auto merge of #7091 : msullivan/rust/default-methods, r=graydon

r? @nikomatsakis

Author: bors

Diff for: src/librustc/middle/trans/base.rs

@@ -506,9 +506,11 @@ pub fn get_res_dtor(ccx: @CrateContext,
             did
         };
         assert_eq!(did.crate, ast::local_crate);
+        let tsubsts = ty::substs { self_r: None, self_ty: None,
+                                  tps: /*bad*/ substs.to_owned() };
         let (val, _) = monomorphize::monomorphic_fn(ccx,
                                                     did,
-                                                    substs,
+                                                    &tsubsts,
                                                     None,
                                                     None,
                                                     None);

Diff for: src/librustc/middle/trans/callee.rs

@@ -41,6 +41,7 @@ use middle::trans::meth;
 use middle::trans::monomorphize;
 use middle::trans::type_of;
 use middle::ty;
+use middle::subst::Subst;
 use middle::typeck;
 use util::ppaux::Repr;
 
@@ -230,11 +231,75 @@ pub fn trans_fn_ref_with_vtables(
     // Polytype of the function item (may have type params)
     let fn_tpt = ty::lookup_item_type(tcx, def_id);
 
-    // Modify the def_id if this is a default method; we want to be
-    // monomorphizing the trait's code.
-    let (def_id, opt_impl_did) = match tcx.provided_method_sources.find(&def_id) {
-        None => (def_id, None),
-        Some(source) => (source.method_id, Some(source.impl_id))
+    let substs = ty::substs { self_r: None, self_ty: None,
+                              tps: /*bad*/ type_params.to_owned() };
+
+
+    // We need to do a bunch of special handling for default methods.
+    // We need to modify the def_id and our substs in order to monomorphize
+    // the function.
+    let (def_id, opt_impl_did, substs) = match tcx.provided_method_sources.find(&def_id) {
+        None => (def_id, None, substs),
+        Some(source) => {
+            // There are two relevant substitutions when compiling
+            // default methods. First, there is the substitution for
+            // the type parameters of the impl we are using and the
+            // method we are calling. This substitution is the substs
+            // argument we already have.
+            // In order to compile a default method, though, we need
+            // to consider another substitution: the substitution for
+            // the type parameters on trait; the impl we are using
+            // implements the trait at some particular type
+            // parameters, and we need to substitute for those first.
+            // So, what we need to do is find this substitution and
+            // compose it with the one we already have.
+
+            // In order to find the substitution for the trait params,
+            // we look up the impl in the ast map, find its trait_ref
+            // id, then look up its trait ref. I feel like there
+            // should be a better way.
+            let map_node = session::expect(
+                ccx.sess,
+                ccx.tcx.items.find_copy(&source.impl_id.node),
+                || fmt!("couldn't find node while monomorphizing \
+                         default method: %?", source.impl_id.node));
+            let item = match map_node {
+                ast_map::node_item(item, _) => item,
+                _ => ccx.tcx.sess.bug("Not an item")
+            };
+            let ast_trait_ref = match copy item.node {
+                ast::item_impl(_, Some(tr), _, _) => tr,
+                _ => ccx.tcx.sess.bug("Not an impl with trait_ref")
+            };
+            let trait_ref = ccx.tcx.trait_refs.get(&ast_trait_ref.ref_id);
+
+            // The substs from the trait_ref only substitues for the
+            // trait parameters. Our substitution also needs to be
+            // able to substitute for the actual method type
+            // params. To do this, we figure out how many method
+            // parameters there are and pad out the substitution with
+            // substitution for the variables.
+            let item_ty = ty::lookup_item_type(tcx, source.method_id);
+            let num_params = item_ty.generics.type_param_defs.len() -
+                trait_ref.substs.tps.len();
+            let id_subst = do vec::from_fn(num_params) |i| {
+                ty::mk_param(tcx, i, ast::def_id {crate: 0, node: 0})
+            };
+            // Merge the two substitions together now.
+            let first_subst = ty::substs {tps: trait_ref.substs.tps + id_subst,
+                                          .. trait_ref.substs};
+
+            // And compose them.
+            let new_substs = first_subst.subst(tcx, &substs);
+            debug!("trans_fn_with_vtables - default method: \
+                    substs = %s, id_subst = %s, trait_subst = %s, \
+                    first_subst = %s, new_subst = %s",
+                   substs.repr(tcx),
+                   id_subst.repr(tcx), trait_ref.substs.repr(tcx),
+                   first_subst.repr(tcx), new_substs.repr(tcx));
+
+            (source.method_id, Some(source.impl_id), new_substs)
+        }
     };
 
     // Check whether this fn has an inlined copy and, if so, redirect
@@ -279,7 +344,7 @@ pub fn trans_fn_ref_with_vtables(
         assert_eq!(def_id.crate, ast::local_crate);
 
         let mut (val, must_cast) =
-            monomorphize::monomorphic_fn(ccx, def_id, type_params,
+            monomorphize::monomorphic_fn(ccx, def_id, &substs,
                                          vtables, opt_impl_did, Some(ref_id));
         if must_cast && ref_id != 0 {
             // Monotype of the REFERENCE to the function (type params

Diff for: src/librustc/middle/trans/meth.rs

@@ -207,7 +207,9 @@ pub fn trans_method_callee(bcx: block,
             let method_name =
                 ty::trait_method(tcx, trait_id, method_index).ident;
             let method_id =
-                method_with_name(bcx.ccx(), impl_def_id, method_name);
+                method_with_name_or_default(bcx.ccx(),
+                                            impl_def_id,
+                                            method_name);
             origin = typeck::method_static(method_id);
         }
         typeck::method_super(trait_id, method_index) => {
@@ -229,9 +231,10 @@ pub fn trans_method_callee(bcx: block,
                 ty::method(tcx, supertrait_method_def_ids[method_index]).ident;
             // Now that we know the impl ID, we can look up the method
             // ID from its name
-            origin = typeck::method_static(method_with_name(bcx.ccx(),
-                                                            impl_id,
-                                                            method_name));
+            origin = typeck::method_static(
+                method_with_name_or_default(bcx.ccx(),
+                                            impl_id,
+                                            method_name));
         }
         typeck::method_static(*) | typeck::method_param(*) |
         typeck::method_trait(*) => {}
@@ -345,7 +348,9 @@ pub fn trans_static_method_callee(bcx: block,
         typeck::vtable_static(impl_did, ref rcvr_substs, rcvr_origins) => {
             assert!(rcvr_substs.all(|t| !ty::type_needs_infer(*t)));
 
-            let mth_id = method_with_name(bcx.ccx(), impl_did, mname);
+            let mth_id = method_with_name_or_default(bcx.ccx(),
+                                                     impl_did,
+                                                     mname);
             let callee_substs = combine_impl_and_methods_tps(
                 bcx, mth_id, impl_did, callee_id, *rcvr_substs);
             let callee_origins = combine_impl_and_methods_origins(
@@ -374,23 +379,6 @@ pub fn method_from_methods(ms: &[@ast::method], name: ast::ident)
     ms.find(|m| m.ident == name).map(|m| ast_util::local_def(m.id))
 }
 
-pub fn method_with_name(ccx: @CrateContext, impl_id: ast::def_id,
-                        name: ast::ident) -> ast::def_id {
-    if impl_id.crate == ast::local_crate {
-        match ccx.tcx.items.get_copy(&impl_id.node) {
-          ast_map::node_item(@ast::item {
-                node: ast::item_impl(_, _, _, ref ms),
-                _
-            }, _) => {
-            method_from_methods(*ms, name).get()
-          }
-          _ => fail!("method_with_name")
-        }
-    } else {
-        csearch::get_impl_method(ccx.sess.cstore, impl_id, name)
-    }
-}
-
 pub fn method_with_name_or_default(ccx: @CrateContext,
                                    impl_id: ast::def_id,
                                    name: ast::ident) -> ast::def_id {
@@ -770,17 +758,17 @@ pub fn vtable_id(ccx: @CrateContext,
 
 /// Creates a returns a dynamic vtable for the given type and vtable origin.
 /// This is used only for objects.
-pub fn get_vtable(ccx: @CrateContext,
+pub fn get_vtable(bcx: block,
                   self_ty: ty::t,
                   origin: typeck::vtable_origin)
                   -> ValueRef {
-    let hash_id = vtable_id(ccx, &origin);
-    match ccx.vtables.find(&hash_id) {
+    let hash_id = vtable_id(bcx.ccx(), &origin);
+    match bcx.ccx().vtables.find(&hash_id) {
         Some(&val) => val,
         None => {
             match origin {
                 typeck::vtable_static(id, substs, sub_vtables) => {
-                    make_impl_vtable(ccx, id, self_ty, substs, sub_vtables)
+                    make_impl_vtable(bcx, id, self_ty, substs, sub_vtables)
                 }
                 _ => fail!("get_vtable: expected a static origin"),
             }
@@ -814,12 +802,13 @@ pub fn make_vtable(ccx: @CrateContext,
 }
 
 /// Generates a dynamic vtable for objects.
-pub fn make_impl_vtable(ccx: @CrateContext,
+pub fn make_impl_vtable(bcx: block,
                         impl_id: ast::def_id,
                         self_ty: ty::t,
                         substs: ~[ty::t],
                         vtables: typeck::vtable_res)
                         -> ValueRef {
+    let ccx = bcx.ccx();
     let _icx = ccx.insn_ctxt("impl::make_impl_vtable");
     let tcx = ccx.tcx;
 
@@ -829,9 +818,6 @@ pub fn make_impl_vtable(ccx: @CrateContext,
                                     make a vtable for a type impl!")
     };
 
-    let has_tps =
-        !ty::lookup_item_type(ccx.tcx, impl_id).generics.type_param_defs.is_empty();
-
     let trait_method_def_ids = ty::trait_method_def_ids(tcx, trt_id);
     let methods = do trait_method_def_ids.map |method_def_id| {
         let im = ty::method(tcx, *method_def_id);
@@ -846,22 +832,11 @@ pub fn make_impl_vtable(ccx: @CrateContext,
         } else {
             debug!("(making impl vtable) adding method to vtable: %s",
                    *tcx.sess.str_of(im.ident));
-            let mut m_id = method_with_name(ccx, impl_id, im.ident);
-            if has_tps {
-                // If the method is in another crate, need to make an inlined
-                // copy first
-                if m_id.crate != ast::local_crate {
-                    // XXX: Set impl ID here?
-                    m_id = inline::maybe_instantiate_inline(ccx, m_id, true);
-                }
-                let (val, _) = monomorphize::monomorphic_fn(ccx, m_id, substs,
-                                Some(vtables), None, None);
-                val
-            } else if m_id.crate == ast::local_crate {
-                get_item_val(ccx, m_id.node)
-            } else {
-                trans_external_path(ccx, m_id, fty)
-            }
+            let m_id = method_with_name_or_default(ccx, impl_id, im.ident);
+
+            trans_fn_ref_with_vtables(bcx, m_id, 0,
+                                      substs, Some(vtables)).llfn
+
         }
     };
 
@@ -903,7 +878,7 @@ pub fn trans_trait_cast(bcx: block,
     // Store the vtable into the pair or triple.
     let orig = /*bad*/copy ccx.maps.vtable_map.get(&id)[0];
     let orig = resolve_vtable_in_fn_ctxt(bcx.fcx, orig);
-    let vtable = get_vtable(bcx.ccx(), v_ty, orig);
+    let vtable = get_vtable(bcx, v_ty, orig);
     Store(bcx, vtable, PointerCast(bcx,
                                    GEPi(bcx, lldest, [0u, abi::trt_field_vtable]),
                                    T_ptr(val_ty(vtable))));

Diff for: src/librustc/middle/trans/monomorphize.rs

@@ -43,7 +43,7 @@ use syntax::abi::AbiSet;
 
 pub fn monomorphic_fn(ccx: @CrateContext,
                       fn_id: ast::def_id,
-                      real_substs: &[ty::t],
+                      real_substs: &ty::substs,
                       vtables: Option<typeck::vtable_res>,
                       impl_did_opt: Option<ast::def_id>,
                       ref_id: Option<ast::node_id>)
@@ -61,17 +61,17 @@ pub fn monomorphic_fn(ccx: @CrateContext,
            impl_did_opt.repr(ccx.tcx),
            ref_id);
 
-    assert!(real_substs.all(|t| !ty::type_needs_infer(*t)));
+    assert!(real_substs.tps.all(|t| !ty::type_needs_infer(*t)));
     let _icx = ccx.insn_ctxt("monomorphic_fn");
     let mut must_cast = false;
-    let substs = vec::map(real_substs, |t| {
+    let substs = vec::map(real_substs.tps, |t| {
         match normalize_for_monomorphization(ccx.tcx, *t) {
           Some(t) => { must_cast = true; t }
           None => *t
         }
     });
 
-    for real_substs.each() |s| { assert!(!ty::type_has_params(*s)); }
+    for real_substs.tps.each() |s| { assert!(!ty::type_has_params(*s)); }
     for substs.each() |s| { assert!(!ty::type_has_params(*s)); }
     let param_uses = type_use::type_uses_for(ccx, fn_id, substs.len());
     let hash_id = make_mono_id(ccx, fn_id, substs, vtables, impl_did_opt,
@@ -145,17 +145,8 @@ pub fn monomorphic_fn(ccx: @CrateContext,
       ast_map::node_struct_ctor(_, i, pt) => (pt, i.ident, i.span)
     };
 
-    // Look up the impl type if we're translating a default method.
-    // XXX: Generics.
-    let impl_ty_opt;
-    match impl_did_opt {
-        None => impl_ty_opt = None,
-        Some(impl_did) => {
-            impl_ty_opt = Some(ty::lookup_item_type(ccx.tcx, impl_did).ty);
-        }
-    }
-
-    let mono_ty = ty::subst_tps(ccx.tcx, substs, impl_ty_opt, llitem_ty);
+    let mono_ty = ty::subst_tps(ccx.tcx, substs,
+                                real_substs.self_ty, llitem_ty);
     let llfty = type_of_fn_from_ty(ccx, mono_ty);
 
     ccx.stats.n_monos += 1;
@@ -186,7 +177,7 @@ pub fn monomorphic_fn(ccx: @CrateContext,
         tys: substs,
         vtables: vtables,
         type_param_defs: tpt.generics.type_param_defs,
-        self_ty: impl_ty_opt
+        self_ty: real_substs.self_ty
     });
 
     let lldecl = match map_node {

Diff for: src/librustc/middle/typeck/check/method.rs

@@ -192,7 +192,7 @@ impl<'self> LookupContext<'self> {
 
         // Prepare the list of candidates
         self.push_inherent_candidates(self_ty);
-        self.push_extension_candidates(self_ty);
+        self.push_extension_candidates();
 
         let mut enum_dids = ~[];
         let mut self_ty = self_ty;
@@ -326,7 +326,7 @@ impl<'self> LookupContext<'self> {
         }
     }
 
-    pub fn push_extension_candidates(&self, self_ty: ty::t) {
+    pub fn push_extension_candidates(&self) {
         // If the method being called is associated with a trait, then
         // find all the impls of that trait.  Each of those are
         // candidates.
@@ -343,17 +343,8 @@ impl<'self> LookupContext<'self> {
                     for impl_infos.each |impl_info| {
                         self.push_candidates_from_impl(
                             self.extension_candidates, *impl_info);
-                    }
-                }
 
-                // Look for default methods.
-                match self.tcx().provided_methods.find(trait_did) {
-                    Some(&methods) => {
-                        self.push_candidates_from_provided_methods(
-                            self.extension_candidates, self_ty, *trait_did,
-                            methods);
                     }
-                    None => {}
                 }
             }
         }
@@ -580,44 +571,6 @@ impl<'self> LookupContext<'self> {
         });
     }
 
-    pub fn push_candidates_from_provided_methods(&self,
-                                                 candidates:
-                                                 &mut ~[Candidate],
-                                                 self_ty: ty::t,
-                                                 trait_def_id: def_id,
-                                                 methods:
-                                                 &mut ~[@ProvidedMethodInfo])
-                                                 {
-        debug!("(pushing candidates from provided methods) considering trait \
-                id %d:%d",
-               trait_def_id.crate,
-               trait_def_id.node);
-
-        for methods.each |provided_method_info| {
-            if provided_method_info.method_info.ident != self.m_name { loop; }
-
-            debug!("(pushing candidates from provided methods) adding \
-                    candidate");
-
-            let method = ty::method(self.tcx(),
-                                    provided_method_info.method_info.did);
-
-            // FIXME #4099 (?) Needs to support generics.
-            let dummy_substs = substs {
-                self_r: None,
-                self_ty: None,
-                tps: ~[]
-            };
-
-            candidates.push(Candidate {
-                rcvr_ty: self_ty,
-                rcvr_substs: dummy_substs,
-                method_ty: method,
-                origin: method_static(provided_method_info.method_info.did)
-            });
-        }
-    }
-
     // ______________________________________________________________________
     // Candidate selection (see comment at start of file)