auto merge of #19683 : nikomatsakis/rust/generalized-where-clauses, r=nrc

This patch does not itself enable generalized where clauses, but it lays the groundwork. Rather than storing a list of bounds per type parameter, the trait selection and other logic is now driven by a unified list of predicates. All predicate handling is now driven through a common interface. This also fixes a number of bugs where region predicates were being dropped on the floor. As a drive-by, this patch also fixes some bugs in the opt-out-copy feature flag.

That said, this patch does not change the parser or AST in any way, so we still *generate* the list of predicates by walking a list of bounds (and we still *store* the bounds on the `TypeParameterDef` and so on). Those will get patched in a follow-up.

The commits in this case are standalone; the first few are simple refactorings.

r? @nick29581 
cc @aturon

Author: bors

src/libcore/kinds.rs

@@ -19,7 +19,7 @@
 
 /// Types able to be transferred across task boundaries.
 #[lang="send"]
-pub trait Send for Sized? {
+pub trait Send for Sized? : 'static {
     // empty.
 }
 

src/librustc/diagnostics.rs

@@ -40,89 +40,8 @@ register_diagnostics!(
     E0019,
     E0020,
     E0022,
-    E0023,
-    E0024,
-    E0025,
-    E0026,
-    E0027,
-    E0029,
-    E0030,
-    E0031,
-    E0033,
-    E0034,
-    E0035,
-    E0036,
-    E0038,
-    E0040,
-    E0044,
-    E0045,
-    E0046,
-    E0049,
-    E0050,
-    E0051,
-    E0052,
-    E0053,
-    E0054,
-    E0055,
-    E0056,
-    E0057,
-    E0059,
-    E0060,
-    E0061,
-    E0062,
-    E0063,
-    E0066,
-    E0067,
-    E0068,
-    E0069,
-    E0070,
-    E0071,
-    E0072,
-    E0073,
-    E0074,
-    E0075,
-    E0076,
-    E0077,
-    E0079,
-    E0080,
-    E0081,
-    E0082,
-    E0083,
-    E0084,
-    E0085,
-    E0086,
-    E0087,
-    E0088,
-    E0089,
-    E0090,
-    E0091,
-    E0092,
-    E0093,
-    E0094,
-    E0100,
-    E0101,
-    E0102,
-    E0103,
-    E0104,
-    E0106,
-    E0107,
-    E0108,
     E0109,
     E0110,
-    E0116,
-    E0117,
-    E0118,
-    E0119,
-    E0120,
-    E0121,
-    E0122,
-    E0124,
-    E0127,
-    E0128,
-    E0129,
-    E0130,
-    E0131,
-    E0132,
     E0133,
     E0134,
     E0135,
@@ -131,16 +50,12 @@ register_diagnostics!(
     E0138,
     E0139,
     E0140,
-    E0141,
     E0152,
     E0153,
     E0157,
     E0158,
-    E0159,
     E0161,
     E0162,
-    E0163,
-    E0164,
     E0165,
     E0166,
     E0167,

src/librustc/metadata/common.rs

@@ -251,3 +251,7 @@ pub const tag_type_param_def: uint = 0xa5;
 
 pub const tag_item_generics: uint = 0xa6;
 pub const tag_method_ty_generics: uint = 0xa7;
+
+pub const tag_predicate: uint = 0xa8;
+pub const tag_predicate_space: uint = 0xa9;
+pub const tag_predicate_data: uint = 0xb0;

src/librustc/metadata/csearch.rs

@@ -21,7 +21,6 @@ use middle::def;
 use middle::lang_items;
 use middle::resolve;
 use middle::ty;
-use middle::subst::VecPerParamSpace;
 
 use rbml;
 use rbml::reader;
@@ -250,9 +249,8 @@ pub fn get_field_type<'tcx>(tcx: &ty::ctxt<'tcx>, class_id: ast::DefId,
         });
     let ty = decoder::item_type(def, the_field, tcx, &*cdata);
     ty::Polytype {
-        generics: ty::Generics {types: VecPerParamSpace::empty(),
-                                regions: VecPerParamSpace::empty()},
-        ty: ty
+        generics: ty::Generics::empty(),
+        ty: ty,
     }
 }
 

src/librustc/metadata/decoder.rs

@@ -23,7 +23,8 @@ use metadata::csearch;
 use metadata::cstore;
 use metadata::tydecode::{parse_ty_data, parse_region_data, parse_def_id,
                          parse_type_param_def_data, parse_bounds_data,
-                         parse_bare_fn_ty_data, parse_trait_ref_data};
+                         parse_bare_fn_ty_data, parse_trait_ref_data,
+                         parse_predicate_data};
 use middle::def;
 use middle::lang_items;
 use middle::resolve::{TraitItemKind, TypeTraitItemKind};
@@ -1437,7 +1438,20 @@ fn doc_generics<'tcx>(base_doc: rbml::Doc,
         true
     });
 
-    ty::Generics { types: types, regions: regions }
+    let mut predicates = subst::VecPerParamSpace::empty();
+    reader::tagged_docs(doc, tag_predicate, |predicate_doc| {
+        let space_doc = reader::get_doc(predicate_doc, tag_predicate_space);
+        let space = subst::ParamSpace::from_uint(reader::doc_as_u8(space_doc) as uint);
+
+        let data_doc = reader::get_doc(predicate_doc, tag_predicate_data);
+        let data = parse_predicate_data(data_doc.data, data_doc.start, cdata.cnum, tcx,
+                                        |_, did| translate_def_id(cdata, did));
+
+        predicates.push(space, data);
+        true
+    });
+
+    ty::Generics { types: types, regions: regions, predicates: predicates }
 }
 
 pub fn is_associated_type(cdata: Cmd, id: ast::NodeId) -> bool {

src/librustc/metadata/encoder.rs

@@ -803,6 +803,18 @@ fn encode_generics<'a, 'tcx>(rbml_w: &mut Encoder,
         rbml_w.end_tag();
     }
 
+    for (space, _, predicate) in generics.predicates.iter_enumerated() {
+        rbml_w.start_tag(tag_predicate);
+
+        rbml_w.wr_tagged_u8(tag_predicate_space, space as u8);
+
+        rbml_w.start_tag(tag_predicate_data);
+        tyencode::enc_predicate(rbml_w.writer, ty_str_ctxt, predicate);
+        rbml_w.end_tag();
+
+        rbml_w.end_tag();
+    }
+
     rbml_w.end_tag();
 }
 

src/librustc/metadata/tydecode.rs

@@ -470,7 +470,7 @@ fn parse_ty<'a, 'tcx>(st: &mut PState<'a, 'tcx>, conv: conv_did) -> Ty<'tcx> {
         st.tcx.rcache.borrow_mut().insert(key, tt);
         return tt;
       }
-      '"' => {
+      '\"' => {
         let _ = parse_def(st, TypeWithId, |x,y| conv(x,y));
         let inner = parse_ty(st, |x,y| conv(x,y));
         inner
@@ -646,6 +646,33 @@ pub fn parse_def_id(buf: &[u8]) -> ast::DefId {
     ast::DefId { krate: crate_num, node: def_num }
 }
 
+pub fn parse_predicate_data<'tcx>(data: &[u8],
+                                  start: uint,
+                                  crate_num: ast::CrateNum,
+                                  tcx: &ty::ctxt<'tcx>,
+                                  conv: conv_did)
+                                  -> ty::Predicate<'tcx>
+{
+    let mut st = parse_state_from_data(data, crate_num, start, tcx);
+    parse_predicate(&mut st, conv)
+}
+
+pub fn parse_predicate<'a,'tcx>(st: &mut PState<'a, 'tcx>,
+                                conv: conv_did)
+                                -> ty::Predicate<'tcx>
+{
+    match next(st) {
+        't' => ty::Predicate::Trait(Rc::new(parse_trait_ref(st, conv))),
+        'e' => ty::Predicate::Equate(parse_ty(st, |x,y| conv(x,y)),
+                                     parse_ty(st, |x,y| conv(x,y))),
+        'r' => ty::Predicate::RegionOutlives(parse_region(st, |x,y| conv(x,y)),
+                                             parse_region(st, |x,y| conv(x,y))),
+        'o' => ty::Predicate::TypeOutlives(parse_ty(st, |x,y| conv(x,y)),
+                                           parse_region(st, |x,y| conv(x,y))),
+        c => panic!("Encountered invalid character in metadata: {}", c)
+    }
+}
+
 pub fn parse_type_param_def_data<'tcx>(data: &[u8], start: uint,
                                        crate_num: ast::CrateNum, tcx: &ty::ctxt<'tcx>,
                                        conv: conv_did) -> ty::TypeParameterDef<'tcx>

src/librustc/metadata/tyencode.rs

@@ -413,3 +413,30 @@ pub fn enc_type_param_def<'a, 'tcx>(w: &mut SeekableMemWriter, cx: &ctxt<'a, 'tc
     enc_bounds(w, cx, &v.bounds);
     enc_opt(w, v.default, |w, t| enc_ty(w, cx, t));
 }
+
+pub fn enc_predicate<'a, 'tcx>(w: &mut SeekableMemWriter,
+                               cx: &ctxt<'a, 'tcx>,
+                               p: &ty::Predicate<'tcx>)
+{
+    match *p {
+        ty::Predicate::Trait(ref trait_ref) => {
+            mywrite!(w, "t");
+            enc_trait_ref(w, cx, &**trait_ref);
+        }
+        ty::Predicate::Equate(a, b) => {
+            mywrite!(w, "e");
+            enc_ty(w, cx, a);
+            enc_ty(w, cx, b);
+        }
+        ty::Predicate::RegionOutlives(a, b) => {
+            mywrite!(w, "r");
+            enc_region(w, cx, a);
+            enc_region(w, cx, b);
+        }
+        ty::Predicate::TypeOutlives(a, b) => {
+            mywrite!(w, "o");
+            enc_ty(w, cx, a);
+            enc_region(w, cx, b);
+        }
+    }
+}

src/librustc/middle/astencode.rs

@@ -830,6 +830,8 @@ trait rbml_writer_helpers<'tcx> {
     fn emit_tys<'a>(&mut self, ecx: &e::EncodeContext<'a, 'tcx>, tys: &[Ty<'tcx>]);
     fn emit_type_param_def<'a>(&mut self, ecx: &e::EncodeContext<'a, 'tcx>,
                                type_param_def: &ty::TypeParameterDef<'tcx>);
+    fn emit_predicate<'a>(&mut self, ecx: &e::EncodeContext<'a, 'tcx>,
+                          predicate: &ty::Predicate<'tcx>);
     fn emit_trait_ref<'a>(&mut self, ecx: &e::EncodeContext<'a, 'tcx>,
                           ty: &ty::TraitRef<'tcx>);
     fn emit_polytype<'a>(&mut self, ecx: &e::EncodeContext<'a, 'tcx>,
@@ -936,6 +938,15 @@ impl<'a, 'tcx> rbml_writer_helpers<'tcx> for Encoder<'a> {
         });
     }
 
+    fn emit_predicate<'a>(&mut self, ecx: &e::EncodeContext<'a, 'tcx>,
+                          predicate: &ty::Predicate<'tcx>) {
+        self.emit_opaque(|this| {
+            Ok(tyencode::enc_predicate(this.writer,
+                                       &ecx.ty_str_ctxt(),
+                                       predicate))
+        });
+    }
+
     fn emit_polytype<'a>(&mut self,
                          ecx: &e::EncodeContext<'a, 'tcx>,
                          pty: ty::Polytype<'tcx>) {
@@ -953,6 +964,11 @@ impl<'a, 'tcx> rbml_writer_helpers<'tcx> for Encoder<'a> {
                         Ok(encode_vec_per_param_space(
                             this, &pty.generics.regions,
                             |this, def| def.encode(this).unwrap()))
+                    });
+                    this.emit_struct_field("predicates", 2, |this| {
+                        Ok(encode_vec_per_param_space(
+                            this, &pty.generics.predicates,
+                            |this, def| this.emit_predicate(ecx, def)))
                     })
                 })
             });
@@ -1336,6 +1352,8 @@ trait rbml_decoder_decoder_helpers<'tcx> {
                               -> Rc<ty::TraitRef<'tcx>>;
     fn read_type_param_def<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
                                    -> ty::TypeParameterDef<'tcx>;
+    fn read_predicate<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
+                              -> ty::Predicate<'tcx>;
     fn read_polytype<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
                              -> ty::Polytype<'tcx>;
     fn read_existential_bounds<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
@@ -1536,6 +1554,15 @@ impl<'a, 'tcx> rbml_decoder_decoder_helpers<'tcx> for reader::Decoder<'a> {
         }).unwrap()
     }
 
+    fn read_predicate<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
+                              -> ty::Predicate<'tcx>
+    {
+        self.read_opaque(|this, doc| {
+            Ok(tydecode::parse_predicate_data(doc.data, doc.start, dcx.cdata.cnum, dcx.tcx,
+                                              |s, a| this.convert_def_id(dcx, s, a)))
+        }).unwrap()
+    }
+
     fn read_polytype<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
                              -> ty::Polytype<'tcx> {
         self.read_struct("Polytype", 2, |this| {
@@ -1553,7 +1580,13 @@ impl<'a, 'tcx> rbml_decoder_decoder_helpers<'tcx> for reader::Decoder<'a> {
                             this.read_struct_field("regions", 1, |this| {
                                 Ok(this.read_vec_per_param_space(
                                     |this| Decodable::decode(this).unwrap()))
-                            }).unwrap()
+                            }).unwrap(),
+
+                            predicates:
+                            this.read_struct_field("predicates", 2, |this| {
+                                Ok(this.read_vec_per_param_space(
+                                    |this| this.read_predicate(dcx)))
+                            }).unwrap(),
                         })
                     })
                 }).unwrap(),

src/librustc/middle/check_static.rs

@@ -31,12 +31,13 @@ use middle::infer;
 use middle::traits;
 use middle::mem_categorization as mc;
 use middle::expr_use_visitor as euv;
+use util::common::ErrorReported;
 use util::nodemap::NodeSet;
 
 use syntax::ast;
 use syntax::print::pprust;
 use syntax::visit::Visitor;
-use syntax::codemap::{DUMMY_SP, Span};
+use syntax::codemap::Span;
 use syntax::visit;
 
 #[deriving(Eq, PartialEq)]
@@ -119,15 +120,17 @@ impl<'a, 'tcx> CheckStaticVisitor<'a, 'tcx> {
         let ty = ty::node_id_to_type(self.tcx, e.id);
         let infcx = infer::new_infer_ctxt(self.tcx);
         let mut fulfill_cx = traits::FulfillmentContext::new();
-        let cause = traits::ObligationCause::misc(DUMMY_SP);
-        let obligation = traits::obligation_for_builtin_bound(self.tcx, cause, ty,
-                                                              ty::BoundSync);
-        fulfill_cx.register_obligation(self.tcx, obligation.unwrap());
-        let env = ty::empty_parameter_environment();
-        let result = fulfill_cx.select_all_or_error(&infcx, &env, self.tcx).is_ok();
-        if !result {
-            self.tcx.sess.span_err(e.span, "shared static items must have a \
-                                            type which implements Sync");
+        match traits::trait_ref_for_builtin_bound(self.tcx, ty::BoundSync, ty) {
+            Ok(trait_ref) => {
+                fulfill_cx.register_trait_ref(self.tcx, trait_ref,
+                                              traits::ObligationCause::dummy());
+                let env = ty::empty_parameter_environment();
+                if !fulfill_cx.select_all_or_error(&infcx, &env, self.tcx).is_ok() {
+                    self.tcx.sess.span_err(e.span, "shared static items must have a \
+                                                    type which implements Sync");
+                }
+            }
+            Err(ErrorReported) => { }
         }
     }
 }