegionMap;
 use rustc::ty;
 use rustc::traits::{self, ObligationCause, ObligationCauseCode, Reveal};
 use rustc::ty::error::{ExpectedFound, TypeError};
 use rustc::ty::subst::{Subst, Substs};
-use rustc::hir::{ImplItemKind, TraitItem_, Ty_};
 use rustc::util::common::ErrorReported;
 
 use syntax::ast;
@@ -456,31 +455,18 @@ fn extract_spans_for_error_reporting<'a, 'gcx, 'tcx>(infcx: &infer::InferCtxt<'a
                     _ => bug!("{:?} is not a MethodTraitItem", trait_m),
                 };
 
-                impl_m_iter.zip(trait_m_iter)
-                           .find(|&(ref impl_arg, ref trait_arg)| {
-                               match (&impl_arg.ty.node, &trait_arg.ty.node) {
-                                   (&Ty_::TyRptr(_, ref impl_mt), &Ty_::TyRptr(_, ref trait_mt)) |
-                                   (&Ty_::TyPtr(ref impl_mt), &Ty_::TyPtr(ref trait_mt)) => {
-                                       impl_mt.mutbl != trait_mt.mutbl
-                                   }
-                                   _ => false,
-                               }
-                           })
-                           .map(|(ref impl_arg, ref trait_arg)| {
-                               match (impl_arg.to_self(), trait_arg.to_self()) {
-                                   (Some(impl_self), Some(trait_self)) => {
-                                       (impl_self.span, Some(trait_self.span))
-                                   }
-                                   (None, None) => (impl_arg.ty.span, Some(trait_arg.ty.span)),
-                                   _ => {
-                                       bug!("impl and trait fns have different first args, impl: \
-                                             {:?}, trait: {:?}",
-                                            impl_arg,
-                                            trait_arg)
-                                   }
-                               }
-                           })
-                           .unwrap_or((cause.span, tcx.map.span_if_local(trait_m.def_id)))
+                impl_m_iter.zip(trait_m_iter).find(|&(ref impl_arg, ref trait_arg)| {
+                    match (&impl_arg.ty.node, &trait_arg.ty.node) {
+                        (&hir::TyRptr(_, ref impl_mt), &hir::TyRptr(_, ref trait_mt)) |
+                        (&hir::TyPtr(ref impl_mt), &hir::TyPtr(ref trait_mt)) => {
+                            impl_mt.mutbl != trait_mt.mutbl
+                        }
+                        _ => false,
+                    }
+                }).map(|(ref impl_arg, ref trait_arg)| {
+                    (impl_arg.ty.span, Some(trait_arg.ty.span))
+                })
+                .unwrap_or_else(|| (cause.span, tcx.map.span_if_local(trait_m.def_id)))
             } else {
                 (cause.span, tcx.map.span_if_local(trait_m.def_id))
             }
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index fdbd2f3647c..a0071fe25cb 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1184,16 +1184,17 @@ pub enum SelfTy {
 
 impl Argument {
     pub fn to_self(&self) -> Option<SelfTy> {
-        if self.name == "self" {
-            match self.type_ {
-                Infer => Some(SelfValue),
-                BorrowedRef{ref lifetime, mutability, ref type_} if **type_ == Infer => {
-                    Some(SelfBorrowed(lifetime.clone(), mutability))
-                }
-                _ => Some(SelfExplicit(self.type_.clone()))
+        if self.name != "self" {
+            return None;
+        }
+        if self.type_.is_self_type() {
+            return Some(SelfValue);
+        }
+        match self.type_ {
+            BorrowedRef{ref lifetime, mutability, ref type_} if type_.is_self_type() => {
+                Some(SelfBorrowed(lifetime.clone(), mutability))
             }
-        } else {
-            None
+            _ => Some(SelfExplicit(self.type_.clone()))
         }
     }
 }
@@ -1353,11 +1354,13 @@ impl<'tcx> Clean<Item> for ty::AssociatedItem {
                     };
                     let self_arg_ty = *fty.sig.input(0).skip_binder();
                     if self_arg_ty == self_ty {
-                        decl.inputs.values[0].type_ = Infer;
+                        decl.inputs.values[0].type_ = Generic(String::from("Self"));
                     } else if let ty::TyRef(_, mt) = self_arg_ty.sty {
                         if mt.ty == self_ty {
                             match decl.inputs.values[0].type_ {
-                                BorrowedRef{ref mut type_, ..} => **type_ = Infer,
+                                BorrowedRef{ref mut type_, ..} => {
+                                    **type_ = Generic(String::from("Self"))
+                                }
                                 _ => unreachable!(),
                             }
                         }
@@ -1568,6 +1571,13 @@ impl Type {
             _ => false,
         }
     }
+
+    pub fn is_self_type(&self) -> bool {
+        match *self {
+            Generic(ref name) => name == "Self",
+            _ => false
+        }
+    }
 }
 
 impl GetDefId for Type {
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index a5abdd922d6..f72985fd91a 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -1471,12 +1471,13 @@ impl Arg {
     }
 
     pub fn from_self(eself: ExplicitSelf, eself_ident: SpannedIdent) -> Arg {
+        let span = mk_sp(eself.span.lo, eself_ident.span.hi);
         let infer_ty = P(Ty {
             id: DUMMY_NODE_ID,
             node: TyKind::ImplicitSelf,
-            span: DUMMY_SP,
+            span: span,
         });
-        let arg = |mutbl, ty, span| Arg {
+        let arg = |mutbl, ty| Arg {
             pat: P(Pat {
                 id: DUMMY_NODE_ID,
                 node: PatKind::Ident(BindingMode::ByValue(mutbl), eself_ident, None),
@@ -1486,15 +1487,13 @@ impl Arg {
             id: DUMMY_NODE_ID,
         };
         match eself.node {
-            SelfKind::Explicit(ty, mutbl) => {
-                arg(mutbl, ty, mk_sp(eself.span.lo, eself_ident.span.hi))
-            }
-            SelfKind::Value(mutbl) => arg(mutbl, infer_ty, eself.span),
+            SelfKind::Explicit(ty, mutbl) => arg(mutbl, ty),
+            SelfKind::Value(mutbl) => arg(mutbl, infer_ty),
             SelfKind::Region(lt, mutbl) => arg(Mutability::Immutable, P(Ty {
                 id: DUMMY_NODE_ID,
                 node: TyKind::Rptr(lt, MutTy { ty: infer_ty, mutbl: mutbl }),
-                span: DUMMY_SP,
-            }), eself.span),
+                span: span,
+            })),
         }
     }
 }
diff --git a/src/test/run-make/pretty-print-path-suffix/foo_method.pp b/src/test/run-make/pretty-print-path-suffix/foo_method.pp
index 696e0544fdc..fae13498687 100644
--- a/src/test/run-make/pretty-print-path-suffix/foo_method.pp
+++ b/src/test/run-make/pretty-print-path-suffix/foo_method.pp
@@ -12,5 +12,6 @@
 
 
 
-fn foo_method(&self) -> &'static str { return "i am very similar to foo."; }
-/* nest::{{impl}}::foo_method */
+fn foo_method(self: &Self)
+ -> &'static str { return "i am very similar to foo."; } /*
+nest::{{impl}}::foo_method */