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Auto merge of #107026 - Dylan-DPC:rollup-4fonvdc, r=Dylan-DPC

Browse Source 
Rollup of 5 pull requests

Successful merges:

 - #103702 (Lift `T: Sized` bounds from some `strict_provenance` pointer methods)
 - #106441 (relax reference requirement on SocketAddrExt::from_abstract_name)
 - #106718 (finish trait solver skeleton work)
 - #106950 (Don't do pointer arithmetic on pointers to deallocated memory)
 - #107014 (rustdoc: remove deprecated / unused code from main.js)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
This commit is contained in:
bors 2023-01-18 10:26:12 +00:00
commit 1f72129ffe
24 changed files with 958 additions and 712 deletions
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1
Cargo.lock
View File

@ -4783,6 +4783,7 @@ dependencies = [
"rustc_middle",
"rustc_parse_format",
"rustc_query_system",
"rustc_serialize",
"rustc_session",
"rustc_span",
"rustc_target",

6
compiler/rustc_middle/src/infer/canonical.rs
View File

@ -339,6 +339,12 @@ TrivialTypeTraversalAndLiftImpls! {
}
impl<'tcx> CanonicalVarValues<'tcx> {
/// Creates dummy var values which should not be used in a
/// canonical response.
pub fn dummy() -> CanonicalVarValues<'tcx> {
CanonicalVarValues { var_values: Default::default() }
}
#[inline]
pub fn len(&self) -> usize {
self.var_values.len()

11
compiler/rustc_middle/src/ty/sty.rs
View File

@ -1113,17 +1113,6 @@ impl<'tcx, T> Binder<'tcx, T> {
if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
}
pub fn no_bound_vars_ignoring_escaping(self, tcx: TyCtxt<'tcx>) -> Option<T>
where
T: TypeFoldable<'tcx>,
{
if !self.0.has_escaping_bound_vars() {
Some(self.skip_binder())
} else {
self.0.try_fold_with(&mut SkipBindersAt { index: ty::INNERMOST, tcx }).ok()
}
}
/// Splits the contents into two things that share the same binder
/// level as the original, returning two distinct binders.
///

1
compiler/rustc_trait_selection/Cargo.toml
View File

@ -19,6 +19,7 @@ rustc_infer = { path = "../rustc_infer" }
rustc_lint_defs = { path = "../rustc_lint_defs" }
rustc_macros = { path = "../rustc_macros" }
rustc_query_system = { path = "../rustc_query_system" }
rustc_serialize = { path = "../rustc_serialize" }
rustc_session = { path = "../rustc_session" }
rustc_span = { path = "../rustc_span" }
rustc_target = { path = "../rustc_target" }

1
compiler/rustc_trait_selection/src/lib.rs
View File

@ -21,6 +21,7 @@
#![feature(never_type)]
#![feature(result_option_inspect)]
#![feature(type_alias_impl_trait)]
#![feature(min_specialization)]
#![recursion_limit = "512"] // For rustdoc
#[macro_use]

302
compiler/rustc_trait_selection/src/solve/assembly.rs
View File

@ -1,38 +1,84 @@
//! Code shared by trait and projection goals for candidate assembly.
use super::infcx_ext::InferCtxtExt;
use super::{
instantiate_canonical_query_response, CanonicalGoal, CanonicalResponse, Certainty, EvalCtxt,
Goal,
};
use super::{CanonicalResponse, Certainty, EvalCtxt, Goal};
use rustc_hir::def_id::DefId;
use rustc_infer::infer::TyCtxtInferExt;
use rustc_infer::infer::{
canonical::{CanonicalVarValues, OriginalQueryValues},
InferCtxt,
};
use rustc_infer::traits::query::NoSolution;
use rustc_middle::ty::TypeFoldable;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_span::DUMMY_SP;
use std::fmt::Debug;
/// A candidate is a possible way to prove a goal.
///
/// It consists of both the `source`, which describes how that goal would be proven,
/// and the `result` when using the given `source`.
///
/// For the list of possible candidates, please look at the documentation of
/// [super::trait_goals::CandidateSource] and [super::project_goals::CandidateSource].
#[derive(Debug, Clone)]
pub(super) struct Candidate<'tcx, G: GoalKind<'tcx>> {
pub(super) source: G::CandidateSource,
pub(super) struct Candidate<'tcx> {
pub(super) source: CandidateSource,
pub(super) result: CanonicalResponse<'tcx>,
}
pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy {
type CandidateSource: Debug + Copy;
/// Possible ways the given goal can be proven.
#[derive(Debug, Clone, Copy)]
pub(super) enum CandidateSource {
/// A user written impl.
///
/// ## Examples
///
/// ```rust
/// fn main() {
/// let x: Vec<u32> = Vec::new();
/// // This uses the impl from the standard library to prove `Vec<T>: Clone`.
/// let y = x.clone();
/// }
/// ```
Impl(DefId),
/// A builtin impl generated by the compiler. When adding a new special
/// trait, try to use actual impls whenever possible. Builtin impls should
/// only be used in cases where the impl cannot be manually be written.
///
/// Notable examples are auto traits, `Sized`, and `DiscriminantKind`.
/// For a list of all traits with builtin impls, check out the
/// [`EvalCtxt::assemble_builtin_impl_candidates`] method. Not
BuiltinImpl,
/// An assumption from the environment.
///
/// More precicely we've used the `n-th` assumption in the `param_env`.
///
/// ## Examples
///
/// ```rust
/// fn is_clone<T: Clone>(x: T) -> (T, T) {
/// // This uses the assumption `T: Clone` from the `where`-bounds
/// // to prove `T: Clone`.
/// (x.clone(), x)
/// }
/// ```
ParamEnv(usize),
/// If the self type is an alias type, e.g. an opaque type or a projection,
/// we know the bounds on that alias to hold even without knowing its concrete
/// underlying type.
///
/// More precisely this candidate is using the `n-th` bound in the `item_bounds` of
/// the self type.
///
/// ## Examples
///
/// ```rust
/// trait Trait {
/// type Assoc: Clone;
/// }
///
/// fn foo<T: Trait>(x: <T as Trait>::Assoc) {
/// // We prove `<T as Trait>::Assoc` by looking at the bounds on `Assoc` in
/// // in the trait definition.
/// let _y = x.clone();
/// }
/// ```
AliasBound(usize),
}
pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy {
fn self_ty(self) -> Ty<'tcx>;
fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self;
@ -40,47 +86,40 @@ pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy {
fn trait_def_id(self, tcx: TyCtxt<'tcx>) -> DefId;
fn consider_impl_candidate(
acx: &mut AssemblyCtxt<'_, 'tcx, Self>,
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
impl_def_id: DefId,
);
) -> Result<Certainty, NoSolution>;
fn consider_builtin_sized_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
) -> Result<Certainty, NoSolution>;
fn consider_assumption(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
assumption: ty::Predicate<'tcx>,
) -> Result<Certainty, NoSolution>;
}
/// An abstraction which correctly deals with the canonical results for candidates.
///
/// It also deduplicates the behavior between trait and projection predicates.
pub(super) struct AssemblyCtxt<'a, 'tcx, G: GoalKind<'tcx>> {
pub(super) cx: &'a mut EvalCtxt<'tcx>,
pub(super) infcx: &'a InferCtxt<'tcx>,
var_values: CanonicalVarValues<'tcx>,
candidates: Vec<Candidate<'tcx, G>>,
}
impl<'a, 'tcx, G: GoalKind<'tcx>> AssemblyCtxt<'a, 'tcx, G> {
pub(super) fn assemble_and_evaluate_candidates(
cx: &'a mut EvalCtxt<'tcx>,
goal: CanonicalGoal<'tcx, G>,
) -> Vec<Candidate<'tcx, G>> {
let (ref infcx, goal, var_values) =
cx.tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &goal);
let mut acx = AssemblyCtxt { cx, infcx, var_values, candidates: Vec::new() };
acx.assemble_candidates_after_normalizing_self_ty(goal);
acx.assemble_impl_candidates(goal);
acx.candidates
}
pub(super) fn try_insert_candidate(
impl<'tcx> EvalCtxt<'_, 'tcx> {
pub(super) fn assemble_and_evaluate_candidates<G: GoalKind<'tcx>>(
&mut self,
source: G::CandidateSource,
certainty: Certainty,
) {
match self.infcx.make_canonical_response(self.var_values.clone(), certainty) {
Ok(result) => self.candidates.push(Candidate { source, result }),
Err(NoSolution) => debug!(?source, ?certainty, "failed leakcheck"),
}
goal: Goal<'tcx, G>,
) -> Vec<Candidate<'tcx>> {
let mut candidates = Vec::new();
self.assemble_candidates_after_normalizing_self_ty(goal, &mut candidates);
self.assemble_impl_candidates(goal, &mut candidates);
self.assemble_builtin_impl_candidates(goal, &mut candidates);
self.assemble_param_env_candidates(goal, &mut candidates);
self.assemble_alias_bound_candidates(goal, &mut candidates);
candidates
}
/// If the self type of a goal is a projection, computing the relevant candidates is difficult.
@ -88,8 +127,12 @@ impl<'a, 'tcx, G: GoalKind<'tcx>> AssemblyCtxt<'a, 'tcx, G> {
/// To deal with this, we first try to normalize the self type and add the candidates for the normalized
/// self type to the list of candidates in case that succeeds. Note that we can't just eagerly return in
/// this case as projections as self types add `
fn assemble_candidates_after_normalizing_self_ty(&mut self, goal: Goal<'tcx, G>) {
let tcx = self.cx.tcx;
fn assemble_candidates_after_normalizing_self_ty<G: GoalKind<'tcx>>(
&mut self,
goal: Goal<'tcx, G>,
candidates: &mut Vec<Candidate<'tcx>>,
) {
let tcx = self.tcx();
// FIXME: We also have to normalize opaque types, not sure where to best fit that in.
let &ty::Alias(ty::Projection, projection_ty) = goal.predicate.self_ty().kind() else {
return
@ -103,45 +146,136 @@ impl<'a, 'tcx, G: GoalKind<'tcx>> AssemblyCtxt<'a, 'tcx, G> {
term: normalized_ty.into(),
}),
);
let normalization_certainty =
match self.cx.evaluate_goal(&self.infcx, normalizes_to_goal) {
let normalization_certainty = match self.evaluate_goal(normalizes_to_goal) {
Ok((_, certainty)) => certainty,
Err(NoSolution) => return,
};
// NOTE: Alternatively we could call `evaluate_goal` here and only have a `Normalized` candidate.
// This doesn't work as long as we use `CandidateSource` in both winnowing and to resolve associated items.
// This doesn't work as long as we use `CandidateSource` in winnowing.
let goal = goal.with(tcx, goal.predicate.with_self_ty(tcx, normalized_ty));
let mut orig_values = OriginalQueryValues::default();
let goal = self.infcx.canonicalize_query(goal, &mut orig_values);
let normalized_candidates =
AssemblyCtxt::assemble_and_evaluate_candidates(self.cx, goal);
// Map each candidate from being canonical wrt the current inference context to being
// canonical wrt the caller.
for Candidate { source, result } in normalized_candidates {
self.infcx.probe(|_| {
let candidate_certainty =
instantiate_canonical_query_response(&self.infcx, &orig_values, result);
// FIXME: This is a bit scary if the `normalizes_to_goal` overflows.
//
// If we have an ambiguous candidate it hides that normalization
// caused an overflow which may cause issues.
self.try_insert_candidate(
source,
normalization_certainty.unify_and(candidate_certainty),
)
})
// FIXME: This is broken if we care about the `usize` of `AliasBound` because the self type
// could be normalized to yet another projection with different item bounds.
let normalized_candidates = self.assemble_and_evaluate_candidates(goal);
for mut normalized_candidate in normalized_candidates {
normalized_candidate.result =
normalized_candidate.result.unchecked_map(|mut response| {
// FIXME: This currently hides overflow in the normalization step of the self type
// which is probably wrong. Maybe `unify_and` should actually keep overflow as
// we treat it as non-fatal anyways.
response.certainty = response.certainty.unify_and(normalization_certainty);
response
});
candidates.push(normalized_candidate);
}
})
}
fn assemble_impl_candidates(&mut self, goal: Goal<'tcx, G>) {
self.cx.tcx.for_each_relevant_impl(
goal.predicate.trait_def_id(self.cx.tcx),
fn assemble_impl_candidates<G: GoalKind<'tcx>>(
&mut self,
goal: Goal<'tcx, G>,
candidates: &mut Vec<Candidate<'tcx>>,
) {
let tcx = self.tcx();
tcx.for_each_relevant_impl(
goal.predicate.trait_def_id(tcx),
goal.predicate.self_ty(),
|impl_def_id| G::consider_impl_candidate(self, goal, impl_def_id),
|impl_def_id| match G::consider_impl_candidate(self, goal, impl_def_id)
.and_then(|certainty| self.make_canonical_response(certainty))
{
Ok(result) => candidates
.push(Candidate { source: CandidateSource::Impl(impl_def_id), result }),
Err(NoSolution) => (),
},
);
}
fn assemble_builtin_impl_candidates<G: GoalKind<'tcx>>(
&mut self,
goal: Goal<'tcx, G>,
candidates: &mut Vec<Candidate<'tcx>>,
) {
let lang_items = self.tcx().lang_items();
let trait_def_id = goal.predicate.trait_def_id(self.tcx());
let result = if lang_items.sized_trait() == Some(trait_def_id) {
G::consider_builtin_sized_candidate(self, goal)
} else {
Err(NoSolution)
};
match result.and_then(|certainty| self.make_canonical_response(certainty)) {
Ok(result) => {
candidates.push(Candidate { source: CandidateSource::BuiltinImpl, result })
}
Err(NoSolution) => (),
}
}
fn assemble_param_env_candidates<G: GoalKind<'tcx>>(
&mut self,
goal: Goal<'tcx, G>,
candidates: &mut Vec<Candidate<'tcx>>,
) {
for (i, assumption) in goal.param_env.caller_bounds().iter().enumerate() {
match G::consider_assumption(self, goal, assumption)
.and_then(|certainty| self.make_canonical_response(certainty))
{
Ok(result) => {
candidates.push(Candidate { source: CandidateSource::ParamEnv(i), result })
}
Err(NoSolution) => (),
}
}
}
fn assemble_alias_bound_candidates<G: GoalKind<'tcx>>(
&mut self,
goal: Goal<'tcx, G>,
candidates: &mut Vec<Candidate<'tcx>>,
) {
let alias_ty = match goal.predicate.self_ty().kind() {
ty::Bool
| ty::Char
| ty::Int(_)
| ty::Uint(_)
| ty::Float(_)
| ty::Adt(_, _)
| ty::Foreign(_)
| ty::Str
| ty::Array(_, _)
| ty::Slice(_)
| ty::RawPtr(_)
| ty::Ref(_, _, _)
| ty::FnDef(_, _)
| ty::FnPtr(_)
| ty::Dynamic(..)
| ty::Closure(..)
| ty::Generator(..)
| ty::GeneratorWitness(_)
| ty::Never
| ty::Tuple(_)
| ty::Param(_)
| ty::Placeholder(..)
| ty::Infer(_)
| ty::Error(_) => return,
ty::Bound(..) => bug!("unexpected bound type: {goal:?}"),
ty::Alias(_, alias_ty) => alias_ty,
};
for (i, (assumption, _)) in self
.tcx()
.bound_explicit_item_bounds(alias_ty.def_id)
.subst_iter_copied(self.tcx(), alias_ty.substs)
.enumerate()
{
match G::consider_assumption(self, goal, assumption)
.and_then(|certainty| self.make_canonical_response(certainty))
{
Ok(result) => {
candidates.push(Candidate { source: CandidateSource::AliasBound(i), result })
}
Err(NoSolution) => (),
}
}
}
}

291
compiler/rustc_trait_selection/src/solve/cache.rs
View File

@ -1,291 +0,0 @@
//! This module both handles the global cache which stores "finished" goals,
//! and the provisional cache which contains partially computed goals.
//!
//! The provisional cache is necessary when dealing with coinductive cycles.
//!
//! For more information about the provisional cache and coinduction in general,
//! check out the relevant section of the rustc-dev-guide.
//!
//! FIXME(@lcnr): Write that section, feel free to ping me if you need help here
//! before then or if I still haven't done that before January 2023.
use super::overflow::OverflowData;
use super::{CanonicalGoal, Certainty, MaybeCause, Response};
use super::{EvalCtxt, QueryResult};
use rustc_data_structures::fx::FxHashMap;
use rustc_infer::infer::canonical::{Canonical, CanonicalVarKind, CanonicalVarValues};
use rustc_middle::ty::{self, TyCtxt};
use std::{cmp::Ordering, collections::hash_map::Entry};
#[derive(Debug, Clone)]
struct ProvisionalEntry<'tcx> {
// In case we have a coinductive cycle, this is the
// the currently least restrictive result of this goal.
response: QueryResult<'tcx>,
// The lowest element on the stack on which this result
// relies on. Starts out as just being the depth at which
// we've proven this obligation, but gets lowered to the
// depth of another goal if we rely on it in a cycle.
depth: usize,
}
struct StackElem<'tcx> {
goal: CanonicalGoal<'tcx>,
has_been_used: bool,
}
/// The cache used for goals which are currently in progress or which depend
/// on in progress results.
///
/// Once we're done with a goal we can store it in the global trait solver
/// cache of the `TyCtxt`. For goals which we're currently proving, or which
/// have only been proven via a coinductive cycle using a goal still on our stack
/// we have to use this separate data structure.
///
/// The current data structure is not perfect, so there may still be room for
/// improvement here. We have the following requirements:
///
/// ## Is there is a provisional entry for the given goal:
///
/// ```ignore (for syntax highlighting)
/// self.entries.get(goal)
/// ```
///
/// ## Get all goals on the stack involved in a cycle:
///
/// ```ignore (for syntax highlighting)
/// let entry = self.entries.get(goal).unwrap();
/// let involved_goals = self.stack.iter().skip(entry.depth);
/// ```
///
/// ## Capping the depth of all entries
///
/// Needed whenever we encounter a cycle. The current implementation always
/// iterates over all entries instead of only the ones with a larger depth.
/// Changing this may result in notable performance improvements.
///
/// ```ignore (for syntax highlighting)
/// let cycle_depth = self.entries.get(goal).unwrap().depth;
/// for e in &mut self.entries {
/// e.depth = e.depth.min(cycle_depth);
/// }
/// ```
///
/// ## Checking whether we have to rerun the current goal
///
/// A goal has to be rerun if its provisional result was used in a cycle
/// and that result is different from its final result. We update
/// [StackElem::has_been_used] for the deepest stack element involved in a cycle.
///
/// ## Moving all finished goals into the global cache
///
/// If `stack_elem.has_been_used` is true, iterate over all entries, moving the ones
/// with equal depth. If not, simply move this single entry.
pub(super) struct ProvisionalCache<'tcx> {
stack: Vec<StackElem<'tcx>>,
entries: FxHashMap<CanonicalGoal<'tcx>, ProvisionalEntry<'tcx>>,
}
impl<'tcx> ProvisionalCache<'tcx> {
pub(super) fn empty() -> ProvisionalCache<'tcx> {
ProvisionalCache { stack: Vec::new(), entries: Default::default() }
}
pub(super) fn current_depth(&self) -> usize {
self.stack.len()
}
}
impl<'tcx> EvalCtxt<'tcx> {
/// Tries putting the new goal on the stack, returning an error if it is already cached.
///
/// This correctly updates the provisional cache if there is a cycle.
pub(super) fn try_push_stack(
&mut self,
goal: CanonicalGoal<'tcx>,
) -> Result<(), QueryResult<'tcx>> {
// FIXME: start by checking the global cache
// Look at the provisional cache to check for cycles.
let cache = &mut self.provisional_cache;
match cache.entries.entry(goal) {
// No entry, simply push this goal on the stack after dealing with overflow.
Entry::Vacant(v) => {
if self.overflow_data.has_overflow(cache.stack.len()) {
return Err(self.deal_with_overflow(goal));
}
v.insert(ProvisionalEntry {
response: response_no_constraints(self.tcx, goal, Certainty::Yes),
depth: cache.stack.len(),
});
cache.stack.push(StackElem { goal, has_been_used: false });
Ok(())
}
// We have a nested goal which relies on a goal `root` deeper in the stack.
//
// We first store that we may have to rerun `evaluate_goal` for `root` in case the
// provisional response is not equal to the final response. We also update the depth
// of all goals which recursively depend on our current goal to depend on `root`
// instead.
//
// Finally we can return either the provisional response for that goal if we have a
// coinductive cycle or an ambiguous result if the cycle is inductive.
Entry::Occupied(entry) => {
// FIXME: `ProvisionalEntry` should be `Copy`.
let entry = entry.get().clone();
cache.stack[entry.depth].has_been_used = true;
for provisional_entry in cache.entries.values_mut() {
provisional_entry.depth = provisional_entry.depth.min(entry.depth);
}
// NOTE: The goals on the stack aren't the only goals involved in this cycle.
// We can also depend on goals which aren't part of the stack but coinductively
// depend on the stack themselves. We already checked whether all the goals
// between these goals and their root on the stack. This means that as long as
// each goal in a cycle is checked for coinductivity by itself simply checking
// the stack is enough.
if cache.stack[entry.depth..]
.iter()
.all(|g| g.goal.value.predicate.is_coinductive(self.tcx))
{
Err(entry.response)
} else {
Err(response_no_constraints(
self.tcx,
goal,
Certainty::Maybe(MaybeCause::Ambiguity),
))
}
}
}
}
/// We cannot simply store the result of [EvalCtxt::compute_goal] as we have to deal with
/// coinductive cycles.
///
/// When we encounter a coinductive cycle, we have to prove the final result of that cycle
/// while we are still computing that result. Because of this we continously recompute the
/// cycle until the result of the previous iteration is equal to the final result, at which
/// point we are done.
///
/// This function returns `true` if we were able to finalize the goal and `false` if it has
/// updated the provisional cache and we have to recompute the current goal.
///
/// FIXME: Refer to the rustc-dev-guide entry once it exists.
pub(super) fn try_finalize_goal(
&mut self,
actual_goal: CanonicalGoal<'tcx>,
response: QueryResult<'tcx>,
) -> bool {
let cache = &mut self.provisional_cache;
let StackElem { goal, has_been_used } = cache.stack.pop().unwrap();
assert_eq!(goal, actual_goal);
let provisional_entry = cache.entries.get_mut(&goal).unwrap();
// Check whether the current stack entry is the root of a cycle.
//
// If so, we either move all participants of that cycle to the global cache
// or, in case the provisional response used in the cycle is not equal to the
// final response, have to recompute the goal after updating the provisional
// response to the final response of this iteration.
if has_been_used {
if provisional_entry.response == response {
// We simply drop all entries according to an immutable condition, so
// query instability is not a concern here.
#[allow(rustc::potential_query_instability)]
cache.entries.retain(|goal, entry| match entry.depth.cmp(&cache.stack.len()) {
Ordering::Less => true,
Ordering::Equal => {
Self::try_move_finished_goal_to_global_cache(
self.tcx,
&mut self.overflow_data,
&cache.stack,
// FIXME: these should be `Copy` :(
goal.clone(),
entry.response.clone(),
);
false
}
Ordering::Greater => bug!("entry with greater depth than the current leaf"),
});
true
} else {
provisional_entry.response = response;
cache.stack.push(StackElem { goal, has_been_used: false });
false
}
} else {
Self::try_move_finished_goal_to_global_cache(
self.tcx,
&mut self.overflow_data,
&cache.stack,
goal,
response,
);
cache.entries.remove(&goal);
true
}
}
fn try_move_finished_goal_to_global_cache(
tcx: TyCtxt<'tcx>,
overflow_data: &mut OverflowData,
stack: &[StackElem<'tcx>],
goal: CanonicalGoal<'tcx>,
response: QueryResult<'tcx>,
) {
// We move goals to the global cache if we either did not hit an overflow or if it's
// the root goal as that will now always hit the same overflow limit.
//
// NOTE: We cannot move any non-root goals to the global cache even if their final result
// isn't impacted by the overflow as that goal still has unstable query dependencies
// because it didn't go its full depth.
//
// FIXME(@lcnr): We could still cache subtrees which are not impacted by overflow though.
// Tracking that info correctly isn't trivial, so I haven't implemented it for now.
let should_cache_globally = !overflow_data.did_overflow() || stack.is_empty();
if should_cache_globally {
// FIXME: move the provisional entry to the global cache.
let _ = (tcx, goal, response);
}
}
}
pub(super) fn response_no_constraints<'tcx>(
tcx: TyCtxt<'tcx>,
goal: Canonical<'tcx, impl Sized>,
certainty: Certainty,
) -> QueryResult<'tcx> {
let var_values = goal
.variables
.iter()
.enumerate()
.map(|(i, info)| match info.kind {
CanonicalVarKind::Ty(_) | CanonicalVarKind::PlaceholderTy(_) => {
tcx.mk_ty(ty::Bound(ty::INNERMOST, ty::BoundVar::from_usize(i).into())).into()
}
CanonicalVarKind::Region(_) | CanonicalVarKind::PlaceholderRegion(_) => {
let br = ty::BoundRegion {
var: ty::BoundVar::from_usize(i),
kind: ty::BrAnon(i as u32, None),
};
tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)).into()
}
CanonicalVarKind::Const(_, ty) | CanonicalVarKind::PlaceholderConst(_, ty) => tcx
.mk_const(ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from_usize(i)), ty)
.into(),
})
.collect();
Ok(Canonical {
max_universe: goal.max_universe,
variables: goal.variables,
value: Response {
var_values: CanonicalVarValues { var_values },
external_constraints: Default::default(),
certainty,
},
})
}

9
compiler/rustc_trait_selection/src/solve/fulfill.rs
View File

@ -10,7 +10,7 @@ use rustc_infer::{
};
use rustc_middle::ty;
use super::{Certainty, EvalCtxt};
use super::{search_graph, Certainty, EvalCtxt};
/// A trait engine using the new trait solver.
///
@ -67,9 +67,10 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
let mut has_changed = false;
for obligation in mem::take(&mut self.obligations) {
let mut cx = EvalCtxt::new(infcx.tcx);
let (changed, certainty) = match cx.evaluate_goal(infcx, obligation.clone().into())
{
let goal = obligation.clone().into();
let search_graph = &mut search_graph::SearchGraph::new(infcx.tcx);
let mut ecx = EvalCtxt::new_outside_solver(infcx, search_graph);
let (changed, certainty) = match ecx.evaluate_goal(goal) {
Ok(result) => result,
Err(NoSolution) => {
errors.push(FulfillmentError {

71
compiler/rustc_trait_selection/src/solve/infcx_ext.rs
View File

@ -1,23 +1,30 @@
use rustc_infer::infer::canonical::CanonicalVarValues;
use rustc_infer::infer::at::ToTrace;
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use rustc_infer::infer::InferCtxt;
use rustc_infer::infer::{InferCtxt, InferOk};
use rustc_infer::traits::query::NoSolution;
use rustc_middle::ty::Ty;
use rustc_infer::traits::ObligationCause;
use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
use rustc_middle::ty::{self, Ty};
use rustc_span::DUMMY_SP;
use crate::solve::ExternalConstraints;
use super::{Certainty, QueryResult, Response};
use super::Goal;
/// Methods used inside of the canonical queries of the solver.
///
/// Most notably these do not care about diagnostics information.
/// If you find this while looking for methods to use outside of the
/// solver, you may look at the implementation of these method for
/// help.
pub(super) trait InferCtxtExt<'tcx> {
fn next_ty_infer(&self) -> Ty<'tcx>;
fn next_const_infer(&self, ty: Ty<'tcx>) -> ty::Const<'tcx>;
fn make_canonical_response(
fn eq<T: ToTrace<'tcx>>(
&self,
var_values: CanonicalVarValues<'tcx>,
certainty: Certainty,
) -> QueryResult<'tcx>;
param_env: ty::ParamEnv<'tcx>,
lhs: T,
rhs: T,
) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution>;
}
impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
@ -27,29 +34,29 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
span: DUMMY_SP,
})
}
fn next_const_infer(&self, ty: Ty<'tcx>) -> ty::Const<'tcx> {
self.next_const_var(
ty,
ConstVariableOrigin { kind: ConstVariableOriginKind::MiscVariable, span: DUMMY_SP },
)
}
fn make_canonical_response(
#[instrument(level = "debug", skip(self, param_env), ret)]
fn eq<T: ToTrace<'tcx>>(
&self,
var_values: CanonicalVarValues<'tcx>,
certainty: Certainty,
) -> QueryResult<'tcx> {
let external_constraints = take_external_constraints(self)?;
Ok(self.canonicalize_response(Response { var_values, external_constraints, certainty }))
param_env: ty::ParamEnv<'tcx>,
lhs: T,
rhs: T,
) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution> {
self.at(&ObligationCause::dummy(), param_env)
.define_opaque_types(false)
.eq(lhs, rhs)
.map(|InferOk { value: (), obligations }| {
obligations.into_iter().map(|o| o.into()).collect()
})
.map_err(|e| {
debug!(?e, "failed to equate");
NoSolution
})
}
}
#[instrument(level = "debug", skip(infcx), ret)]
fn take_external_constraints<'tcx>(
infcx: &InferCtxt<'tcx>,
) -> Result<ExternalConstraints<'tcx>, NoSolution> {
let region_obligations = infcx.take_registered_region_obligations();
let opaque_types = infcx.take_opaque_types_for_query_response();
Ok(ExternalConstraints {
// FIXME: Now that's definitely wrong :)
//
// Should also do the leak check here I think
regions: drop(region_obligations),
opaque_types,
})
}

229
compiler/rustc_trait_selection/src/solve/mod.rs
View File

@ -19,27 +19,23 @@
use std::mem;
use rustc_infer::infer::canonical::{Canonical, CanonicalVarKind, CanonicalVarValues};
use rustc_infer::infer::canonical::{OriginalQueryValues, QueryRegionConstraints, QueryResponse};
use rustc_infer::infer::{InferCtxt, InferOk, TyCtxtInferExt};
use rustc_infer::traits::query::NoSolution;
use rustc_infer::traits::Obligation;
use rustc_middle::infer::canonical::Certainty as OldCertainty;
use rustc_middle::infer::canonical::{Canonical, CanonicalVarValues};
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::ty::{RegionOutlivesPredicate, ToPredicate, TypeOutlivesPredicate};
use rustc_span::DUMMY_SP;
use crate::traits::ObligationCause;
use self::cache::response_no_constraints;
use self::infcx_ext::InferCtxtExt;
mod assembly;
mod cache;
mod fulfill;
mod infcx_ext;
mod overflow;
mod project_goals;
mod search_graph;
mod trait_goals;
pub use fulfill::FulfillmentCtxt;
@ -146,45 +142,42 @@ pub trait TyCtxtExt<'tcx> {
impl<'tcx> TyCtxtExt<'tcx> for TyCtxt<'tcx> {
fn evaluate_goal(self, goal: CanonicalGoal<'tcx>) -> QueryResult<'tcx> {
let mut cx = EvalCtxt::new(self);
cx.evaluate_canonical_goal(goal)
let mut search_graph = search_graph::SearchGraph::new(self);
EvalCtxt::evaluate_canonical_goal(self, &mut search_graph, goal)
}
}
struct EvalCtxt<'tcx> {
struct EvalCtxt<'a, 'tcx> {
infcx: &'a InferCtxt<'tcx>,
var_values: CanonicalVarValues<'tcx>,
search_graph: &'a mut search_graph::SearchGraph<'tcx>,
}
impl<'a, 'tcx> EvalCtxt<'a, 'tcx> {
fn tcx(&self) -> TyCtxt<'tcx> {
self.infcx.tcx
}
/// Creates a new evaluation context outside of the trait solver.
///
/// With this solver making a canonical response doesn't make much sense.
/// The `search_graph` for this solver has to be completely empty.
fn new_outside_solver(
infcx: &'a InferCtxt<'tcx>,
search_graph: &'a mut search_graph::SearchGraph<'tcx>,
) -> EvalCtxt<'a, 'tcx> {
assert!(search_graph.is_empty());
EvalCtxt { infcx, var_values: CanonicalVarValues::dummy(), search_graph }
}
#[instrument(level = "debug", skip(tcx, search_graph), ret)]
fn evaluate_canonical_goal(
tcx: TyCtxt<'tcx>,
provisional_cache: cache::ProvisionalCache<'tcx>,
overflow_data: overflow::OverflowData,
}
impl<'tcx> EvalCtxt<'tcx> {
fn new(tcx: TyCtxt<'tcx>) -> EvalCtxt<'tcx> {
EvalCtxt {
tcx,
provisional_cache: cache::ProvisionalCache::empty(),
overflow_data: overflow::OverflowData::new(tcx),
}
}
/// Recursively evaluates `goal`, returning whether any inference vars have
/// been constrained and the certainty of the result.
fn evaluate_goal(
&mut self,
infcx: &InferCtxt<'tcx>,
goal: Goal<'tcx, ty::Predicate<'tcx>>,
) -> Result<(bool, Certainty), NoSolution> {
let mut orig_values = OriginalQueryValues::default();
let canonical_goal = infcx.canonicalize_query(goal, &mut orig_values);
let canonical_response = self.evaluate_canonical_goal(canonical_goal)?;
Ok((
!canonical_response.value.var_values.is_identity(),
instantiate_canonical_query_response(infcx, &orig_values, canonical_response),
))
}
fn evaluate_canonical_goal(&mut self, goal: CanonicalGoal<'tcx>) -> QueryResult<'tcx> {
match self.try_push_stack(goal) {
search_graph: &'a mut search_graph::SearchGraph<'tcx>,
canonical_goal: CanonicalGoal<'tcx>,
) -> QueryResult<'tcx> {
match search_graph.try_push_stack(tcx, canonical_goal) {
Ok(()) => {}
// Our goal is already on the stack, eager return.
Err(response) => return response,
@ -195,41 +188,61 @@ impl<'tcx> EvalCtxt<'tcx> {
//
// FIXME: Similar to `evaluate_all`, this has to check for overflow.
loop {
let result = self.compute_goal(goal);
let (ref infcx, goal, var_values) =
tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &canonical_goal);
let mut ecx = EvalCtxt { infcx, var_values, search_graph };
let result = ecx.compute_goal(goal);
// FIXME: `Response` should be `Copy`
if self.try_finalize_goal(goal, result.clone()) {
if search_graph.try_finalize_goal(tcx, canonical_goal, result.clone()) {
return result;
}
}
}
fn compute_goal(&mut self, canonical_goal: CanonicalGoal<'tcx>) -> QueryResult<'tcx> {
// WARNING: We're looking at a canonical value without instantiating it here.
//
// We have to be incredibly careful to not change the order of bound variables or
// remove any. As we go from `Goal<'tcx, Predicate>` to `Goal` with the variants
// of `PredicateKind` this is the case and it is and faster than instantiating and
// recanonicalizing.
let Goal { param_env, predicate } = canonical_goal.value;
fn make_canonical_response(&self, certainty: Certainty) -> QueryResult<'tcx> {
let external_constraints = take_external_constraints(self.infcx)?;
if let Some(kind) = predicate.kind().no_bound_vars_ignoring_escaping(self.tcx) {
Ok(self.infcx.canonicalize_response(Response {
var_values: self.var_values.clone(),
external_constraints,
certainty,
}))
}
/// Recursively evaluates `goal`, returning whether any inference vars have
/// been constrained and the certainty of the result.
fn evaluate_goal(
&mut self,
goal: Goal<'tcx, ty::Predicate<'tcx>>,
) -> Result<(bool, Certainty), NoSolution> {
let mut orig_values = OriginalQueryValues::default();
let canonical_goal = self.infcx.canonicalize_query(goal, &mut orig_values);
let canonical_response =
EvalCtxt::evaluate_canonical_goal(self.tcx(), self.search_graph, canonical_goal)?;
Ok((
!canonical_response.value.var_values.is_identity(),
instantiate_canonical_query_response(self.infcx, &orig_values, canonical_response),
))
}
fn compute_goal(&mut self, goal: Goal<'tcx, ty::Predicate<'tcx>>) -> QueryResult<'tcx> {
let Goal { param_env, predicate } = goal;
let kind = predicate.kind();
if let Some(kind) = kind.no_bound_vars() {
match kind {
ty::PredicateKind::Clause(ty::Clause::Trait(predicate)) => self.compute_trait_goal(
canonical_goal.unchecked_rebind(Goal { param_env, predicate }),
),
ty::PredicateKind::Clause(ty::Clause::Projection(predicate)) => self
.compute_projection_goal(
canonical_goal.unchecked_rebind(Goal { param_env, predicate }),
),
ty::PredicateKind::Clause(ty::Clause::TypeOutlives(predicate)) => self
.compute_type_outlives_goal(
canonical_goal.unchecked_rebind(Goal { param_env, predicate }),
),
ty::PredicateKind::Clause(ty::Clause::RegionOutlives(predicate)) => self
.compute_region_outlives_goal(
canonical_goal.unchecked_rebind(Goal { param_env, predicate }),
),
ty::PredicateKind::Clause(ty::Clause::Trait(predicate)) => {
self.compute_trait_goal(Goal { param_env, predicate })
}
ty::PredicateKind::Clause(ty::Clause::Projection(predicate)) => {
self.compute_projection_goal(Goal { param_env, predicate })
}
ty::PredicateKind::Clause(ty::Clause::TypeOutlives(predicate)) => {
self.compute_type_outlives_goal(Goal { param_env, predicate })
}
ty::PredicateKind::Clause(ty::Clause::RegionOutlives(predicate)) => {
self.compute_region_outlives_goal(Goal { param_env, predicate })
}
// FIXME: implement these predicates :)
ty::PredicateKind::WellFormed(_)
| ty::PredicateKind::ObjectSafe(_)
@ -239,49 +252,41 @@ impl<'tcx> EvalCtxt<'tcx> {
| ty::PredicateKind::ConstEvaluatable(_)
| ty::PredicateKind::ConstEquate(_, _)
| ty::PredicateKind::TypeWellFormedFromEnv(_)
| ty::PredicateKind::Ambiguous => {
// FIXME
response_no_constraints(self.tcx, canonical_goal, Certainty::Yes)
}
| ty::PredicateKind::Ambiguous => self.make_canonical_response(Certainty::Yes),
}
} else {
let (infcx, goal, var_values) =
self.tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &canonical_goal);
let kind = infcx.replace_bound_vars_with_placeholders(goal.predicate.kind());
let goal = goal.with(self.tcx, ty::Binder::dummy(kind));
let (_, certainty) = self.evaluate_goal(&infcx, goal)?;
infcx.make_canonical_response(var_values, certainty)
let kind = self.infcx.replace_bound_vars_with_placeholders(kind);
let goal = goal.with(self.tcx(), ty::Binder::dummy(kind));
let (_, certainty) = self.evaluate_goal(goal)?;
self.make_canonical_response(certainty)
}
}
fn compute_type_outlives_goal(
&mut self,
goal: CanonicalGoal<'tcx, TypeOutlivesPredicate<'tcx>>,
_goal: Goal<'tcx, TypeOutlivesPredicate<'tcx>>,
) -> QueryResult<'tcx> {
// FIXME
response_no_constraints(self.tcx, goal, Certainty::Yes)
self.make_canonical_response(Certainty::Yes)
}
fn compute_region_outlives_goal(
&mut self,
goal: CanonicalGoal<'tcx, RegionOutlivesPredicate<'tcx>>,
_goal: Goal<'tcx, RegionOutlivesPredicate<'tcx>>,
) -> QueryResult<'tcx> {
// FIXME
response_no_constraints(self.tcx, goal, Certainty::Yes)
self.make_canonical_response(Certainty::Yes)
}
}
impl<'tcx> EvalCtxt<'tcx> {
impl<'tcx> EvalCtxt<'_, 'tcx> {
fn evaluate_all(
&mut self,
infcx: &InferCtxt<'tcx>,
mut goals: Vec<Goal<'tcx, ty::Predicate<'tcx>>>,
) -> Result<Certainty, NoSolution> {
let mut new_goals = Vec::new();
self.repeat_while_none(|this| {
let mut has_changed = Err(Certainty::Yes);
for goal in goals.drain(..) {
let (changed, certainty) = match this.evaluate_goal(infcx, goal) {
let (changed, certainty) = match this.evaluate_goal(goal) {
Ok(result) => result,
Err(NoSolution) => return Some(Err(NoSolution)),
};
@ -310,6 +315,21 @@ impl<'tcx> EvalCtxt<'tcx> {
}
}
#[instrument(level = "debug", skip(infcx), ret)]
fn take_external_constraints<'tcx>(
infcx: &InferCtxt<'tcx>,
) -> Result<ExternalConstraints<'tcx>, NoSolution> {
let region_obligations = infcx.take_registered_region_obligations();
let opaque_types = infcx.take_opaque_types_for_query_response();
Ok(ExternalConstraints {
// FIXME: Now that's definitely wrong :)
//
// Should also do the leak check here I think
regions: drop(region_obligations),
opaque_types,
})
}
fn instantiate_canonical_query_response<'tcx>(
infcx: &InferCtxt<'tcx>,
original_values: &OriginalQueryValues<'tcx>,
@ -334,3 +354,40 @@ fn instantiate_canonical_query_response<'tcx>(
assert!(obligations.is_empty());
value
}
pub(super) fn response_no_constraints<'tcx>(
tcx: TyCtxt<'tcx>,
goal: Canonical<'tcx, impl Sized>,
certainty: Certainty,
) -> QueryResult<'tcx> {
let var_values = goal
.variables
.iter()
.enumerate()
.map(|(i, info)| match info.kind {
CanonicalVarKind::Ty(_) | CanonicalVarKind::PlaceholderTy(_) => {
tcx.mk_ty(ty::Bound(ty::INNERMOST, ty::BoundVar::from_usize(i).into())).into()
}
CanonicalVarKind::Region(_) | CanonicalVarKind::PlaceholderRegion(_) => {
let br = ty::BoundRegion {
var: ty::BoundVar::from_usize(i),
kind: ty::BrAnon(i as u32, None),
};
tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)).into()
}
CanonicalVarKind::Const(_, ty) | CanonicalVarKind::PlaceholderConst(_, ty) => tcx
.mk_const(ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from_usize(i)), ty)
.into(),
})
.collect();
Ok(Canonical {
max_universe: goal.max_universe,
variables: goal.variables,
value: Response {
var_values: CanonicalVarValues { var_values },
external_constraints: Default::default(),
certainty,
},
})
}

216
compiler/rustc_trait_selection/src/solve/project_goals.rs
View File

@ -1,38 +1,123 @@
use crate::traits::{specialization_graph, translate_substs};
use super::assembly::{self, AssemblyCtxt};
use super::{CanonicalGoal, EvalCtxt, Goal, QueryResult};
use super::assembly::{self, Candidate, CandidateSource};
use super::infcx_ext::InferCtxtExt;
use super::{Certainty, EvalCtxt, Goal, MaybeCause, QueryResult};
use rustc_errors::ErrorGuaranteed;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::DefId;
use rustc_infer::infer::{InferCtxt, InferOk};
use rustc_infer::infer::InferCtxt;
use rustc_infer::traits::query::NoSolution;
use rustc_infer::traits::specialization_graph::LeafDef;
use rustc_infer::traits::{ObligationCause, Reveal};
use rustc_infer::traits::Reveal;
use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
use rustc_middle::ty::ProjectionPredicate;
use rustc_middle::ty::TypeVisitable;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::ty::{ProjectionPredicate, TypeSuperVisitable, TypeVisitor};
use rustc_span::DUMMY_SP;
use std::iter;
use std::ops::ControlFlow;
#[allow(dead_code)] // FIXME: implement and use all variants.
#[derive(Debug, Clone, Copy)]
pub(super) enum CandidateSource {
Impl(DefId),
ParamEnv(usize),
Builtin,
}
type Candidate<'tcx> = assembly::Candidate<'tcx, ProjectionPredicate<'tcx>>;
impl<'tcx> EvalCtxt<'tcx> {
impl<'tcx> EvalCtxt<'_, 'tcx> {
pub(super) fn compute_projection_goal(
&mut self,
goal: CanonicalGoal<'tcx, ProjectionPredicate<'tcx>>,
goal: Goal<'tcx, ProjectionPredicate<'tcx>>,
) -> QueryResult<'tcx> {
let candidates = AssemblyCtxt::assemble_and_evaluate_candidates(self, goal);
// To only compute normalization ones for each projection we only
// normalize if the expected term is an unconstrained inference variable.
//
// E.g. for `<T as Trait>::Assoc = u32` we recursively compute the goal
// `exists<U> <T as Trait>::Assoc = U` and then take the resulting type for
// `U` and equate it with `u32`. This means that we don't need a separate
// projection cache in the solver.
if self.term_is_fully_unconstrained(goal) {
let candidates = self.assemble_and_evaluate_candidates(goal);
self.merge_project_candidates(candidates)
} else {
let predicate = goal.predicate;
let unconstrained_rhs = match predicate.term.unpack() {
ty::TermKind::Ty(_) => self.infcx.next_ty_infer().into(),
ty::TermKind::Const(ct) => self.infcx.next_const_infer(ct.ty()).into(),
};
let unconstrained_predicate = ty::Clause::Projection(ProjectionPredicate {
projection_ty: goal.predicate.projection_ty,
term: unconstrained_rhs,
});
let (_has_changed, normalize_certainty) =
self.evaluate_goal(goal.with(self.tcx(), unconstrained_predicate))?;
let nested_eq_goals =
self.infcx.eq(goal.param_env, unconstrained_rhs, predicate.term)?;
let eval_certainty = self.evaluate_all(nested_eq_goals)?;
self.make_canonical_response(normalize_certainty.unify_and(eval_certainty))
}
}
/// Is the projection predicate is of the form `exists<T> <Ty as Trait>::Assoc = T`.
///
/// This is the case if the `term` is an inference variable in the innermost universe
/// and does not occur in any other part of the predicate.
fn term_is_fully_unconstrained(&self, goal: Goal<'tcx, ProjectionPredicate<'tcx>>) -> bool {
let infcx = self.infcx;
let term_is_infer = match goal.predicate.term.unpack() {
ty::TermKind::Ty(ty) => {
if let &ty::Infer(ty::TyVar(vid)) = ty.kind() {
match infcx.probe_ty_var(vid) {
Ok(value) => bug!("resolved var in query: {goal:?} {value:?}"),
Err(universe) => universe == infcx.universe(),
}
} else {
false
}
}
ty::TermKind::Const(ct) => {
if let ty::ConstKind::Infer(ty::InferConst::Var(vid)) = ct.kind() {
match self.infcx.probe_const_var(vid) {
Ok(value) => bug!("resolved var in query: {goal:?} {value:?}"),
Err(universe) => universe == infcx.universe(),
}
} else {
false
}
}
};
// Guard against `<T as Trait<?0>>::Assoc = ?0>`.
struct ContainsTerm<'tcx> {
term: ty::Term<'tcx>,
}
impl<'tcx> TypeVisitor<'tcx> for ContainsTerm<'tcx> {
type BreakTy = ();
fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
if t.needs_infer() {
if ty::Term::from(t) == self.term {
ControlFlow::BREAK
} else {
t.super_visit_with(self)
}
} else {
ControlFlow::CONTINUE
}
}
fn visit_const(&mut self, c: ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> {
if c.needs_infer() {
if ty::Term::from(c) == self.term {
ControlFlow::BREAK
} else {
c.super_visit_with(self)
}
} else {
ControlFlow::CONTINUE
}
}
}
let mut visitor = ContainsTerm { term: goal.predicate.term };
term_is_infer
&& goal.predicate.projection_ty.visit_with(&mut visitor).is_continue()
&& goal.param_env.visit_with(&mut visitor).is_continue()
}
fn merge_project_candidates(
@ -83,14 +168,13 @@ impl<'tcx> EvalCtxt<'tcx> {
match (candidate.source, other.source) {
(CandidateSource::Impl(_), _)
| (CandidateSource::ParamEnv(_), _)
| (CandidateSource::Builtin, _) => unimplemented!(),
| (CandidateSource::BuiltinImpl, _)
| (CandidateSource::AliasBound(_), _) => unimplemented!(),
}
}
}
impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
type CandidateSource = CandidateSource;
fn self_ty(self) -> Ty<'tcx> {
self.self_ty()
}
@ -104,33 +188,26 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
}
fn consider_impl_candidate(
acx: &mut AssemblyCtxt<'_, 'tcx, ProjectionPredicate<'tcx>>,
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, ProjectionPredicate<'tcx>>,
impl_def_id: DefId,
) {
let tcx = acx.cx.tcx;
) -> Result<Certainty, NoSolution> {
let tcx = ecx.tcx();
let goal_trait_ref = goal.predicate.projection_ty.trait_ref(tcx);
let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap();
let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::AsPlaceholder };
if iter::zip(goal_trait_ref.substs, impl_trait_ref.skip_binder().substs)
.any(|(goal, imp)| !drcx.generic_args_may_unify(goal, imp))
{
return;
return Err(NoSolution);
}
acx.infcx.probe(|_| {
let impl_substs = acx.infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
ecx.infcx.probe(|_| {
let impl_substs = ecx.infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
let impl_trait_ref = impl_trait_ref.subst(tcx, impl_substs);
let Ok(InferOk { obligations, .. }) = acx
.infcx
.at(&ObligationCause::dummy(), goal.param_env)
.define_opaque_types(false)
.eq(goal_trait_ref, impl_trait_ref)
.map_err(|e| debug!("failed to equate trait refs: {e:?}"))
else {
return
};
let mut nested_goals = ecx.infcx.eq(goal.param_env, goal_trait_ref, impl_trait_ref)?;
let where_clause_bounds = tcx
.predicates_of(impl_def_id)
.instantiate(tcx, impl_substs)
@ -138,17 +215,21 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
.into_iter()
.map(|pred| goal.with(tcx, pred));
let nested_goals = obligations.into_iter().map(|o| o.into()).chain(where_clause_bounds).collect();
let Ok(trait_ref_certainty) = acx.cx.evaluate_all(acx.infcx, nested_goals) else { return };
nested_goals.extend(where_clause_bounds);
let trait_ref_certainty = ecx.evaluate_all(nested_goals)?;
// In case the associated item is hidden due to specialization, we have to
// return ambiguity this would otherwise be incomplete, resulting in
// unsoundness during coherence (#105782).
let Some(assoc_def) = fetch_eligible_assoc_item_def(
acx.infcx,
ecx.infcx,
goal.param_env,
goal_trait_ref,
goal.predicate.def_id(),
impl_def_id
) else {
return
)? else {
let certainty = Certainty::Maybe(MaybeCause::Ambiguity);
return Ok(trait_ref_certainty.unify_and(certainty));
};
if !assoc_def.item.defaultness(tcx).has_value() {
@ -174,7 +255,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
impl_substs,
);
let substs = translate_substs(
acx.infcx,
ecx.infcx,
goal.param_env,
impl_def_id,
impl_substs_with_gat,
@ -185,7 +266,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
let is_const = matches!(tcx.def_kind(assoc_def.item.def_id), DefKind::AssocConst);
let ty = tcx.bound_type_of(assoc_def.item.def_id);
let term: ty::EarlyBinder<ty::Term<'tcx>> = if is_const {
let identity_substs = ty::InternalSubsts::identity_for_item(tcx, assoc_def.item.def_id);
let identity_substs =
ty::InternalSubsts::identity_for_item(tcx, assoc_def.item.def_id);
let did = ty::WithOptConstParam::unknown(assoc_def.item.def_id);
let kind =
ty::ConstKind::Unevaluated(ty::UnevaluatedConst::new(did, identity_substs));
@ -194,23 +276,38 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
ty.map_bound(|ty| ty.into())
};
let Ok(InferOk { obligations, .. }) = acx
// The term of our goal should be fully unconstrained, so this should never fail.
//
// It can however be ambiguous when the resolved type is a projection.
let nested_goals = ecx
.infcx
.at(&ObligationCause::dummy(), goal.param_env)
.define_opaque_types(false)
.eq(goal.predicate.term, term.subst(tcx, substs))
.map_err(|e| debug!("failed to equate trait refs: {e:?}"))
else {
return
};
.eq(goal.param_env, goal.predicate.term, term.subst(tcx, substs))
.expect("failed to unify with unconstrained term");
let rhs_certainty =
ecx.evaluate_all(nested_goals).expect("failed to unify with unconstrained term");
let nested_goals = obligations.into_iter().map(|o| o.into()).collect();
let Ok(rhs_certainty) = acx.cx.evaluate_all(acx.infcx, nested_goals) else { return };
let certainty = trait_ref_certainty.unify_and(rhs_certainty);
acx.try_insert_candidate(CandidateSource::Impl(impl_def_id), certainty);
Ok(trait_ref_certainty.unify_and(rhs_certainty))
})
}
fn consider_builtin_sized_candidate(
_ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
) -> Result<Certainty, NoSolution> {
bug!("`Sized` does not have an associated type: {:?}", goal);
}
fn consider_assumption(
_ecx: &mut EvalCtxt<'_, 'tcx>,
_goal: Goal<'tcx, Self>,
assumption: ty::Predicate<'tcx>,
) -> Result<Certainty, NoSolution> {
if let Some(_poly_projection_pred) = assumption.to_opt_poly_projection_pred() {
unimplemented!()
} else {
Err(NoSolution)
}
}
}
/// This behavior is also implemented in `rustc_ty_utils` and in the old `project` code.
@ -224,10 +321,9 @@ fn fetch_eligible_assoc_item_def<'tcx>(
goal_trait_ref: ty::TraitRef<'tcx>,
trait_assoc_def_id: DefId,
impl_def_id: DefId,
) -> Option<LeafDef> {
) -> Result<Option<LeafDef>, NoSolution> {
let node_item = specialization_graph::assoc_def(infcx.tcx, impl_def_id, trait_assoc_def_id)
.map_err(|ErrorGuaranteed { .. }| ())
.ok()?;
.map_err(|ErrorGuaranteed { .. }| NoSolution)?;
let eligible = if node_item.is_final() {
// Non-specializable items are always projectable.
@ -246,5 +342,5 @@ fn fetch_eligible_assoc_item_def<'tcx>(
}
};
if eligible { Some(node_item) } else { None }
if eligible { Ok(Some(node_item)) } else { Ok(None) }
}

123
compiler/rustc_trait_selection/src/solve/search_graph/cache.rs Normal file
View File

@ -0,0 +1,123 @@
//! This module both handles the global cache which stores "finished" goals,
//! and the provisional cache which contains partially computed goals.
//!
//! The provisional cache is necessary when dealing with coinductive cycles.
//!
//! For more information about the provisional cache and coinduction in general,
//! check out the relevant section of the rustc-dev-guide.
//!
//! FIXME(@lcnr): Write that section, feel free to ping me if you need help here
//! before then or if I still haven't done that before January 2023.
use super::overflow::OverflowData;
use super::StackDepth;
use crate::solve::{CanonicalGoal, QueryResult};
use rustc_data_structures::fx::FxHashMap;
use rustc_index::vec::IndexVec;
use rustc_middle::ty::TyCtxt;
rustc_index::newtype_index! {
pub struct EntryIndex {}
}
#[derive(Debug, Clone)]
pub(super) struct ProvisionalEntry<'tcx> {
// In case we have a coinductive cycle, this is the
// the currently least restrictive result of this goal.
pub(super) response: QueryResult<'tcx>,
// In case of a cycle, the position of deepest stack entry involved
// in that cycle. This is monotonically decreasing in the stack as all
// elements between the current stack element in the deepest stack entry
// involved have to also be involved in that cycle.
//
// We can only move entries to the global cache once we're complete done
// with the cycle. If this entry has not been involved in a cycle,
// this is just its own depth.
pub(super) depth: StackDepth,
// The goal for this entry. Should always be equal to the corresponding goal
// in the lookup table.
pub(super) goal: CanonicalGoal<'tcx>,
}
pub(super) struct ProvisionalCache<'tcx> {
pub(super) entries: IndexVec<EntryIndex, ProvisionalEntry<'tcx>>,
// FIXME: This is only used to quickly check whether a given goal
// is in the cache. We should experiment with using something like
// `SsoHashSet` here because in most cases there are only a few entries.
pub(super) lookup_table: FxHashMap<CanonicalGoal<'tcx>, EntryIndex>,
}
impl<'tcx> ProvisionalCache<'tcx> {
pub(super) fn empty() -> ProvisionalCache<'tcx> {
ProvisionalCache { entries: Default::default(), lookup_table: Default::default() }
}
pub(super) fn is_empty(&self) -> bool {
self.entries.is_empty() && self.lookup_table.is_empty()
}
/// Adds a dependency from the current leaf to `target` in the cache
/// to prevent us from moving any goals which depend on the current leaf
/// to the global cache while we're still computing `target`.
///
/// Its important to note that `target` may already be part of a different cycle.
/// In this case we have to ensure that we also depend on all other goals
/// in the existing cycle in addition to the potentially direct cycle with `target`.
pub(super) fn add_dependency_of_leaf_on(&mut self, target: EntryIndex) {
let depth = self.entries[target].depth;
for provisional_entry in &mut self.entries.raw[target.index()..] {
// The depth of `target` is the position of the deepest goal in the stack
// on which `target` depends. That goal is the `root` of this cycle.
//
// Any entry which was added after `target` is either on the stack itself
// at which point its depth is definitely at least as high as the depth of
// `root`. If it's not on the stack itself it has to depend on a goal
// between `root` and `leaf`. If it were to depend on a goal deeper in the
// stack than `root`, then `root` would also depend on that goal, at which
// point `root` wouldn't be the root anymore.
debug_assert!(provisional_entry.depth >= depth);
provisional_entry.depth = depth;
}
// We only update entries which were added after `target` as no other
// entry should have a higher depth.
//
// Any entry which previously had a higher depth than target has to
// be between `target` and `root`. Because of this we would have updated
// its depth when calling `add_dependency_of_leaf_on(root)` for `target`.
if cfg!(debug_assertions) {
self.entries.iter().all(|e| e.depth <= depth);
}
}
pub(super) fn depth(&self, entry_index: EntryIndex) -> StackDepth {
self.entries[entry_index].depth
}
pub(super) fn provisional_result(&self, entry_index: EntryIndex) -> QueryResult<'tcx> {
self.entries[entry_index].response.clone()
}
}
pub(super) fn try_move_finished_goal_to_global_cache<'tcx>(
tcx: TyCtxt<'tcx>,
overflow_data: &mut OverflowData,
stack: &IndexVec<super::StackDepth, super::StackElem<'tcx>>,
goal: CanonicalGoal<'tcx>,
response: QueryResult<'tcx>,
) {
// We move goals to the global cache if we either did not hit an overflow or if it's
// the root goal as that will now always hit the same overflow limit.
//
// NOTE: We cannot move any non-root goals to the global cache even if their final result
// isn't impacted by the overflow as that goal still has unstable query dependencies
// because it didn't go its full depth.
//
// FIXME(@lcnr): We could still cache subtrees which are not impacted by overflow though.
// Tracking that info correctly isn't trivial, so I haven't implemented it for now.
let should_cache_globally = !overflow_data.did_overflow() || stack.is_empty();
if should_cache_globally {
// FIXME: move the provisional entry to the global cache.
let _ = (tcx, goal, response);
}
}

178
compiler/rustc_trait_selection/src/solve/search_graph/mod.rs Normal file
View File

@ -0,0 +1,178 @@
mod cache;
mod overflow;
use self::cache::ProvisionalEntry;
use super::{CanonicalGoal, Certainty, MaybeCause, QueryResult};
use cache::ProvisionalCache;
use overflow::OverflowData;
use rustc_index::vec::IndexVec;
use rustc_middle::ty::TyCtxt;
use std::collections::hash_map::Entry;
rustc_index::newtype_index! {
pub struct StackDepth {}
}
struct StackElem<'tcx> {
goal: CanonicalGoal<'tcx>,
has_been_used: bool,
}
pub(super) struct SearchGraph<'tcx> {
/// The stack of goals currently being computed.
///
/// An element is *deeper* in the stack if its index is *lower*.
stack: IndexVec<StackDepth, StackElem<'tcx>>,
overflow_data: OverflowData,
provisional_cache: ProvisionalCache<'tcx>,
}
impl<'tcx> SearchGraph<'tcx> {
pub(super) fn new(tcx: TyCtxt<'tcx>) -> SearchGraph<'tcx> {
Self {
stack: Default::default(),
overflow_data: OverflowData::new(tcx),
provisional_cache: ProvisionalCache::empty(),
}
}
pub(super) fn is_empty(&self) -> bool {
self.stack.is_empty()
&& self.provisional_cache.is_empty()
&& !self.overflow_data.did_overflow()
}
/// Tries putting the new goal on the stack, returning an error if it is already cached.
///
/// This correctly updates the provisional cache if there is a cycle.
pub(super) fn try_push_stack(
&mut self,
tcx: TyCtxt<'tcx>,
goal: CanonicalGoal<'tcx>,
) -> Result<(), QueryResult<'tcx>> {
// FIXME: start by checking the global cache
// Look at the provisional cache to check for cycles.
let cache = &mut self.provisional_cache;
match cache.lookup_table.entry(goal) {
// No entry, simply push this goal on the stack after dealing with overflow.
Entry::Vacant(v) => {
if self.overflow_data.has_overflow(self.stack.len()) {
return Err(self.deal_with_overflow(tcx, goal));
}
let depth = self.stack.push(StackElem { goal, has_been_used: false });
let response = super::response_no_constraints(tcx, goal, Certainty::Yes);
let entry_index = cache.entries.push(ProvisionalEntry { response, depth, goal });
v.insert(entry_index);
Ok(())
}
// We have a nested goal which relies on a goal `root` deeper in the stack.
//
// We first store that we may have to rerun `evaluate_goal` for `root` in case the
// provisional response is not equal to the final response. We also update the depth
// of all goals which recursively depend on our current goal to depend on `root`
// instead.
//
// Finally we can return either the provisional response for that goal if we have a
// coinductive cycle or an ambiguous result if the cycle is inductive.
Entry::Occupied(entry_index) => {
let entry_index = *entry_index.get();
cache.add_dependency_of_leaf_on(entry_index);
let stack_depth = cache.depth(entry_index);
self.stack[stack_depth].has_been_used = true;
// NOTE: The goals on the stack aren't the only goals involved in this cycle.
// We can also depend on goals which aren't part of the stack but coinductively
// depend on the stack themselves. We already checked whether all the goals
// between these goals and their root on the stack. This means that as long as
// each goal in a cycle is checked for coinductivity by itself, simply checking
// the stack is enough.
if self.stack.raw[stack_depth.index()..]
.iter()
.all(|g| g.goal.value.predicate.is_coinductive(tcx))
{
Err(cache.provisional_result(entry_index))
} else {
Err(super::response_no_constraints(
tcx,
goal,
Certainty::Maybe(MaybeCause::Overflow),
))
}
}
}
}
/// We cannot simply store the result of [super::EvalCtxt::compute_goal] as we have to deal with
/// coinductive cycles.
///
/// When we encounter a coinductive cycle, we have to prove the final result of that cycle
/// while we are still computing that result. Because of this we continously recompute the
/// cycle until the result of the previous iteration is equal to the final result, at which
/// point we are done.
///
/// This function returns `true` if we were able to finalize the goal and `false` if it has
/// updated the provisional cache and we have to recompute the current goal.
///
/// FIXME: Refer to the rustc-dev-guide entry once it exists.
pub(super) fn try_finalize_goal(
&mut self,
tcx: TyCtxt<'tcx>,
actual_goal: CanonicalGoal<'tcx>,
response: QueryResult<'tcx>,
) -> bool {
let StackElem { goal, has_been_used } = self.stack.pop().unwrap();
assert_eq!(goal, actual_goal);
let cache = &mut self.provisional_cache;
let provisional_entry_index = *cache.lookup_table.get(&goal).unwrap();
let provisional_entry = &mut cache.entries[provisional_entry_index];
let depth = provisional_entry.depth;
// Was the current goal the root of a cycle and was the provisional response
// different from the final one.
if has_been_used && provisional_entry.response != response {
// If so, update the provisional reponse for this goal...
provisional_entry.response = response;
// ...remove all entries whose result depends on this goal
// from the provisional cache...
//
// That's not completely correct, as a nested goal can also
// depend on a goal which is lower in the stack so it doesn't
// actually depend on the current goal. This should be fairly
// rare and is hopefully not relevant for performance.
#[allow(rustc::potential_query_instability)]
cache.lookup_table.retain(|_key, index| *index <= provisional_entry_index);
cache.entries.truncate(provisional_entry_index.index() + 1);
// ...and finally push our goal back on the stack and reevaluate it.
self.stack.push(StackElem { goal, has_been_used: false });
false
} else {
// If not, we're done with this goal.
//
// Check whether that this goal doesn't depend on a goal deeper on the stack
// and if so, move it and all nested goals to the global cache.
//
// Note that if any nested goal were to depend on something deeper on the stack,
// this would have also updated the depth of the current goal.
if depth == self.stack.next_index() {
for (i, entry) in cache.entries.drain_enumerated(provisional_entry_index.index()..)
{
let actual_index = cache.lookup_table.remove(&entry.goal);
debug_assert_eq!(Some(i), actual_index);
debug_assert!(entry.depth == depth);
cache::try_move_finished_goal_to_global_cache(
tcx,
&mut self.overflow_data,
&self.stack,
entry.goal,
entry.response,
);
}
}
true
}
}
}

29
compiler/rustc_trait_selection/src/solve/overflow.rs → compiler/rustc_trait_selection/src/solve/search_graph/overflow.rs
View File

@ -3,8 +3,8 @@ use rustc_infer::traits::query::NoSolution;
use rustc_middle::ty::TyCtxt;
use rustc_session::Limit;
use super::cache::response_no_constraints;
use super::{Certainty, EvalCtxt, MaybeCause, QueryResult};
use super::SearchGraph;
use crate::solve::{response_no_constraints, Certainty, EvalCtxt, MaybeCause, QueryResult};
/// When detecting a solver overflow, we return ambiguity. Overflow can be
/// *hidden* by either a fatal error in an **AND** or a trivial success in an **OR**.
@ -50,32 +50,35 @@ impl OverflowData {
}
}
impl<'tcx> EvalCtxt<'tcx> {
pub(super) fn deal_with_overflow(
impl<'tcx> SearchGraph<'tcx> {
pub fn deal_with_overflow(
&mut self,
tcx: TyCtxt<'tcx>,
goal: Canonical<'tcx, impl Sized>,
) -> QueryResult<'tcx> {
self.overflow_data.deal_with_overflow();
response_no_constraints(self.tcx, goal, Certainty::Maybe(MaybeCause::Overflow))
response_no_constraints(tcx, goal, Certainty::Maybe(MaybeCause::Overflow))
}
}
impl<'tcx> EvalCtxt<'_, 'tcx> {
/// A `while`-loop which tracks overflow.
pub(super) fn repeat_while_none(
pub fn repeat_while_none(
&mut self,
mut loop_body: impl FnMut(&mut Self) -> Option<Result<Certainty, NoSolution>>,
) -> Result<Certainty, NoSolution> {
let start_depth = self.overflow_data.additional_depth;
let depth = self.provisional_cache.current_depth();
while !self.overflow_data.has_overflow(depth) {
let start_depth = self.search_graph.overflow_data.additional_depth;
let depth = self.search_graph.stack.len();
while !self.search_graph.overflow_data.has_overflow(depth) {
if let Some(result) = loop_body(self) {
self.overflow_data.additional_depth = start_depth;
self.search_graph.overflow_data.additional_depth = start_depth;
return result;
}
self.overflow_data.additional_depth += 1;
self.search_graph.overflow_data.additional_depth += 1;
}
self.overflow_data.additional_depth = start_depth;
self.overflow_data.deal_with_overflow();
self.search_graph.overflow_data.additional_depth = start_depth;
self.search_graph.overflow_data.deal_with_overflow();
Ok(Certainty::Maybe(MaybeCause::Overflow))
}
}

108
compiler/rustc_trait_selection/src/solve/trait_goals.rs
View File

@ -2,58 +2,17 @@
use std::iter;
use super::assembly::{self, AssemblyCtxt};
use super::{CanonicalGoal, EvalCtxt, Goal, QueryResult};
use super::assembly::{self, Candidate, CandidateSource};
use super::infcx_ext::InferCtxtExt;
use super::{Certainty, EvalCtxt, Goal, QueryResult};
use rustc_hir::def_id::DefId;
use rustc_infer::infer::InferOk;
use rustc_infer::traits::query::NoSolution;
use rustc_infer::traits::ObligationCause;
use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
use rustc_middle::ty::TraitPredicate;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_span::DUMMY_SP;
#[allow(dead_code)] // FIXME: implement and use all variants.
#[derive(Debug, Clone, Copy)]
pub(super) enum CandidateSource {
/// Some user-defined impl with the given `DefId`.
Impl(DefId),
/// The n-th caller bound in the `param_env` of our goal.
///
/// This is pretty much always a bound from the `where`-clauses of the
/// currently checked item.
ParamEnv(usize),
/// A bound on the `self_ty` in case it is a projection or an opaque type.
///
/// # Examples
///
/// ```ignore (for syntax highlighting)
/// trait Trait {
/// type Assoc: OtherTrait;
/// }
/// ```
///
/// We know that `<Whatever as Trait>::Assoc: OtherTrait` holds by looking at
/// the bounds on `Trait::Assoc`.
AliasBound(usize),
/// A builtin implementation for some specific traits, used in cases
/// where we cannot rely an ordinary library implementations.
///
/// The most notable examples are `Sized`, `Copy` and `Clone`. This is also
/// used for the `DiscriminantKind` and `Pointee` trait, both of which have
/// an associated type.
Builtin,
/// An automatic impl for an auto trait, e.g. `Send`. These impls recursively look
/// at the constituent types of the `self_ty` to check whether the auto trait
/// is implemented for those.
AutoImpl,
}
type Candidate<'tcx> = assembly::Candidate<'tcx, TraitPredicate<'tcx>>;
impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
type CandidateSource = CandidateSource;
fn self_ty(self) -> Ty<'tcx> {
self.self_ty()
}
@ -67,55 +26,63 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
}
fn consider_impl_candidate(
acx: &mut AssemblyCtxt<'_, 'tcx, Self>,
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, TraitPredicate<'tcx>>,
impl_def_id: DefId,
) {
let tcx = acx.cx.tcx;
) -> Result<Certainty, NoSolution> {
let tcx = ecx.tcx();
let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap();
let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::AsPlaceholder };
if iter::zip(goal.predicate.trait_ref.substs, impl_trait_ref.skip_binder().substs)
.any(|(goal, imp)| !drcx.generic_args_may_unify(goal, imp))
{
return;
return Err(NoSolution);
}
acx.infcx.probe(|_| {
let impl_substs = acx.infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
ecx.infcx.probe(|_| {
let impl_substs = ecx.infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
let impl_trait_ref = impl_trait_ref.subst(tcx, impl_substs);
let Ok(InferOk { obligations, .. }) = acx
.infcx
.at(&ObligationCause::dummy(), goal.param_env)
.define_opaque_types(false)
.eq(goal.predicate.trait_ref, impl_trait_ref)
.map_err(|e| debug!("failed to equate trait refs: {e:?}"))
else {
return
};
let mut nested_goals =
ecx.infcx.eq(goal.param_env, goal.predicate.trait_ref, impl_trait_ref)?;
let where_clause_bounds = tcx
.predicates_of(impl_def_id)
.instantiate(tcx, impl_substs)
.predicates
.into_iter()
.map(|pred| goal.with(tcx, pred));
let nested_goals =
obligations.into_iter().map(|o| o.into()).chain(where_clause_bounds).collect();
let Ok(certainty) = acx.cx.evaluate_all(acx.infcx, nested_goals) else { return };
acx.try_insert_candidate(CandidateSource::Impl(impl_def_id), certainty);
nested_goals.extend(where_clause_bounds);
ecx.evaluate_all(nested_goals)
})
}
fn consider_builtin_sized_candidate(
_ecx: &mut EvalCtxt<'_, 'tcx>,
_goal: Goal<'tcx, Self>,
) -> Result<Certainty, NoSolution> {
unimplemented!();
}
fn consider_assumption(
_ecx: &mut EvalCtxt<'_, 'tcx>,
_goal: Goal<'tcx, Self>,
assumption: ty::Predicate<'tcx>,
) -> Result<Certainty, NoSolution> {
if let Some(_poly_trait_pred) = assumption.to_opt_poly_trait_pred() {
unimplemented!()
} else {
Err(NoSolution)
}
}
}
impl<'tcx> EvalCtxt<'tcx> {
impl<'tcx> EvalCtxt<'_, 'tcx> {
pub(super) fn compute_trait_goal(
&mut self,
goal: CanonicalGoal<'tcx, TraitPredicate<'tcx>>,
goal: Goal<'tcx, TraitPredicate<'tcx>>,
) -> QueryResult<'tcx> {
let candidates = AssemblyCtxt::assemble_and_evaluate_candidates(self, goal);
let candidates = self.assemble_and_evaluate_candidates(goal);
self.merge_trait_candidates_discard_reservation_impls(candidates)
}
@ -169,14 +136,13 @@ impl<'tcx> EvalCtxt<'tcx> {
(CandidateSource::Impl(_), _)
| (CandidateSource::ParamEnv(_), _)
| (CandidateSource::AliasBound(_), _)
| (CandidateSource::Builtin, _)
| (CandidateSource::AutoImpl, _) => unimplemented!(),
| (CandidateSource::BuiltinImpl, _) => unimplemented!(),
}
}
fn discard_reservation_impl(&self, candidate: Candidate<'tcx>) -> Candidate<'tcx> {
if let CandidateSource::Impl(def_id) = candidate.source {
if let ty::ImplPolarity::Reservation = self.tcx.impl_polarity(def_id) {
if let ty::ImplPolarity::Reservation = self.tcx().impl_polarity(def_id) {
debug!("Selected reservation impl");
// FIXME: reduce candidate to ambiguous
// FIXME: replace `var_values` with identity, yeet external constraints.

6
library/alloc/src/vec/drain.rs
View File

@ -223,9 +223,9 @@ impl<T, A: Allocator> Drop for Drain<'_, T, A> {
}
// as_slice() must only be called when iter.len() is > 0 because
// vec::Splice modifies vec::Drain fields and may grow the vec which would invalidate
// the iterator's internal pointers. Creating a reference to deallocated memory
// is invalid even when it is zero-length
// it also gets touched by vec::Splice which may turn it into a dangling pointer
// which would make it and the vec pointer point to different allocations which would
// lead to invalid pointer arithmetic below.
let drop_ptr = iter.as_slice().as_ptr();
unsafe {

6
library/alloc/src/vec/splice.rs
View File

@ -54,6 +54,12 @@ impl<I: Iterator, A: Allocator> ExactSizeIterator for Splice<'_, I, A> {}
impl<I: Iterator, A: Allocator> Drop for Splice<'_, I, A> {
fn drop(&mut self) {
self.drain.by_ref().for_each(drop);
// At this point draining is done and the only remaining tasks are splicing
// and moving things into the final place.
// Which means we can replace the slice::Iter with pointers that won't point to deallocated
// memory, so that Drain::drop is still allowed to call iter.len(), otherwise it would break
// the ptr.sub_ptr contract.
self.drain.iter = (&[]).iter();
unsafe {
if self.drain.tail_len == 0 {

24
library/core/src/ptr/const_ptr.rs
View File

@ -202,14 +202,11 @@ impl<T: ?Sized> *const T {
#[must_use]
#[inline(always)]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn addr(self) -> usize
where
T: Sized,
{
pub fn addr(self) -> usize {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
// SAFETY: Pointer-to-integer transmutes are valid (if you are okay with losing the
// provenance).
unsafe { mem::transmute(self) }
unsafe { mem::transmute(self.cast::<()>()) }
}
/// Gets the "address" portion of the pointer, and 'exposes' the "provenance" part for future
@ -239,12 +236,9 @@ impl<T: ?Sized> *const T {
#[must_use]
#[inline(always)]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn expose_addr(self) -> usize
where
T: Sized,
{
pub fn expose_addr(self) -> usize {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
self as usize
self.cast::<()>() as usize
}
/// Creates a new pointer with the given address.
@ -262,10 +256,7 @@ impl<T: ?Sized> *const T {
#[must_use]
#[inline]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn with_addr(self, addr: usize) -> Self
where
T: Sized,
{
pub fn with_addr(self, addr: usize) -> Self {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
//
// In the mean-time, this operation is defined to be "as if" it was
@ -288,10 +279,7 @@ impl<T: ?Sized> *const T {
#[must_use]
#[inline]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self
where
T: Sized,
{
pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self {
self.with_addr(f(self.addr()))
}

24
library/core/src/ptr/mut_ptr.rs
View File

@ -208,14 +208,11 @@ impl<T: ?Sized> *mut T {
#[must_use]
#[inline(always)]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn addr(self) -> usize
where
T: Sized,
{
pub fn addr(self) -> usize {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
// SAFETY: Pointer-to-integer transmutes are valid (if you are okay with losing the
// provenance).
unsafe { mem::transmute(self) }
unsafe { mem::transmute(self.cast::<()>()) }
}
/// Gets the "address" portion of the pointer, and 'exposes' the "provenance" part for future
@ -245,12 +242,9 @@ impl<T: ?Sized> *mut T {
#[must_use]
#[inline(always)]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn expose_addr(self) -> usize
where
T: Sized,
{
pub fn expose_addr(self) -> usize {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
self as usize
self.cast::<()>() as usize
}
/// Creates a new pointer with the given address.
@ -268,10 +262,7 @@ impl<T: ?Sized> *mut T {
#[must_use]
#[inline]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn with_addr(self, addr: usize) -> Self
where
T: Sized,
{
pub fn with_addr(self, addr: usize) -> Self {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
//
// In the mean-time, this operation is defined to be "as if" it was
@ -294,10 +285,7 @@ impl<T: ?Sized> *mut T {
#[must_use]
#[inline]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self
where
T: Sized,
{
pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self {
self.with_addr(f(self.addr()))
}

15
library/core/src/ptr/non_null.rs
View File

@ -268,10 +268,7 @@ impl<T: ?Sized> NonNull<T> {
#[must_use]
#[inline]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn addr(self) -> NonZeroUsize
where
T: Sized,
{
pub fn addr(self) -> NonZeroUsize {
// SAFETY: The pointer is guaranteed by the type to be non-null,
// meaning that the address will be non-zero.
unsafe { NonZeroUsize::new_unchecked(self.pointer.addr()) }
@ -286,10 +283,7 @@ impl<T: ?Sized> NonNull<T> {
#[must_use]
#[inline]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn with_addr(self, addr: NonZeroUsize) -> Self
where
T: Sized,
{
pub fn with_addr(self, addr: NonZeroUsize) -> Self {
// SAFETY: The result of `ptr::from::with_addr` is non-null because `addr` is guaranteed to be non-zero.
unsafe { NonNull::new_unchecked(self.pointer.with_addr(addr.get()) as *mut _) }
}
@ -303,10 +297,7 @@ impl<T: ?Sized> NonNull<T> {
#[must_use]
#[inline]
#[unstable(feature = "strict_provenance", issue = "95228")]
pub fn map_addr(self, f: impl FnOnce(NonZeroUsize) -> NonZeroUsize) -> Self
where
T: Sized,
{
pub fn map_addr(self, f: impl FnOnce(NonZeroUsize) -> NonZeroUsize) -> Self {
self.with_addr(f(self.addr()))
}

2
library/std/src/os/net/linux_ext/addr.rs
View File

@ -38,7 +38,7 @@ pub trait SocketAddrExt: Sealed {
/// Ok(())
/// }
/// ```
fn from_abstract_name<N>(name: &N) -> crate::io::Result<SocketAddr>
fn from_abstract_name<N>(name: N) -> crate::io::Result<SocketAddr>
where
N: AsRef<[u8]>;

2
library/std/src/os/unix/net/addr.rs
View File

@ -256,7 +256,7 @@ impl linux_ext::addr::SocketAddrExt for SocketAddr {
if let AddressKind::Abstract(name) = self.address() { Some(name) } else { None }
}
fn from_abstract_name<N>(name: &N) -> crate::io::Result<Self>
fn from_abstract_name<N>(name: N) -> crate::io::Result<Self>
where
N: AsRef<[u8]>,
{

13
src/librustdoc/html/static/js/main.js
View File

@ -803,15 +803,10 @@ function loadCss(cssUrl) {
}
});
function handleClick(id, f) {
const elem = document.getElementById(id);
if (elem) {
elem.addEventListener("click", f);
const mainElem = document.getElementById(MAIN_ID);
if (mainElem) {
mainElem.addEventListener("click", hideSidebar);
}
}
handleClick(MAIN_ID, () => {
hideSidebar();
});
onEachLazy(document.querySelectorAll("a[href^='#']"), el => {
// For clicks on internal links (<A> tags with a hash property), we expand the section we're
@ -945,7 +940,7 @@ function loadCss(cssUrl) {
return;
}
if (!this.NOTABLE_FORCE_VISIBLE &&
!elemIsInParent(event.relatedTarget, window.CURRENT_NOTABLE_ELEMENT)) {
!elemIsInParent(ev.relatedTarget, window.CURRENT_NOTABLE_ELEMENT)) {
hideNotable(true);
}
};

6
src/tools/miri/tests/pass/vec.rs
View File

@ -162,6 +162,11 @@ fn reverse() {
assert!(v[0].0 == 49);
}
fn miri_issue_2759() {
let mut input = "1".to_string();
input.replace_range(0..0, "0");
}
fn main() {
assert_eq!(vec_reallocate().len(), 5);
@ -191,4 +196,5 @@ fn main() {
swap();
swap_remove();
reverse();
miri_issue_2759();
}