Complete the removal of ty_nil, ast::LitNil, ast::TyBot and ast::TyUniq

[breaking-change]

This will break any uses of macros that assumed () being a valid literal.

17 files changed, 184 insertions, 218 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 7c5de627d08..0e1921a0773 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -893,7 +893,6 @@ pub enum Lit_ {
     LitInt(u64, LitIntType),
     LitFloat(InternedString, FloatTy),
     LitFloatUnsuffixed(InternedString),
-    LitNil,
     LitBool(bool),
 }
 
@@ -1086,12 +1085,6 @@ pub struct BareFnTy {
 #[deriving(Clone, PartialEq, Eq, Encodable, Decodable, Hash, Show)]
 /// The different kinds of types recognized by the compiler
 pub enum Ty_ {
-    /// The unit type (`()`)
-    TyNil,
-    /// The bottom type (`!`)
-    TyBot,
-    TyUniq(P<Ty>),
-    /// An array (`[T]`)
     TyVec(P<Ty>),
     /// A fixed length array (`[T, ..n]`)
     TyFixedLengthVec(P<Ty>, P<Expr>),
@@ -1175,8 +1168,7 @@ impl Arg {
 #[deriving(Clone, PartialEq, Eq, Encodable, Decodable, Hash, Show)]
 pub struct FnDecl {
     pub inputs: Vec<Arg>,
-    pub output: P<Ty>,
-    pub cf: RetStyle,
+    pub output: FunctionRetTy,
     pub variadic: bool
 }
 
@@ -1198,12 +1190,21 @@ impl fmt::Show for FnStyle {
 }
 
 #[deriving(Clone, PartialEq, Eq, Encodable, Decodable, Hash, Show)]
-pub enum RetStyle {
+pub enum FunctionRetTy {
     /// Functions with return type ! that always
     /// raise an error or exit (i.e. never return to the caller)
-    NoReturn,
+    NoReturn(Span),
     /// Everything else
-    Return,
+    Return(P<Ty>),
+}
+
+impl FunctionRetTy {
+    pub fn span(&self) -> Span {
+        match *self {
+            NoReturn(span) => span,
+            Return(ref ty) => ty.span
+        }
+    }
 }
 
 /// Represents the kind of 'self' associated with a method
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 1e2d935af00..0c7a3cf4a6c 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -248,7 +248,7 @@ impl DummyResult {
     pub fn raw_expr(sp: Span) -> P<ast::Expr> {
         P(ast::Expr {
             id: ast::DUMMY_NODE_ID,
-            node: ast::ExprLit(P(codemap::respan(sp, ast::LitNil))),
+            node: ast::ExprLit(P(codemap::respan(sp, ast::LitBool(false)))),
             span: sp,
         })
     }
diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index 862cbf3d7ca..ffc42b67033 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -54,11 +54,9 @@ pub trait AstBuilder {
     fn ty_ptr(&self, span: Span,
               ty: P<ast::Ty>,
               mutbl: ast::Mutability) -> P<ast::Ty>;
-    fn ty_uniq(&self, span: Span, ty: P<ast::Ty>) -> P<ast::Ty>;
 
     fn ty_option(&self, ty: P<ast::Ty>) -> P<ast::Ty>;
     fn ty_infer(&self, sp: Span) -> P<ast::Ty>;
-    fn ty_nil(&self) -> P<ast::Ty>;
 
     fn ty_vars(&self, ty_params: &OwnedSlice<ast::TyParam>) -> Vec<P<ast::Ty>> ;
     fn ty_vars_global(&self, ty_params: &OwnedSlice<ast::TyParam>) -> Vec<P<ast::Ty>> ;
@@ -377,9 +375,6 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         self.ty(span,
                 ast::TyPtr(self.ty_mt(ty, mutbl)))
     }
-    fn ty_uniq(&self, span: Span, ty: P<ast::Ty>) -> P<ast::Ty> {
-        self.ty(span, ast::TyUniq(ty))
-    }
 
     fn ty_option(&self, ty: P<ast::Ty>) -> P<ast::Ty> {
         self.ty_path(
@@ -406,14 +401,6 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         self.ty(span, ast::TyInfer)
     }
 
-    fn ty_nil(&self) -> P<ast::Ty> {
-        P(ast::Ty {
-            id: ast::DUMMY_NODE_ID,
-            node: ast::TyNil,
-            span: DUMMY_SP,
-        })
-    }
-
     fn typaram(&self,
                span: Span,
                id: ast::Ident,
@@ -809,8 +796,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         self.pat(span, pat)
     }
     fn pat_tuple(&self, span: Span, pats: Vec<P<ast::Pat>>) -> P<ast::Pat> {
-        let pat = ast::PatTup(pats);
-        self.pat(span, pat)
+        self.pat(span, ast::PatTup(pats))
     }
 
     fn pat_some(&self, span: Span, pat: P<ast::Pat>) -> P<ast::Pat> {
@@ -931,11 +917,10 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
     }
 
     // FIXME unused self
-    fn fn_decl(&self, inputs: Vec<ast::Arg> , output: P<ast::Ty>) -> P<ast::FnDecl> {
+    fn fn_decl(&self, inputs: Vec<ast::Arg>, output: P<ast::Ty>) -> P<ast::FnDecl> {
         P(ast::FnDecl {
             inputs: inputs,
-            output: output,
-            cf: ast::Return,
+            output: ast::Return(output),
             variadic: false
         })
     }
diff --git a/src/libsyntax/ext/concat.rs b/src/libsyntax/ext/concat.rs
index af7cd4157ec..e2867c2fbab 100644
--- a/src/libsyntax/ext/concat.rs
+++ b/src/libsyntax/ext/concat.rs
@@ -46,7 +46,6 @@ pub fn expand_syntax_ext(cx: &mut base::ExtCtxt,
                     ast::LitInt(i, ast::UnsuffixedIntLit(ast::Minus)) => {
                         accumulator.push_str(format!("-{}", i).as_slice());
                     }
-                    ast::LitNil => {}
                     ast::LitBool(b) => {
                         accumulator.push_str(format!("{}", b).as_slice());
                     }
diff --git a/src/libsyntax/ext/deriving/encodable.rs b/src/libsyntax/ext/deriving/encodable.rs
index 69eb260b8c4..62f3b5d01b4 100644
--- a/src/libsyntax/ext/deriving/encodable.rs
+++ b/src/libsyntax/ext/deriving/encodable.rs
@@ -88,7 +88,7 @@
 //! }
 //! ```
 
-use ast::{MetaItem, Item, Expr, ExprRet, MutMutable, LitNil};
+use ast::{MetaItem, Item, Expr, ExprRet, MutMutable};
 use codemap::Span;
 use ext::base::ExtCtxt;
 use ext::build::AstBuilder;
@@ -186,7 +186,7 @@ fn encodable_substructure(cx: &mut ExtCtxt, trait_span: Span,
             if stmts.is_empty() {
                 let ret_ok = cx.expr(trait_span,
                                      ExprRet(Some(cx.expr_ok(trait_span,
-                                                             cx.expr_lit(trait_span, LitNil)))));
+                                                             cx.expr_tuple(trait_span, vec![])))));
                 stmts.push(cx.stmt_expr(ret_ok));
             }
 
@@ -231,7 +231,7 @@ fn encodable_substructure(cx: &mut ExtCtxt, trait_span: Span,
             if stmts.len() == 0 {
                 let ret_ok = cx.expr(trait_span,
                                      ExprRet(Some(cx.expr_ok(trait_span,
-                                                             cx.expr_lit(trait_span, LitNil)))));
+                                                             cx.expr_tuple(trait_span, vec![])))));
                 stmts.push(cx.stmt_expr(ret_ok));
             }
 
diff --git a/src/libsyntax/ext/deriving/generic/mod.rs b/src/libsyntax/ext/deriving/generic/mod.rs
index 7c32b845508..4be299994fd 100644
--- a/src/libsyntax/ext/deriving/generic/mod.rs
+++ b/src/libsyntax/ext/deriving/generic/mod.rs
@@ -922,7 +922,7 @@ impl<'a> MethodDef<'a> {
                 }
 
                 // Here is the pat = `(&VariantK, &VariantK, ...)`
-                let single_pat = cx.pat(sp, ast::PatTup(subpats));
+                let single_pat = cx.pat_tuple(sp, subpats);
 
                 // For the BodyK, we need to delegate to our caller,
                 // passing it an EnumMatching to indicate which case
diff --git a/src/libsyntax/ext/deriving/generic/ty.rs b/src/libsyntax/ext/deriving/generic/ty.rs
index 1ec1e3b1224..8b46769d633 100644
--- a/src/libsyntax/ext/deriving/generic/ty.rs
+++ b/src/libsyntax/ext/deriving/generic/ty.rs
@@ -152,14 +152,9 @@ impl<'a> Ty<'a> {
                 cx.ty_path(self.to_path(cx, span, self_ty, self_generics), None)
             }
             Tuple(ref fields) => {
-                let ty = if fields.is_empty() {
-                    ast::TyNil
-                } else {
-                    ast::TyTup(fields.iter()
-                                     .map(|f| f.to_ty(cx, span, self_ty, self_generics))
-                                     .collect())
-                };
-
+                let ty = ast::TyTup(fields.iter()
+                    .map(|f| f.to_ty(cx, span, self_ty, self_generics))
+                    .collect());
                 cx.ty(span, ty)
             }
         }
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 87406081aae..fa69495fa42 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -159,7 +159,7 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
             // `_ => [<elseopt> | ()]`
             let else_arm = {
                 let pat_under = fld.cx.pat_wild(span);
-                let else_expr = elseopt.unwrap_or_else(|| fld.cx.expr_lit(span, ast::LitNil));
+                let else_expr = elseopt.unwrap_or_else(|| fld.cx.expr_tuple(span, vec![]));
                 fld.cx.arm(span, vec![pat_under], else_expr)
             };
 
diff --git a/src/libsyntax/ext/format.rs b/src/libsyntax/ext/format.rs
index a28f24e7663..a816b479630 100644
--- a/src/libsyntax/ext/format.rs
+++ b/src/libsyntax/ext/format.rs
@@ -654,7 +654,7 @@ impl<'a, 'b> Context<'a, 'b> {
         //
         // But the nested match expression is proved to perform not as well
         // as series of let's; the first approach does.
-        let pat = self.ecx.pat(self.fmtsp, ast::PatTup(pats));
+        let pat = self.ecx.pat_tuple(self.fmtsp, pats);
         let arm = self.ecx.arm(self.fmtsp, vec!(pat), body);
         let head = self.ecx.expr(self.fmtsp, ast::ExprTup(heads));
         self.ecx.expr_match(self.fmtsp, head, vec!(arm))
diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs
index d7c3ca8efc4..56d91282437 100644
--- a/src/libsyntax/fold.rs
+++ b/src/libsyntax/fold.rs
@@ -391,8 +391,7 @@ pub fn noop_fold_ty<T: Folder>(t: P<Ty>, fld: &mut T) -> P<Ty> {
     t.map(|Ty {id, node, span}| Ty {
         id: fld.new_id(id),
         node: match node {
-            TyNil | TyBot | TyInfer => node,
-            TyUniq(ty) => TyUniq(fld.fold_ty(ty)),
+            TyInfer => node,
             TyVec(ty) => TyVec(fld.fold_ty(ty)),
             TyPtr(mt) => TyPtr(fld.fold_mt(mt)),
             TyRptr(region, mt) => {
@@ -706,10 +705,12 @@ pub fn noop_fold_interpolated<T: Folder>(nt: token::Nonterminal, fld: &mut T)
 }
 
 pub fn noop_fold_fn_decl<T: Folder>(decl: P<FnDecl>, fld: &mut T) -> P<FnDecl> {
-    decl.map(|FnDecl {inputs, output, cf, variadic}| FnDecl {
+    decl.map(|FnDecl {inputs, output, variadic}| FnDecl {
         inputs: inputs.move_map(|x| fld.fold_arg(x)),
-        output: fld.fold_ty(output),
-        cf: cf,
+        output: match output {
+            Return(ty) => Return(fld.fold_ty(ty)),
+            NoReturn(span) => NoReturn(span)
+        },
         variadic: variadic
     })
 }
@@ -1146,10 +1147,12 @@ pub fn noop_fold_foreign_item<T: Folder>(ni: P<ForeignItem>, folder: &mut T) ->
         attrs: attrs.move_map(|x| folder.fold_attribute(x)),
         node: match node {
             ForeignItemFn(fdec, generics) => {
-                ForeignItemFn(fdec.map(|FnDecl {inputs, output, cf, variadic}| FnDecl {
+                ForeignItemFn(fdec.map(|FnDecl {inputs, output, variadic}| FnDecl {
                     inputs: inputs.move_map(|a| folder.fold_arg(a)),
-                    output: folder.fold_ty(output),
-                    cf: cf,
+                    output: match output {
+                        Return(ty) => Return(folder.fold_ty(ty)),
+                        NoReturn(span) => NoReturn(span)
+                    },
                     variadic: variadic
                 }), folder.fold_generics(generics))
             }
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 4881be8996a..fa10cb90f83 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -24,7 +24,7 @@
        html_root_url = "http://doc.rust-lang.org/nightly/")]
 
 #![allow(unknown_features)]
-#![feature(macro_rules, globs, default_type_params, phase, slicing_syntax)]
+#![feature(if_let, macro_rules, globs, default_type_params, phase, slicing_syntax)]
 #![feature(quote, struct_variant, unsafe_destructor, import_shadowing)]
 
 extern crate arena;
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 51738ece80f..2810db4eadd 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -1037,10 +1037,9 @@ mod test {
                                     }),
                                         id: ast::DUMMY_NODE_ID
                                     }),
-                                output: P(ast::Ty{id: ast::DUMMY_NODE_ID,
-                                                  node: ast::TyNil,
-                                                  span:sp(15,15)}), // not sure
-                                cf: ast::Return,
+                                output: ast::Return(P(ast::Ty{id: ast::DUMMY_NODE_ID,
+                                                  node: ast::TyTup(vec![]),
+                                                  span:sp(15,15)})), // not sure
                                 variadic: false
                             }),
                                     ast::NormalFn,
diff --git a/src/libsyntax/parse/obsolete.rs b/src/libsyntax/parse/obsolete.rs
index 73787763c8b..1b2ab3c235d 100644
--- a/src/libsyntax/parse/obsolete.rs
+++ b/src/libsyntax/parse/obsolete.rs
@@ -17,8 +17,8 @@ Obsolete syntax that becomes too hard to parse can be
 removed.
 */
 
-use ast::{Expr, ExprLit, LitNil};
-use codemap::{Span, respan};
+use ast::{Expr, ExprTup};
+use codemap::Span;
 use parse::parser;
 use parse::token;
 use ptr::P;
@@ -96,7 +96,7 @@ impl<'a> ParserObsoleteMethods for parser::Parser<'a> {
     /// a placeholder expression
     fn obsolete_expr(&mut self, sp: Span, kind: ObsoleteSyntax) -> P<Expr> {
         self.obsolete(sp, kind);
-        self.mk_expr(sp.lo, sp.hi, ExprLit(P(respan(sp, LitNil))))
+        self.mk_expr(sp.lo, sp.hi, ExprTup(vec![]))
     }
 
     fn report(&mut self,
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index db10dc1bc90..4f487a10e98 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -30,13 +30,13 @@ use ast::{ExprVec, ExprWhile, ExprWhileLet, ExprForLoop, Field, FnDecl};
 use ast::{Once, Many};
 use ast::{FnUnboxedClosureKind, FnMutUnboxedClosureKind};
 use ast::{FnOnceUnboxedClosureKind};
-use ast::{ForeignItem, ForeignItemStatic, ForeignItemFn, ForeignMod};
+use ast::{ForeignItem, ForeignItemStatic, ForeignItemFn, ForeignMod, FunctionRetTy};
 use ast::{Ident, NormalFn, Inherited, ImplItem, Item, Item_, ItemStatic};
 use ast::{ItemEnum, ItemFn, ItemForeignMod, ItemImpl, ItemConst};
 use ast::{ItemMac, ItemMod, ItemStruct, ItemTrait, ItemTy};
 use ast::{LifetimeDef, Lit, Lit_};
 use ast::{LitBool, LitChar, LitByte, LitBinary};
-use ast::{LitNil, LitStr, LitInt, Local, LocalLet};
+use ast::{LitStr, LitInt, Local, LocalLet};
 use ast::{MutImmutable, MutMutable, Mac_, MacInvocTT, MatchNormal};
 use ast::{Method, MutTy, BiMul, Mutability};
 use ast::{MethodImplItem, NamedField, UnNeg, NoReturn, UnNot};
@@ -44,18 +44,18 @@ use ast::{Pat, PatEnum, PatIdent, PatLit, PatRange, PatRegion, PatStruct};
 use ast::{PatTup, PatBox, PatWild, PatWildMulti, PatWildSingle};
 use ast::{PolyTraitRef};
 use ast::{QPath, RequiredMethod};
-use ast::{RetStyle, Return, BiShl, BiShr, Stmt, StmtDecl};
+use ast::{Return, BiShl, BiShr, Stmt, StmtDecl};
 use ast::{StmtExpr, StmtSemi, StmtMac, StructDef, StructField};
 use ast::{StructVariantKind, BiSub};
 use ast::StrStyle;
 use ast::{SelfExplicit, SelfRegion, SelfStatic, SelfValue};
 use ast::{Delimited, SequenceRepetition, TokenTree, TraitItem, TraitRef};
 use ast::{TtDelimited, TtSequence, TtToken};
-use ast::{TupleVariantKind, Ty, Ty_, TyBot};
+use ast::{TupleVariantKind, Ty, Ty_};
 use ast::{TypeField, TyFixedLengthVec, TyClosure, TyProc, TyBareFn};
 use ast::{TyTypeof, TyInfer, TypeMethod};
-use ast::{TyNil, TyParam, TyParamBound, TyParen, TyPath, TyPolyTraitRef, TyPtr, TyQPath};
-use ast::{TyRptr, TyTup, TyU32, TyUniq, TyVec, UnUniq};
+use ast::{TyParam, TyParamBound, TyParen, TyPath, TyPolyTraitRef, TyPtr, TyQPath};
+use ast::{TyRptr, TyTup, TyU32, TyVec, UnUniq};
 use ast::{TypeImplItem, TypeTraitItem, Typedef, UnboxedClosureKind};
 use ast::{UnnamedField, UnsafeBlock};
 use ast::{UnsafeFn, ViewItem, ViewItem_, ViewItemExternCrate, ViewItemUse};
@@ -1066,11 +1066,10 @@ impl<'a> Parser<'a> {
         self.expect_keyword(keywords::Fn);
         let lifetime_defs = self.parse_legacy_lifetime_defs(lifetime_defs);
         let (inputs, variadic) = self.parse_fn_args(false, true);
-        let (ret_style, ret_ty) = self.parse_ret_ty();
+        let ret_ty = self.parse_ret_ty();
         let decl = P(FnDecl {
             inputs: inputs,
             output: ret_ty,
-            cf: ret_style,
             variadic: variadic
         });
         TyBareFn(P(BareFnTy {
@@ -1100,11 +1099,10 @@ impl<'a> Parser<'a> {
         let lifetime_defs = self.parse_legacy_lifetime_defs(lifetime_defs);
         let (inputs, variadic) = self.parse_fn_args(false, false);
         let bounds = self.parse_colon_then_ty_param_bounds();
-        let (ret_style, ret_ty) = self.parse_ret_ty();
+        let ret_ty = self.parse_ret_ty();
         let decl = P(FnDecl {
             inputs: inputs,
             output: ret_ty,
-            cf: ret_style,
             variadic: variadic
         });
         TyProc(P(ClosureTy {
@@ -1200,11 +1198,10 @@ impl<'a> Parser<'a> {
 
         let bounds = self.parse_colon_then_ty_param_bounds();
 
-        let (return_style, output) = self.parse_ret_ty();
+        let output = self.parse_ret_ty();
         let decl = P(FnDecl {
             inputs: inputs,
             output: output,
-            cf: return_style,
             variadic: false
         });
 
@@ -1384,31 +1381,20 @@ impl<'a> Parser<'a> {
     }
 
     /// Parse optional return type [ -> TY ] in function decl
-    pub fn parse_ret_ty(&mut self) -> (RetStyle, P<Ty>) {
-        return if self.eat(&token::RArrow) {
-            let lo = self.span.lo;
+    pub fn parse_ret_ty(&mut self) -> FunctionRetTy {
+        if self.eat(&token::RArrow) {
             if self.eat(&token::Not) {
-                (
-                    NoReturn,
-                    P(Ty {
-                        id: ast::DUMMY_NODE_ID,
-                        node: TyBot,
-                        span: mk_sp(lo, self.last_span.hi)
-                    })
-                )
+                NoReturn(self.span)
             } else {
-                (Return, self.parse_ty(true))
+                Return(self.parse_ty(true))
             }
         } else {
             let pos = self.span.lo;
-            (
-                Return,
-                P(Ty {
-                    id: ast::DUMMY_NODE_ID,
-                    node: TyNil,
-                    span: mk_sp(pos, pos),
-                })
-            )
+            Return(P(Ty {
+                id: ast::DUMMY_NODE_ID,
+                node: TyTup(vec![]),
+                span: mk_sp(pos, pos),
+            }))
         }
     }
 
@@ -1423,34 +1409,29 @@ impl<'a> Parser<'a> {
 
         let t = if self.token == token::OpenDelim(token::Paren) {
             self.bump();
-            if self.token == token::CloseDelim(token::Paren) {
-                self.bump();
-                TyNil
-            } else {
-                // (t) is a parenthesized ty
-                // (t,) is the type of a tuple with only one field,
-                // of type t
-                let mut ts = vec!(self.parse_ty(true));
-                let mut one_tuple = false;
-                while self.token == token::Comma {
-                    self.bump();
-                    if self.token != token::CloseDelim(token::Paren) {
-                        ts.push(self.parse_ty(true));
-                    }
-                    else {
-                        one_tuple = true;
-                    }
-                }
 
-                if ts.len() == 1 && !one_tuple {
-                    self.expect(&token::CloseDelim(token::Paren));
-                    TyParen(ts.into_iter().nth(0).unwrap())
+            // (t) is a parenthesized ty
+            // (t,) is the type of a tuple with only one field,
+            // of type t
+            let mut ts = vec![];
+            let mut last_comma = false;
+            while self.token != token::CloseDelim(token::Paren) {
+                ts.push(self.parse_ty(true));
+                if self.token == token::Comma {
+                    last_comma = true;
+                    self.bump();
                 } else {
-                    let t = TyTup(ts);
-                    self.expect(&token::CloseDelim(token::Paren));
-                    t
+                    last_comma = false;
+                    break;
                 }
             }
+
+            self.expect(&token::CloseDelim(token::Paren));
+            if ts.len() == 1 && !last_comma {
+                TyParen(ts.into_iter().nth(0).unwrap())
+            } else {
+                TyTup(ts)
+            }
         } else if self.token == token::Tilde {
             // OWNED POINTER
             self.bump();
@@ -1459,7 +1440,7 @@ impl<'a> Parser<'a> {
                 token::OpenDelim(token::Bracket) => self.obsolete(last_span, ObsoleteOwnedVector),
                 _ => self.obsolete(last_span, ObsoleteOwnedType)
             }
-            TyUniq(self.parse_ty(false))
+            TyTup(vec![self.parse_ty(false)])
         } else if self.token == token::BinOp(token::Star) {
             // STAR POINTER (bare pointer?)
             self.bump();
@@ -1662,10 +1643,6 @@ impl<'a> Parser<'a> {
                 LitBinary(parse::binary_lit(i.as_str())),
             token::LitBinaryRaw(i, _) =>
                 LitBinary(Rc::new(i.as_str().as_bytes().iter().map(|&x| x).collect())),
-            token::OpenDelim(token::Paren) => {
-                self.expect(&token::CloseDelim(token::Paren));
-                LitNil
-            },
             _ => { self.unexpected_last(tok); }
         }
     }
@@ -2126,33 +2103,29 @@ impl<'a> Parser<'a> {
         match self.token {
             token::OpenDelim(token::Paren) => {
                 self.bump();
+
                 // (e) is parenthesized e
                 // (e,) is a tuple with only one field, e
+                let mut es = vec![];
                 let mut trailing_comma = false;
-                if self.token == token::CloseDelim(token::Paren) {
-                    hi = self.span.hi;
-                    self.bump();
-                    let lit = P(spanned(lo, hi, LitNil));
-                    return self.mk_expr(lo, hi, ExprLit(lit));
-                }
-                let mut es = vec!(self.parse_expr());
-                self.commit_expr(&**es.last().unwrap(), &[],
-                                 &[token::Comma, token::CloseDelim(token::Paren)]);
-                while self.token == token::Comma {
-                    self.bump();
-                    if self.token != token::CloseDelim(token::Paren) {
-                        es.push(self.parse_expr());
-                        self.commit_expr(&**es.last().unwrap(), &[],
-                                         &[token::Comma, token::CloseDelim(token::Paren)]);
-                    } else {
+                while self.token != token::CloseDelim(token::Paren) {
+                    es.push(self.parse_expr());
+                    self.commit_expr(&**es.last().unwrap(), &[],
+                                     &[token::Comma, token::CloseDelim(token::Paren)]);
+                    if self.token == token::Comma {
                         trailing_comma = true;
+
+                        self.bump();
+                    } else {
+                        trailing_comma = false;
+                        break;
                     }
                 }
-                hi = self.span.hi;
-                self.commit_expr_expecting(&**es.last().unwrap(), token::CloseDelim(token::Paren));
+                self.bump();
 
+                hi = self.span.hi;
                 return if es.len() == 1 && !trailing_comma {
-                   self.mk_expr(lo, hi, ExprParen(es.into_iter().nth(0).unwrap()))
+                    self.mk_expr(lo, hi, ExprParen(es.into_iter().nth(0).unwrap()))
                 } else {
                     self.mk_expr(lo, hi, ExprTup(es))
                 }
@@ -3293,13 +3266,8 @@ impl<'a> Parser<'a> {
             // parse (pat,pat,pat,...) as tuple
             self.bump();
             if self.token == token::CloseDelim(token::Paren) {
-                hi = self.span.hi;
                 self.bump();
-                let lit = P(codemap::Spanned {
-                    node: LitNil,
-                    span: mk_sp(lo, hi)});
-                let expr = self.mk_expr(lo, hi, ExprLit(lit));
-                pat = PatLit(expr);
+                pat = PatTup(vec![]);
             } else {
                 let mut fields = vec!(self.parse_pat());
                 if self.look_ahead(1, |t| *t != token::CloseDelim(token::Paren)) {
@@ -4137,12 +4105,11 @@ impl<'a> Parser<'a> {
     pub fn parse_fn_decl(&mut self, allow_variadic: bool) -> P<FnDecl> {
 
         let (args, variadic) = self.parse_fn_args(true, allow_variadic);
-        let (ret_style, ret_ty) = self.parse_ret_ty();
+        let ret_ty = self.parse_ret_ty();
 
         P(FnDecl {
             inputs: args,
             output: ret_ty,
-            cf: ret_style,
             variadic: variadic
         })
     }
@@ -4337,12 +4304,11 @@ impl<'a> Parser<'a> {
 
         let hi = self.span.hi;
 
-        let (ret_style, ret_ty) = self.parse_ret_ty();
+        let ret_ty = self.parse_ret_ty();
 
         let fn_decl = P(FnDecl {
             inputs: fn_inputs,
             output: ret_ty,
-            cf: ret_style,
             variadic: false
         });
 
@@ -4368,10 +4334,10 @@ impl<'a> Parser<'a> {
                 (optional_unboxed_closure_kind, args)
             }
         };
-        let (style, output) = if self.token == token::RArrow {
+        let output = if self.token == token::RArrow {
             self.parse_ret_ty()
         } else {
-            (Return, P(Ty {
+            Return(P(Ty {
                 id: ast::DUMMY_NODE_ID,
                 node: TyInfer,
                 span: self.span,
@@ -4381,7 +4347,6 @@ impl<'a> Parser<'a> {
         (P(FnDecl {
             inputs: inputs_captures,
             output: output,
-            cf: style,
             variadic: false
         }), optional_unboxed_closure_kind)
     }
@@ -4394,10 +4359,10 @@ impl<'a> Parser<'a> {
                                      seq_sep_trailing_allowed(token::Comma),
                                      |p| p.parse_fn_block_arg());
 
-        let (style, output) = if self.token == token::RArrow {
+        let output = if self.token == token::RArrow {
             self.parse_ret_ty()
         } else {
-            (Return, P(Ty {
+            Return(P(Ty {
                 id: ast::DUMMY_NODE_ID,
                 node: TyInfer,
                 span: self.span,
@@ -4407,7 +4372,6 @@ impl<'a> Parser<'a> {
         P(FnDecl {
             inputs: inputs,
             output: output,
-            cf: style,
             variadic: false
         })
     }
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index c1515a36bec..7025555ab40 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -645,12 +645,6 @@ impl<'a> State<'a> {
         try!(self.maybe_print_comment(ty.span.lo));
         try!(self.ibox(0u));
         match ty.node {
-            ast::TyNil => try!(word(&mut self.s, "()")),
-            ast::TyBot => try!(word(&mut self.s, "!")),
-            ast::TyUniq(ref ty) => {
-                try!(word(&mut self.s, "~"));
-                try!(self.print_type(&**ty));
-            }
             ast::TyVec(ref ty) => {
                 try!(word(&mut self.s, "["));
                 try!(self.print_type(&**ty));
@@ -2307,15 +2301,7 @@ impl<'a> State<'a> {
         }
         try!(self.pclose());
 
-        try!(self.maybe_print_comment(decl.output.span.lo));
-        match decl.output.node {
-            ast::TyNil => Ok(()),
-            _ => {
-                try!(self.space_if_not_bol());
-                try!(self.word_space("->"));
-                self.print_type(&*decl.output)
-            }
-        }
+        self.print_fn_output(decl)
     }
 
     pub fn print_fn_block_args(
@@ -2333,16 +2319,24 @@ impl<'a> State<'a> {
         try!(self.print_fn_args(decl, None));
         try!(word(&mut self.s, "|"));
 
-        match decl.output.node {
-            ast::TyInfer => {}
-            _ => {
-                try!(self.space_if_not_bol());
-                try!(self.word_space("->"));
-                try!(self.print_type(&*decl.output));
+        if let ast::Return(ref ty) = decl.output {
+            if ty.node == ast::TyInfer {
+                return self.maybe_print_comment(ty.span.lo);
             }
         }
 
-        self.maybe_print_comment(decl.output.span.lo)
+        try!(self.space_if_not_bol());
+        try!(self.word_space("->"));
+        match decl.output {
+            ast::Return(ref ty) => {
+                try!(self.print_type(&**ty));
+                self.maybe_print_comment(ty.span.lo)
+            }
+            ast::NoReturn(span) => {
+                try!(self.word_nbsp("!"));
+                self.maybe_print_comment(span.lo)
+            }
+        }
     }
 
     pub fn print_capture_clause(&mut self, capture_clause: ast::CaptureClause)
@@ -2359,16 +2353,24 @@ impl<'a> State<'a> {
         try!(self.print_fn_args(decl, None));
         try!(word(&mut self.s, ")"));
 
-        match decl.output.node {
-            ast::TyInfer => {}
-            _ => {
-                try!(self.space_if_not_bol());
-                try!(self.word_space("->"));
-                try!(self.print_type(&*decl.output));
+        if let ast::Return(ref ty) = decl.output {
+            if ty.node == ast::TyInfer {
+                return self.maybe_print_comment(ty.span.lo);
             }
         }
 
-        self.maybe_print_comment(decl.output.span.lo)
+        try!(self.space_if_not_bol());
+        try!(self.word_space("->"));
+        match decl.output {
+            ast::Return(ref ty) => {
+                try!(self.print_type(&**ty));
+                self.maybe_print_comment(ty.span.lo)
+            }
+            ast::NoReturn(span) => {
+                try!(self.word_nbsp("!"));
+                self.maybe_print_comment(span.lo)
+            }
+        }
     }
 
     pub fn print_bounds(&mut self,
@@ -2627,20 +2629,30 @@ impl<'a> State<'a> {
     }
 
     pub fn print_fn_output(&mut self, decl: &ast::FnDecl) -> IoResult<()> {
-        match decl.output.node {
-            ast::TyNil => Ok(()),
-            _ => {
-                try!(self.space_if_not_bol());
-                try!(self.ibox(indent_unit));
-                try!(self.word_space("->"));
-                if decl.cf == ast::NoReturn {
-                    try!(self.word_nbsp("!"));
-                } else {
-                    try!(self.print_type(&*decl.output));
+        if let ast::Return(ref ty) = decl.output {
+            match ty.node {
+                ast::TyTup(ref tys) if tys.is_empty() => {
+                    return self.maybe_print_comment(ty.span.lo);
                 }
-                self.end()
+                _ => ()
             }
         }
+
+        try!(self.space_if_not_bol());
+        try!(self.ibox(indent_unit));
+        try!(self.word_space("->"));
+        match decl.output {
+            ast::NoReturn(_) =>
+                try!(self.word_nbsp("!")),
+            ast::Return(ref ty) =>
+                try!(self.print_type(&**ty))
+        }
+        try!(self.end());
+
+        match decl.output {
+            ast::Return(ref output) => self.maybe_print_comment(output.span.lo),
+            _ => Ok(())
+        }
     }
 
     pub fn print_ty_fn(&mut self,
@@ -2700,8 +2712,6 @@ impl<'a> State<'a> {
 
         try!(self.print_bounds(":", bounds));
 
-        try!(self.maybe_print_comment(decl.output.span.lo));
-
         try!(self.print_fn_output(decl));
 
         match generics {
@@ -2807,7 +2817,6 @@ impl<'a> State<'a> {
                          ast_util::float_ty_to_string(t).as_slice()).as_slice())
             }
             ast::LitFloatUnsuffixed(ref f) => word(&mut self.s, f.get()),
-            ast::LitNil => word(&mut self.s, "()"),
             ast::LitBool(val) => {
                 if val { word(&mut self.s, "true") } else { word(&mut self.s, "false") }
             }
@@ -3003,10 +3012,9 @@ mod test {
 
         let decl = ast::FnDecl {
             inputs: Vec::new(),
-            output: P(ast::Ty {id: 0,
-                               node: ast::TyNil,
-                               span: codemap::DUMMY_SP}),
-            cf: ast::Return,
+            output: ast::Return(P(ast::Ty {id: 0,
+                               node: ast::TyTup(vec![]),
+                               span: codemap::DUMMY_SP})),
             variadic: false
         };
         let generics = ast_util::empty_generics();
diff --git a/src/libsyntax/test.rs b/src/libsyntax/test.rs
index 29637e88dd5..8b6d752d484 100644
--- a/src/libsyntax/test.rs
+++ b/src/libsyntax/test.rs
@@ -289,9 +289,12 @@ fn is_test_fn(cx: &TestCtxt, i: &ast::Item) -> bool {
     fn has_test_signature(i: &ast::Item) -> HasTestSignature {
         match &i.node {
           &ast::ItemFn(ref decl, _, _, ref generics, _) => {
-            let no_output = match decl.output.node {
-                ast::TyNil => true,
-                _ => false,
+            let no_output = match decl.output {
+                ast::Return(ref ret_ty) => match ret_ty.node {
+                    ast::TyTup(ref tys) if tys.is_empty() => true,
+                    _ => false,
+                },
+                ast::NoReturn(_) => false
             };
             if decl.inputs.is_empty()
                    && no_output
@@ -325,9 +328,12 @@ fn is_bench_fn(cx: &TestCtxt, i: &ast::Item) -> bool {
         match i.node {
             ast::ItemFn(ref decl, _, _, ref generics, _) => {
                 let input_cnt = decl.inputs.len();
-                let no_output = match decl.output.node {
-                    ast::TyNil => true,
-                    _ => false
+                let no_output = match decl.output {
+                    ast::Return(ref ret_ty) => match ret_ty.node {
+                        ast::TyTup(ref tys) if tys.is_empty() => true,
+                        _ => false,
+                    },
+                    ast::NoReturn(_) => false
                 };
                 let tparm_cnt = generics.ty_params.len();
                 // NB: inadequate check, but we're running
diff --git a/src/libsyntax/visit.rs b/src/libsyntax/visit.rs
index 1b1d1e9cace..f30a4325eb8 100644
--- a/src/libsyntax/visit.rs
+++ b/src/libsyntax/visit.rs
@@ -341,7 +341,7 @@ pub fn skip_ty<'v, V: Visitor<'v>>(_: &mut V, _: &'v Ty) {
 
 pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty) {
     match typ.node {
-        TyUniq(ref ty) | TyVec(ref ty) | TyParen(ref ty) => {
+        TyVec(ref ty) | TyParen(ref ty) => {
             visitor.visit_ty(&**ty)
         }
         TyPtr(ref mutable_type) => {
@@ -360,7 +360,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty) {
             for argument in function_declaration.decl.inputs.iter() {
                 visitor.visit_ty(&*argument.ty)
             }
-            visitor.visit_ty(&*function_declaration.decl.output);
+            walk_fn_ret_ty(visitor, &function_declaration.decl.output);
             walk_ty_param_bounds(visitor, &function_declaration.bounds);
             walk_lifetime_decls(visitor, &function_declaration.lifetimes);
         }
@@ -368,7 +368,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty) {
             for argument in function_declaration.decl.inputs.iter() {
                 visitor.visit_ty(&*argument.ty)
             }
-            visitor.visit_ty(&*function_declaration.decl.output);
+            walk_fn_ret_ty(visitor, &function_declaration.decl.output);
             walk_ty_param_bounds(visitor, &function_declaration.bounds);
             walk_lifetime_decls(visitor, &function_declaration.lifetimes);
         }
@@ -376,7 +376,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty) {
             for argument in function_declaration.decl.inputs.iter() {
                 visitor.visit_ty(&*argument.ty)
             }
-            visitor.visit_ty(&*function_declaration.decl.output);
+            walk_fn_ret_ty(visitor, &function_declaration.decl.output);
             walk_lifetime_decls(visitor, &function_declaration.lifetimes);
         }
         TyPath(ref path, ref opt_bounds, id) => {
@@ -403,7 +403,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty) {
         TyTypeof(ref expression) => {
             visitor.visit_expr(&**expression)
         }
-        TyNil | TyBot | TyInfer => {}
+        TyInfer => {}
     }
 }
 
@@ -538,12 +538,18 @@ pub fn walk_generics<'v, V: Visitor<'v>>(visitor: &mut V, generics: &'v Generics
     }
 }
 
+pub fn walk_fn_ret_ty<'v, V: Visitor<'v>>(visitor: &mut V, ret_ty: &'v FunctionRetTy) {
+    if let Return(ref output_ty) = *ret_ty {
+        visitor.visit_ty(&**output_ty)
+    }
+}
+
 pub fn walk_fn_decl<'v, V: Visitor<'v>>(visitor: &mut V, function_declaration: &'v FnDecl) {
     for argument in function_declaration.inputs.iter() {
         visitor.visit_pat(&*argument.pat);
         visitor.visit_ty(&*argument.ty)
     }
-    visitor.visit_ty(&*function_declaration.output)
+    walk_fn_ret_ty(visitor, &function_declaration.output)
 }
 
 // Note: there is no visit_method() method in the visitor, instead override
@@ -601,7 +607,7 @@ pub fn walk_ty_method<'v, V: Visitor<'v>>(visitor: &mut V, method_type: &'v Type
         visitor.visit_ty(&*argument_type.ty)
     }
     visitor.visit_generics(&method_type.generics);
-    visitor.visit_ty(&*method_type.decl.output);
+    walk_fn_ret_ty(visitor, &method_type.decl.output);
     for attr in method_type.attrs.iter() {
         visitor.visit_attribute(attr);
     }