libstd: Remove "dual impls" from the language and enforce coherence rules. r=brson

"Dual impls" are impls that are both type implementations and trait
implementations. They can lead to ambiguity and so this patch removes them
from the language.

This also enforces coherence rules. Without this patch, records can implement
traits not defined in the current crate. This patch fixes this, and updates
all of rustc to adhere to the new enforcement. Most of this patch is fixing
rustc to obey the coherence rules, which involves converting a bunch of records
to structs.

Author: pcwalton

src/libcore/gc.rs

@@ -42,6 +42,7 @@ with destructors.
 #[allow(structural_records)];
 
 use cast;
+use container::{Container, Mutable, Map, Set};
 use io;
 use libc::{size_t, uintptr_t};
 use option::{None, Option, Some};

src/libcore/hashmap.rs

@@ -16,7 +16,6 @@
 
 use cmp::Eq;
 use hash::Hash;
-use prelude::*;
 use to_bytes::IterBytes;
 
 /// Open addressing with linear probing.
@@ -464,6 +463,7 @@ pub mod linear {
 
 #[test]
 pub mod test {
+    use container::{Container, Mutable, Map, Set};
     use option::{None, Some};
     use hashmap::linear::LinearMap;
     use hashmap::linear;

src/libcore/num.rs

@@ -23,6 +23,11 @@ pub trait Num {
     static pure fn from_int(n: int) -> self;
 }
 
+pub trait IntConvertible {
+    pure fn to_int(&self) -> int;
+    static pure fn from_int(n: int) -> self;
+}
+
 pub trait Zero {
     static pure fn zero() -> self;
 }

src/libcore/pipes.rs

@@ -96,10 +96,9 @@ use either::{Either, Left, Right};
 use kinds::Owned;
 use libc;
 use option;
-use option::unwrap;
+use option::{None, Option, Some, unwrap};
 use pipes;
 use ptr;
-use prelude::*;
 use private;
 use task;
 use vec;

src/libcore/prelude.rs

@@ -35,6 +35,8 @@ pub use vec::{ImmutableEqVector, ImmutableCopyableVector};
 pub use vec::{OwnedVector, OwnedCopyableVector};
 pub use iter::{BaseIter, ExtendedIter, EqIter, CopyableIter};
 pub use iter::{CopyableOrderedIter, CopyableNonstrictIter, Times};
+pub use container::{Container, Mutable, Map, Set};
+pub use pipes::{GenericChan, GenericPort};
 
 pub use num::Num;
 pub use ptr::Ptr;

src/libcore/private/weak_task.rs

@@ -22,7 +22,7 @@ use option::{Some, None, swap_unwrap};
 use private::at_exit::at_exit;
 use private::global::global_data_clone_create;
 use private::finally::Finally;
-use pipes::{Port, Chan, SharedChan, stream};
+use pipes::{Port, Chan, SharedChan, GenericSmartChan, stream};
 use task::{Task, task, spawn};
 use task::rt::{task_id, get_task_id};
 use hashmap::linear::LinearMap;

src/libcore/task/mod.rs

@@ -45,7 +45,7 @@ use iter;
 use libc;
 use option;
 use result::Result;
-use pipes::{stream, Chan, Port, SharedChan};
+use pipes::{stream, Chan, GenericChan, GenericPort, Port, SharedChan};
 use pipes;
 use prelude::*;
 use ptr;

src/libcore/task/spawn.rs

@@ -74,8 +74,10 @@
 #[warn(deprecated_mode)];
 
 use cast;
+use container::Map;
+use oldcomm;
 use option;
-use pipes::{stream, Chan, Port};
+use pipes::{Chan, GenericChan, GenericPort, Port};
 use pipes;
 use prelude::*;
 use private;

src/librustc/metadata/encoder.rs

@@ -37,6 +37,7 @@ use core::to_bytes::IterBytes;
 use core::uint;
 use core::vec;
 use std::map::HashMap;
+use std::serialize::Encodable;
 use std::{ebml, map};
 use std;
 use syntax::ast::*;

src/librustc/metadata/tydecode.rs

@@ -17,7 +17,8 @@
 use core::prelude::*;
 
 use middle::ty;
-use middle::ty::{FnTyBase, FnMeta, FnSig};
+use middle::ty::{FnTyBase, FnMeta, FnSig, arg, creader_cache_key, field};
+use middle::ty::{substs};
 
 use core::io;
 use core::str;
@@ -174,9 +175,11 @@ fn parse_substs(st: @pstate, conv: conv_did) -> ty::substs {
     while peek(st) != ']' { params.push(parse_ty(st, conv)); }
     st.pos = st.pos + 1u;
 
-    return {self_r: self_r,
-         self_ty: self_ty,
-         tps: params};
+    return substs {
+        self_r: self_r,
+        self_ty: self_ty,
+        tps: params
+    };
 }
 
 fn parse_bound_region(st: @pstate) -> ty::bound_region {
@@ -308,7 +311,7 @@ fn parse_ty(st: @pstate, conv: conv_did) -> ty::t {
         let mut fields: ~[ty::field] = ~[];
         while peek(st) != ']' {
             let name = st.tcx.sess.ident_of(parse_str(st, '='));
-            fields.push({ident: name, mt: parse_mt(st, conv)});
+            fields.push(ty::field { ident: name, mt: parse_mt(st, conv) });
         }
         st.pos = st.pos + 1u;
         return ty::mk_rec(st.tcx, fields);
@@ -333,12 +336,13 @@ fn parse_ty(st: @pstate, conv: conv_did) -> ty::t {
         assert (next(st) == ':');
         let len = parse_hex(st);
         assert (next(st) == '#');
-        match st.tcx.rcache.find({cnum: st.crate, pos: pos, len: len}) {
+        let key = creader_cache_key { cnum: st.crate, pos: pos, len: len };
+        match st.tcx.rcache.find(key) {
           Some(tt) => return tt,
           None => {
             let ps = @{pos: pos ,.. copy *st};
             let tt = parse_ty(ps, conv);
-            st.tcx.rcache.insert({cnum: st.crate, pos: pos, len: len}, tt);
+            st.tcx.rcache.insert(key, tt);
             return tt;
           }
         }
@@ -421,8 +425,7 @@ fn parse_onceness(c: char) -> ast::Onceness {
 }
 
 fn parse_arg(st: @pstate, conv: conv_did) -> ty::arg {
-    {mode: parse_mode(st),
-     ty: parse_ty(st, conv)}
+    ty::arg { mode: parse_mode(st), ty: parse_ty(st, conv) }
 }
 
 fn parse_mode(st: @pstate) -> ast::mode {
@@ -446,7 +449,7 @@ fn parse_ty_fn(st: @pstate, conv: conv_did) -> ty::FnTy {
     let mut inputs: ~[ty::arg] = ~[];
     while peek(st) != ']' {
         let mode = parse_mode(st);
-        inputs.push({mode: mode, ty: parse_ty(st, conv)});
+        inputs.push(ty::arg { mode: mode, ty: parse_ty(st, conv) });
     }
     st.pos += 1u; // eat the ']'
     let ret_ty = parse_ty(st, conv);

src/librustc/metadata/tyencode.rs

@@ -13,8 +13,8 @@
 
 use core::prelude::*;
 
+use middle::ty::{Vid, param_ty};
 use middle::ty;
-use middle::ty::Vid;
 
 use core::io::WriterUtil;
 use core::io;
@@ -301,7 +301,7 @@ fn enc_sty(w: io::Writer, cx: @ctxt, +st: ty::sty) {
       ty::ty_infer(_) => {
         cx.diag.handler().bug(~"Cannot encode inference variable types");
       }
-      ty::ty_param({idx: id, def_id: did}) => {
+      ty::ty_param(param_ty {idx: id, def_id: did}) => {
         w.write_char('p');
         w.write_str((cx.ds)(did));
         w.write_char('|');

src/librustc/middle/borrowck/check_loans.rs

@@ -20,7 +20,7 @@
 use core::prelude::*;
 
 use middle::borrowck::{Loan, bckerr, borrowck_ctxt, cmt, inherent_mutability};
-use middle::borrowck::{req_maps, save_and_restore};
+use middle::borrowck::{req_maps, root_map_key, save_and_restore};
 use middle::mem_categorization::{cat_arg, cat_binding, cat_comp, cat_deref};
 use middle::mem_categorization::{cat_local, cat_rvalue, cat_self};
 use middle::mem_categorization::{cat_special, gc_ptr, loan_path, lp_arg};
@@ -396,7 +396,10 @@ impl check_loan_ctxt {
 
                 match ptr_kind {
                     gc_ptr(ast::m_mutbl) => {
-                        let key = { id: base.id, derefs: deref_count };
+                        let key = root_map_key {
+                            id: base.id,
+                            derefs: deref_count
+                        };
                         self.bccx.write_guard_map.insert(key, ());
                     }
                     _ => {}

src/librustc/middle/borrowck/gather_loans.rs

@@ -19,7 +19,8 @@
 use core::prelude::*;
 
 use middle::borrowck::preserve::{preserve_condition, pc_ok, pc_if_pure};
-use middle::borrowck::{Loan, bckres, borrowck_ctxt, err_mutbl, req_maps};
+use middle::borrowck::{Loan, bckerr, bckres, borrowck_ctxt, err_mutbl};
+use middle::borrowck::{req_maps};
 use middle::mem_categorization::{cat_binding, cat_discr, cmt, comp_variant};
 use middle::mem_categorization::{mem_categorization_ctxt};
 use middle::mem_categorization::{opt_deref_kind};
@@ -452,8 +453,7 @@ impl gather_loan_ctxt {
             debug!("required is const or they are the same");
             Ok(pc_ok)
         } else {
-            let e = {cmt: cmt,
-                     code: err_mutbl(req_mutbl)};
+            let e = bckerr { cmt: cmt, code: err_mutbl(req_mutbl) };
             if req_mutbl == m_imm {
                 // if this is an @mut box, then it's generally OK to borrow as
                 // &imm; this will result in a write guard

src/librustc/middle/borrowck/loan.rs

@@ -43,7 +43,7 @@ XXX --- much more needed, don't have time to write this all up now
 
 use core::prelude::*;
 
-use middle::borrowck::{Loan, bckres, borrowck_ctxt, cmt, err_mutbl};
+use middle::borrowck::{Loan, bckerr, bckres, borrowck_ctxt, cmt, err_mutbl};
 use middle::borrowck::{err_out_of_scope};
 use middle::mem_categorization::{cat_arg, cat_binding, cat_discr, cat_comp};
 use middle::mem_categorization::{cat_deref, cat_discr, cat_local, cat_self};
@@ -309,8 +309,10 @@ impl LoanContext {
                     // We do not allow non-mutable data to be loaned
                     // out as mutable under any circumstances.
                     if cmt.mutbl != m_mutbl {
-                        return Err({cmt:cmt,
-                                    code:err_mutbl(req_mutbl)});
+                        return Err(bckerr {
+                            cmt:cmt,
+                            code:err_mutbl(req_mutbl)
+                        });
                     }
                 }
                 m_const | m_imm => {
@@ -332,9 +334,10 @@ impl LoanContext {
         } else {
             // The loan being requested lives longer than the data
             // being loaned out!
-            return Err({cmt:cmt,
-                        code:err_out_of_scope(scope_ub,
-                                              self.scope_region)});
+            return Err(bckerr {
+                cmt:cmt,
+                code:err_out_of_scope(scope_ub, self.scope_region)
+            });
         }
     }
 }

src/librustc/middle/borrowck/mod.rs

@@ -344,7 +344,11 @@ type root_map = HashMap<root_map_key, RootInfo>;
 // if you have an expression `x.f` and x has type ~@T, we could add an
 // entry {id:x, derefs:0} to refer to `x` itself, `{id:x, derefs:1}`
 // to refer to the deref of the unique pointer, and so on.
-type root_map_key = {id: ast::node_id, derefs: uint};
+#[deriving_eq]
+struct root_map_key {
+    id: ast::node_id,
+    derefs: uint
+}
 
 // set of ids of local vars / formal arguments that are modified / moved.
 // this is used in trans for optimization purposes.
@@ -411,13 +415,10 @@ impl bckerr_code : cmp::Eq {
 
 // Combination of an error code and the categorization of the expression
 // that caused it
-type bckerr = {cmt: cmt, code: bckerr_code};
-
-impl bckerr : cmp::Eq {
-    pure fn eq(&self, other: &bckerr) -> bool {
-        (*self).cmt == (*other).cmt && (*self).code == (*other).code
-    }
-    pure fn ne(&self, other: &bckerr) -> bool { !(*self).eq(other) }
+#[deriving_eq]
+struct bckerr {
+    cmt: cmt,
+    code: bckerr_code
 }
 
 // shorthand for something that fails with `bckerr` or succeeds with `T`
@@ -446,15 +447,6 @@ fn save_and_restore<T:Copy,U>(save_and_restore_t: &mut T, f: fn() -> U) -> U {
 
 /// Creates and returns a new root_map
 
-impl root_map_key : cmp::Eq {
-    pure fn eq(&self, other: &root_map_key) -> bool {
-        (*self).id == (*other).id && (*self).derefs == (*other).derefs
-    }
-    pure fn ne(&self, other: &root_map_key) -> bool {
-        ! ((*self) == (*other))
-    }
-}
-
 impl root_map_key : to_bytes::IterBytes {
     pure fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
         to_bytes::iter_bytes_2(&self.id, &self.derefs, lsb0, f);
@@ -501,7 +493,7 @@ impl borrowck_ctxt {
     }
 
     fn cat_discr(cmt: cmt, match_id: ast::node_id) -> cmt {
-        return @{cat:cat_discr(cmt, match_id),.. *cmt};
+        return @cmt_ { cat: cat_discr(cmt, match_id),.. *cmt };
     }
 
     fn mc_ctxt() -> mem_categorization_ctxt {

src/librustc/middle/borrowck/preserve.rs

@@ -18,7 +18,7 @@ use core::prelude::*;
 use middle::borrowck::{RootInfo, bckerr, bckerr_code, bckres, borrowck_ctxt};
 use middle::borrowck::{cmt, err_mut_uniq, err_mut_variant};
 use middle::borrowck::{err_out_of_root_scope, err_out_of_scope};
-use middle::borrowck::{err_root_not_permitted};
+use middle::borrowck::{err_root_not_permitted, root_map_key};
 use middle::mem_categorization::{cat_arg, cat_binding, cat_comp, cat_deref};
 use middle::mem_categorization::{cat_discr, cat_local, cat_self, cat_special};
 use middle::mem_categorization::{cat_stack_upvar, comp_field, comp_index};
@@ -291,7 +291,7 @@ priv impl &preserve_ctxt {
           Ok(pc_ok) => {
             match cmt_base.mutbl {
               m_mutbl | m_const => {
-                Ok(pc_if_pure({cmt:cmt, code:code}))
+                Ok(pc_if_pure(bckerr { cmt: cmt, code: code }))
               }
               m_imm => {
                 Ok(pc_ok)
@@ -318,8 +318,10 @@ priv impl &preserve_ctxt {
         if self.bccx.is_subregion_of(self.scope_region, scope_ub) {
             Ok(pc_ok)
         } else {
-            Err({cmt:cmt, code:err_out_of_scope(scope_ub,
-                                                self.scope_region)})
+            Err(bckerr {
+                cmt:cmt,
+                code:err_out_of_scope(scope_ub, self.scope_region)
+            })
         }
     }
 
@@ -345,7 +347,7 @@ priv impl &preserve_ctxt {
             // would be sort of pointless to avoid rooting the inner
             // box by rooting an outer box, as it would just keep more
             // memory live than necessary, so we set root_ub to none.
-            return Err({cmt:cmt, code:err_root_not_permitted});
+            return Err(bckerr { cmt: cmt, code: err_root_not_permitted });
         }
 
         let root_region = ty::re_scope(self.root_ub);
@@ -359,7 +361,7 @@ priv impl &preserve_ctxt {
                    derefs, scope_id, self.root_ub);
             if self.bccx.is_subregion_of(self.scope_region, root_region) {
                 debug!("Elected to root");
-                let rk = {id: base.id, derefs: derefs};
+                let rk = root_map_key { id: base.id, derefs: derefs };
                 // This code could potentially lead cause boxes to be frozen
                 // for longer than necessarily at runtime. It prevents an
                 // ICE in trans; the fundamental problem is that it's hard
@@ -389,17 +391,20 @@ priv impl &preserve_ctxt {
                 return Ok(pc_ok);
             } else {
                 debug!("Unable to root");
-                return Err({cmt:cmt,
-                            code:err_out_of_root_scope(root_region,
-                                                       self.scope_region)});
+                return Err(bckerr {
+                    cmt: cmt,
+                    code: err_out_of_root_scope(root_region,
+                                                self.scope_region)
+                });
             }
           }
 
           // we won't be able to root long enough
           _ => {
-              return Err({cmt:cmt,
-                          code:err_out_of_root_scope(root_region,
-                                                     self.scope_region)});
+              return Err(bckerr {
+                cmt:cmt,
+                code:err_out_of_root_scope(root_region, self.scope_region)
+              });
           }
 
         }