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Auto merge of #77792 - matthewjasper:instrument-trait-selection, r=oli-obk

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Use tracing spans in rustc_trait_selection

Spans are very helpful when debugging this code. It's also hot enough to make a good benchmark.

r? `@oli-obk`
This commit is contained in:
bors 2020-10-12 23:04:55 +00:00
commit abbdec3be6
5 changed files with 166 additions and 290 deletions
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33
compiler/rustc_trait_selection/src/traits/fulfill.rs
View File

@ -120,7 +120,8 @@ impl<'a, 'tcx> FulfillmentContext<'tcx> {
&mut self,
selcx: &mut SelectionContext<'a, 'tcx>,
) -> Result<(), Vec<FulfillmentError<'tcx>>> {
debug!("select(obligation-forest-size={})", self.predicates.len());
let span = debug_span!("select", obligation_forest_size = ?self.predicates.len());
let _enter = span.enter();
let mut errors = Vec::new();
@ -173,7 +174,7 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentContext<'tcx> {
projection_ty: ty::ProjectionTy<'tcx>,
cause: ObligationCause<'tcx>,
) -> Ty<'tcx> {
debug!("normalize_projection_type(projection_ty={:?})", projection_ty);
debug!(?projection_ty, "normalize_projection_type");
debug_assert!(!projection_ty.has_escaping_bound_vars());
@ -191,7 +192,7 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentContext<'tcx> {
);
self.register_predicate_obligations(infcx, obligations);
debug!("normalize_projection_type: result={:?}", normalized_ty);
debug!(?normalized_ty);
normalized_ty
}
@ -205,7 +206,7 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentContext<'tcx> {
// debug output much nicer to read and so on.
let obligation = infcx.resolve_vars_if_possible(&obligation);
debug!("register_predicate_obligation(obligation={:?})", obligation);
debug!(?obligation, "register_predicate_obligation");
assert!(!infcx.is_in_snapshot() || self.usable_in_snapshot);
@ -342,7 +343,7 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
self.selcx.infcx().resolve_vars_if_possible(&obligation.predicate);
}
debug!("process_obligation: obligation = {:?} cause = {:?}", obligation, obligation.cause);
debug!(?obligation, ?obligation.cause, "process_obligation");
let infcx = self.selcx.infcx();
@ -509,7 +510,7 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
}
ty::PredicateAtom::ConstEquate(c1, c2) => {
debug!("equating consts: c1={:?} c2={:?}", c1, c2);
debug!(?c1, ?c2, "equating consts");
if self.selcx.tcx().features().const_evaluatable_checked {
// FIXME: we probably should only try to unify abstract constants
// if the constants depend on generic parameters.
@ -601,6 +602,7 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
}
}
#[instrument(level = "debug", skip(self, obligation, stalled_on))]
fn process_trait_obligation(
&mut self,
obligation: &PredicateObligation<'tcx>,
@ -613,8 +615,8 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
// FIXME: consider caching errors too.
if infcx.predicate_must_hold_considering_regions(obligation) {
debug!(
"selecting trait `{:?}` at depth {} evaluated to holds",
obligation.predicate, obligation.recursion_depth
"selecting trait at depth {} evaluated to holds",
obligation.recursion_depth
);
return ProcessResult::Changed(vec![]);
}
@ -622,17 +624,11 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
match self.selcx.select(&trait_obligation) {
Ok(Some(impl_source)) => {
debug!(
"selecting trait `{:?}` at depth {} yielded Ok(Some)",
trait_obligation.predicate, obligation.recursion_depth
);
debug!("selecting trait at depth {} yielded Ok(Some)", obligation.recursion_depth);
ProcessResult::Changed(mk_pending(impl_source.nested_obligations()))
}
Ok(None) => {
debug!(
"selecting trait `{:?}` at depth {} yielded Ok(None)",
trait_obligation.predicate, obligation.recursion_depth
);
debug!("selecting trait at depth {} yielded Ok(None)", obligation.recursion_depth);
// This is a bit subtle: for the most part, the
// only reason we can fail to make progress on
@ -652,10 +648,7 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
ProcessResult::Unchanged
}
Err(selection_err) => {
info!(
"selecting trait `{:?}` at depth {} yielded Err",
trait_obligation.predicate, obligation.recursion_depth
);
info!("selecting trait at depth {} yielded Err", obligation.recursion_depth);
ProcessResult::Error(CodeSelectionError(selection_err))
}

145
compiler/rustc_trait_selection/src/traits/project.rs
View File

@ -157,6 +157,7 @@ impl<'tcx> ProjectionTyCandidateSet<'tcx> {
/// the given obligations. If the projection cannot be normalized because
/// the required trait bound doesn't hold this returned with `obligations`
/// being a predicate that cannot be proven.
#[instrument(level = "debug", skip(selcx))]
pub(super) fn poly_project_and_unify_type<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
obligation: &PolyProjectionObligation<'tcx>,
@ -164,8 +165,6 @@ pub(super) fn poly_project_and_unify_type<'cx, 'tcx>(
Result<Option<Vec<PredicateObligation<'tcx>>>, InProgress>,
MismatchedProjectionTypes<'tcx>,
> {
debug!("poly_project_and_unify_type(obligation={:?})", obligation);
let infcx = selcx.infcx();
infcx.commit_if_ok(|_snapshot| {
let placeholder_predicate =
@ -191,7 +190,7 @@ fn project_and_unify_type<'cx, 'tcx>(
Result<Option<Vec<PredicateObligation<'tcx>>>, InProgress>,
MismatchedProjectionTypes<'tcx>,
> {
debug!("project_and_unify_type(obligation={:?})", obligation);
debug!(?obligation, "project_and_unify_type");
let mut obligations = vec![];
let normalized_ty = match opt_normalize_projection_type(
@ -207,10 +206,7 @@ fn project_and_unify_type<'cx, 'tcx>(
Err(InProgress) => return Ok(Err(InProgress)),
};
debug!(
"project_and_unify_type: normalized_ty={:?} obligations={:?}",
normalized_ty, obligations
);
debug!(?normalized_ty, ?obligations, "project_and_unify_type result");
let infcx = selcx.infcx();
match infcx
@ -275,6 +271,7 @@ where
Normalized { value, obligations }
}
#[instrument(level = "debug", skip(selcx, param_env, cause, obligations))]
pub fn normalize_with_depth_to<'a, 'b, 'tcx, T>(
selcx: &'a mut SelectionContext<'b, 'tcx>,
param_env: ty::ParamEnv<'tcx>,
@ -286,16 +283,10 @@ pub fn normalize_with_depth_to<'a, 'b, 'tcx, T>(
where
T: TypeFoldable<'tcx>,
{
debug!("normalize_with_depth(depth={}, value={:?})", depth, value);
let mut normalizer = AssocTypeNormalizer::new(selcx, param_env, cause, depth, obligations);
let result = ensure_sufficient_stack(|| normalizer.fold(value));
debug!(
"normalize_with_depth: depth={} result={:?} with {} obligations",
depth,
result,
normalizer.obligations.len()
);
debug!("normalize_with_depth: depth={} obligations={:?}", depth, normalizer.obligations);
debug!(?result, obligations.len = normalizer.obligations.len());
debug!(?normalizer.obligations,);
result
}
@ -396,12 +387,11 @@ impl<'a, 'b, 'tcx> TypeFolder<'tcx> for AssocTypeNormalizer<'a, 'b, 'tcx> {
&mut self.obligations,
);
debug!(
"AssocTypeNormalizer: depth={} normalized {:?} to {:?}, \
now with {} obligations",
self.depth,
ty,
normalized_ty,
self.obligations.len()
?self.depth,
?ty,
?normalized_ty,
obligations.len = ?self.obligations.len(),
"AssocTypeNormalizer: normalized type"
);
normalized_ty
}
@ -473,6 +463,7 @@ pub fn normalize_projection_type<'a, 'b, 'tcx>(
/// often immediately appended to another obligations vector. So now this
/// function takes an obligations vector and appends to it directly, which is
/// slightly uglier but avoids the need for an extra short-lived allocation.
#[instrument(level = "debug", skip(selcx, param_env, cause, obligations))]
fn opt_normalize_projection_type<'a, 'b, 'tcx>(
selcx: &'a mut SelectionContext<'b, 'tcx>,
param_env: ty::ParamEnv<'tcx>,
@ -486,13 +477,6 @@ fn opt_normalize_projection_type<'a, 'b, 'tcx>(
let projection_ty = infcx.resolve_vars_if_possible(&projection_ty);
let cache_key = ProjectionCacheKey::new(projection_ty);
debug!(
"opt_normalize_projection_type(\
projection_ty={:?}, \
depth={})",
projection_ty, depth
);
// FIXME(#20304) For now, I am caching here, which is good, but it
// means we don't capture the type variables that are created in
// the case of ambiguity. Which means we may create a large stream
@ -508,10 +492,7 @@ fn opt_normalize_projection_type<'a, 'b, 'tcx>(
// If we found ambiguity the last time, that means we will continue
// to do so until some type in the key changes (and we know it
// hasn't, because we just fully resolved it).
debug!(
"opt_normalize_projection_type: \
found cache entry: ambiguous"
);
debug!("found cache entry: ambiguous");
return Ok(None);
}
Err(ProjectionCacheEntry::InProgress) => {
@ -529,10 +510,7 @@ fn opt_normalize_projection_type<'a, 'b, 'tcx>(
// with `A::B`, which can trigger a recursive
// normalization.
debug!(
"opt_normalize_projection_type: \
found cache entry: in-progress"
);
debug!("found cache entry: in-progress");
return Err(InProgress);
}
@ -548,11 +526,7 @@ fn opt_normalize_projection_type<'a, 'b, 'tcx>(
// discarded as duplicated). But when doing trait
// evaluation this is not the case, and dropping the trait
// evaluations can causes ICEs (e.g., #43132).
debug!(
"opt_normalize_projection_type: \
found normalized ty `{:?}`",
ty
);
debug!(?ty, "found normalized ty");
// Once we have inferred everything we need to know, we
// can ignore the `obligations` from that point on.
@ -565,10 +539,7 @@ fn opt_normalize_projection_type<'a, 'b, 'tcx>(
return Ok(Some(ty.value));
}
Err(ProjectionCacheEntry::Error) => {
debug!(
"opt_normalize_projection_type: \
found error"
);
debug!("opt_normalize_projection_type: found error");
let result = normalize_to_error(selcx, param_env, projection_ty, cause, depth);
obligations.extend(result.obligations);
return Ok(Some(result.value));
@ -586,13 +557,7 @@ fn opt_normalize_projection_type<'a, 'b, 'tcx>(
// an impl, where-clause etc) and hence we must
// re-normalize it
debug!(
"opt_normalize_projection_type: \
projected_ty={:?} \
depth={} \
projected_obligations={:?}",
projected_ty, depth, projected_obligations
);
debug!(?projected_ty, ?depth, ?projected_obligations);
let result = if projected_ty.has_projections() {
let mut normalizer = AssocTypeNormalizer::new(
@ -604,11 +569,7 @@ fn opt_normalize_projection_type<'a, 'b, 'tcx>(
);
let normalized_ty = normalizer.fold(&projected_ty);
debug!(
"opt_normalize_projection_type: \
normalized_ty={:?} depth={}",
normalized_ty, depth
);
debug!(?normalized_ty, ?depth);
Normalized { value: normalized_ty, obligations: projected_obligations }
} else {
@ -621,21 +582,14 @@ fn opt_normalize_projection_type<'a, 'b, 'tcx>(
Ok(Some(result.value))
}
Ok(ProjectedTy::NoProgress(projected_ty)) => {
debug!(
"opt_normalize_projection_type: \
projected_ty={:?} no progress",
projected_ty
);
debug!(?projected_ty, "opt_normalize_projection_type: no progress");
let result = Normalized { value: projected_ty, obligations: vec![] };
infcx.inner.borrow_mut().projection_cache().insert_ty(cache_key, result.clone());
// No need to extend `obligations`.
Ok(Some(result.value))
}
Err(ProjectionTyError::TooManyCandidates) => {
debug!(
"opt_normalize_projection_type: \
too many candidates"
);
debug!("opt_normalize_projection_type: too many candidates");
infcx.inner.borrow_mut().projection_cache().ambiguous(cache_key);
Ok(None)
}
@ -755,15 +709,12 @@ impl<'tcx> Progress<'tcx> {
fn with_addl_obligations(mut self, mut obligations: Vec<PredicateObligation<'tcx>>) -> Self {
debug!(
"with_addl_obligations: self.obligations.len={} obligations.len={}",
self.obligations.len(),
obligations.len()
self.obligations.len = ?self.obligations.len(),
obligations.len = obligations.len(),
"with_addl_obligations"
);
debug!(
"with_addl_obligations: self.obligations={:?} obligations={:?}",
self.obligations, obligations
);
debug!(?self.obligations, ?obligations, "with_addl_obligations");
self.obligations.append(&mut obligations);
self
@ -778,7 +729,7 @@ fn project_type<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
obligation: &ProjectionTyObligation<'tcx>,
) -> Result<ProjectedTy<'tcx>, ProjectionTyError<'tcx>> {
debug!("project(obligation={:?})", obligation);
debug!(?obligation, "project_type");
if !selcx.tcx().sess.recursion_limit().value_within_limit(obligation.recursion_depth) {
debug!("project: overflow!");
@ -787,7 +738,7 @@ fn project_type<'cx, 'tcx>(
let obligation_trait_ref = &obligation.predicate.trait_ref(selcx.tcx());
debug!("project: obligation_trait_ref={:?}", obligation_trait_ref);
debug!(?obligation_trait_ref);
if obligation_trait_ref.references_error() {
return Ok(ProjectedTy::Progress(Progress::error(selcx.tcx())));
@ -951,10 +902,11 @@ fn assemble_candidates_from_predicates<'cx, 'tcx>(
env_predicates: impl Iterator<Item = ty::Predicate<'tcx>>,
potentially_unnormalized_candidates: bool,
) {
debug!("assemble_candidates_from_predicates(obligation={:?})", obligation);
debug!(?obligation, "assemble_candidates_from_predicates");
let infcx = selcx.infcx();
for predicate in env_predicates {
debug!("assemble_candidates_from_predicates: predicate={:?}", predicate);
debug!(?predicate);
if let ty::PredicateAtom::Projection(data) = predicate.skip_binders() {
let data = ty::Binder::bind(data);
let same_def_id = data.projection_def_id() == obligation.predicate.item_def_id;
@ -969,11 +921,7 @@ fn assemble_candidates_from_predicates<'cx, 'tcx>(
)
});
debug!(
"assemble_candidates_from_predicates: candidate={:?} \
is_match={} same_def_id={}",
data, is_match, same_def_id
);
debug!(?data, ?is_match, ?same_def_id);
if is_match {
candidate_set.push_candidate(ctor(data));
@ -997,6 +945,8 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
obligation_trait_ref: &ty::TraitRef<'tcx>,
candidate_set: &mut ProjectionTyCandidateSet<'tcx>,
) {
debug!("assemble_candidates_from_impls");
// If we are resolving `<T as TraitRef<...>>::Item == Type`,
// start out by selecting the predicate `T as TraitRef<...>`:
let poly_trait_ref = obligation_trait_ref.to_poly_trait_ref();
@ -1009,7 +959,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
return Err(());
}
Err(e) => {
debug!("assemble_candidates_from_impls: selection error {:?}", e);
debug!(error = ?e, "selection error");
candidate_set.mark_error(e);
return Err(());
}
@ -1020,7 +970,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
| super::ImplSource::Generator(_)
| super::ImplSource::FnPointer(_)
| super::ImplSource::TraitAlias(_) => {
debug!("assemble_candidates_from_impls: impl_source={:?}", impl_source);
debug!(?impl_source);
true
}
super::ImplSource::UserDefined(impl_data) => {
@ -1066,10 +1016,9 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
!poly_trait_ref.still_further_specializable()
} else {
debug!(
"assemble_candidates_from_impls: not eligible due to default: \
assoc_ty={} predicate={}",
selcx.tcx().def_path_str(node_item.item.def_id),
obligation.predicate,
assoc_ty = ?selcx.tcx().def_path_str(node_item.item.def_id),
?obligation.predicate,
"assemble_candidates_from_impls: not eligible due to default",
);
false
}
@ -1176,8 +1125,7 @@ fn confirm_candidate<'cx, 'tcx>(
obligation: &ProjectionTyObligation<'tcx>,
candidate: ProjectionTyCandidate<'tcx>,
) -> Progress<'tcx> {
debug!("confirm_candidate(candidate={:?}, obligation={:?})", candidate, obligation);
debug!(?obligation, ?candidate, "confirm_candidate");
let mut progress = match candidate {
ProjectionTyCandidate::ParamEnv(poly_projection)
| ProjectionTyCandidate::Object(poly_projection) => {
@ -1220,9 +1168,8 @@ fn confirm_select_candidate<'cx, 'tcx>(
| super::ImplSource::AutoImpl(..)
| super::ImplSource::Param(..)
| super::ImplSource::Builtin(..)
| super::ImplSource::TraitAlias(..) =>
// we don't create Select candidates with this kind of resolution
{
| super::ImplSource::TraitAlias(..) => {
// we don't create Select candidates with this kind of resolution
span_bug!(
obligation.cause.span,
"Cannot project an associated type from `{:?}`",
@ -1246,10 +1193,7 @@ fn confirm_generator_candidate<'cx, 'tcx>(
&gen_sig,
);
debug!(
"confirm_generator_candidate: obligation={:?},gen_sig={:?},obligations={:?}",
obligation, gen_sig, obligations
);
debug!(?obligation, ?gen_sig, ?obligations, "confirm_generator_candidate");
let tcx = selcx.tcx();
@ -1339,10 +1283,7 @@ fn confirm_closure_candidate<'cx, 'tcx>(
&closure_sig,
);
debug!(
"confirm_closure_candidate: obligation={:?},closure_sig={:?},obligations={:?}",
obligation, closure_sig, obligations
);
debug!(?obligation, ?closure_sig, ?obligations, "confirm_closure_candidate");
confirm_callable_candidate(selcx, obligation, closure_sig, util::TupleArgumentsFlag::No)
.with_addl_obligations(impl_source.nested)
@ -1357,7 +1298,7 @@ fn confirm_callable_candidate<'cx, 'tcx>(
) -> Progress<'tcx> {
let tcx = selcx.tcx();
debug!("confirm_callable_candidate({:?},{:?})", obligation, fn_sig);
debug!(?obligation, ?fn_sig, "confirm_callable_candidate");
let fn_once_def_id = tcx.require_lang_item(LangItem::FnOnce, None);
let fn_once_output_def_id = tcx.require_lang_item(LangItem::FnOnceOutput, None);

51
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
View File

@ -22,6 +22,7 @@ use super::SelectionCandidate::{self, *};
use super::{EvaluatedCandidate, SelectionCandidateSet, SelectionContext, TraitObligationStack};
impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
#[instrument(level = "debug", skip(self))]
pub(super) fn candidate_from_obligation<'o>(
&mut self,
stack: &TraitObligationStack<'o, 'tcx>,
@ -35,16 +36,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// this is because we want the unbound variables to be
// replaced with fresh types starting from index 0.
let cache_fresh_trait_pred = self.infcx.freshen(stack.obligation.predicate);
debug!(
"candidate_from_obligation(cache_fresh_trait_pred={:?}, obligation={:?})",
cache_fresh_trait_pred, stack
);
debug!(?cache_fresh_trait_pred);
debug_assert!(!stack.obligation.predicate.has_escaping_bound_vars());
if let Some(c) =
self.check_candidate_cache(stack.obligation.param_env, cache_fresh_trait_pred)
{
debug!("CACHE HIT: SELECT({:?})={:?}", cache_fresh_trait_pred, c);
debug!(candidate = ?c, "CACHE HIT");
return c;
}
@ -57,7 +55,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let (candidate, dep_node) =
self.in_task(|this| this.candidate_from_obligation_no_cache(stack));
debug!("CACHE MISS: SELECT({:?})={:?}", cache_fresh_trait_pred, candidate);
debug!(?candidate, "CACHE MISS");
self.insert_candidate_cache(
stack.obligation.param_env,
cache_fresh_trait_pred,
@ -103,7 +101,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
} else {
IntercrateAmbiguityCause::DownstreamCrate { trait_desc, self_desc }
};
debug!("evaluate_stack: pushing cause = {:?}", cause);
debug!(?cause, "evaluate_stack: pushing cause");
self.intercrate_ambiguity_causes.as_mut().unwrap().push(cause);
}
}
@ -120,7 +118,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let mut candidates = candidate_set.vec;
debug!("assembled {} candidates for {:?}: {:?}", candidates.len(), stack, candidates);
debug!(?stack, ?candidates, "assembled {} candidates", candidates.len());
// At this point, we know that each of the entries in the
// candidate set is *individually* applicable. Now we have to
@ -163,7 +161,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
.flat_map(Result::transpose)
.collect::<Result<Vec<_>, _>>()?;
debug!("winnowed to {} candidates for {:?}: {:?}", candidates.len(), stack, candidates);
debug!(?stack, ?candidates, "winnowed to {} candidates", candidates.len());
let needs_infer = stack.obligation.predicate.has_infer_types_or_consts();
@ -181,10 +179,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
)
});
if is_dup {
debug!("Dropping candidate #{}/{}: {:?}", i, candidates.len(), candidates[i]);
debug!(candidate = ?candidates[i], "Dropping candidate #{}/{}", i, candidates.len());
candidates.swap_remove(i);
} else {
debug!("Retaining candidate #{}/{}: {:?}", i, candidates.len(), candidates[i]);
debug!(candidate = ?candidates[i], "Retaining candidate #{}/{}", i, candidates.len());
i += 1;
// If there are *STILL* multiple candidates, give up
@ -257,7 +255,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let lang_items = self.tcx().lang_items();
if lang_items.copy_trait() == Some(def_id) {
debug!("obligation self ty is {:?}", obligation.predicate.skip_binder().self_ty());
debug!(obligation_self_ty = ?obligation.predicate.skip_binder().self_ty());
// User-defined copy impls are permitted, but only for
// structs and enums.
@ -308,7 +306,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &TraitObligation<'tcx>,
candidates: &mut SelectionCandidateSet<'tcx>,
) {
debug!("assemble_candidates_for_projected_tys({:?})", obligation);
debug!(?obligation, "assemble_candidates_from_projected_tys");
// Before we go into the whole placeholder thing, just
// quickly check if the self-type is a projection at all.
@ -341,7 +339,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
stack: &TraitObligationStack<'o, 'tcx>,
candidates: &mut SelectionCandidateSet<'tcx>,
) -> Result<(), SelectionError<'tcx>> {
debug!("assemble_candidates_from_caller_bounds({:?})", stack.obligation);
debug!(?stack.obligation, "assemble_candidates_from_caller_bounds");
let all_bounds = stack
.obligation
@ -383,10 +381,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let self_ty = obligation.self_ty().skip_binder();
match self_ty.kind() {
ty::Generator(..) => {
debug!(
"assemble_generator_candidates: self_ty={:?} obligation={:?}",
self_ty, obligation
);
debug!(?self_ty, ?obligation, "assemble_generator_candidates",);
candidates.vec.push(GeneratorCandidate);
}
@ -423,10 +418,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// type/region parameters
match *obligation.self_ty().skip_binder().kind() {
ty::Closure(_, closure_substs) => {
debug!("assemble_unboxed_candidates: kind={:?} obligation={:?}", kind, obligation);
debug!(?kind, ?obligation, "assemble_unboxed_candidates");
match self.infcx.closure_kind(closure_substs) {
Some(closure_kind) => {
debug!("assemble_unboxed_candidates: closure_kind = {:?}", closure_kind);
debug!(?closure_kind, "assemble_unboxed_candidates");
if closure_kind.extends(kind) {
candidates.vec.push(ClosureCandidate);
}
@ -503,7 +498,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &TraitObligation<'tcx>,
candidates: &mut SelectionCandidateSet<'tcx>,
) -> Result<(), SelectionError<'tcx>> {
debug!("assemble_candidates_from_impls(obligation={:?})", obligation);
debug!(?obligation, "assemble_candidates_from_impls");
// Essentially any user-written impl will match with an error type,
// so creating `ImplCandidates` isn't useful. However, we might
@ -537,7 +532,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
) -> Result<(), SelectionError<'tcx>> {
// Okay to skip binder here because the tests we do below do not involve bound regions.
let self_ty = obligation.self_ty().skip_binder();
debug!("assemble_candidates_from_auto_impls(self_ty={:?})", self_ty);
debug!(?self_ty, "assemble_candidates_from_auto_impls");
let def_id = obligation.predicate.def_id();
@ -604,8 +599,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
candidates: &mut SelectionCandidateSet<'tcx>,
) {
debug!(
"assemble_candidates_from_object_ty(self_ty={:?})",
obligation.self_ty().skip_binder()
self_ty = ?obligation.self_ty().skip_binder(),
"assemble_candidates_from_object_ty",
);
self.infcx.probe(|_snapshot| {
@ -645,7 +640,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
_ => return,
};
debug!("assemble_candidates_from_object_ty: poly_trait_ref={:?}", poly_trait_ref);
debug!(?poly_trait_ref, "assemble_candidates_from_object_ty");
// Count only those upcast versions that match the trait-ref
// we are looking for. Specifically, do not only check for the
@ -697,7 +692,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
};
let target = obligation.predicate.skip_binder().trait_ref.substs.type_at(1);
debug!("assemble_candidates_for_unsizing(source={:?}, target={:?})", source, target);
debug!(?source, ?target, "assemble_candidates_for_unsizing");
let may_apply = match (source.kind(), target.kind()) {
// Trait+Kx+'a -> Trait+Ky+'b (upcasts).
@ -758,7 +753,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
) -> Result<(), SelectionError<'tcx>> {
// Okay to skip binder here because the tests we do below do not involve bound regions.
let self_ty = obligation.self_ty().skip_binder();
debug!("assemble_candidates_for_trait_alias(self_ty={:?})", self_ty);
debug!(?self_ty, "assemble_candidates_for_trait_alias");
let def_id = obligation.predicate.def_id();
@ -778,7 +773,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
) -> Result<(), SelectionError<'tcx>> {
match conditions {
BuiltinImplConditions::Where(nested) => {
debug!("builtin_bound: nested={:?}", nested);
debug!(?nested, "builtin_bound");
candidates
.vec
.push(BuiltinCandidate { has_nested: !nested.skip_binder().is_empty() });

59
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View File

@ -42,13 +42,12 @@ use super::SelectionContext;
use std::iter;
impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
#[instrument(level = "debug", skip(self))]
pub(super) fn confirm_candidate(
&mut self,
obligation: &TraitObligation<'tcx>,
candidate: SelectionCandidate<'tcx>,
) -> Result<Selection<'tcx>, SelectionError<'tcx>> {
debug!("confirm_candidate({:?}, {:?})", obligation, candidate);
match candidate {
BuiltinCandidate { has_nested } => {
let data = self.confirm_builtin_candidate(obligation, has_nested);
@ -191,7 +190,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &TraitObligation<'tcx>,
param: ty::PolyTraitRef<'tcx>,
) -> Vec<PredicateObligation<'tcx>> {
debug!("confirm_param_candidate({:?},{:?})", obligation, param);
debug!(?obligation, ?param, "confirm_param_candidate");
// During evaluation, we already checked that this
// where-clause trait-ref could be unified with the obligation
@ -214,7 +213,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &TraitObligation<'tcx>,
has_nested: bool,
) -> ImplSourceBuiltinData<PredicateObligation<'tcx>> {
debug!("confirm_builtin_candidate({:?}, {:?})", obligation, has_nested);
debug!(?obligation, ?has_nested, "confirm_builtin_candidate");
let lang_items = self.tcx().lang_items();
let obligations = if has_nested {
@ -247,7 +246,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
vec![]
};
debug!("confirm_builtin_candidate: obligations={:?}", obligations);
debug!(?obligations);
ImplSourceBuiltinData { nested: obligations }
}
@ -262,7 +261,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &TraitObligation<'tcx>,
trait_def_id: DefId,
) -> ImplSourceAutoImplData<PredicateObligation<'tcx>> {
debug!("confirm_auto_impl_candidate({:?}, {:?})", obligation, trait_def_id);
debug!(?obligation, ?trait_def_id, "confirm_auto_impl_candidate");
let types = obligation.predicate.map_bound(|inner| {
let self_ty = self.infcx.shallow_resolve(inner.self_ty());
@ -278,7 +277,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
trait_def_id: DefId,
nested: ty::Binder<Vec<Ty<'tcx>>>,
) -> ImplSourceAutoImplData<PredicateObligation<'tcx>> {
debug!("vtable_auto_impl: nested={:?}", nested);
debug!(?nested, "vtable_auto_impl");
ensure_sufficient_stack(|| {
let cause = obligation.derived_cause(BuiltinDerivedObligation);
let mut obligations = self.collect_predicates_for_types(
@ -308,7 +307,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// predicate as usual. It won't have any effect since auto traits are coinductive.
obligations.extend(trait_obligations);
debug!("vtable_auto_impl: obligations={:?}", obligations);
debug!(?obligations, "vtable_auto_impl");
ImplSourceAutoImplData { trait_def_id, nested: obligations }
})
@ -319,13 +318,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &TraitObligation<'tcx>,
impl_def_id: DefId,
) -> ImplSourceUserDefinedData<'tcx, PredicateObligation<'tcx>> {
debug!("confirm_impl_candidate({:?},{:?})", obligation, impl_def_id);
debug!(?obligation, ?impl_def_id, "confirm_impl_candidate");
// First, create the substitutions by matching the impl again,
// this time not in a probe.
self.infcx.commit_unconditionally(|_| {
let substs = self.rematch_impl(impl_def_id, obligation);
debug!("confirm_impl_candidate: substs={:?}", substs);
debug!(?substs, "impl substs");
let cause = obligation.derived_cause(ImplDerivedObligation);
ensure_sufficient_stack(|| {
self.vtable_impl(
@ -347,10 +346,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
recursion_depth: usize,
param_env: ty::ParamEnv<'tcx>,
) -> ImplSourceUserDefinedData<'tcx, PredicateObligation<'tcx>> {
debug!(
"vtable_impl(impl_def_id={:?}, substs={:?}, recursion_depth={})",
impl_def_id, substs, recursion_depth,
);
debug!(?impl_def_id, ?substs, ?recursion_depth, "vtable_impl");
let mut impl_obligations = self.impl_or_trait_obligations(
cause,
@ -360,10 +356,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
&substs.value,
);
debug!(
"vtable_impl: impl_def_id={:?} impl_obligations={:?}",
impl_def_id, impl_obligations
);
debug!(?impl_obligations, "vtable_impl");
// Because of RFC447, the impl-trait-ref and obligations
// are sufficient to determine the impl substs, without
@ -379,8 +372,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
&mut self,
obligation: &TraitObligation<'tcx>,
) -> ImplSourceObjectData<'tcx, PredicateObligation<'tcx>> {
debug!(?obligation, "confirm_object_candidate");
let tcx = self.tcx();
debug!("confirm_object_candidate({:?})", obligation);
let trait_predicate =
self.infcx.replace_bound_vars_with_placeholders(&obligation.predicate);
@ -507,7 +500,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
}
debug!("confirm_object_candidate: nested: {:?}", nested);
debug!(?nested, "object nested obligations");
ImplSourceObjectData { upcast_trait_ref, vtable_base, nested }
}
@ -516,7 +509,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &TraitObligation<'tcx>,
) -> Result<ImplSourceFnPointerData<'tcx, PredicateObligation<'tcx>>, SelectionError<'tcx>>
{
debug!("confirm_fn_pointer_candidate({:?})", obligation);
debug!(?obligation, "confirm_fn_pointer_candidate");
// Okay to skip binder; it is reintroduced below.
let self_ty = self.infcx.shallow_resolve(obligation.self_ty().skip_binder());
@ -554,7 +547,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &TraitObligation<'tcx>,
alias_def_id: DefId,
) -> ImplSourceTraitAliasData<'tcx, PredicateObligation<'tcx>> {
debug!("confirm_trait_alias_candidate({:?}, {:?})", obligation, alias_def_id);
debug!(?obligation, ?alias_def_id, "confirm_trait_alias_candidate");
self.infcx.commit_unconditionally(|_| {
let predicate =
@ -571,10 +564,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
&substs,
);
debug!(
"confirm_trait_alias_candidate: trait_def_id={:?} trait_obligations={:?}",
trait_def_id, trait_obligations
);
debug!(?trait_def_id, ?trait_obligations, "trait alias obligations");
ImplSourceTraitAliasData { alias_def_id, substs, nested: trait_obligations }
})
@ -594,7 +584,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
_ => bug!("closure candidate for non-closure {:?}", obligation),
};
debug!("confirm_generator_candidate({:?},{:?},{:?})", obligation, generator_def_id, substs);
debug!(?obligation, ?generator_def_id, ?substs, "confirm_generator_candidate");
let trait_ref = self.generator_trait_ref_unnormalized(obligation, substs);
let Normalized { value: trait_ref, mut obligations } = ensure_sufficient_stack(|| {
@ -607,11 +597,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
)
});
debug!(
"confirm_generator_candidate(generator_def_id={:?}, \
trait_ref={:?}, obligations={:?})",
generator_def_id, trait_ref, obligations
);
debug!(?trait_ref, ?obligations, "generator candidate obligations");
obligations.extend(self.confirm_poly_trait_refs(
obligation.cause.clone(),
@ -627,7 +613,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
&mut self,
obligation: &TraitObligation<'tcx>,
) -> Result<ImplSourceClosureData<'tcx, PredicateObligation<'tcx>>, SelectionError<'tcx>> {
debug!("confirm_closure_candidate({:?})", obligation);
debug!(?obligation, "confirm_closure_candidate");
let kind = self
.tcx()
@ -654,10 +640,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
)
});
debug!(
"confirm_closure_candidate(closure_def_id={:?}, trait_ref={:?}, obligations={:?})",
closure_def_id, trait_ref, obligations
);
debug!(?closure_def_id, ?trait_ref, ?obligations, "confirm closure candidate obligations");
obligations.extend(self.confirm_poly_trait_refs(
obligation.cause.clone(),
@ -731,7 +714,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let target = obligation.predicate.skip_binder().trait_ref.substs.type_at(1);
let target = self.infcx.shallow_resolve(target);
debug!("confirm_builtin_unsize_candidate(source={:?}, target={:?})", source, target);
debug!(?source, ?target, "confirm_builtin_unsize_candidate");
let mut nested = vec![];
match (source.kind(), target.kind()) {

168
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@ -236,7 +236,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
infcx: &'cx InferCtxt<'cx, 'tcx>,
allow_negative_impls: bool,
) -> SelectionContext<'cx, 'tcx> {
debug!("with_negative({:?})", allow_negative_impls);
debug!(?allow_negative_impls, "with_negative");
SelectionContext {
infcx,
freshener: infcx.freshener(),
@ -251,7 +251,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
infcx: &'cx InferCtxt<'cx, 'tcx>,
query_mode: TraitQueryMode,
) -> SelectionContext<'cx, 'tcx> {
debug!("with_query_mode({:?})", query_mode);
debug!(?query_mode, "with_query_mode");
SelectionContext {
infcx,
freshener: infcx.freshener(),
@ -311,11 +311,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
/// Attempts to satisfy the obligation. If successful, this will affect the surrounding
/// type environment by performing unification.
#[instrument(level = "debug", skip(self))]
pub fn select(
&mut self,
obligation: &TraitObligation<'tcx>,
) -> SelectionResult<'tcx, Selection<'tcx>> {
debug!("select({:?})", obligation);
debug_assert!(!obligation.predicate.has_escaping_bound_vars());
let pec = &ProvisionalEvaluationCache::default();
@ -344,7 +344,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
Err(e) => Err(e),
Ok(candidate) => {
debug!("select: candidate = {:?}", candidate);
debug!(?candidate);
Ok(Some(candidate))
}
}
@ -362,7 +362,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
/// Evaluates whether the obligation `obligation` can be satisfied (by any means).
pub fn predicate_may_hold_fatal(&mut self, obligation: &PredicateObligation<'tcx>) -> bool {
debug!("predicate_may_hold_fatal({:?})", obligation);
debug!(?obligation, "predicate_may_hold_fatal");
// This fatal query is a stopgap that should only be used in standard mode,
// where we do not expect overflow to be propagated.
@ -419,10 +419,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
I: IntoIterator<Item = PredicateObligation<'tcx>> + std::fmt::Debug,
{
let mut result = EvaluatedToOk;
debug!("evaluate_predicates_recursively({:?})", predicates);
debug!(?predicates, "evaluate_predicates_recursively");
for obligation in predicates {
let eval = self.evaluate_predicate_recursively(stack, obligation.clone())?;
debug!("evaluate_predicate_recursively({:?}) = {:?}", obligation, eval);
if let EvaluatedToErr = eval {
// fast-path - EvaluatedToErr is the top of the lattice,
// so we don't need to look on the other predicates.
@ -434,17 +433,16 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
Ok(result)
}
#[instrument(
level = "debug",
skip(self, previous_stack),
fields(previous_stack = ?previous_stack.head())
)]
fn evaluate_predicate_recursively<'o>(
&mut self,
previous_stack: TraitObligationStackList<'o, 'tcx>,
obligation: PredicateObligation<'tcx>,
) -> Result<EvaluationResult, OverflowError> {
debug!(
"evaluate_predicate_recursively(obligation={:?}, previous_stack={:?})",
obligation,
previous_stack.head()
);
// `previous_stack` stores a `TraitObligation`, while `obligation` is
// a `PredicateObligation`. These are distinct types, so we can't
// use any `Option` combinator method that would force them to be
@ -454,7 +452,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
None => self.check_recursion_limit(&obligation, &obligation)?,
}
ensure_sufficient_stack(|| {
let result = ensure_sufficient_stack(|| {
match obligation.predicate.skip_binders() {
ty::PredicateAtom::Trait(t, _) => {
let t = ty::Binder::bind(t);
@ -561,10 +559,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
ty::PredicateAtom::ConstEquate(c1, c2) => {
debug!(
"evaluate_predicate_recursively: equating consts c1={:?} c2={:?}",
c1, c2
);
debug!(?c1, ?c2, "evaluate_predicate_recursively: equating consts");
let evaluate = |c: &'tcx ty::Const<'tcx>| {
if let ty::ConstKind::Unevaluated(def, substs, promoted) = c.val {
@ -610,7 +605,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
bug!("TypeWellFormedFromEnv is only used for chalk")
}
}
})
});
debug!(?result);
result
}
fn evaluate_trait_predicate_recursively<'o>(
@ -618,7 +617,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
previous_stack: TraitObligationStackList<'o, 'tcx>,
mut obligation: TraitObligation<'tcx>,
) -> Result<EvaluationResult, OverflowError> {
debug!("evaluate_trait_predicate_recursively({:?})", obligation);
debug!(?obligation, "evaluate_trait_predicate_recursively");
if !self.intercrate
&& obligation.is_global()
@ -627,19 +626,22 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// If a param env has no global bounds, global obligations do not
// depend on its particular value in order to work, so we can clear
// out the param env and get better caching.
debug!("evaluate_trait_predicate_recursively({:?}) - in global", obligation);
debug!("evaluate_trait_predicate_recursively - in global");
obligation.param_env = obligation.param_env.without_caller_bounds();
}
let stack = self.push_stack(previous_stack, &obligation);
let fresh_trait_ref = stack.fresh_trait_ref;
debug!(?fresh_trait_ref);
if let Some(result) = self.check_evaluation_cache(obligation.param_env, fresh_trait_ref) {
debug!("CACHE HIT: EVAL({:?})={:?}", fresh_trait_ref, result);
debug!(?result, "CACHE HIT");
return Ok(result);
}
if let Some(result) = stack.cache().get_provisional(fresh_trait_ref) {
debug!("PROVISIONAL CACHE HIT: EVAL({:?})={:?}", fresh_trait_ref, result);
debug!(?result, "PROVISIONAL CACHE HIT");
stack.update_reached_depth(stack.cache().current_reached_depth());
return Ok(result);
}
@ -662,7 +664,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let reached_depth = stack.reached_depth.get();
if reached_depth >= stack.depth {
debug!("CACHE MISS: EVAL({:?})={:?}", fresh_trait_ref, result);
debug!(?result, "CACHE MISS");
self.insert_evaluation_cache(obligation.param_env, fresh_trait_ref, dep_node, result);
stack.cache().on_completion(stack.depth, |fresh_trait_ref, provisional_result| {
@ -674,7 +676,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
);
});
} else {
debug!("PROVISIONAL: {:?}={:?}", fresh_trait_ref, result);
debug!(?result, "PROVISIONAL");
debug!(
"evaluate_trait_predicate_recursively: caching provisionally because {:?} \
is a cycle participant (at depth {}, reached depth {})",
@ -719,10 +721,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
})
.map(|stack| stack.depth)
{
debug!(
"evaluate_stack({:?}) --> recursive at depth {}",
stack.fresh_trait_ref, cycle_depth,
);
debug!("evaluate_stack --> recursive at depth {}", cycle_depth);
// If we have a stack like `A B C D E A`, where the top of
// the stack is the final `A`, then this will iterate over
@ -742,10 +741,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let cycle =
cycle.map(|stack| stack.obligation.predicate.without_const().to_predicate(tcx));
if self.coinductive_match(cycle) {
debug!("evaluate_stack({:?}) --> recursive, coinductive", stack.fresh_trait_ref);
debug!("evaluate_stack --> recursive, coinductive");
Some(EvaluatedToOk)
} else {
debug!("evaluate_stack({:?}) --> recursive, inductive", stack.fresh_trait_ref);
debug!("evaluate_stack --> recursive, inductive");
Some(EvaluatedToRecur)
}
} else {
@ -786,10 +785,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// This check was an imperfect workaround for a bug in the old
// intercrate mode; it should be removed when that goes away.
if unbound_input_types && self.intercrate {
debug!(
"evaluate_stack({:?}) --> unbound argument, intercrate --> ambiguous",
stack.fresh_trait_ref
);
debug!("evaluate_stack --> unbound argument, intercrate --> ambiguous",);
// Heuristics: show the diagnostics when there are no candidates in crate.
if self.intercrate_ambiguity_causes.is_some() {
debug!("evaluate_stack: intercrate_ambiguity_causes is some");
@ -807,7 +803,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
},
});
debug!("evaluate_stack: pushing cause = {:?}", cause);
debug!(?cause, "evaluate_stack: pushing cause");
self.intercrate_ambiguity_causes.as_mut().unwrap().push(cause);
}
}
@ -824,10 +820,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
)
})
{
debug!(
"evaluate_stack({:?}) --> unbound argument, recursive --> giving up",
stack.fresh_trait_ref
);
debug!("evaluate_stack --> unbound argument, recursive --> giving up",);
return Ok(EvaluatedToUnknown);
}
@ -860,27 +853,28 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
ty::PredicateAtom::Trait(ref data, _) => self.tcx().trait_is_auto(data.def_id()),
_ => false,
};
debug!("coinductive_predicate({:?}) = {:?}", predicate, result);
debug!(?predicate, ?result, "coinductive_predicate");
result
}
/// Further evaluates `candidate` to decide whether all type parameters match and whether nested
/// obligations are met. Returns whether `candidate` remains viable after this further
/// scrutiny.
#[instrument(
level = "debug",
skip(self, stack),
fields(depth = stack.obligation.recursion_depth)
)]
fn evaluate_candidate<'o>(
&mut self,
stack: &TraitObligationStack<'o, 'tcx>,
candidate: &SelectionCandidate<'tcx>,
) -> Result<EvaluationResult, OverflowError> {
debug!(
"evaluate_candidate: depth={} candidate={:?}",
stack.obligation.recursion_depth, candidate
);
let result = self.evaluation_probe(|this| {
let candidate = (*candidate).clone();
match this.confirm_candidate(stack.obligation, candidate) {
Ok(selection) => {
debug!("evaluate_candidate: selection = {:?}", selection);
debug!(?selection);
this.evaluate_predicates_recursively(
stack.list(),
selection.nested_obligations().into_iter(),
@ -889,10 +883,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
Err(..) => Ok(EvaluatedToErr),
}
})?;
debug!(
"evaluate_candidate: depth={} result={:?}",
stack.obligation.recursion_depth, result
);
debug!(?result);
Ok(result)
}
@ -925,10 +916,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
if self.can_use_global_caches(param_env) {
if !trait_ref.needs_infer() {
debug!(
"insert_evaluation_cache(trait_ref={:?}, candidate={:?}) global",
trait_ref, result,
);
debug!(?trait_ref, ?result, "insert_evaluation_cache global");
// This may overwrite the cache with the same value
// FIXME: Due to #50507 this overwrites the different values
// This should be changed to use HashMapExt::insert_same
@ -938,7 +926,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
}
debug!("insert_evaluation_cache(trait_ref={:?}, candidate={:?})", trait_ref, result,);
debug!(?trait_ref, ?result, "insert_evaluation_cache");
self.infcx.evaluation_cache.insert(param_env.and(trait_ref), dep_node, result);
}
@ -1127,11 +1115,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let trait_ref = cache_fresh_trait_pred.skip_binder().trait_ref;
if !self.can_cache_candidate(&candidate) {
debug!(
"insert_candidate_cache(trait_ref={:?}, candidate={:?} -\
candidate is not cacheable",
trait_ref, candidate
);
debug!(?trait_ref, ?candidate, "insert_candidate_cache - candidate is not cacheable");
return;
}
@ -1140,10 +1124,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// Don't cache overflow globally; we only produce this in certain modes.
} else if !trait_ref.needs_infer() {
if !candidate.needs_infer() {
debug!(
"insert_candidate_cache(trait_ref={:?}, candidate={:?}) global",
trait_ref, candidate,
);
debug!(?trait_ref, ?candidate, "insert_candidate_cache global");
// This may overwrite the cache with the same value.
tcx.selection_cache.insert(param_env.and(trait_ref), dep_node, candidate);
return;
@ -1151,10 +1132,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
}
debug!(
"insert_candidate_cache(trait_ref={:?}, candidate={:?}) local",
trait_ref, candidate,
);
debug!(?trait_ref, ?candidate, "insert_candidate_cache local");
self.infcx.selection_cache.insert(param_env.and(trait_ref), dep_node, candidate);
}
@ -1172,9 +1150,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let placeholder_trait_predicate =
self.infcx().replace_bound_vars_with_placeholders(&poly_trait_predicate);
debug!(
"match_projection_obligation_against_definition_bounds: \
placeholder_trait_predicate={:?}",
placeholder_trait_predicate,
?placeholder_trait_predicate,
"match_projection_obligation_against_definition_bounds"
);
let tcx = self.infcx.tcx;
@ -1225,11 +1202,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
})
.collect();
debug!(
"match_projection_obligation_against_definition_bounds: \
matching_bounds={:?}",
matching_bounds
);
debug!(?matching_bounds, "match_projection_obligation_against_definition_bounds");
matching_bounds
}
@ -1816,6 +1789,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
impl_def_id: DefId,
obligation: &TraitObligation<'tcx>,
) -> Result<Normalized<'tcx, SubstsRef<'tcx>>, ()> {
debug!(?impl_def_id, ?obligation, "match_impl");
let impl_trait_ref = self.tcx().impl_trait_ref(impl_def_id).unwrap();
// Before we create the substitutions and everything, first
@ -1844,11 +1818,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
)
});
debug!(
"match_impl(impl_def_id={:?}, obligation={:?}, \
impl_trait_ref={:?}, placeholder_obligation_trait_ref={:?})",
impl_def_id, obligation, impl_trait_ref, placeholder_obligation_trait_ref
);
debug!(?impl_trait_ref, ?placeholder_obligation_trait_ref);
let InferOk { obligations, .. } = self
.infcx
@ -1864,7 +1834,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
return Err(());
}
debug!("match_impl: success impl_substs={:?}", impl_substs);
debug!(?impl_substs, "match_impl: success");
Ok(Normalized { value: impl_substs, obligations: nested_obligations })
}
@ -1926,10 +1896,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &TraitObligation<'tcx>,
poly_trait_ref: ty::PolyTraitRef<'tcx>,
) -> Result<Vec<PredicateObligation<'tcx>>, ()> {
debug!(
"match_poly_trait_ref: obligation={:?} poly_trait_ref={:?}",
obligation, poly_trait_ref
);
debug!(?obligation, ?poly_trait_ref, "match_poly_trait_ref");
self.infcx
.at(&obligation.cause, obligation.param_env)
@ -1976,10 +1943,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &TraitObligation<'tcx>,
substs: SubstsRef<'tcx>,
) -> ty::PolyTraitRef<'tcx> {
debug!("closure_trait_ref_unnormalized(obligation={:?}, substs={:?})", obligation, substs);
debug!(?obligation, ?substs, "closure_trait_ref_unnormalized");
let closure_sig = substs.as_closure().sig();
debug!("closure_trait_ref_unnormalized: closure_sig = {:?}", closure_sig);
debug!(?closure_sig);
// (1) Feels icky to skip the binder here, but OTOH we know
// that the self-type is an unboxed closure type and hence is
@ -2030,7 +1997,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
def_id: DefId, // of impl or trait
substs: SubstsRef<'tcx>, // for impl or trait
) -> Vec<PredicateObligation<'tcx>> {
debug!("impl_or_trait_obligations(def_id={:?})", def_id);
debug!(?def_id, "impl_or_trait_obligations");
let tcx = self.tcx();
// To allow for one-pass evaluation of the nested obligation,
@ -2152,10 +2119,10 @@ impl<'o, 'tcx> TraitObligationStack<'o, 'tcx> {
self.depth,
reached_depth,
);
debug!("update_reached_depth(reached_depth={})", reached_depth);
debug!(reached_depth, "update_reached_depth");
let mut p = self;
while reached_depth < p.depth {
debug!("update_reached_depth: marking {:?} as cycle participant", p.fresh_trait_ref);
debug!(?p.fresh_trait_ref, "update_reached_depth: marking as cycle participant");
p.reached_depth.set(p.reached_depth.get().min(reached_depth));
p = p.previous.head.unwrap();
}
@ -2282,10 +2249,10 @@ impl<'tcx> ProvisionalEvaluationCache<'tcx> {
/// `self.current_reached_depth()` and above.
fn get_provisional(&self, fresh_trait_ref: ty::PolyTraitRef<'tcx>) -> Option<EvaluationResult> {
debug!(
"get_provisional(fresh_trait_ref={:?}) = {:#?} with reached-depth {}",
fresh_trait_ref,
?fresh_trait_ref,
reached_depth = ?self.reached_depth.get(),
"get_provisional = {:#?}",
self.map.borrow().get(&fresh_trait_ref),
self.reached_depth.get(),
);
Some(self.map.borrow().get(&fresh_trait_ref)?.result)
}
@ -2308,14 +2275,11 @@ impl<'tcx> ProvisionalEvaluationCache<'tcx> {
fresh_trait_ref: ty::PolyTraitRef<'tcx>,
result: EvaluationResult,
) {
debug!(
"insert_provisional(from_dfn={}, reached_depth={}, fresh_trait_ref={:?}, result={:?})",
from_dfn, reached_depth, fresh_trait_ref, result,
);
debug!(?from_dfn, ?reached_depth, ?fresh_trait_ref, ?result, "insert_provisional");
let r_d = self.reached_depth.get();
self.reached_depth.set(r_d.min(reached_depth));
debug!("insert_provisional: reached_depth={:?}", self.reached_depth.get());
debug!(reached_depth = self.reached_depth.get());
self.map.borrow_mut().insert(fresh_trait_ref, ProvisionalEvaluation { from_dfn, result });
}
@ -2329,7 +2293,7 @@ impl<'tcx> ProvisionalEvaluationCache<'tcx> {
/// these provisional entries must either depend on it or some
/// ancestor of it.
fn on_failure(&self, dfn: usize) {
debug!("on_failure(dfn={:?})", dfn,);
debug!(?dfn, "on_failure");
self.map.borrow_mut().retain(|key, eval| {
if !eval.from_dfn >= dfn {
debug!("on_failure: removing {:?}", key);
@ -2350,7 +2314,7 @@ impl<'tcx> ProvisionalEvaluationCache<'tcx> {
depth: usize,
mut op: impl FnMut(ty::PolyTraitRef<'tcx>, EvaluationResult),
) {
debug!("on_completion(depth={}, reached_depth={})", depth, self.reached_depth.get(),);
debug!(?depth, reached_depth = ?self.reached_depth.get(), "on_completion");
if self.reached_depth.get() < depth {
debug!("on_completion: did not yet reach depth to complete");
@ -2358,7 +2322,7 @@ impl<'tcx> ProvisionalEvaluationCache<'tcx> {
}
for (fresh_trait_ref, eval) in self.map.borrow_mut().drain() {
debug!("on_completion: fresh_trait_ref={:?} eval={:?}", fresh_trait_ref, eval,);
debug!(?fresh_trait_ref, ?eval, "on_completion");
op(fresh_trait_ref, eval.result);
}