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Reworked auto trait functionality in rustdoc.

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This commit is contained in:
Inokentiy Babushkin 2018-04-05 20:10:15 +02:00
parent 136abb9fb5
commit 5e1f92cd84
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GPG key ID: 7EFC8EC5224DE8EC
3 changed files with 62 additions and 734 deletions
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220
src/librustc/traits/auto_trait.rs
View file

@ -15,8 +15,6 @@ use std::collections::hash_map::Entry;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use hir::WherePredicate;
use infer::{InferCtxt, RegionObligation};
use infer::region_constraints::{Constraint, RegionConstraintData};
@ -36,32 +34,42 @@ pub struct RegionDeps<'tcx> {
smaller: FxHashSet<RegionTarget<'tcx>>
}
pub enum AutoTraitResult {
pub enum AutoTraitResult<A> {
ExplicitImpl,
PositiveImpl, /*(ty::Generics), TODO(twk)*/
PositiveImpl(A),
NegativeImpl,
}
impl AutoTraitResult {
impl<A> AutoTraitResult<A> {
fn is_auto(&self) -> bool {
match *self {
AutoTraitResult::PositiveImpl | AutoTraitResult::NegativeImpl => true,
AutoTraitResult::PositiveImpl(_) | AutoTraitResult::NegativeImpl => true,
_ => false,
}
}
}
pub struct AutoTraitInfo<'cx> {
pub full_user_env: ty::ParamEnv<'cx>,
pub region_data: RegionConstraintData<'cx>,
pub names_map: FxHashMap<String, String>,
pub vid_to_region: FxHashMap<ty::RegionVid, ty::Region<'cx>>,
}
pub struct AutoTraitFinder<'a, 'tcx: 'a> {
pub tcx: &'a TyCtxt<'a, 'tcx, 'tcx>,
}
impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
pub fn find_auto_trait_generics(
pub fn find_auto_trait_generics<A, F>(
&self,
did: DefId,
trait_did: DefId,
generics: &ty::Generics,
) -> AutoTraitResult {
auto_trait_callback: F)
-> AutoTraitResult<A>
where F: for<'b, 'cx, 'cx2> Fn(&InferCtxt<'b, 'cx, 'cx2>, AutoTraitInfo<'cx2>) -> A
{
let tcx = self.tcx;
let ty = self.tcx.type_of(did);
@ -72,7 +80,7 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
substs: tcx.mk_substs_trait(ty, &[]),
};
let trait_pred = ty::Binder(trait_ref);
let trait_pred = ty::Binder::bind(trait_ref);
let bail_out = tcx.infer_ctxt().enter(|infcx| {
let mut selcx = SelectionContext::with_negative(&infcx, true);
@ -149,7 +157,7 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
None => return AutoTraitResult::NegativeImpl,
};
let (full_env, _full_user_env) = self.evaluate_predicates(
let (full_env, full_user_env) = self.evaluate_predicates(
&mut infcx,
did,
trait_did,
@ -193,8 +201,9 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
let names_map: FxHashMap<String, String> = generics
.regions
.iter()
.map(|l| (l.name.as_str().to_string(), l.name.to_string()))
// TODO(twk): Lifetime branding
.map(|l| (l.name.to_string(), l.name.to_string()))
// TODO(twk): Lifetime branding and why is this map a set?!
// l.clean(self.cx) was present in the original code
.collect();
let body_ids: FxHashSet<_> = infcx
@ -213,33 +222,16 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
.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 info = AutoTraitInfo { full_user_env, region_data, names_map, 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 \
<generics placeholder here>",
did, trait_did, generics /* , new_generics */
);
return AutoTraitResult::PositiveImpl;
return AutoTraitResult::PositiveImpl(auto_trait_callback(&infcx, info));
});
}
}
impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
// 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,
@ -294,7 +286,7 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
let mut already_visited = FxHashSet();
let mut predicates = VecDeque::new();
predicates.push_back(ty::Binder(ty::TraitPredicate {
predicates.push_back(ty::Binder::bind(ty::TraitPredicate {
trait_ref: ty::TraitRef {
def_id: trait_did,
substs: infcx.tcx.mk_substs_trait(ty, &[]),
@ -359,14 +351,12 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
new_env = ty::ParamEnv::new(
tcx.mk_predicates(normalized_preds),
param_env.reveal,
ty::UniverseIndex::ROOT,
);
}
let final_user_env = ty::ParamEnv::new(
tcx.mk_predicates(user_computed_preds.into_iter()),
user_env.reveal,
ty::UniverseIndex::ROOT,
);
debug!(
"evaluate_nested_obligations(ty_did={:?}, trait_did={:?}): succeeded with '{:?}' \
@ -377,165 +367,9 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
return Some((new_env, final_user_env));
}
// 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.
pub fn handle_lifetimes<'cx>(
&self,
regions: &RegionConstraintData<'cx>,
names_map: &FxHashMap<String, String>, // TODO(twk): lifetime branding
) -> 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<String> = finished // TODO(twk): lifetime branding
.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(),
}) */
None // TODO(twk): use the correct WherePredicate and rebuild the code above
})
.collect();
lifetime_predicates
}
pub fn region_name(&self, region: Region) -> Option<String> {
match region {
&ty::ReEarlyBound(r) => Some(r.name.as_str().to_string()),
&ty::ReEarlyBound(r) => Some(r.name.to_string()),
_ => None,
}
}

566
src/librustdoc/clean/auto_trait.rs
View file

@ -8,6 +8,7 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use rustc::traits::auto_trait as auto;
use rustc::ty::TypeFoldable;
use std::fmt::Debug;
@ -15,9 +16,16 @@ use super::*;
pub struct AutoTraitFinder<'a, 'tcx: 'a, 'rcx: 'a> {
pub cx: &'a core::DocContext<'a, 'tcx, 'rcx>,
pub f: auto::AutoTraitFinder<'a, 'tcx>,
}
impl<'a, 'tcx, 'rcx> AutoTraitFinder<'a, 'tcx, 'rcx> {
pub fn new(cx: &'a core::DocContext<'a, 'tcx, 'rcx>) -> Self {
let f = auto::AutoTraitFinder { tcx: &cx.tcx };
AutoTraitFinder { cx, f }
}
pub fn get_with_def_id(&self, def_id: DefId) -> Vec<Item> {
let ty = self.cx.tcx.type_of(def_id);
@ -276,443 +284,37 @@ impl<'a, 'tcx, 'rcx> AutoTraitFinder<'a, 'tcx, 'rcx> {
trait_did: DefId,
generics: &ty::Generics,
) -> AutoTraitResult {
let tcx = self.cx.tcx;
let ty = self.cx.tcx.type_of(did);
match self.f.find_auto_trait_generics(did, trait_did, generics,
|infcx, mut info| {
let region_data = info.region_data;
let names_map =
info.names_map
.drain()
.map(|(name, lifetime)| (name, Lifetime(lifetime)))
.collect();
let lifetime_predicates =
self.handle_lifetimes(&region_data, &names_map);
let new_generics = self.param_env_to_generics(
infcx.tcx,
did,
info.full_user_env,
generics.clone(),
lifetime_predicates,
info.vid_to_region,
);
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::bind(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
finished with {:?}",
did, trait_did, generics, new_generics
);
return true;
}
_ => return false,
};
});
// If an explicit impl exists, it always takes priority over an auto impl
if bail_out {
return AutoTraitResult::ExplicitImpl;
new_generics
}) {
auto::AutoTraitResult::ExplicitImpl => AutoTraitResult::ExplicitImpl,
auto::AutoTraitResult::NegativeImpl => AutoTraitResult::NegativeImpl,
auto::AutoTraitResult::PositiveImpl(res) => AutoTraitResult::PositiveImpl(res),
}
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.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::bind(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 {
@ -733,108 +335,6 @@ impl<'a, 'tcx, 'rcx> AutoTraitFinder<'a, 'tcx, 'rcx> {
}
}
// This is very similar to handle_lifetimes. However, instead of matching ty::Region's
// to each other, 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
//

10
src/librustdoc/clean/mod.rs
View file

@ -40,17 +40,13 @@ 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, TyCtxt, Region, RegionVid, Ty, AdtKind};
use rustc::middle::stability;
use rustc::util::nodemap::{FxHashMap, FxHashSet};
use rustc_typeck::hir_ty_to_ty;
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 std::default::Default;
@ -3524,14 +3520,12 @@ pub struct Impl {
}
pub fn get_auto_traits_with_node_id(cx: &DocContext, id: ast::NodeId, name: String) -> Vec<Item> {
let finder = AutoTraitFinder { cx };
let finder = AutoTraitFinder::new(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,
};
let finder = AutoTraitFinder::new(cx);
finder.get_with_def_id(id)
}