Make supertrait methods callable on object types.

This requires changes to method search and to codegen. We now emit a
vtable for objects that includes methods from all supertraits.
Closes #4100.

Also, actually populate the cache for vtables, and also key it by type
so that it actually works.

src/librustc/middle/astencode.rs

@@ -586,8 +586,13 @@ impl tr for method_origin {
                 }
             )
           }
-          typeck::method_trait(did, m) => {
-              typeck::method_trait(did.tr(xcx), m)
+          typeck::method_object(ref mo) => {
+            typeck::method_object(
+                typeck::method_object {
+                    trait_id: mo.trait_id.tr(xcx),
+                    .. *mo
+                }
+            )
           }
         }
     }

src/librustc/middle/privacy.rs

@@ -16,7 +16,7 @@ use metadata::csearch;
 use middle::ty::{ty_struct, ty_enum};
 use middle::ty;
 use middle::typeck::{method_map, method_origin, method_param};
-use middle::typeck::{method_static, method_trait};
+use middle::typeck::{method_static, method_object};
 
 use std::util::ignore;
 use syntax::ast::{decl_item, def, def_fn, def_id, def_static_method};
@@ -280,10 +280,14 @@ impl PrivacyVisitor {
             }
             method_param(method_param {
                 trait_id: trait_id,
-                 method_num: method_num,
+                method_num: method_num,
                  _
             }) |
-            method_trait(trait_id, method_num) => {
+            method_object(method_object {
+                trait_id: trait_id,
+                method_num: method_num,
+                 _
+            }) => {
                 if trait_id.crate == LOCAL_CRATE {
                     match self.tcx.items.find(&trait_id.node) {
                         Some(&node_item(item, _)) => {

src/librustc/middle/trans/common.rs

@@ -1015,6 +1015,8 @@ pub fn node_vtables(bcx: @mut Block, id: ast::NodeId)
     raw_vtables.map_move(|vts| resolve_vtables_in_fn_ctxt(bcx.fcx, *vts))
 }
 
+// Apply the typaram substitutions in the FunctionContext to some
+// vtables. This should eliminate any vtable_params.
 pub fn resolve_vtables_in_fn_ctxt(fcx: &FunctionContext, vts: typeck::vtable_res)
     -> typeck::vtable_res {
     resolve_vtables_under_param_substs(fcx.ccx.tcx,
@@ -1047,15 +1049,6 @@ pub fn resolve_param_vtables_under_param_substs(
 
 
 
-// Apply the typaram substitutions in the FunctionContext to a vtable. This should
-// eliminate any vtable_params.
-pub fn resolve_vtable_in_fn_ctxt(fcx: &FunctionContext, vt: &typeck::vtable_origin)
-    -> typeck::vtable_origin {
-    resolve_vtable_under_param_substs(fcx.ccx.tcx,
-                                      fcx.param_substs,
-                                      vt)
-}
-
 pub fn resolve_vtable_under_param_substs(tcx: ty::ctxt,
                                          param_substs: Option<@param_substs>,
                                          vt: &typeck::vtable_origin)
@@ -1081,8 +1074,8 @@ pub fn resolve_vtable_under_param_substs(tcx: ty::ctxt,
                 }
                 _ => {
                     tcx.sess.bug(fmt!(
-                        "resolve_vtable_in_fn_ctxt: asked to lookup but \
-                         no vtables in the fn_ctxt!"))
+                        "resolve_vtable_under_param_substs: asked to lookup \
+                         but no vtables in the fn_ctxt!"))
                 }
             }
         }

src/librustc/middle/trans/context.rs

@@ -67,7 +67,7 @@ pub struct CrateContext {
      // Cache computed type parameter uses (see type_use.rs)
      type_use_cache: HashMap<ast::def_id, @~[type_use::type_uses]>,
      // Cache generated vtables
-     vtables: HashMap<mono_id, ValueRef>,
+     vtables: HashMap<(ty::t, mono_id), ValueRef>,
      // Cache of constant strings,
      const_cstr_cache: HashMap<@str, ValueRef>,
 

src/librustc/middle/trans/meth.rs

@@ -186,10 +186,10 @@ pub fn trans_method_callee(bcx: @mut Block,
             }
         }
 
-        typeck::method_trait(_, off) => {
+        typeck::method_object(ref mt) => {
             trans_trait_callee(bcx,
                                callee_id,
-                               off,
+                               mt.real_index,
                                this)
         }
     }
@@ -398,7 +398,6 @@ pub fn combine_impl_and_methods_tps(bcx: @mut Block,
     return (ty_substs, vtables);
 }
 
-
 pub fn trans_trait_callee(bcx: @mut Block,
                           callee_id: ast::NodeId,
                           n_method: uint,
@@ -506,20 +505,35 @@ pub fn vtable_id(ccx: @mut CrateContext,
 /// This is used only for objects.
 pub fn get_vtable(bcx: @mut Block,
                   self_ty: ty::t,
-                  origin: typeck::vtable_origin)
+                  origins: typeck::vtable_param_res)
                   -> ValueRef {
-    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(bcx, id, self_ty, substs, sub_vtables)
-                }
-                _ => fail!("get_vtable: expected a static origin"),
+    let ccx = bcx.ccx();
+    let _icx = push_ctxt("impl::get_vtable");
+
+    // Check the cache.
+    let hash_id = (self_ty, vtable_id(ccx, &origins[0]));
+    match ccx.vtables.find(&hash_id) {
+        Some(&val) => { return val }
+        None => { }
+    }
+
+    // Not in the cache. Actually build it.
+    let methods = do origins.flat_map |origin| {
+        match *origin {
+            typeck::vtable_static(id, ref substs, sub_vtables) => {
+                emit_vtable_methods(bcx, id, *substs, sub_vtables)
             }
+            _ => ccx.sess.bug("get_vtable: expected a static origin"),
         }
-    }
+    };
+
+    // Generate a type descriptor for the vtable.
+    let tydesc = get_tydesc(ccx, self_ty);
+    glue::lazily_emit_all_tydesc_glue(ccx, tydesc);
+
+    let vtable = make_vtable(ccx, tydesc, methods);
+    ccx.vtables.insert(hash_id, vtable);
+    return vtable;
 }
 
 /// Helper function to declare and initialize the vtable.
@@ -547,15 +561,12 @@ pub fn make_vtable(ccx: &mut CrateContext,
     }
 }
 
-/// Generates a dynamic vtable for objects.
-pub fn make_impl_vtable(bcx: @mut Block,
-                        impl_id: ast::def_id,
-                        self_ty: ty::t,
-                        substs: &[ty::t],
-                        vtables: typeck::vtable_res)
-                        -> ValueRef {
+fn emit_vtable_methods(bcx: @mut Block,
+                       impl_id: ast::def_id,
+                       substs: &[ty::t],
+                       vtables: typeck::vtable_res)
+                       -> ~[ValueRef] {
     let ccx = bcx.ccx();
-    let _icx = push_ctxt("impl::make_impl_vtable");
     let tcx = ccx.tcx;
 
     let trt_id = match ty::impl_trait_ref(tcx, impl_id) {
@@ -565,7 +576,7 @@ pub fn make_impl_vtable(bcx: @mut Block,
     };
 
     let trait_method_def_ids = ty::trait_method_def_ids(tcx, trt_id);
-    let methods = do trait_method_def_ids.map |method_def_id| {
+    do trait_method_def_ids.map |method_def_id| {
         let im = ty::method(tcx, *method_def_id);
         let fty = ty::subst_tps(tcx,
                                 substs,
@@ -583,13 +594,7 @@ pub fn make_impl_vtable(bcx: @mut Block,
             trans_fn_ref_with_vtables(bcx, m_id, 0,
                                       substs, Some(vtables)).llfn
         }
-    };
-
-    // Generate a type descriptor for the vtable.
-    let tydesc = get_tydesc(ccx, self_ty);
-    glue::lazily_emit_all_tydesc_glue(ccx, tydesc);
-
-    make_vtable(ccx, tydesc, methods)
+    }
 }
 
 pub fn trans_trait_cast(bcx: @mut Block,
@@ -621,9 +626,13 @@ pub fn trans_trait_cast(bcx: @mut Block,
     bcx = expr::trans_into(bcx, val, SaveIn(llboxdest));
 
     // Store the vtable into the pair or triple.
-    let orig = ccx.maps.vtable_map.get(&id)[0][0].clone();
-    let orig = resolve_vtable_in_fn_ctxt(bcx.fcx, &orig);
-    let vtable = get_vtable(bcx, v_ty, orig);
+    // This is structured a bit funny because of dynamic borrow failures.
+    let origins = {
+        let res = ccx.maps.vtable_map.get(&id);
+        let res = resolve_vtables_in_fn_ctxt(bcx.fcx, *res);
+        res[0]
+    };
+    let vtable = get_vtable(bcx, v_ty, origins);
     Store(bcx, vtable, PointerCast(bcx,
                                    GEPi(bcx, lldest, [0u, abi::trt_field_vtable]),
                                    val_ty(vtable).ptr_to()));

src/librustc/middle/ty.rs

@@ -59,6 +59,7 @@ pub struct field {
     mt: mt
 }
 
+#[deriving(Clone)]
 pub struct Method {
     ident: ast::ident,
     generics: ty::Generics,
@@ -3136,12 +3137,14 @@ pub fn method_call_type_param_defs(tcx: ctxt,
           typeck::method_param(typeck::method_param {
               trait_id: trt_id,
               method_num: n_mth, _}) |
-          typeck::method_trait(trt_id, n_mth) => {
+          typeck::method_object(typeck::method_object {
+              trait_id: trt_id,
+              method_num: n_mth, _}) => {
             // ...trait methods bounds, in contrast, include only the
             // method bounds, so we must preprend the tps from the
             // trait itself.  This ought to be harmonized.
             let trait_type_param_defs =
-                ty::lookup_trait_def(tcx, trt_id).generics.type_param_defs;
+                lookup_trait_def(tcx, trt_id).generics.type_param_defs;
             @vec::append(
                 (*trait_type_param_defs).clone(),
                 *ty::trait_method(tcx,