auto merge of rust-lang#6336 : nikomatsakis/rust/issue-6308-closure-bounds, r=nikomatsakis

Use a bitset to represent built-in bounds. There are several places in the language where only builtin bounds (aka kinds) will be accepted, e.g. on closures, destructor type parameters perhaps, and on trait types.

r? @brson

Author: bors

src/librustc/metadata/tydecode.rs

@@ -555,18 +555,34 @@ fn parse_type_param_def(st: @mut PState, conv: conv_did) -> ty::TypeParameterDef
                           bounds: parse_bounds(st, conv)}
 }
 
-fn parse_bounds(st: @mut PState, conv: conv_did) -> @~[ty::param_bound] {
-    let mut bounds = ~[];
+fn parse_bounds(st: @mut PState, conv: conv_did) -> @ty::ParamBounds {
+    let mut param_bounds = ty::ParamBounds {
+        builtin_bounds: ty::EmptyBuiltinBounds(),
+        trait_bounds: ~[]
+    };
     loop {
-        bounds.push(match next(st) {
-          'S' => ty::bound_owned,
-          'C' => ty::bound_copy,
-          'K' => ty::bound_const,
-          'O' => ty::bound_durable,
-          'I' => ty::bound_trait(@parse_trait_ref(st, conv)),
-          '.' => break,
-          _ => fail!(~"parse_bounds: bad bounds")
-        });
+        match next(st) {
+            'S' => {
+                param_bounds.builtin_bounds.add(ty::BoundOwned);
+            }
+            'C' => {
+                param_bounds.builtin_bounds.add(ty::BoundCopy);
+            }
+            'K' => {
+                param_bounds.builtin_bounds.add(ty::BoundConst);
+            }
+            'O' => {
+                param_bounds.builtin_bounds.add(ty::BoundStatic);
+            }
+            'I' => {
+                param_bounds.trait_bounds.push(@parse_trait_ref(st, conv));
+            }
+            '.' => {
+                return @param_bounds;
+            }
+            _ => {
+                fail!(~"parse_bounds: bad bounds")
+            }
+        }
     }
-    @bounds
 }

src/librustc/metadata/tyencode.rs

@@ -396,19 +396,21 @@ fn enc_fn_sig(w: @io::Writer, cx: @ctxt, fsig: &ty::FnSig) {
     enc_ty(w, cx, fsig.output);
 }
 
-fn enc_bounds(w: @io::Writer, cx: @ctxt, bs: @~[ty::param_bound]) {
-    for (*bs).each |bound| {
-        match *bound {
-          ty::bound_owned => w.write_char('S'),
-          ty::bound_copy => w.write_char('C'),
-          ty::bound_const => w.write_char('K'),
-          ty::bound_durable => w.write_char('O'),
-          ty::bound_trait(tp) => {
-              w.write_char('I');
-              enc_trait_ref(w, cx, tp);
-          }
+fn enc_bounds(w: @io::Writer, cx: @ctxt, bs: @ty::ParamBounds) {
+    for bs.builtin_bounds.each |bound| {
+        match bound {
+            ty::BoundOwned => w.write_char('S'),
+            ty::BoundCopy => w.write_char('C'),
+            ty::BoundConst => w.write_char('K'),
+            ty::BoundStatic => w.write_char('O'),
         }
     }
+
+    for bs.trait_bounds.each |&tp| {
+        w.write_char('I');
+        enc_trait_ref(w, cx, tp);
+    }
+
     w.write_char('.');
 }
 

src/librustc/middle/kind.rs

@@ -14,6 +14,7 @@ use middle::pat_util;
 use middle::ty;
 use middle::typeck;
 use util::ppaux::{Repr, ty_to_str};
+use util::ppaux::UserString;
 
 use syntax::ast::*;
 use syntax::attr::attrs_contains_name;
@@ -338,46 +339,19 @@ pub fn check_bounds(cx: Context,
                     type_param_def: &ty::TypeParameterDef)
 {
     let kind = ty::type_contents(cx.tcx, ty);
-    let mut missing = ~[];
-    for type_param_def.bounds.each |bound| {
-        match *bound {
-            ty::bound_trait(_) => {
-                /* Not our job, checking in typeck */
-            }
-
-            ty::bound_copy => {
-                if !kind.is_copy(cx.tcx) {
-                    missing.push("Copy");
-                }
-            }
-
-            ty::bound_durable => {
-                if !kind.is_durable(cx.tcx) {
-                    missing.push("'static");
-                }
-            }
-
-            ty::bound_owned => {
-                if !kind.is_owned(cx.tcx) {
-                    missing.push("Owned");
-                }
-            }
-
-            ty::bound_const => {
-                if !kind.is_const(cx.tcx) {
-                    missing.push("Const");
-                }
-            }
+    let mut missing = ty::EmptyBuiltinBounds();
+    for type_param_def.bounds.builtin_bounds.each |bound| {
+        if !kind.meets_bound(cx.tcx, bound) {
+            missing.add(bound);
         }
     }
-
     if !missing.is_empty() {
         cx.tcx.sess.span_err(
             sp,
             fmt!("instantiating a type parameter with an incompatible type \
                   `%s`, which does not fulfill `%s`",
                  ty_to_str(cx.tcx, ty),
-                 str::connect_slices(missing, " ")));
+                 missing.user_string(cx.tcx)));
     }
 }
 
@@ -440,7 +414,7 @@ pub fn check_owned(cx: Context, ty: ty::t, sp: span) -> bool {
 
 // note: also used from middle::typeck::regionck!
 pub fn check_durable(tcx: ty::ctxt, ty: ty::t, sp: span) -> bool {
-    if !ty::type_is_durable(tcx, ty) {
+    if !ty::type_is_static(tcx, ty) {
         match ty::get(ty).sty {
           ty::ty_param(*) => {
             tcx.sess.span_err(sp, "value may contain borrowed \

src/librustc/middle/subst.rs

@@ -78,9 +78,11 @@ impl<T:Subst> Subst for ~[T] {
     }
 }
 
-impl<T:Subst> Subst for @~[T] {
-    fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> @~[T] {
-        @(**self).subst(tcx, substs)
+impl<T:Subst> Subst for @T {
+    fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> @T {
+        match self {
+            &@ref t => @t.subst(tcx, substs)
+        }
     }
 }
 
@@ -115,19 +117,11 @@ impl Subst for ty::BareFnTy {
     }
 }
 
-impl Subst for ty::param_bound {
-    fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::param_bound {
-        match self {
-            &ty::bound_copy |
-            &ty::bound_durable |
-            &ty::bound_owned |
-            &ty::bound_const => {
-                *self
-            }
-
-            &ty::bound_trait(tref) => {
-                ty::bound_trait(@tref.subst(tcx, substs))
-            }
+impl Subst for ty::ParamBounds {
+    fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::ParamBounds {
+        ty::ParamBounds {
+            builtin_bounds: self.builtin_bounds,
+            trait_bounds: self.trait_bounds.subst(tcx, substs)
         }
     }
 }

src/librustc/middle/trans/monomorphize.rs

@@ -348,14 +348,9 @@ pub fn make_mono_id(ccx: @CrateContext,
         let mut i = 0;
         vec::map_zip(*item_ty.generics.type_param_defs, substs, |type_param_def, subst| {
             let mut v = ~[];
-            for type_param_def.bounds.each |bound| {
-                match *bound {
-                  ty::bound_trait(_) => {
-                    v.push(meth::vtable_id(ccx, /*bad*/copy vts[i]));
-                    i += 1;
-                  }
-                  _ => ()
-                }
+            for type_param_def.bounds.trait_bounds.each |_bound| {
+                v.push(meth::vtable_id(ccx, /*bad*/copy vts[i]));
+                i += 1;
             }
             (*subst, if !v.is_empty() { Some(v) } else { None })
         })

src/librustc/middle/ty.rs

@@ -26,6 +26,7 @@ use util::ppaux::{note_and_explain_region, bound_region_to_str};
 use util::ppaux::{trait_store_to_str, ty_to_str, vstore_to_str};
 use util::ppaux::Repr;
 use util::common::{indenter};
+use util::enum_set::{EnumSet, CLike};
 
 use core;
 use core::ptr::to_unsafe_ptr;
@@ -58,8 +59,6 @@ pub struct field {
     mt: mt
 }
 
-pub type param_bounds = @~[param_bound];
-
 pub struct method {
     ident: ast::ident,
     generics: ty::Generics,
@@ -655,12 +654,32 @@ pub enum type_err {
 }
 
 #[deriving(Eq, IterBytes)]
-pub enum param_bound {
-    bound_copy,
-    bound_durable,
-    bound_owned,
-    bound_const,
-    bound_trait(@TraitRef),
+pub struct ParamBounds {
+    builtin_bounds: BuiltinBounds,
+    trait_bounds: ~[@TraitRef]
+}
+
+pub type BuiltinBounds = EnumSet<BuiltinBound>;
+
+#[deriving(Eq, IterBytes)]
+pub enum BuiltinBound {
+    BoundCopy,
+    BoundStatic,
+    BoundOwned,
+    BoundConst,
+}
+
+pub fn EmptyBuiltinBounds() -> BuiltinBounds {
+    EnumSet::empty()
+}
+
+impl CLike for BuiltinBound {
+    pub fn to_uint(&self) -> uint {
+        *self as uint
+    }
+    pub fn from_uint(v: uint) -> BuiltinBound {
+        unsafe { cast::transmute(v) }
+    }
 }
 
 #[deriving(Eq)]
@@ -817,7 +836,7 @@ impl to_bytes::IterBytes for RegionVid {
 
 pub struct TypeParameterDef {
     def_id: ast::def_id,
-    bounds: param_bounds
+    bounds: @ParamBounds
 }
 
 /// Information about the type/lifetime parametesr associated with an item.
@@ -1497,14 +1516,6 @@ pub fn substs_to_str(cx: ctxt, substs: &substs) -> ~str {
     substs.repr(cx)
 }
 
-pub fn param_bound_to_str(cx: ctxt, pb: &param_bound) -> ~str {
-    pb.repr(cx)
-}
-
-pub fn param_bounds_to_str(cx: ctxt, pbs: param_bounds) -> ~str {
-    pbs.repr(cx)
-}
-
 pub fn subst(cx: ctxt,
              substs: &substs,
              typ: t)
@@ -1795,6 +1806,19 @@ pub struct TypeContents {
 }
 
 pub impl TypeContents {
+    fn meets_bounds(&self, cx: ctxt, bbs: BuiltinBounds) -> bool {
+        iter::all(|bb| self.meets_bound(cx, bb), |f| bbs.each(f))
+    }
+
+    fn meets_bound(&self, cx: ctxt, bb: BuiltinBound) -> bool {
+        match bb {
+            BoundCopy => self.is_copy(cx),
+            BoundStatic => self.is_static(cx),
+            BoundConst => self.is_const(cx),
+            BoundOwned => self.is_owned(cx)
+        }
+    }
+
     fn intersects(&self, tc: TypeContents) -> bool {
         (self.bits & tc.bits) != 0
     }
@@ -1808,11 +1832,11 @@ pub impl TypeContents {
             TC_EMPTY_ENUM
     }
 
-    fn is_durable(&self, cx: ctxt) -> bool {
-        !self.intersects(TypeContents::nondurable(cx))
+    fn is_static(&self, cx: ctxt) -> bool {
+        !self.intersects(TypeContents::nonstatic(cx))
     }
 
-    fn nondurable(_cx: ctxt) -> TypeContents {
+    fn nonstatic(_cx: ctxt) -> TypeContents {
         TC_BORROWED_POINTER
     }
 
@@ -1917,8 +1941,8 @@ pub fn type_is_copyable(cx: ctxt, t: ty::t) -> bool {
     type_contents(cx, t).is_copy(cx)
 }
 
-pub fn type_is_durable(cx: ctxt, t: ty::t) -> bool {
-    type_contents(cx, t).is_durable(cx)
+pub fn type_is_static(cx: ctxt, t: ty::t) -> bool {
+    type_contents(cx, t).is_static(cx)
 }
 
 pub fn type_is_owned(cx: ctxt, t: ty::t) -> bool {
@@ -2198,19 +2222,19 @@ pub fn type_contents(cx: ctxt, ty: t) -> TypeContents {
         debug!("type_param_def_to_contents(%s)", type_param_def.repr(cx));
         let _i = indenter();
 
-        let r = type_param_def.bounds.foldl(TC_ALL, |tc, bound| {
+        let mut tc = TC_ALL;
+        for type_param_def.bounds.builtin_bounds.each |bound| {
             debug!("tc = %s, bound = %?", tc.to_str(), bound);
-            match *bound {
-                bound_copy => tc - TypeContents::nonimplicitly_copyable(cx),
-                bound_durable => tc - TypeContents::nondurable(cx),
-                bound_owned => tc - TypeContents::nonowned(cx),
-                bound_const => tc - TypeContents::nonconst(cx),
-                bound_trait(_) => *tc
-            }
-        });
+            tc = tc - match bound {
+                BoundCopy => TypeContents::nonimplicitly_copyable(cx),
+                BoundStatic => TypeContents::nonstatic(cx),
+                BoundOwned => TypeContents::nonowned(cx),
+                BoundConst => TypeContents::nonconst(cx),
+            };
+        }
 
-        debug!("result = %s", r.to_str());
-        return r;
+        debug!("result = %s", tc.to_str());
+        return tc;
     }
 }
 
@@ -3577,7 +3601,7 @@ pub fn trait_supertraits(cx: ctxt,
 pub fn trait_ref_supertraits(cx: ctxt, trait_ref: &ty::TraitRef) -> ~[@TraitRef] {
     let supertrait_refs = trait_supertraits(cx, trait_ref.def_id);
     supertrait_refs.map(
-        |supertrait_ref| @supertrait_ref.subst(cx, &trait_ref.substs))
+        |supertrait_ref| supertrait_ref.subst(cx, &trait_ref.substs))
 }
 
 fn lookup_locally_or_in_crate_store<V:Copy>(
@@ -4261,18 +4285,9 @@ pub fn determine_inherited_purity(parent: (ast::purity, ast::node_id),
 // relation on the supertraits from each bounded trait's constraint
 // list.
 pub fn each_bound_trait_and_supertraits(tcx: ctxt,
-                                         bounds: param_bounds,
-                                         f: &fn(&TraitRef) -> bool) {
-    for bounds.each |bound| {
-        let bound_trait_ref = match *bound {
-            ty::bound_trait(bound_t) => bound_t,
-
-            ty::bound_copy | ty::bound_owned |
-            ty::bound_const | ty::bound_durable => {
-                loop; // skip non-trait bounds
-            }
-        };
-
+                                        bounds: &ParamBounds,
+                                        f: &fn(@TraitRef) -> bool) {
+    for bounds.trait_bounds.each |&bound_trait_ref| {
         let mut supertrait_set = HashMap::new();
         let mut trait_refs = ~[];
         let mut i = 0;