Correctly subst defaults with the in-scope substs

src/librustc/middle/infer/mod.rs

@@ -1047,12 +1047,15 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             .collect()
     }
 
+    // We have to take `&mut Substs` in order to provide the correct substitutions for defaults
+    // along the way, for this reason we don't return them.
     pub fn type_vars_for_defs(&self,
                               span: Span,
-                              // substs: Substs,
-                              defs: &[ty::TypeParameterDef<'tcx>])
-                              -> Vec<ty::Ty<'tcx>> {
+                              space: subst::ParamSpace,
+                              substs: &mut Substs<'tcx>,
+                              defs: &[ty::TypeParameterDef<'tcx>]) {
 
+        // This doesn't work ...
         fn definition_span<'tcx>(tcx: &ty::ctxt<'tcx>, def_id: ast::DefId) -> Span {
             let parent = tcx.map.get_parent(def_id.node);
             debug!("definition_span def_id={:?} parent={:?} node={:?} parent_node={:?}",
@@ -1069,24 +1072,21 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             }
         }
 
-        let mut substs = Substs::empty();
         let mut vars = Vec::with_capacity(defs.len());
 
         for def in defs.iter() {
-            let default = def.default.map(|default| {
+            let default = def.default.subst_spanned(self.tcx, substs, Some(span)).map(|default| {
                 type_variable::Default {
                     ty: default,
                     origin_span: span,
                     definition_span: definition_span(self.tcx, def.def_id)
                 }
             });
-            //.subst(self.tcx, &substs)
+
             let ty_var = self.next_ty_var_with_default(default);
-            substs.types.push(subst::ParamSpace::SelfSpace, ty_var);
+            substs.types.push(space, ty_var);
             vars.push(ty_var)
         }
-
-        vars
     }
 
     /// Given a set of generics defined on a type or impl, returns a substitution mapping each
@@ -1096,17 +1096,23 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                                      generics: &ty::Generics<'tcx>)
                                      -> subst::Substs<'tcx>
     {
-        let mut type_params = subst::VecPerParamSpace::empty();
-
-        for space in subst::ParamSpace::all().iter() {
-            type_params.replace(*space,
-                                self.type_vars_for_defs(span, generics.types.get_slice(*space)))
-        }
+        let type_params = subst::VecPerParamSpace::empty();
 
         let region_params =
             generics.regions.map(
                 |d| self.next_region_var(EarlyBoundRegion(span, d.name)));
-        subst::Substs::new(type_params, region_params)
+
+        let mut substs = subst::Substs::new(type_params, region_params);
+
+        for space in subst::ParamSpace::all().iter() {
+            self.type_vars_for_defs(
+                span,
+                *space,
+                &mut substs,
+                generics.types.get_slice(*space));
+        }
+
+        return substs;
     }
 
     /// Given a set of generics defined on a trait, returns a substitution mapping each output
@@ -1124,13 +1130,17 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         assert!(generics.regions.len(subst::SelfSpace) == 0);
         assert!(generics.regions.len(subst::FnSpace) == 0);
 
-        let type_parameter_defs = generics.types.get_slice(subst::TypeSpace);
-        let type_parameters = self.type_vars_for_defs(span, type_parameter_defs);
+        let type_params = Vec::new();
 
         let region_param_defs = generics.regions.get_slice(subst::TypeSpace);
         let regions = self.region_vars_for_defs(span, region_param_defs);
 
-        subst::Substs::new_trait(type_parameters, regions, self_ty)
+        let mut substs = subst::Substs::new_trait(type_params, regions, self_ty);
+
+        let type_parameter_defs = generics.types.get_slice(subst::TypeSpace);
+        self.type_vars_for_defs(span, subst::TypeSpace, &mut substs, type_parameter_defs);
+
+        return substs;
     }
 
     pub fn fresh_bound_region(&self, debruijn: ty::DebruijnIndex) -> ty::Region {

src/librustc/middle/subst.rs

@@ -154,7 +154,7 @@ impl<'tcx> Substs<'tcx> {
 }
 
 impl RegionSubsts {
-    fn map<F>(self, op: F) -> RegionSubsts where
+    pub fn map<F>(self, op: F) -> RegionSubsts where
         F: FnOnce(VecPerParamSpace<ty::Region>) -> VecPerParamSpace<ty::Region>,
     {
         match self {

src/librustc_typeck/check/method/confirm.rs

@@ -84,9 +84,12 @@ impl<'a,'tcx> ConfirmContext<'a,'tcx> {
 
         // Create substitutions for the method's type parameters.
         let rcvr_substs = self.fresh_receiver_substs(self_ty, &pick);
-        let (method_types, method_regions) =
-            self.instantiate_method_substs(&pick, supplied_method_types);
-        let all_substs = rcvr_substs.with_method(method_types, method_regions);
+        let all_substs =
+            self.instantiate_method_substs(
+                &pick,
+                supplied_method_types,
+                rcvr_substs);
+
         debug!("all_substs={:?}", all_substs);
 
         // Create the final signature for the method, replacing late-bound regions.
@@ -302,8 +305,9 @@ impl<'a,'tcx> ConfirmContext<'a,'tcx> {
 
     fn instantiate_method_substs(&mut self,
                                  pick: &probe::Pick<'tcx>,
-                                 supplied_method_types: Vec<Ty<'tcx>>)
-                                 -> (Vec<Ty<'tcx>>, Vec<ty::Region>)
+                                 supplied_method_types: Vec<Ty<'tcx>>,
+                                 substs: subst::Substs<'tcx>)
+                                 -> subst::Substs<'tcx>
     {
         // Determine the values for the generic parameters of the method.
         // If they were not explicitly supplied, just construct fresh
@@ -313,21 +317,6 @@ impl<'a,'tcx> ConfirmContext<'a,'tcx> {
         let method_types = method.generics.types.get_slice(subst::FnSpace);
         let num_method_types = method_types.len();
 
-        let method_types = {
-            if num_supplied_types == 0 {
-                self.fcx.infcx().type_vars_for_defs(self.span, method_types)
-            } else if num_method_types == 0 {
-                span_err!(self.tcx().sess, self.span, E0035,
-                    "does not take type parameters");
-                self.fcx.infcx().type_vars_for_defs(self.span, method_types)
-            } else if num_supplied_types != num_method_types {
-                span_err!(self.tcx().sess, self.span, E0036,
-                    "incorrect number of type parameters given for this method");
-                vec![self.tcx().types.err; num_method_types]
-            } else {
-                supplied_method_types
-            }
-        };
 
         // Create subst for early-bound lifetime parameters, combining
         // parameters from the type and those from the method.
@@ -339,7 +328,33 @@ impl<'a,'tcx> ConfirmContext<'a,'tcx> {
                 pick.item.as_opt_method().unwrap()
                     .generics.regions.get_slice(subst::FnSpace));
 
-        (method_types, method_regions)
+        let subst::Substs { types, regions } = substs;
+        let regions = regions.map(|r| r.with_vec(subst::FnSpace, method_regions));
+        let mut final_substs = subst::Substs { types: types, regions: regions };
+
+        if num_supplied_types == 0 {
+            self.fcx.infcx().type_vars_for_defs(
+                self.span,
+                subst::FnSpace,
+                &mut final_substs,
+                method_types);
+        } else if num_method_types == 0 {
+            span_err!(self.tcx().sess, self.span, E0035,
+                "does not take type parameters");
+            self.fcx.infcx().type_vars_for_defs(
+                self.span,
+                subst::FnSpace,
+                &mut final_substs,
+                method_types);
+        } else if num_supplied_types != num_method_types {
+            span_err!(self.tcx().sess, self.span, E0036,
+                "incorrect number of type parameters given for this method");
+            final_substs.types.replace(subst::FnSpace, vec![self.tcx().types.err; num_method_types]);
+        } else {
+            final_substs.types.replace(subst::FnSpace, supplied_method_types);
+        }
+
+        return final_substs;
     }
 
     fn unify_receivers(&mut self,

src/librustc_typeck/check/method/mod.rs

@@ -169,22 +169,28 @@ pub fn lookup_in_trait_adjusted<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
 
     let type_parameter_defs = trait_def.generics.types.get_slice(subst::TypeSpace);
     let expected_number_of_input_types = type_parameter_defs.len();
-    let input_types = match opt_input_types {
-        Some(input_types) => {
-            assert_eq!(expected_number_of_input_types, input_types.len());
-            input_types
-        }
-
-        None => {
-            fcx.inh.infcx.type_vars_for_defs(span, type_parameter_defs)
-        }
-    };
 
     assert_eq!(trait_def.generics.types.len(subst::FnSpace), 0);
     assert!(trait_def.generics.regions.is_empty());
 
     // Construct a trait-reference `self_ty : Trait<input_tys>`
-    let substs = subst::Substs::new_trait(input_types, Vec::new(), self_ty);
+    let mut substs = subst::Substs::new_trait(Vec::new(), Vec::new(), self_ty);
+
+    match opt_input_types {
+        Some(input_types) => {
+            assert_eq!(expected_number_of_input_types, input_types.len());
+            substs.types.replace(subst::ParamSpace::TypeSpace, input_types);
+        }
+
+        None => {
+            fcx.inh.infcx.type_vars_for_defs(
+                span,
+                subst::ParamSpace::TypeSpace,
+                &mut substs,
+                type_parameter_defs);
+        }
+    }
+    
     let trait_ref = ty::TraitRef::new(trait_def_id, fcx.tcx().mk_substs(substs));
 
     // Construct an obligation

src/librustc_typeck/check/method/probe.rs

@@ -1200,16 +1200,12 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
             return impl_ty;
         }
 
-        let placeholder;
+        let mut placeholder;
         let mut substs = substs;
         if
             !method.generics.types.is_empty_in(subst::FnSpace) ||
             !method.generics.regions.is_empty_in(subst::FnSpace)
         {
-            let method_types =
-                self.infcx().type_vars_for_defs(self.span,
-                    method.generics.types.get_slice(subst::FnSpace));
-
             // In general, during probe we erase regions. See
             // `impl_self_ty()` for an explanation.
             let method_regions =
@@ -1218,7 +1214,14 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
                 .map(|_| ty::ReStatic)
                 .collect();
 
-            placeholder = (*substs).clone().with_method(method_types, method_regions);
+            placeholder = (*substs).clone().with_method(Vec::new(), method_regions);
+
+            self.infcx().type_vars_for_defs(
+                self.span,
+                subst::FnSpace,
+                &mut placeholder,
+                method.generics.types.get_slice(subst::FnSpace));
+
             substs = &placeholder;
         }
 

src/librustc_typeck/check/mod.rs

@@ -2616,8 +2616,10 @@ pub fn impl_self_ty<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
     debug!("impl_self_ty: tps={:?} rps={:?} raw_ty={:?}", tps, rps, raw_ty);
 
     let rps = fcx.inh.infcx.region_vars_for_defs(span, rps);
-    let tps = fcx.inh.infcx.type_vars_for_defs(span, tps);
-    let substs = subst::Substs::new_type(tps, rps);
+    let mut substs = subst::Substs::new(
+        VecPerParamSpace::empty(),
+        VecPerParamSpace::new(rps, Vec::new(), Vec::new()));
+    fcx.inh.infcx.type_vars_for_defs(span, ParamSpace::TypeSpace, &mut substs, tps);
     let substd_ty = fcx.instantiate_type_scheme(span, &substs, &raw_ty);
 
     TypeAndSubsts { substs: substs, ty: substd_ty }
@@ -4611,6 +4613,7 @@ pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
             }
         }
     }
+
     if let Some(self_ty) = opt_self_ty {
         if type_defs.len(subst::SelfSpace) == 1 {
             substs.types.push(subst::SelfSpace, self_ty);
@@ -4623,7 +4626,7 @@ pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
     // variables. If the user provided some types, we may still need
     // to add defaults. If the user provided *too many* types, that's
     // a problem.
-    for &space in &ParamSpace::all() {
+    for &space in &[subst::SelfSpace, subst::TypeSpace, subst::FnSpace] {
         adjust_type_parameters(fcx, span, space, type_defs,
                                require_type_space, &mut substs);
         assert_eq!(substs.types.len(space), type_defs.len(space));
@@ -4836,7 +4839,7 @@ pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
         // Nothing specified at all: supply inference variables for
         // everything.
         if provided_len == 0 && !(require_type_space && space == subst::TypeSpace) {
-            substs.types.replace(space, fcx.infcx().type_vars_for_defs(span, &desired[..]));
+            fcx.infcx().type_vars_for_defs(span, space, substs, &desired[..]);
             return;
         }