about summary refs log tree commit diff
path: root/src/librustdoc/clean
diff options
context:
space:
mode:
Diffstat (limited to 'src/librustdoc/clean')
-rw-r--r--src/librustdoc/clean/auto_trait.rs1455
-rw-r--r--src/librustdoc/clean/cfg.rs2
-rw-r--r--src/librustdoc/clean/inline.rs42
-rw-r--r--src/librustdoc/clean/mod.rs441
4 files changed, 1869 insertions, 71 deletions
diff --git a/src/librustdoc/clean/auto_trait.rs b/src/librustdoc/clean/auto_trait.rs
new file mode 100644
index 00000000000..8f0d3929b52
--- /dev/null
+++ b/src/librustdoc/clean/auto_trait.rs
@@ -0,0 +1,1455 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use rustc::ty::TypeFoldable;
+
+use super::*;
+
+pub struct AutoTraitFinder<'a, 'tcx: 'a, 'rcx: 'a> {
+    pub cx: &'a core::DocContext<'a, 'tcx, 'rcx>,
+}
+
+impl<'a, 'tcx, 'rcx> AutoTraitFinder<'a, 'tcx, 'rcx> {
+    pub fn get_with_def_id(&self, def_id: DefId) -> Vec<Item> {
+        let ty = self.cx.tcx.type_of(def_id);
+
+        let def_ctor: fn(DefId) -> Def = match ty.sty {
+            ty::TyAdt(adt, _) => match adt.adt_kind() {
+                AdtKind::Struct => Def::Struct,
+                AdtKind::Enum => Def::Enum,
+                AdtKind::Union => Def::Union,
+            },
+            _ => panic!("Unexpected type {:?}", def_id),
+        };
+
+        self.get_auto_trait_impls(def_id, def_ctor, None)
+    }
+
+    pub fn get_with_node_id(&self, id: ast::NodeId, name: String) -> Vec<Item> {
+        let item = &self.cx.tcx.hir.expect_item(id).node;
+        let did = self.cx.tcx.hir.local_def_id(id);
+
+        let def_ctor = match *item {
+            hir::ItemStruct(_, _) => Def::Struct,
+            hir::ItemUnion(_, _) => Def::Union,
+            hir::ItemEnum(_, _) => Def::Enum,
+            _ => panic!("Unexpected type {:?} {:?}", item, id),
+        };
+
+        self.get_auto_trait_impls(did, def_ctor, Some(name))
+    }
+
+    pub fn get_auto_trait_impls(
+        &self,
+        def_id: DefId,
+        def_ctor: fn(DefId) -> Def,
+        name: Option<String>,
+    ) -> Vec<Item> {
+        if self.cx
+            .tcx
+            .get_attrs(def_id)
+            .lists("doc")
+            .has_word("hidden")
+        {
+            debug!(
+                "get_auto_trait_impls(def_id={:?}, def_ctor={:?}): item has doc('hidden'), \
+                 aborting",
+                def_id, def_ctor
+            );
+            return Vec::new();
+        }
+
+        let tcx = self.cx.tcx;
+        let generics = self.cx.tcx.generics_of(def_id);
+
+        debug!(
+            "get_auto_trait_impls(def_id={:?}, def_ctor={:?}, generics={:?}",
+            def_id, def_ctor, generics
+        );
+        let auto_traits: Vec<_> = self.cx
+            .send_trait
+            .and_then(|send_trait| {
+                self.get_auto_trait_impl_for(
+                    def_id,
+                    name.clone(),
+                    generics.clone(),
+                    def_ctor,
+                    send_trait,
+                )
+            })
+            .into_iter()
+            .chain(self.get_auto_trait_impl_for(
+                def_id,
+                name.clone(),
+                generics.clone(),
+                def_ctor,
+                tcx.require_lang_item(lang_items::SyncTraitLangItem),
+            ).into_iter())
+            .collect();
+
+        debug!(
+            "get_auto_traits: type {:?} auto_traits {:?}",
+            def_id, auto_traits
+        );
+        auto_traits
+    }
+
+    fn get_auto_trait_impl_for(
+        &self,
+        def_id: DefId,
+        name: Option<String>,
+        generics: ty::Generics,
+        def_ctor: fn(DefId) -> Def,
+        trait_def_id: DefId,
+    ) -> Option<Item> {
+        if !self.cx
+            .generated_synthetics
+            .borrow_mut()
+            .insert((def_id, trait_def_id))
+        {
+            debug!(
+                "get_auto_trait_impl_for(def_id={:?}, generics={:?}, def_ctor={:?}, \
+                 trait_def_id={:?}): already generated, aborting",
+                def_id, generics, def_ctor, trait_def_id
+            );
+            return None;
+        }
+
+        let result = self.find_auto_trait_generics(def_id, trait_def_id, &generics);
+
+        if result.is_auto() {
+            let trait_ = hir::TraitRef {
+                path: get_path_for_type(self.cx.tcx, trait_def_id, hir::def::Def::Trait),
+                ref_id: ast::DUMMY_NODE_ID,
+            };
+
+            let polarity;
+
+            let new_generics = match result {
+                AutoTraitResult::PositiveImpl(new_generics) => {
+                    polarity = None;
+                    new_generics
+                }
+                AutoTraitResult::NegativeImpl => {
+                    polarity = Some(ImplPolarity::Negative);
+
+                    // For negative impls, we use the generic params, but *not* the predicates,
+                    // from the original type. Otherwise, the displayed impl appears to be a
+                    // conditional negative impl, when it's really unconditional.
+                    //
+                    // For example, consider the struct Foo<T: Copy>(*mut T). Using
+                    // the original predicates in our impl would cause us to generate
+                    // `impl !Send for Foo<T: Copy>`, which makes it appear that Foo
+                    // implements Send where T is not copy.
+                    //
+                    // Instead, we generate `impl !Send for Foo<T>`, which better
+                    // expresses the fact that `Foo<T>` never implements `Send`,
+                    // regardless of the choice of `T`.
+                    let real_generics = (&generics, &Default::default());
+
+                    // Clean the generics, but ignore the '?Sized' bounds generated
+                    // by the `Clean` impl
+                    let clean_generics = real_generics.clean(self.cx);
+
+                    Generics {
+                        params: clean_generics.params,
+                        where_predicates: Vec::new(),
+                    }
+                }
+                _ => unreachable!(),
+            };
+
+            let path = get_path_for_type(self.cx.tcx, def_id, def_ctor);
+            let mut segments = path.segments.into_vec();
+            let last = segments.pop().unwrap();
+
+            let real_name = name.as_ref().map(|n| Symbol::from(n.as_str()));
+
+            segments.push(hir::PathSegment::new(
+                real_name.unwrap_or(last.name),
+                self.generics_to_path_params(generics.clone()),
+                false,
+            ));
+
+            let new_path = hir::Path {
+                span: path.span,
+                def: path.def,
+                segments: HirVec::from_vec(segments),
+            };
+
+            let ty = hir::Ty {
+                id: ast::DUMMY_NODE_ID,
+                node: hir::Ty_::TyPath(hir::QPath::Resolved(None, P(new_path))),
+                span: DUMMY_SP,
+                hir_id: hir::DUMMY_HIR_ID,
+            };
+
+            return Some(Item {
+                source: Span::empty(),
+                name: None,
+                attrs: Default::default(),
+                visibility: None,
+                def_id: self.next_def_id(def_id.krate),
+                stability: None,
+                deprecation: None,
+                inner: ImplItem(Impl {
+                    unsafety: hir::Unsafety::Normal,
+                    generics: new_generics,
+                    provided_trait_methods: FxHashSet(),
+                    trait_: Some(trait_.clean(self.cx)),
+                    for_: ty.clean(self.cx),
+                    items: Vec::new(),
+                    polarity,
+                    synthetic: true,
+                }),
+            });
+        }
+        None
+    }
+
+    fn generics_to_path_params(&self, generics: ty::Generics) -> hir::PathParameters {
+        let lifetimes = HirVec::from_vec(
+            generics
+                .regions
+                .iter()
+                .map(|p| {
+                    let name = if p.name == "" {
+                        hir::LifetimeName::Static
+                    } else {
+                        hir::LifetimeName::Name(p.name)
+                    };
+
+                    hir::Lifetime {
+                        id: ast::DUMMY_NODE_ID,
+                        span: DUMMY_SP,
+                        name,
+                    }
+                })
+                .collect(),
+        );
+        let types = HirVec::from_vec(
+            generics
+                .types
+                .iter()
+                .map(|p| P(self.ty_param_to_ty(p.clone())))
+                .collect(),
+        );
+
+        hir::PathParameters {
+            lifetimes: lifetimes,
+            types: types,
+            bindings: HirVec::new(),
+            parenthesized: false,
+        }
+    }
+
+    fn ty_param_to_ty(&self, param: ty::TypeParameterDef) -> hir::Ty {
+        debug!("ty_param_to_ty({:?}) {:?}", param, param.def_id);
+        hir::Ty {
+            id: ast::DUMMY_NODE_ID,
+            node: hir::Ty_::TyPath(hir::QPath::Resolved(
+                None,
+                P(hir::Path {
+                    span: DUMMY_SP,
+                    def: Def::TyParam(param.def_id),
+                    segments: HirVec::from_vec(vec![hir::PathSegment::from_name(param.name)]),
+                }),
+            )),
+            span: DUMMY_SP,
+            hir_id: hir::DUMMY_HIR_ID,
+        }
+    }
+
+    fn find_auto_trait_generics(
+        &self,
+        did: DefId,
+        trait_did: DefId,
+        generics: &ty::Generics,
+    ) -> AutoTraitResult {
+        let tcx = self.cx.tcx;
+        let ty = self.cx.tcx.type_of(did);
+
+        let orig_params = tcx.param_env(did);
+
+        let trait_ref = ty::TraitRef {
+            def_id: trait_did,
+            substs: tcx.mk_substs_trait(ty, &[]),
+        };
+
+        let trait_pred = ty::Binder(trait_ref);
+
+        let bail_out = tcx.infer_ctxt().enter(|infcx| {
+            let mut selcx = SelectionContext::with_negative(&infcx, true);
+            let result = selcx.select(&Obligation::new(
+                ObligationCause::dummy(),
+                orig_params,
+                trait_pred.to_poly_trait_predicate(),
+            ));
+            match result {
+                Ok(Some(Vtable::VtableImpl(_))) => {
+                    debug!(
+                        "find_auto_trait_generics(did={:?}, trait_did={:?}, generics={:?}): \
+                         manual impl found, bailing out",
+                        did, trait_did, generics
+                    );
+                    return true;
+                }
+                _ => return false,
+            };
+        });
+
+        // If an explicit impl exists, it always takes priority over an auto impl
+        if bail_out {
+            return AutoTraitResult::ExplicitImpl;
+        }
+
+        return tcx.infer_ctxt().enter(|mut infcx| {
+            let mut fresh_preds = FxHashSet();
+
+            // Due to the way projections are handled by SelectionContext, we need to run
+            // evaluate_predicates twice: once on the original param env, and once on the result of
+            // the first evaluate_predicates call
+            //
+            // The problem is this: most of rustc, including SelectionContext and traits::project,
+            // are designed to work with a concrete usage of a type (e.g. Vec<u8>
+            // fn<T>() { Vec<T> }. This information will generally never change - given
+            // the 'T' in fn<T>() { ... }, we'll never know anything else about 'T'.
+            // If we're unable to prove that 'T' implements a particular trait, we're done -
+            // there's nothing left to do but error out.
+            //
+            // However, synthesizing an auto trait impl works differently. Here, we start out with
+            // a set of initial conditions - the ParamEnv of the struct/enum/union we're dealing
+            // with - and progressively discover the conditions we need to fulfill for it to
+            // implement a certain auto trait. This ends up breaking two assumptions made by trait
+            // selection and projection:
+            //
+            // * We can always cache the result of a particular trait selection for the lifetime of
+            // an InfCtxt
+            // * Given a projection bound such as '<T as SomeTrait>::SomeItem = K', if 'T:
+            // SomeTrait' doesn't hold, then we don't need to care about the 'SomeItem = K'
+            //
+            // We fix the first assumption by manually clearing out all of the InferCtxt's caches
+            // in between calls to SelectionContext.select. This allows us to keep all of the
+            // intermediate types we create bound to the 'tcx lifetime, rather than needing to lift
+            // them between calls
+            //
+            // We fix the second assumption by reprocessing the result of our first call to
+            // evaluate_predicates. Using the example of '<T as SomeTrait>::SomeItem = K', our first
+            // pass will pick up 'T: SomeTrait', but not 'SomeItem = K'. On our second pass,
+            // traits::project will see that 'T: SomeTrait' is in our ParamEnv, allowing
+            // SelectionContext to return it back to us.
+
+            let (new_env, user_env) = match self.evaluate_predicates(
+                &mut infcx,
+                did,
+                trait_did,
+                ty,
+                orig_params.clone(),
+                orig_params,
+                &mut fresh_preds,
+                false,
+            ) {
+                Some(e) => e,
+                None => return AutoTraitResult::NegativeImpl,
+            };
+
+            let (full_env, full_user_env) = self.evaluate_predicates(
+                &mut infcx,
+                did,
+                trait_did,
+                ty,
+                new_env.clone(),
+                user_env,
+                &mut fresh_preds,
+                true,
+            ).unwrap_or_else(|| {
+                panic!(
+                    "Failed to fully process: {:?} {:?} {:?}",
+                    ty, trait_did, orig_params
+                )
+            });
+
+            debug!(
+                "find_auto_trait_generics(did={:?}, trait_did={:?}, generics={:?}): fulfilling \
+                 with {:?}",
+                did, trait_did, generics, full_env
+            );
+            infcx.clear_caches();
+
+            // At this point, we already have all of the bounds we need. FulfillmentContext is used
+            // to store all of the necessary region/lifetime bounds in the InferContext, as well as
+            // an additional sanity check.
+            let mut fulfill = FulfillmentContext::new();
+            fulfill.register_bound(
+                &infcx,
+                full_env,
+                ty,
+                trait_did,
+                ObligationCause::misc(DUMMY_SP, ast::DUMMY_NODE_ID),
+            );
+            fulfill.select_all_or_error(&infcx).unwrap_or_else(|e| {
+                panic!(
+                    "Unable to fulfill trait {:?} for '{:?}': {:?}",
+                    trait_did, ty, e
+                )
+            });
+
+            let names_map: FxHashMap<String, Lifetime> = generics
+                .regions
+                .iter()
+                .map(|l| (l.name.as_str().to_string(), l.clean(self.cx)))
+                .collect();
+
+            let body_ids: FxHashSet<_> = infcx
+                .region_obligations
+                .borrow()
+                .iter()
+                .map(|&(id, _)| id)
+                .collect();
+
+            for id in body_ids {
+                infcx.process_registered_region_obligations(&[], None, full_env.clone(), id);
+            }
+
+            let region_data = infcx
+                .borrow_region_constraints()
+                .region_constraint_data()
+                .clone();
+
+            let lifetime_predicates = self.handle_lifetimes(&region_data, &names_map);
+            let vid_to_region = self.map_vid_to_region(&region_data);
+
+            debug!(
+                "find_auto_trait_generics(did={:?}, trait_did={:?}, generics={:?}): computed \
+                 lifetime information '{:?}' '{:?}'",
+                did, trait_did, generics, lifetime_predicates, vid_to_region
+            );
+
+            let new_generics = self.param_env_to_generics(
+                infcx.tcx,
+                did,
+                full_user_env,
+                generics.clone(),
+                lifetime_predicates,
+                vid_to_region,
+            );
+            debug!(
+                "find_auto_trait_generics(did={:?}, trait_did={:?}, generics={:?}): finished with \
+                 {:?}",
+                did, trait_did, generics, new_generics
+            );
+            return AutoTraitResult::PositiveImpl(new_generics);
+        });
+    }
+
+    fn clean_pred<'c, 'd, 'cx>(
+        &self,
+        infcx: &InferCtxt<'c, 'd, 'cx>,
+        p: ty::Predicate<'cx>,
+    ) -> ty::Predicate<'cx> {
+        infcx.freshen(p)
+    }
+
+    fn evaluate_nested_obligations<
+        'b,
+        'c,
+        'd,
+        'cx,
+        T: Iterator<Item = Obligation<'cx, ty::Predicate<'cx>>>,
+    >(
+        &self,
+        ty: ty::Ty,
+        nested: T,
+        computed_preds: &'b mut FxHashSet<ty::Predicate<'cx>>,
+        fresh_preds: &'b mut FxHashSet<ty::Predicate<'cx>>,
+        predicates: &'b mut VecDeque<ty::PolyTraitPredicate<'cx>>,
+        select: &mut traits::SelectionContext<'c, 'd, 'cx>,
+        only_projections: bool,
+    ) -> bool {
+        let dummy_cause = ObligationCause::misc(DUMMY_SP, ast::DUMMY_NODE_ID);
+
+        for (obligation, predicate) in nested
+            .filter(|o| o.recursion_depth == 1)
+            .map(|o| (o.clone(), o.predicate.clone()))
+        {
+            let is_new_pred =
+                fresh_preds.insert(self.clean_pred(select.infcx(), predicate.clone()));
+
+            match &predicate {
+                &ty::Predicate::Trait(ref p) => {
+                    let substs = &p.skip_binder().trait_ref.substs;
+
+                    if self.is_of_param(substs) && !only_projections && is_new_pred {
+                        computed_preds.insert(predicate);
+                    }
+                    predicates.push_back(p.clone());
+                }
+                &ty::Predicate::Projection(p) => {
+                    // If the projection isn't all type vars, then
+                    // we don't want to add it as a bound
+                    if self.is_of_param(p.skip_binder().projection_ty.substs) && is_new_pred {
+                        computed_preds.insert(predicate);
+                    } else {
+                        match traits::poly_project_and_unify_type(
+                            select,
+                            &obligation.with(p.clone()),
+                        ) {
+                            Err(e) => {
+                                debug!(
+                                    "evaluate_nested_obligations: Unable to unify predicate \
+                                     '{:?}' '{:?}', bailing out",
+                                    ty, e
+                                );
+                                return false;
+                            }
+                            Ok(Some(v)) => {
+                                if !self.evaluate_nested_obligations(
+                                    ty,
+                                    v.clone().iter().cloned(),
+                                    computed_preds,
+                                    fresh_preds,
+                                    predicates,
+                                    select,
+                                    only_projections,
+                                ) {
+                                    return false;
+                                }
+                            }
+                            Ok(None) => {
+                                panic!("Unexpected result when selecting {:?} {:?}", ty, obligation)
+                            }
+                        }
+                    }
+                }
+                &ty::Predicate::RegionOutlives(ref binder) => {
+                    if let Err(_) = select
+                        .infcx()
+                        .region_outlives_predicate(&dummy_cause, binder)
+                    {
+                        return false;
+                    }
+                }
+                &ty::Predicate::TypeOutlives(ref binder) => {
+                    match (
+                        binder.no_late_bound_regions(),
+                        binder.map_bound_ref(|pred| pred.0).no_late_bound_regions(),
+                    ) {
+                        (None, Some(t_a)) => {
+                            select.infcx().register_region_obligation(
+                                ast::DUMMY_NODE_ID,
+                                RegionObligation {
+                                    sup_type: t_a,
+                                    sub_region: select.infcx().tcx.types.re_static,
+                                    cause: dummy_cause.clone(),
+                                },
+                            );
+                        }
+                        (Some(ty::OutlivesPredicate(t_a, r_b)), _) => {
+                            select.infcx().register_region_obligation(
+                                ast::DUMMY_NODE_ID,
+                                RegionObligation {
+                                    sup_type: t_a,
+                                    sub_region: r_b,
+                                    cause: dummy_cause.clone(),
+                                },
+                            );
+                        }
+                        _ => {}
+                    };
+                }
+                _ => panic!("Unexpected predicate {:?} {:?}", ty, predicate),
+            };
+        }
+        return true;
+    }
+
+    // The core logic responsible for computing the bounds for our synthesized impl.
+    //
+    // To calculate the bounds, we call SelectionContext.select in a loop. Like FulfillmentContext,
+    // we recursively select the nested obligations of predicates we encounter. However, whenver we
+    // encounter an UnimplementedError involving a type parameter, we add it to our ParamEnv. Since
+    // our goal is to determine when a particular type implements an auto trait, Unimplemented
+    // errors tell us what conditions need to be met.
+    //
+    // This method ends up working somewhat similary to FulfillmentContext, but with a few key
+    // differences. FulfillmentContext works under the assumption that it's dealing with concrete
+    // user code. According, it considers all possible ways that a Predicate could be met - which
+    // isn't always what we want for a synthesized impl. For example, given the predicate 'T:
+    // Iterator', FulfillmentContext can end up reporting an Unimplemented error for T:
+    // IntoIterator - since there's an implementation of Iteratpr where T: IntoIterator,
+    // FulfillmentContext will drive SelectionContext to consider that impl before giving up. If we
+    // were to rely on FulfillmentContext's decision, we might end up synthesizing an impl like
+    // this:
+    // 'impl<T> Send for Foo<T> where T: IntoIterator'
+    //
+    // While it might be technically true that Foo implements Send where T: IntoIterator,
+    // the bound is overly restrictive - it's really only necessary that T: Iterator.
+    //
+    // For this reason, evaluate_predicates handles predicates with type variables specially. When
+    // we encounter an Unimplemented error for a bound such as 'T: Iterator', we immediately add it
+    // to our ParamEnv, and add it to our stack for recursive evaluation. When we later select it,
+    // we'll pick up any nested bounds, without ever inferring that 'T: IntoIterator' needs to
+    // hold.
+    //
+    // One additonal consideration is supertrait bounds. Normally, a ParamEnv is only ever
+    // consutrcted once for a given type. As part of the construction process, the ParamEnv will
+    // have any supertrait bounds normalized - e.g. if we have a type 'struct Foo<T: Copy>', the
+    // ParamEnv will contain 'T: Copy' and 'T: Clone', since 'Copy: Clone'. When we construct our
+    // own ParamEnv, we need to do this outselves, through traits::elaborate_predicates, or else
+    // SelectionContext will choke on the missing predicates. However, this should never show up in
+    // the final synthesized generics: we don't want our generated docs page to contain something
+    // like 'T: Copy + Clone', as that's redundant. Therefore, we keep track of a separate
+    // 'user_env', which only holds the predicates that will actually be displayed to the user.
+    fn evaluate_predicates<'b, 'gcx, 'c>(
+        &self,
+        infcx: &mut InferCtxt<'b, 'tcx, 'c>,
+        ty_did: DefId,
+        trait_did: DefId,
+        ty: ty::Ty<'c>,
+        param_env: ty::ParamEnv<'c>,
+        user_env: ty::ParamEnv<'c>,
+        fresh_preds: &mut FxHashSet<ty::Predicate<'c>>,
+        only_projections: bool,
+    ) -> Option<(ty::ParamEnv<'c>, ty::ParamEnv<'c>)> {
+        let tcx = infcx.tcx;
+
+        let mut select = traits::SelectionContext::new(&infcx);
+
+        let mut already_visited = FxHashSet();
+        let mut predicates = VecDeque::new();
+        predicates.push_back(ty::Binder(ty::TraitPredicate {
+            trait_ref: ty::TraitRef {
+                def_id: trait_did,
+                substs: infcx.tcx.mk_substs_trait(ty, &[]),
+            },
+        }));
+
+        let mut computed_preds: FxHashSet<_> = param_env.caller_bounds.iter().cloned().collect();
+        let mut user_computed_preds: FxHashSet<_> =
+            user_env.caller_bounds.iter().cloned().collect();
+
+        let mut new_env = param_env.clone();
+        let dummy_cause = ObligationCause::misc(DUMMY_SP, ast::DUMMY_NODE_ID);
+
+        while let Some(pred) = predicates.pop_front() {
+            infcx.clear_caches();
+
+            if !already_visited.insert(pred.clone()) {
+                continue;
+            }
+
+            let result = select.select(&Obligation::new(dummy_cause.clone(), new_env, pred));
+
+            match &result {
+                &Ok(Some(ref vtable)) => {
+                    let obligations = vtable.clone().nested_obligations().into_iter();
+
+                    if !self.evaluate_nested_obligations(
+                        ty,
+                        obligations,
+                        &mut user_computed_preds,
+                        fresh_preds,
+                        &mut predicates,
+                        &mut select,
+                        only_projections,
+                    ) {
+                        return None;
+                    }
+                }
+                &Ok(None) => {}
+                &Err(SelectionError::Unimplemented) => {
+                    if self.is_of_param(pred.skip_binder().trait_ref.substs) {
+                        already_visited.remove(&pred);
+                        user_computed_preds.insert(ty::Predicate::Trait(pred.clone()));
+                        predicates.push_back(pred);
+                    } else {
+                        debug!(
+                            "evaluate_nested_obligations: Unimplemented found, bailing: {:?} {:?} \
+                             {:?}",
+                            ty,
+                            pred,
+                            pred.skip_binder().trait_ref.substs
+                        );
+                        return None;
+                    }
+                }
+                _ => panic!("Unexpected error for '{:?}': {:?}", ty, result),
+            };
+
+            computed_preds.extend(user_computed_preds.iter().cloned());
+            let normalized_preds =
+                traits::elaborate_predicates(tcx, computed_preds.clone().into_iter().collect());
+            new_env = ty::ParamEnv::new(tcx.mk_predicates(normalized_preds), param_env.reveal);
+        }
+
+        let final_user_env = ty::ParamEnv::new(
+            tcx.mk_predicates(user_computed_preds.into_iter()),
+            user_env.reveal,
+        );
+        debug!(
+            "evaluate_nested_obligations(ty_did={:?}, trait_did={:?}): succeeded with '{:?}' \
+             '{:?}'",
+            ty_did, trait_did, new_env, final_user_env
+        );
+
+        return Some((new_env, final_user_env));
+    }
+
+    fn is_of_param(&self, substs: &Substs) -> bool {
+        if substs.is_noop() {
+            return false;
+        }
+
+        return match substs.type_at(0).sty {
+            ty::TyParam(_) => true,
+            ty::TyProjection(p) => self.is_of_param(p.substs),
+            _ => false,
+        };
+    }
+
+    fn get_lifetime(&self, region: Region, names_map: &FxHashMap<String, Lifetime>) -> Lifetime {
+        self.region_name(region)
+            .map(|name| {
+                names_map.get(&name).unwrap_or_else(|| {
+                    panic!("Missing lifetime with name {:?} for {:?}", name, region)
+                })
+            })
+            .unwrap_or(&Lifetime::statik())
+            .clone()
+    }
+
+    fn region_name(&self, region: Region) -> Option<String> {
+        match region {
+            &ty::ReEarlyBound(r) => Some(r.name.as_str().to_string()),
+            _ => None,
+        }
+    }
+
+    // This is very simiiar to handle_lifetimes. Instead of matching ty::Region's to ty::Region's,
+    // however, we match ty::RegionVid's to ty::Region's
+    fn map_vid_to_region<'cx>(
+        &self,
+        regions: &RegionConstraintData<'cx>,
+    ) -> FxHashMap<ty::RegionVid, ty::Region<'cx>> {
+        let mut vid_map: FxHashMap<RegionTarget<'cx>, RegionDeps<'cx>> = FxHashMap();
+        let mut finished_map = FxHashMap();
+
+        for constraint in regions.constraints.keys() {
+            match constraint {
+                &Constraint::VarSubVar(r1, r2) => {
+                    {
+                        let deps1 = vid_map
+                            .entry(RegionTarget::RegionVid(r1))
+                            .or_insert_with(|| Default::default());
+                        deps1.larger.insert(RegionTarget::RegionVid(r2));
+                    }
+
+                    let deps2 = vid_map
+                        .entry(RegionTarget::RegionVid(r2))
+                        .or_insert_with(|| Default::default());
+                    deps2.smaller.insert(RegionTarget::RegionVid(r1));
+                }
+                &Constraint::RegSubVar(region, vid) => {
+                    {
+                        let deps1 = vid_map
+                            .entry(RegionTarget::Region(region))
+                            .or_insert_with(|| Default::default());
+                        deps1.larger.insert(RegionTarget::RegionVid(vid));
+                    }
+
+                    let deps2 = vid_map
+                        .entry(RegionTarget::RegionVid(vid))
+                        .or_insert_with(|| Default::default());
+                    deps2.smaller.insert(RegionTarget::Region(region));
+                }
+                &Constraint::VarSubReg(vid, region) => {
+                    finished_map.insert(vid, region);
+                }
+                &Constraint::RegSubReg(r1, r2) => {
+                    {
+                        let deps1 = vid_map
+                            .entry(RegionTarget::Region(r1))
+                            .or_insert_with(|| Default::default());
+                        deps1.larger.insert(RegionTarget::Region(r2));
+                    }
+
+                    let deps2 = vid_map
+                        .entry(RegionTarget::Region(r2))
+                        .or_insert_with(|| Default::default());
+                    deps2.smaller.insert(RegionTarget::Region(r1));
+                }
+            }
+        }
+
+        while !vid_map.is_empty() {
+            let target = vid_map.keys().next().expect("Keys somehow empty").clone();
+            let deps = vid_map.remove(&target).expect("Entry somehow missing");
+
+            for smaller in deps.smaller.iter() {
+                for larger in deps.larger.iter() {
+                    match (smaller, larger) {
+                        (&RegionTarget::Region(_), &RegionTarget::Region(_)) => {
+                            if let Entry::Occupied(v) = vid_map.entry(*smaller) {
+                                let smaller_deps = v.into_mut();
+                                smaller_deps.larger.insert(*larger);
+                                smaller_deps.larger.remove(&target);
+                            }
+
+                            if let Entry::Occupied(v) = vid_map.entry(*larger) {
+                                let larger_deps = v.into_mut();
+                                larger_deps.smaller.insert(*smaller);
+                                larger_deps.smaller.remove(&target);
+                            }
+                        }
+                        (&RegionTarget::RegionVid(v1), &RegionTarget::Region(r1)) => {
+                            finished_map.insert(v1, r1);
+                        }
+                        (&RegionTarget::Region(_), &RegionTarget::RegionVid(_)) => {
+                            // Do nothing - we don't care about regions that are smaller than vids
+                        }
+                        (&RegionTarget::RegionVid(_), &RegionTarget::RegionVid(_)) => {
+                            if let Entry::Occupied(v) = vid_map.entry(*smaller) {
+                                let smaller_deps = v.into_mut();
+                                smaller_deps.larger.insert(*larger);
+                                smaller_deps.larger.remove(&target);
+                            }
+
+                            if let Entry::Occupied(v) = vid_map.entry(*larger) {
+                                let larger_deps = v.into_mut();
+                                larger_deps.smaller.insert(*smaller);
+                                larger_deps.smaller.remove(&target);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        finished_map
+    }
+
+    // This method calculates two things: Lifetime constraints of the form 'a: 'b,
+    // and region constraints of the form ReVar: 'a
+    //
+    // This is essentially a simplified version of lexical_region_resolve. However,
+    // handle_lifetimes determines what *needs be* true in order for an impl to hold.
+    // lexical_region_resolve, along with much of the rest of the compiler, is concerned
+    // with determining if a given set up constraints/predicates *are* met, given some
+    // starting conditions (e.g. user-provided code). For this reason, it's easier
+    // to perform the calculations we need on our own, rather than trying to make
+    // existing inference/solver code do what we want
+    fn handle_lifetimes<'cx>(
+        &self,
+        regions: &RegionConstraintData<'cx>,
+        names_map: &FxHashMap<String, Lifetime>,
+    ) -> Vec<WherePredicate> {
+        // Our goal is to 'flatten' the list of constraints by eliminating
+        // all intermediate RegionVids. At the end, all constraints should
+        // be between Regions (aka region variables). This gives us the information
+        // we need to create the Generics
+        //
+        let mut finished = FxHashMap();
+
+        let mut vid_map: FxHashMap<RegionTarget, RegionDeps> = FxHashMap();
+
+        // Flattening is done in two parts. First, we insert all of the constraints
+        // into a map. Each RegionTarget (either a RegionVid or a Region) maps
+        // to its smaller and larger regions. Note that 'larger' regions correspond
+        // to sub-regions in Rust code (e.g. in 'a: 'b, 'a is the larger region).
+        for constraint in regions.constraints.keys() {
+            match constraint {
+                &Constraint::VarSubVar(r1, r2) => {
+                    {
+                        let deps1 = vid_map
+                            .entry(RegionTarget::RegionVid(r1))
+                            .or_insert_with(|| Default::default());
+                        deps1.larger.insert(RegionTarget::RegionVid(r2));
+                    }
+
+                    let deps2 = vid_map
+                        .entry(RegionTarget::RegionVid(r2))
+                        .or_insert_with(|| Default::default());
+                    deps2.smaller.insert(RegionTarget::RegionVid(r1));
+                }
+                &Constraint::RegSubVar(region, vid) => {
+                    let deps = vid_map
+                        .entry(RegionTarget::RegionVid(vid))
+                        .or_insert_with(|| Default::default());
+                    deps.smaller.insert(RegionTarget::Region(region));
+                }
+                &Constraint::VarSubReg(vid, region) => {
+                    let deps = vid_map
+                        .entry(RegionTarget::RegionVid(vid))
+                        .or_insert_with(|| Default::default());
+                    deps.larger.insert(RegionTarget::Region(region));
+                }
+                &Constraint::RegSubReg(r1, r2) => {
+                    // The constraint is already in the form that we want, so we're done with it
+                    // Desired order is 'larger, smaller', so flip then
+                    if self.region_name(r1) != self.region_name(r2) {
+                        finished
+                            .entry(self.region_name(r2).unwrap())
+                            .or_insert_with(|| Vec::new())
+                            .push(r1);
+                    }
+                }
+            }
+        }
+
+        // Here, we 'flatten' the map one element at a time.
+        // All of the element's sub and super regions are connected
+        // to each other. For example, if we have a graph that looks like this:
+        //
+        // (A, B) - C - (D, E)
+        // Where (A, B) are subregions, and (D,E) are super-regions
+        //
+        // then after deleting 'C', the graph will look like this:
+        //  ... - A - (D, E ...)
+        //  ... - B - (D, E, ...)
+        //  (A, B, ...) - D - ...
+        //  (A, B, ...) - E - ...
+        //
+        //  where '...' signifies the existing sub and super regions of an entry
+        //  When two adjacent ty::Regions are encountered, we've computed a final
+        //  constraint, and add it to our list. Since we make sure to never re-add
+        //  deleted items, this process will always finish.
+        while !vid_map.is_empty() {
+            let target = vid_map.keys().next().expect("Keys somehow empty").clone();
+            let deps = vid_map.remove(&target).expect("Entry somehow missing");
+
+            for smaller in deps.smaller.iter() {
+                for larger in deps.larger.iter() {
+                    match (smaller, larger) {
+                        (&RegionTarget::Region(r1), &RegionTarget::Region(r2)) => {
+                            if self.region_name(r1) != self.region_name(r2) {
+                                finished
+                                    .entry(self.region_name(r2).unwrap())
+                                    .or_insert_with(|| Vec::new())
+                                    .push(r1) // Larger, smaller
+                            }
+                        }
+                        (&RegionTarget::RegionVid(_), &RegionTarget::Region(_)) => {
+                            if let Entry::Occupied(v) = vid_map.entry(*smaller) {
+                                let smaller_deps = v.into_mut();
+                                smaller_deps.larger.insert(*larger);
+                                smaller_deps.larger.remove(&target);
+                            }
+                        }
+                        (&RegionTarget::Region(_), &RegionTarget::RegionVid(_)) => {
+                            if let Entry::Occupied(v) = vid_map.entry(*larger) {
+                                let deps = v.into_mut();
+                                deps.smaller.insert(*smaller);
+                                deps.smaller.remove(&target);
+                            }
+                        }
+                        (&RegionTarget::RegionVid(_), &RegionTarget::RegionVid(_)) => {
+                            if let Entry::Occupied(v) = vid_map.entry(*smaller) {
+                                let smaller_deps = v.into_mut();
+                                smaller_deps.larger.insert(*larger);
+                                smaller_deps.larger.remove(&target);
+                            }
+
+                            if let Entry::Occupied(v) = vid_map.entry(*larger) {
+                                let larger_deps = v.into_mut();
+                                larger_deps.smaller.insert(*smaller);
+                                larger_deps.smaller.remove(&target);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        let lifetime_predicates = names_map
+            .iter()
+            .flat_map(|(name, lifetime)| {
+                let empty = Vec::new();
+                let bounds: FxHashSet<Lifetime> = finished
+                    .get(name)
+                    .unwrap_or(&empty)
+                    .iter()
+                    .map(|region| self.get_lifetime(region, names_map))
+                    .collect();
+
+                if bounds.is_empty() {
+                    return None;
+                }
+                Some(WherePredicate::RegionPredicate {
+                    lifetime: lifetime.clone(),
+                    bounds: bounds.into_iter().collect(),
+                })
+            })
+            .collect();
+
+        lifetime_predicates
+    }
+
+    fn extract_for_generics<'b, 'c, 'd>(
+        &self,
+        tcx: TyCtxt<'b, 'c, 'd>,
+        pred: ty::Predicate<'d>,
+    ) -> FxHashSet<GenericParam> {
+        pred.walk_tys()
+            .flat_map(|t| {
+                let mut regions = FxHashSet();
+                tcx.collect_regions(&t, &mut regions);
+
+                regions.into_iter().flat_map(|r| {
+                    match r {
+                        // We only care about late bound regions, as we need to add them
+                        // to the 'for<>' section
+                        &ty::ReLateBound(_, ty::BoundRegion::BrNamed(_, name)) => {
+                            Some(GenericParam::Lifetime(Lifetime(name.as_str().to_string())))
+                        }
+                        &ty::ReVar(_) | &ty::ReEarlyBound(_) => None,
+                        _ => panic!("Unexpected region type {:?}", r),
+                    }
+                })
+            })
+            .collect()
+    }
+
+    fn make_final_bounds<'b, 'c, 'cx>(
+        &self,
+        ty_to_bounds: FxHashMap<Type, FxHashSet<TyParamBound>>,
+        ty_to_fn: FxHashMap<Type, (Option<PolyTrait>, Option<Type>)>,
+        lifetime_to_bounds: FxHashMap<Lifetime, FxHashSet<Lifetime>>,
+    ) -> Vec<WherePredicate> {
+        let final_predicates = ty_to_bounds
+            .into_iter()
+            .flat_map(|(ty, mut bounds)| {
+                if let Some(data) = ty_to_fn.get(&ty) {
+                    let (poly_trait, output) =
+                        (data.0.as_ref().unwrap().clone(), data.1.as_ref().cloned());
+                    let new_ty = match &poly_trait.trait_ {
+                        &Type::ResolvedPath {
+                            ref path,
+                            ref typarams,
+                            ref did,
+                            ref is_generic,
+                        } => {
+                            let mut new_path = path.clone();
+                            let last_segment = new_path.segments.pop().unwrap();
+
+                            let (old_input, old_output) = match last_segment.params {
+                                PathParameters::AngleBracketed { types, .. } => (types, None),
+                                PathParameters::Parenthesized { inputs, output, .. } => {
+                                    (inputs, output)
+                                }
+                            };
+
+                            if old_output.is_some() && old_output != output {
+                                panic!(
+                                    "Output mismatch for {:?} {:?} {:?}",
+                                    ty, old_output, data.1
+                                );
+                            }
+
+                            let new_params = PathParameters::Parenthesized {
+                                inputs: old_input,
+                                output,
+                            };
+
+                            new_path.segments.push(PathSegment {
+                                name: last_segment.name,
+                                params: new_params,
+                            });
+
+                            Type::ResolvedPath {
+                                path: new_path,
+                                typarams: typarams.clone(),
+                                did: did.clone(),
+                                is_generic: *is_generic,
+                            }
+                        }
+                        _ => panic!("Unexpected data: {:?}, {:?}", ty, data),
+                    };
+                    bounds.insert(TyParamBound::TraitBound(
+                        PolyTrait {
+                            trait_: new_ty,
+                            generic_params: poly_trait.generic_params,
+                        },
+                        hir::TraitBoundModifier::None,
+                    ));
+                }
+                if bounds.is_empty() {
+                    return None;
+                }
+
+                Some(WherePredicate::BoundPredicate {
+                    ty,
+                    bounds: bounds.into_iter().collect(),
+                })
+            })
+            .chain(
+                lifetime_to_bounds
+                    .into_iter()
+                    .filter(|&(_, ref bounds)| !bounds.is_empty())
+                    .map(|(lifetime, bounds)| WherePredicate::RegionPredicate {
+                        lifetime,
+                        bounds: bounds.into_iter().collect(),
+                    }),
+            )
+            .collect();
+
+        final_predicates
+    }
+
+    // Converts the calculated ParamEnv and lifetime information to a clean::Generics, suitable for
+    // display on the docs page. Cleaning the Predicates produces sub-optimal WherePredicate's,
+    // so we fix them up:
+    //
+    // * Multiple bounds for the same type are coalesced into one: e.g. 'T: Copy', 'T: Debug'
+    // becomes 'T: Copy + Debug'
+    // * Fn bounds are handled specially - instead of leaving it as 'T: Fn(), <T as Fn::Output> =
+    // K', we use the dedicated syntax 'T: Fn() -> K'
+    // * We explcitly add a '?Sized' bound if we didn't find any 'Sized' predicates for a type
+    fn param_env_to_generics<'b, 'c, 'cx>(
+        &self,
+        tcx: TyCtxt<'b, 'c, 'cx>,
+        did: DefId,
+        param_env: ty::ParamEnv<'cx>,
+        type_generics: ty::Generics,
+        mut existing_predicates: Vec<WherePredicate>,
+        vid_to_region: FxHashMap<ty::RegionVid, ty::Region<'cx>>,
+    ) -> Generics {
+        debug!(
+            "param_env_to_generics(did={:?}, param_env={:?}, type_generics={:?}, \
+             existing_predicates={:?})",
+            did, param_env, type_generics, existing_predicates
+        );
+
+        // The `Sized` trait must be handled specially, since we only only display it when
+        // it is *not* required (i.e. '?Sized')
+        let sized_trait = self.cx
+            .tcx
+            .require_lang_item(lang_items::SizedTraitLangItem);
+
+        let mut replacer = RegionReplacer {
+            vid_to_region: &vid_to_region,
+            tcx,
+        };
+
+        let orig_bounds: FxHashSet<_> = self.cx.tcx.param_env(did).caller_bounds.iter().collect();
+        let clean_where_predicates = param_env
+            .caller_bounds
+            .iter()
+            .filter(|p| {
+                !orig_bounds.contains(p) || match p {
+                    &&ty::Predicate::Trait(pred) => pred.def_id() == sized_trait,
+                    _ => false,
+                }
+            })
+            .map(|p| {
+                let replaced = p.fold_with(&mut replacer);
+                (replaced.clone(), replaced.clean(self.cx))
+            });
+
+        let full_generics = (&type_generics, &tcx.predicates_of(did));
+        let Generics {
+            params: mut generic_params,
+            ..
+        } = full_generics.clean(self.cx);
+
+        let mut has_sized = FxHashSet();
+        let mut ty_to_bounds = FxHashMap();
+        let mut lifetime_to_bounds = FxHashMap();
+        let mut ty_to_traits: FxHashMap<Type, FxHashSet<Type>> = FxHashMap();
+
+        let mut ty_to_fn: FxHashMap<Type, (Option<PolyTrait>, Option<Type>)> = FxHashMap();
+
+        for (orig_p, p) in clean_where_predicates {
+            match p {
+                WherePredicate::BoundPredicate { ty, mut bounds } => {
+                    // Writing a projection trait bound of the form
+                    // <T as Trait>::Name : ?Sized
+                    // is illegal, because ?Sized bounds can only
+                    // be written in the (here, nonexistant) definition
+                    // of the type.
+                    // Therefore, we make sure that we never add a ?Sized
+                    // bound for projections
+                    match &ty {
+                        &Type::QPath { .. } => {
+                            has_sized.insert(ty.clone());
+                        }
+                        _ => {}
+                    }
+
+                    if bounds.is_empty() {
+                        continue;
+                    }
+
+                    let mut for_generics = self.extract_for_generics(tcx, orig_p.clone());
+
+                    assert!(bounds.len() == 1);
+                    let mut b = bounds.pop().unwrap();
+
+                    if b.is_sized_bound(self.cx) {
+                        has_sized.insert(ty.clone());
+                    } else if !b.get_trait_type()
+                        .and_then(|t| {
+                            ty_to_traits
+                                .get(&ty)
+                                .map(|bounds| bounds.contains(&strip_type(t.clone())))
+                        })
+                        .unwrap_or(false)
+                    {
+                        // If we've already added a projection bound for the same type, don't add
+                        // this, as it would be a duplicate
+
+                        // Handle any 'Fn/FnOnce/FnMut' bounds specially,
+                        // as we want to combine them with any 'Output' qpaths
+                        // later
+
+                        let is_fn = match &mut b {
+                            &mut TyParamBound::TraitBound(ref mut p, _) => {
+                                // Insert regions into the for_generics hash map first, to ensure
+                                // that we don't end up with duplicate bounds (e.g. for<'b, 'b>)
+                                for_generics.extend(p.generic_params.clone());
+                                p.generic_params = for_generics.into_iter().collect();
+                                self.is_fn_ty(&tcx, &p.trait_)
+                            }
+                            _ => false,
+                        };
+
+                        let poly_trait = b.get_poly_trait().unwrap();
+
+                        if is_fn {
+                            ty_to_fn
+                                .entry(ty.clone())
+                                .and_modify(|e| *e = (Some(poly_trait.clone()), e.1.clone()))
+                                .or_insert(((Some(poly_trait.clone())), None));
+
+                            ty_to_bounds
+                                .entry(ty.clone())
+                                .or_insert_with(|| FxHashSet());
+                        } else {
+                            ty_to_bounds
+                                .entry(ty.clone())
+                                .or_insert_with(|| FxHashSet())
+                                .insert(b.clone());
+                        }
+                    }
+                }
+                WherePredicate::RegionPredicate { lifetime, bounds } => {
+                    lifetime_to_bounds
+                        .entry(lifetime)
+                        .or_insert_with(|| FxHashSet())
+                        .extend(bounds);
+                }
+                WherePredicate::EqPredicate { lhs, rhs } => {
+                    match &lhs {
+                        &Type::QPath {
+                            name: ref left_name,
+                            ref self_type,
+                            ref trait_,
+                        } => {
+                            let ty = &*self_type;
+                            match **trait_ {
+                                Type::ResolvedPath {
+                                    path: ref trait_path,
+                                    ref typarams,
+                                    ref did,
+                                    ref is_generic,
+                                } => {
+                                    let mut new_trait_path = trait_path.clone();
+
+                                    if self.is_fn_ty(&tcx, trait_) && left_name == FN_OUTPUT_NAME {
+                                        ty_to_fn
+                                            .entry(*ty.clone())
+                                            .and_modify(|e| *e = (e.0.clone(), Some(rhs.clone())))
+                                            .or_insert((None, Some(rhs)));
+                                        continue;
+                                    }
+
+                                    // FIXME: Remove this scope when NLL lands
+                                    {
+                                        let params =
+                                            &mut new_trait_path.segments.last_mut().unwrap().params;
+
+                                        match params {
+                                            // Convert somethiung like '<T as Iterator::Item> = u8'
+                                            // to 'T: Iterator<Item=u8>'
+                                            &mut PathParameters::AngleBracketed {
+                                                ref mut bindings,
+                                                ..
+                                            } => {
+                                                bindings.push(TypeBinding {
+                                                    name: left_name.clone(),
+                                                    ty: rhs,
+                                                });
+                                            }
+                                            &mut PathParameters::Parenthesized { .. } => {
+                                                existing_predicates.push(
+                                                    WherePredicate::EqPredicate {
+                                                        lhs: lhs.clone(),
+                                                        rhs,
+                                                    },
+                                                );
+                                                continue; // If something other than a Fn ends up
+                                                          // with parenthesis, leave it alone
+                                            }
+                                        }
+                                    }
+
+                                    let bounds = ty_to_bounds
+                                        .entry(*ty.clone())
+                                        .or_insert_with(|| FxHashSet());
+
+                                    bounds.insert(TyParamBound::TraitBound(
+                                        PolyTrait {
+                                            trait_: Type::ResolvedPath {
+                                                path: new_trait_path,
+                                                typarams: typarams.clone(),
+                                                did: did.clone(),
+                                                is_generic: *is_generic,
+                                            },
+                                            generic_params: Vec::new(),
+                                        },
+                                        hir::TraitBoundModifier::None,
+                                    ));
+
+                                    // Remove any existing 'plain' bound (e.g. 'T: Iterator`) so
+                                    // that we don't see a
+                                    // duplicate bound like `T: Iterator + Iterator<Item=u8>`
+                                    // on the docs page.
+                                    bounds.remove(&TyParamBound::TraitBound(
+                                        PolyTrait {
+                                            trait_: *trait_.clone(),
+                                            generic_params: Vec::new(),
+                                        },
+                                        hir::TraitBoundModifier::None,
+                                    ));
+                                    // Avoid creating any new duplicate bounds later in the outer
+                                    // loop
+                                    ty_to_traits
+                                        .entry(*ty.clone())
+                                        .or_insert_with(|| FxHashSet())
+                                        .insert(*trait_.clone());
+                                }
+                                _ => panic!("Unexpected trait {:?} for {:?}", trait_, did),
+                            }
+                        }
+                        _ => panic!("Unexpected LHS {:?} for {:?}", lhs, did),
+                    }
+                }
+            };
+        }
+
+        let final_bounds = self.make_final_bounds(ty_to_bounds, ty_to_fn, lifetime_to_bounds);
+
+        existing_predicates.extend(final_bounds);
+
+        for p in generic_params.iter_mut() {
+            match p {
+                &mut GenericParam::Type(ref mut ty) => {
+                    // We never want something like 'impl<T=Foo>'
+                    ty.default.take();
+
+                    let generic_ty = Type::Generic(ty.name.clone());
+
+                    if !has_sized.contains(&generic_ty) {
+                        ty.bounds.insert(0, TyParamBound::maybe_sized(self.cx));
+                    }
+                }
+                _ => {}
+            }
+        }
+
+        Generics {
+            params: generic_params,
+            where_predicates: existing_predicates,
+        }
+    }
+
+    fn is_fn_ty(&self, tcx: &TyCtxt, ty: &Type) -> bool {
+        match &ty {
+            &&Type::ResolvedPath { ref did, .. } => {
+                *did == tcx.require_lang_item(lang_items::FnTraitLangItem)
+                    || *did == tcx.require_lang_item(lang_items::FnMutTraitLangItem)
+                    || *did == tcx.require_lang_item(lang_items::FnOnceTraitLangItem)
+            }
+            _ => false,
+        }
+    }
+
+    // This is an ugly hack, but it's the simplest way to handle synthetic impls without greatly
+    // refactorying either librustdoc or librustc. In particular, allowing new DefIds to be
+    // registered after the AST is constructed would require storing the defid mapping in a
+    // RefCell, decreasing the performance for normal compilation for very little gain.
+    //
+    // Instead, we construct 'fake' def ids, which start immediately after the last DefId in
+    // DefIndexAddressSpace::Low. In the Debug impl for clean::Item, we explicitly check for fake
+    // def ids, as we'll end up with a panic if we use the DefId Debug impl for fake DefIds
+    fn next_def_id(&self, crate_num: CrateNum) -> DefId {
+        let start_def_id = {
+            let next_id = if crate_num == LOCAL_CRATE {
+                self.cx
+                    .tcx
+                    .hir
+                    .definitions()
+                    .def_path_table()
+                    .next_id(DefIndexAddressSpace::Low)
+            } else {
+                self.cx
+                    .cstore
+                    .def_path_table(crate_num)
+                    .next_id(DefIndexAddressSpace::Low)
+            };
+
+            DefId {
+                krate: crate_num,
+                index: next_id,
+            }
+        };
+
+        let mut fake_ids = self.cx.fake_def_ids.borrow_mut();
+
+        let def_id = fake_ids.entry(crate_num).or_insert(start_def_id).clone();
+        fake_ids.insert(
+            crate_num,
+            DefId {
+                krate: crate_num,
+                index: DefIndex::from_array_index(
+                    def_id.index.as_array_index() + 1,
+                    def_id.index.address_space(),
+                ),
+            },
+        );
+
+        MAX_DEF_ID.with(|m| {
+            m.borrow_mut()
+                .entry(def_id.krate.clone())
+                .or_insert(start_def_id);
+        });
+
+        self.cx.all_fake_def_ids.borrow_mut().insert(def_id);
+
+        def_id.clone()
+    }
+}
+
+// Replaces all ReVars in a type with ty::Region's, using the provided map
+struct RegionReplacer<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
+    vid_to_region: &'a FxHashMap<ty::RegionVid, ty::Region<'tcx>>,
+    tcx: TyCtxt<'a, 'gcx, 'tcx>,
+}
+
+impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for RegionReplacer<'a, 'gcx, 'tcx> {
+    fn tcx<'b>(&'b self) -> TyCtxt<'b, 'gcx, 'tcx> {
+        self.tcx
+    }
+
+    fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
+        (match r {
+            &ty::ReVar(vid) => self.vid_to_region.get(&vid).cloned(),
+            _ => None,
+        }).unwrap_or_else(|| r.super_fold_with(self))
+    }
+}
diff --git a/src/librustdoc/clean/cfg.rs b/src/librustdoc/clean/cfg.rs
index 5eb3e38d5b3..a769771f8aa 100644
--- a/src/librustdoc/clean/cfg.rs
+++ b/src/librustdoc/clean/cfg.rs
@@ -25,7 +25,7 @@ use syntax_pos::Span;
 
 use html::escape::Escape;
 
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug, PartialEq)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug, PartialEq, Eq, Hash)]
 pub enum Cfg {
     /// Accepts all configurations.
     True,
diff --git a/src/librustdoc/clean/inline.rs b/src/librustdoc/clean/inline.rs
index 9aba399b3b0..f32dbcb8a08 100644
--- a/src/librustdoc/clean/inline.rs
+++ b/src/librustdoc/clean/inline.rs
@@ -12,8 +12,8 @@
 
 use std::collections::BTreeMap;
 use std::io;
-use std::iter::once;
 use std::rc::Rc;
+use std::iter::once;
 
 use syntax::ast;
 use rustc::hir;
@@ -25,7 +25,7 @@ use rustc::util::nodemap::FxHashSet;
 
 use core::{DocContext, DocAccessLevels};
 use doctree;
-use clean::{self, GetDefId};
+use clean::{self, GetDefId, get_auto_traits_with_def_id};
 
 use super::Clean;
 
@@ -50,7 +50,7 @@ pub fn try_inline(cx: &DocContext, def: Def, name: ast::Name)
     let inner = match def {
         Def::Trait(did) => {
             record_extern_fqn(cx, did, clean::TypeKind::Trait);
-            ret.extend(build_impls(cx, did));
+            ret.extend(build_impls(cx, did, false));
             clean::TraitItem(build_external_trait(cx, did))
         }
         Def::Fn(did) => {
@@ -59,27 +59,27 @@ pub fn try_inline(cx: &DocContext, def: Def, name: ast::Name)
         }
         Def::Struct(did) => {
             record_extern_fqn(cx, did, clean::TypeKind::Struct);
-            ret.extend(build_impls(cx, did));
+            ret.extend(build_impls(cx, did, true));
             clean::StructItem(build_struct(cx, did))
         }
         Def::Union(did) => {
             record_extern_fqn(cx, did, clean::TypeKind::Union);
-            ret.extend(build_impls(cx, did));
+            ret.extend(build_impls(cx, did, true));
             clean::UnionItem(build_union(cx, did))
         }
         Def::TyAlias(did) => {
             record_extern_fqn(cx, did, clean::TypeKind::Typedef);
-            ret.extend(build_impls(cx, did));
+            ret.extend(build_impls(cx, did, true));
             clean::TypedefItem(build_type_alias(cx, did), false)
         }
         Def::Enum(did) => {
             record_extern_fqn(cx, did, clean::TypeKind::Enum);
-            ret.extend(build_impls(cx, did));
+            ret.extend(build_impls(cx, did, true));
             clean::EnumItem(build_enum(cx, did))
         }
         Def::TyForeign(did) => {
             record_extern_fqn(cx, did, clean::TypeKind::Foreign);
-            ret.extend(build_impls(cx, did));
+            ret.extend(build_impls(cx, did, false));
             clean::ForeignTypeItem
         }
         // Never inline enum variants but leave them shown as re-exports.
@@ -120,11 +120,17 @@ pub fn load_attrs(cx: &DocContext, did: DefId) -> clean::Attributes {
     cx.tcx.get_attrs(did).clean(cx)
 }
 
+
 /// Record an external fully qualified name in the external_paths cache.
 ///
 /// These names are used later on by HTML rendering to generate things like
 /// source links back to the original item.
 pub fn record_extern_fqn(cx: &DocContext, did: DefId, kind: clean::TypeKind) {
+    if did.is_local() {
+        debug!("record_extern_fqn(did={:?}, kind+{:?}): def_id is local, aborting", did, kind);
+        return;
+    }
+
     let crate_name = cx.tcx.crate_name(did.krate).to_string();
     let relative = cx.tcx.def_path(did).data.into_iter().filter_map(|elem| {
         // extern blocks have an empty name
@@ -144,6 +150,7 @@ pub fn record_extern_fqn(cx: &DocContext, did: DefId, kind: clean::TypeKind) {
 }
 
 pub fn build_external_trait(cx: &DocContext, did: DefId) -> clean::Trait {
+    let auto_trait = cx.tcx.trait_def(did).has_auto_impl;
     let trait_items = cx.tcx.associated_items(did).map(|item| item.clean(cx)).collect();
     let predicates = cx.tcx.predicates_of(did);
     let generics = (cx.tcx.generics_of(did), &predicates).clean(cx);
@@ -152,6 +159,7 @@ pub fn build_external_trait(cx: &DocContext, did: DefId) -> clean::Trait {
     let is_spotlight = load_attrs(cx, did).has_doc_flag("spotlight");
     let is_auto = cx.tcx.trait_is_auto(did);
     clean::Trait {
+        auto: auto_trait,
         unsafety: cx.tcx.trait_def(did).unsafety,
         generics,
         items: trait_items,
@@ -227,7 +235,7 @@ fn build_type_alias(cx: &DocContext, did: DefId) -> clean::Typedef {
     }
 }
 
-pub fn build_impls(cx: &DocContext, did: DefId) -> Vec<clean::Item> {
+pub fn build_impls(cx: &DocContext, did: DefId, auto_traits: bool) -> Vec<clean::Item> {
     let tcx = cx.tcx;
     let mut impls = Vec::new();
 
@@ -235,6 +243,16 @@ pub fn build_impls(cx: &DocContext, did: DefId) -> Vec<clean::Item> {
         build_impl(cx, did, &mut impls);
     }
 
+    if auto_traits {
+        let auto_impls = get_auto_traits_with_def_id(cx, did);
+        let mut renderinfo = cx.renderinfo.borrow_mut();
+
+        let new_impls: Vec<clean::Item> = auto_impls.into_iter()
+            .filter(|i| renderinfo.inlined.insert(i.def_id)).collect();
+
+        impls.extend(new_impls);
+    }
+
     // If this is the first time we've inlined something from another crate, then
     // we inline *all* impls from all the crates into this crate. Note that there's
     // currently no way for us to filter this based on type, and we likely need
@@ -249,6 +267,7 @@ pub fn build_impls(cx: &DocContext, did: DefId) -> Vec<clean::Item> {
 
     cx.populated_all_crate_impls.set(true);
 
+
     for &cnum in tcx.crates().iter() {
         for did in tcx.all_trait_implementations(cnum).iter() {
             build_impl(cx, *did, &mut impls);
@@ -347,13 +366,14 @@ pub fn build_impl(cx: &DocContext, did: DefId, ret: &mut Vec<clean::Item>) {
 
     ret.push(clean::Item {
         inner: clean::ImplItem(clean::Impl {
-            unsafety: hir::Unsafety::Normal, // FIXME: this should be decoded
+            unsafety: hir::Unsafety::Normal,
+            generics: (tcx.generics_of(did), &predicates).clean(cx),
             provided_trait_methods: provided,
             trait_,
             for_,
-            generics: (tcx.generics_of(did), &predicates).clean(cx),
             items: trait_items,
             polarity: Some(polarity.clean(cx)),
+            synthetic: false
         }),
         source: tcx.def_span(did).clean(cx),
         name: None,
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 7f51b8f68ae..fcefe6cf642 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -26,31 +26,41 @@ use syntax::codemap::Spanned;
 use syntax::feature_gate::UnstableFeatures;
 use syntax::ptr::P;
 use syntax::symbol::keywords;
+use syntax::symbol::Symbol;
 use syntax_pos::{self, DUMMY_SP, Pos, FileName};
 
 use rustc::middle::const_val::ConstVal;
 use rustc::middle::privacy::AccessLevels;
 use rustc::middle::resolve_lifetime as rl;
+use rustc::ty::fold::TypeFolder;
 use rustc::middle::lang_items;
-use rustc::hir::def::{Def, CtorKind};
-use rustc::hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
+use rustc::hir::{self, HirVec};
+use rustc::hir::def::{self, Def, CtorKind};
+use rustc::hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX, LOCAL_CRATE};
+use rustc::hir::def_id::DefIndexAddressSpace;
+use rustc::traits;
 use rustc::ty::subst::Substs;
-use rustc::ty::{self, Ty, AdtKind};
+use rustc::ty::{self, TyCtxt, Region, RegionVid, Ty, AdtKind};
 use rustc::middle::stability;
 use rustc::util::nodemap::{FxHashMap, FxHashSet};
 use rustc_typeck::hir_ty_to_ty;
-
-use rustc::hir;
+use rustc::infer::{InferCtxt, RegionObligation};
+use rustc::infer::region_constraints::{RegionConstraintData, Constraint};
+use rustc::traits::*;
+use std::collections::hash_map::Entry;
+use std::collections::VecDeque;
+use std::fmt;
 
 use rustc_const_math::ConstInt;
 use std::default::Default;
 use std::{mem, slice, vec};
-use std::iter::FromIterator;
+use std::iter::{FromIterator, once};
 use std::rc::Rc;
+use std::cell::RefCell;
 use std::sync::Arc;
 use std::u32;
 
-use core::DocContext;
+use core::{self, DocContext};
 use doctree;
 use visit_ast;
 use html::item_type::ItemType;
@@ -59,8 +69,14 @@ use html::markdown::markdown_links;
 pub mod inline;
 pub mod cfg;
 mod simplify;
+mod auto_trait;
 
 use self::cfg::Cfg;
+use self::auto_trait::AutoTraitFinder;
+
+thread_local!(static MAX_DEF_ID: RefCell<FxHashMap<CrateNum, DefId>> = RefCell::new(FxHashMap()));
+
+const FN_OUTPUT_NAME: &'static str = "Output";
 
 // extract the stability index for a node from tcx, if possible
 fn get_stability(cx: &DocContext, def_id: DefId) -> Option<Stability> {
@@ -282,7 +298,7 @@ impl Clean<ExternalCrate> for CrateNum {
 /// Anything with a source location and set of attributes and, optionally, a
 /// name. That is, anything that can be documented. This doesn't correspond
 /// directly to the AST's concept of an item; it's a strict superset.
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable)]
 pub struct Item {
     /// Stringified span
     pub source: Span,
@@ -296,6 +312,26 @@ pub struct Item {
     pub deprecation: Option<Deprecation>,
 }
 
+impl fmt::Debug for Item {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+
+        let fake = MAX_DEF_ID.with(|m| m.borrow().get(&self.def_id.krate)
+                                   .map(|id| self.def_id >= *id).unwrap_or(false));
+        let def_id: &fmt::Debug = if fake { &"**FAKE**" } else { &self.def_id };
+
+        fmt.debug_struct("Item")
+            .field("source", &self.source)
+            .field("name", &self.name)
+            .field("attrs", &self.attrs)
+            .field("inner", &self.inner)
+            .field("visibility", &self.visibility)
+            .field("def_id", def_id)
+            .field("stability", &self.stability)
+            .field("deprecation", &self.deprecation)
+            .finish()
+    }
+}
+
 impl Item {
     /// Finds the `doc` attribute as a NameValue and returns the corresponding
     /// value found.
@@ -492,9 +528,9 @@ impl Clean<Item> for doctree::Module {
         let mut items: Vec<Item> = vec![];
         items.extend(self.extern_crates.iter().map(|x| x.clean(cx)));
         items.extend(self.imports.iter().flat_map(|x| x.clean(cx)));
-        items.extend(self.structs.iter().map(|x| x.clean(cx)));
-        items.extend(self.unions.iter().map(|x| x.clean(cx)));
-        items.extend(self.enums.iter().map(|x| x.clean(cx)));
+        items.extend(self.structs.iter().flat_map(|x| x.clean(cx)));
+        items.extend(self.unions.iter().flat_map(|x| x.clean(cx)));
+        items.extend(self.enums.iter().flat_map(|x| x.clean(cx)));
         items.extend(self.fns.iter().map(|x| x.clean(cx)));
         items.extend(self.foreigns.iter().flat_map(|x| x.clean(cx)));
         items.extend(self.mods.iter().map(|x| x.clean(cx)));
@@ -601,7 +637,7 @@ impl<I: IntoIterator<Item=ast::NestedMetaItem>> NestedAttributesExt for I {
 /// Included files are kept separate from inline doc comments so that proper line-number
 /// information can be given when a doctest fails. Sugared doc comments and "raw" doc comments are
 /// kept separate because of issue #42760.
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub enum DocFragment {
     // FIXME #44229 (misdreavus): sugared and raw doc comments can be brought back together once
     // hoedown is completely removed from rustdoc.
@@ -653,7 +689,7 @@ impl<'a> FromIterator<&'a DocFragment> for String {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug, Default)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Default, Hash)]
 pub struct Attributes {
     pub doc_strings: Vec<DocFragment>,
     pub other_attrs: Vec<ast::Attribute>,
@@ -1177,7 +1213,7 @@ impl Clean<Attributes> for [ast::Attribute] {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub struct TyParam {
     pub name: String,
     pub did: DefId,
@@ -1212,7 +1248,7 @@ impl<'tcx> Clean<TyParam> for ty::TypeParameterDef {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub enum TyParamBound {
     RegionBound(Lifetime),
     TraitBound(PolyTrait, hir::TraitBoundModifier)
@@ -1245,6 +1281,21 @@ impl TyParamBound {
         }
         false
     }
+
+    fn get_poly_trait(&self) -> Option<PolyTrait> {
+        if let TyParamBound::TraitBound(ref p, _) = *self {
+            return Some(p.clone())
+        }
+        None
+    }
+
+    fn get_trait_type(&self) -> Option<Type> {
+
+        if let TyParamBound::TraitBound(PolyTrait { ref trait_, .. }, _) = *self {
+            return Some(trait_.clone());
+        }
+        None
+    }
 }
 
 impl Clean<TyParamBound> for hir::TyParamBound {
@@ -1363,7 +1414,7 @@ impl<'tcx> Clean<Option<Vec<TyParamBound>>> for Substs<'tcx> {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub struct Lifetime(String);
 
 impl Lifetime {
@@ -1380,17 +1431,19 @@ impl Lifetime {
 
 impl Clean<Lifetime> for hir::Lifetime {
     fn clean(&self, cx: &DocContext) -> Lifetime {
-        let hir_id = cx.tcx.hir.node_to_hir_id(self.id);
-        let def = cx.tcx.named_region(hir_id);
-        match def {
-            Some(rl::Region::EarlyBound(_, node_id, _)) |
-            Some(rl::Region::LateBound(_, node_id, _)) |
-            Some(rl::Region::Free(_, node_id)) => {
-                if let Some(lt) = cx.lt_substs.borrow().get(&node_id).cloned() {
-                    return lt;
+        if self.id != ast::DUMMY_NODE_ID {
+            let hir_id = cx.tcx.hir.node_to_hir_id(self.id);
+            let def = cx.tcx.named_region(hir_id);
+            match def {
+                Some(rl::Region::EarlyBound(_, node_id, _)) |
+                Some(rl::Region::LateBound(_, node_id, _)) |
+                Some(rl::Region::Free(_, node_id)) => {
+                    if let Some(lt) = cx.lt_substs.borrow().get(&node_id).cloned() {
+                        return lt;
+                    }
                 }
+                _ => {}
             }
-            _ => {}
         }
         Lifetime(self.name.name().to_string())
     }
@@ -1437,7 +1490,7 @@ impl Clean<Option<Lifetime>> for ty::RegionKind {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub enum WherePredicate {
     BoundPredicate { ty: Type, bounds: Vec<TyParamBound> },
     RegionPredicate { lifetime: Lifetime, bounds: Vec<Lifetime>},
@@ -1562,7 +1615,7 @@ impl<'tcx> Clean<Type> for ty::ProjectionTy<'tcx> {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub enum GenericParam {
     Lifetime(Lifetime),
     Type(TyParam),
@@ -1577,7 +1630,8 @@ impl Clean<GenericParam> for hir::GenericParam {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug, Default)]
+// maybe use a Generic enum and use Vec<Generic>?
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Default, Hash)]
 pub struct Generics {
     pub params: Vec<GenericParam>,
     pub where_predicates: Vec<WherePredicate>,
@@ -1747,7 +1801,7 @@ impl Clean<Item> for doctree::Function {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub struct FnDecl {
     pub inputs: Arguments,
     pub output: FunctionRetTy,
@@ -1765,7 +1819,7 @@ impl FnDecl {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub struct Arguments {
     pub values: Vec<Argument>,
 }
@@ -1840,7 +1894,7 @@ impl<'a, 'tcx> Clean<FnDecl> for (DefId, ty::PolyFnSig<'tcx>) {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub struct Argument {
     pub type_: Type,
     pub name: String,
@@ -1870,7 +1924,7 @@ impl Argument {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub enum FunctionRetTy {
     Return(Type),
     DefaultReturn,
@@ -1896,6 +1950,7 @@ impl GetDefId for FunctionRetTy {
 
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Trait {
+    pub auto: bool,
     pub unsafety: hir::Unsafety,
     pub items: Vec<Item>,
     pub generics: Generics,
@@ -1917,6 +1972,7 @@ impl Clean<Item> for doctree::Trait {
             stability: self.stab.clean(cx),
             deprecation: self.depr.clean(cx),
             inner: TraitItem(Trait {
+                auto: self.is_auto.clean(cx),
                 unsafety: self.unsafety,
                 items: self.items.clean(cx),
                 generics: self.generics.clean(cx),
@@ -2158,7 +2214,7 @@ impl<'tcx> Clean<Item> for ty::AssociatedItem {
 }
 
 /// A trait reference, which may have higher ranked lifetimes.
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub struct PolyTrait {
     pub trait_: Type,
     pub generic_params: Vec<GenericParam>,
@@ -2167,7 +2223,7 @@ pub struct PolyTrait {
 /// A representation of a Type suitable for hyperlinking purposes. Ideally one can get the original
 /// type out of the AST/TyCtxt given one of these, if more information is needed. Most importantly
 /// it does not preserve mutability or boxes.
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub enum Type {
     /// structs/enums/traits (most that'd be an hir::TyPath)
     ResolvedPath {
@@ -2782,10 +2838,13 @@ pub struct Union {
     pub fields_stripped: bool,
 }
 
-impl Clean<Item> for doctree::Struct {
-    fn clean(&self, cx: &DocContext) -> Item {
-        Item {
-            name: Some(self.name.clean(cx)),
+impl Clean<Vec<Item>> for doctree::Struct {
+    fn clean(&self, cx: &DocContext) -> Vec<Item> {
+        let name = self.name.clean(cx);
+        let mut ret = get_auto_traits_with_node_id(cx, self.id, name.clone());
+
+        ret.push(Item {
+            name: Some(name),
             attrs: self.attrs.clean(cx),
             source: self.whence.clean(cx),
             def_id: cx.tcx.hir.local_def_id(self.id),
@@ -2798,14 +2857,19 @@ impl Clean<Item> for doctree::Struct {
                 fields: self.fields.clean(cx),
                 fields_stripped: false,
             }),
-        }
+        });
+
+        ret
     }
 }
 
-impl Clean<Item> for doctree::Union {
-    fn clean(&self, cx: &DocContext) -> Item {
-        Item {
-            name: Some(self.name.clean(cx)),
+impl Clean<Vec<Item>> for doctree::Union {
+    fn clean(&self, cx: &DocContext) -> Vec<Item> {
+        let name = self.name.clean(cx);
+        let mut ret = get_auto_traits_with_node_id(cx, self.id, name.clone());
+
+        ret.push(Item {
+            name: Some(name),
             attrs: self.attrs.clean(cx),
             source: self.whence.clean(cx),
             def_id: cx.tcx.hir.local_def_id(self.id),
@@ -2818,7 +2882,9 @@ impl Clean<Item> for doctree::Union {
                 fields: self.fields.clean(cx),
                 fields_stripped: false,
             }),
-        }
+        });
+
+        ret
     }
 }
 
@@ -2849,10 +2915,13 @@ pub struct Enum {
     pub variants_stripped: bool,
 }
 
-impl Clean<Item> for doctree::Enum {
-    fn clean(&self, cx: &DocContext) -> Item {
-        Item {
-            name: Some(self.name.clean(cx)),
+impl Clean<Vec<Item>> for doctree::Enum {
+    fn clean(&self, cx: &DocContext) -> Vec<Item> {
+        let name = self.name.clean(cx);
+        let mut ret = get_auto_traits_with_node_id(cx, self.id, name.clone());
+
+        ret.push(Item {
+            name: Some(name),
             attrs: self.attrs.clean(cx),
             source: self.whence.clean(cx),
             def_id: cx.tcx.hir.local_def_id(self.id),
@@ -2864,7 +2933,9 @@ impl Clean<Item> for doctree::Enum {
                 generics: self.generics.clean(cx),
                 variants_stripped: false,
             }),
-        }
+        });
+
+        ret
     }
 }
 
@@ -2989,7 +3060,7 @@ impl Clean<Span> for syntax_pos::Span {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub struct Path {
     pub global: bool,
     pub def: Def,
@@ -3027,7 +3098,7 @@ impl Clean<Path> for hir::Path {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub enum PathParameters {
     AngleBracketed {
         lifetimes: Vec<Lifetime>,
@@ -3062,7 +3133,7 @@ impl Clean<PathParameters> for hir::PathParameters {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub struct PathSegment {
     pub name: String,
     pub params: PathParameters,
@@ -3077,6 +3148,50 @@ impl Clean<PathSegment> for hir::PathSegment {
     }
 }
 
+fn strip_type(ty: Type) -> Type {
+    match ty {
+        Type::ResolvedPath { path, typarams, did, is_generic } => {
+            Type::ResolvedPath { path: strip_path(&path), typarams, did, is_generic }
+        },
+        Type::Tuple(inner_tys) => {
+            Type::Tuple(inner_tys.iter().map(|t| strip_type(t.clone())).collect())
+        },
+        Type::Slice(inner_ty) => Type::Slice(Box::new(strip_type(*inner_ty))),
+        Type::Array(inner_ty, s) => Type::Array(Box::new(strip_type(*inner_ty)), s),
+        Type::Unique(inner_ty) => Type::Unique(Box::new(strip_type(*inner_ty))),
+        Type::RawPointer(m, inner_ty) => Type::RawPointer(m, Box::new(strip_type(*inner_ty))),
+        Type::BorrowedRef { lifetime, mutability, type_ } => {
+            Type::BorrowedRef { lifetime, mutability, type_: Box::new(strip_type(*type_)) }
+        },
+        Type::QPath { name, self_type, trait_ } => {
+            Type::QPath {
+                name,
+                self_type: Box::new(strip_type(*self_type)), trait_: Box::new(strip_type(*trait_))
+            }
+        },
+        _ => ty
+    }
+}
+
+fn strip_path(path: &Path) -> Path {
+    let segments = path.segments.iter().map(|s| {
+        PathSegment {
+            name: s.name.clone(),
+            params: PathParameters::AngleBracketed {
+                lifetimes: Vec::new(),
+                types: Vec::new(),
+                bindings: Vec::new()
+            }
+        }
+    }).collect();
+
+    Path {
+        global: path.global,
+        def: path.def.clone(),
+        segments
+    }
+}
+
 fn qpath_to_string(p: &hir::QPath) -> String {
     let segments = match *p {
         hir::QPath::Resolved(_, ref path) => &path.segments,
@@ -3125,7 +3240,7 @@ impl Clean<Item> for doctree::Typedef {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
 pub struct BareFunctionDecl {
     pub unsafety: hir::Unsafety,
     pub generic_params: Vec<GenericParam>,
@@ -3198,7 +3313,7 @@ impl Clean<Item> for doctree::Constant {
     }
 }
 
-#[derive(Debug, Clone, RustcEncodable, RustcDecodable, PartialEq, Copy)]
+#[derive(Debug, Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Copy, Hash)]
 pub enum Mutability {
     Mutable,
     Immutable,
@@ -3213,7 +3328,7 @@ impl Clean<Mutability> for hir::Mutability {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Copy, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Copy, Debug, Hash)]
 pub enum ImplPolarity {
     Positive,
     Negative,
@@ -3237,6 +3352,21 @@ pub struct Impl {
     pub for_: Type,
     pub items: Vec<Item>,
     pub polarity: Option<ImplPolarity>,
+    pub synthetic: bool,
+}
+
+pub fn get_auto_traits_with_node_id(cx: &DocContext, id: ast::NodeId, name: String) -> Vec<Item> {
+    let finder = AutoTraitFinder { cx };
+    finder.get_with_node_id(id, name)
+}
+
+pub fn get_auto_traits_with_def_id(cx: &DocContext, id: DefId) -> Vec<Item> {
+
+    let finder = AutoTraitFinder {
+        cx,
+    };
+
+    finder.get_with_def_id(id)
 }
 
 impl Clean<Vec<Item>> for doctree::Impl {
@@ -3274,7 +3404,8 @@ impl Clean<Vec<Item>> for doctree::Impl {
                 for_: self.for_.clean(cx),
                 items,
                 polarity: Some(self.polarity.clean(cx)),
-            }),
+                synthetic: false
+            })
         });
         ret
     }
@@ -3294,7 +3425,7 @@ fn build_deref_target_impls(cx: &DocContext,
         let primitive = match *target {
             ResolvedPath { did, .. } if did.is_local() => continue,
             ResolvedPath { did, .. } => {
-                ret.extend(inline::build_impls(cx, did));
+                ret.extend(inline::build_impls(cx, did, true));
                 continue
             }
             _ => match target.primitive_type() {
@@ -3514,7 +3645,11 @@ fn print_const_expr(cx: &DocContext, body: hir::BodyId) -> String {
 fn resolve_type(cx: &DocContext,
                 path: Path,
                 id: ast::NodeId) -> Type {
-    debug!("resolve_type({:?},{:?})", path, id);
+    if id == ast::DUMMY_NODE_ID {
+        debug!("resolve_type({:?})", path);
+    } else {
+        debug!("resolve_type({:?},{:?})", path, id);
+    }
 
     let is_generic = match path.def {
         Def::PrimTy(p) => match p {
@@ -3669,7 +3804,7 @@ impl Clean<Deprecation> for attr::Deprecation {
 }
 
 /// An equality constraint on an associated type, e.g. `A=Bar` in `Foo<A=Bar>`
-#[derive(Clone, PartialEq, RustcDecodable, RustcEncodable, Debug)]
+#[derive(Clone, PartialEq, Eq, RustcDecodable, RustcEncodable, Debug, Hash)]
 pub struct TypeBinding {
     pub name: String,
     pub ty: Type
@@ -3683,3 +3818,191 @@ impl Clean<TypeBinding> for hir::TypeBinding {
         }
     }
 }
+
+
+
+pub fn def_id_to_path(cx: &DocContext, did: DefId, name: Option<String>) -> Vec<String> {
+    let crate_name = name.unwrap_or_else(|| cx.tcx.crate_name(did.krate).to_string());
+    let relative = cx.tcx.def_path(did).data.into_iter().filter_map(|elem| {
+        // extern blocks have an empty name
+        let s = elem.data.to_string();
+        if !s.is_empty() {
+            Some(s)
+        } else {
+            None
+        }
+    });
+    once(crate_name).chain(relative).collect()
+}
+
+
+// Start of code copied from rust-clippy
+
+pub fn get_trait_def_id(tcx: &TyCtxt, path: &[&str], use_local: bool) -> Option<DefId> {
+    return if use_local {
+        path_to_def_local(tcx, path)
+    } else {
+        path_to_def(tcx, path)
+    };
+}
+
+pub fn path_to_def_local(tcx: &TyCtxt, path: &[&str]) -> Option<DefId> {
+    let krate = tcx.hir.krate();
+    let mut items = krate.module.item_ids.clone();
+    let mut path_it = path.iter().peekable();
+
+    loop {
+        let segment = match path_it.next() {
+            Some(segment) => segment,
+            None => return None,
+        };
+
+        for item_id in mem::replace(&mut items, HirVec::new()).iter() {
+            let item = tcx.hir.expect_item(item_id.id);
+            if item.name == *segment {
+                if path_it.peek().is_none() {
+                    return Some(tcx.hir.local_def_id(item_id.id))
+                }
+
+                items = match &item.node {
+                    &hir::ItemMod(ref m) => m.item_ids.clone(),
+                    _ => panic!("Unexpected item {:?} in path {:?} path")
+                };
+                break;
+            }
+        }
+    }
+
+}
+
+pub fn path_to_def(tcx: &TyCtxt, path: &[&str]) -> Option<DefId> {
+    let crates = tcx.crates();
+
+
+    let krate = crates
+        .iter()
+        .find(|&&krate| tcx.crate_name(krate) == path[0]);
+
+    if let Some(krate) = krate {
+        let krate = DefId {
+            krate: *krate,
+            index: CRATE_DEF_INDEX,
+        };
+        let mut items = tcx.item_children(krate);
+        let mut path_it = path.iter().skip(1).peekable();
+
+        loop {
+            let segment = match path_it.next() {
+                Some(segment) => segment,
+                None => return None,
+            };
+
+            for item in mem::replace(&mut items, Rc::new(vec![])).iter() {
+                if item.ident.name == *segment {
+                    if path_it.peek().is_none() {
+                        return match item.def {
+                            def::Def::Trait(did) => Some(did),
+                            _ => None
+                        }
+                    }
+
+                    items = tcx.item_children(item.def.def_id());
+                    break;
+                }
+            }
+        }
+    } else {
+        None
+    }
+}
+
+fn get_path_for_type(tcx: TyCtxt, def_id: DefId, def_ctor: fn(DefId) -> Def) -> hir::Path {
+    struct AbsolutePathBuffer {
+        names: Vec<String>,
+    }
+
+    impl ty::item_path::ItemPathBuffer for AbsolutePathBuffer {
+        fn root_mode(&self) -> &ty::item_path::RootMode {
+            const ABSOLUTE: &'static ty::item_path::RootMode = &ty::item_path::RootMode::Absolute;
+            ABSOLUTE
+        }
+
+        fn push(&mut self, text: &str) {
+            self.names.push(text.to_owned());
+        }
+    }
+
+    let mut apb = AbsolutePathBuffer { names: vec![] };
+
+    tcx.push_item_path(&mut apb, def_id);
+
+    hir::Path {
+        span: DUMMY_SP,
+        def: def_ctor(def_id),
+        segments: hir::HirVec::from_vec(apb.names.iter().map(|s| hir::PathSegment {
+            name: ast::Name::intern(&s),
+            parameters: None,
+            infer_types: false
+        }).collect())
+    }
+}
+
+// End of code copied from rust-clippy
+
+
+#[derive(Eq, PartialEq, Hash, Copy, Clone, Debug)]
+enum RegionTarget<'tcx> {
+    Region(Region<'tcx>),
+    RegionVid(RegionVid)
+}
+
+#[derive(Default, Debug, Clone)]
+struct RegionDeps<'tcx> {
+    larger: FxHashSet<RegionTarget<'tcx>>,
+    smaller: FxHashSet<RegionTarget<'tcx>>
+}
+
+#[derive(Eq, PartialEq, Hash, Debug)]
+enum SimpleBound {
+    RegionBound(Lifetime),
+    TraitBound(Vec<PathSegment>, Vec<SimpleBound>, Vec<GenericParam>, hir::TraitBoundModifier)
+}
+
+enum AutoTraitResult {
+    ExplicitImpl,
+
+    PositiveImpl(Generics),
+
+    NegativeImpl,
+}
+
+impl AutoTraitResult {
+
+    fn is_auto(&self) -> bool {
+        match *self {
+            AutoTraitResult::PositiveImpl(_) | AutoTraitResult::NegativeImpl => true,
+            _ => false
+        }
+    }
+}
+
+impl From<TyParamBound> for SimpleBound {
+
+    fn from(bound: TyParamBound) -> Self {
+        match bound.clone() {
+            TyParamBound::RegionBound(l) => SimpleBound::RegionBound(l),
+            TyParamBound::TraitBound(t, mod_) => match t.trait_ {
+                Type::ResolvedPath { path, typarams, .. } => {
+                    SimpleBound::TraitBound(path.segments,
+                                            typarams
+                                                .map_or_else(|| Vec::new(), |v| v.iter()
+                                                        .map(|p| SimpleBound::from(p.clone()))
+                                                        .collect()),
+                                            t.generic_params,
+                                            mod_)
+                },
+                _ => panic!("Unexpected bound {:?}", bound)
+            }
+        }
+    }
+}