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cleanup our region error API #110220

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merged 3 commits into from
Apr 13, 2023
Merged

cleanup our region error API #110220

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a19adef
region error cleanup
lcnr Apr 12, 2023
cc82ccb
`#[must_use]` for fns returning a list of errors
lcnr Apr 12, 2023
c0d3d32
fix comment
lcnr Apr 12, 2023
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7 changes: 2 additions & 5 deletions compiler/rustc_hir_analysis/src/check/check.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -452,11 +452,8 @@ fn check_opaque_meets_bounds<'tcx>(
hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..) => {}
// Can have different predicates to their defining use
hir::OpaqueTyOrigin::TyAlias => {
let outlives_environment = OutlivesEnvironment::new(param_env);
let _ = infcx.err_ctxt().check_region_obligations_and_report_errors(
defining_use_anchor,
&outlives_environment,
);
let outlives_env = OutlivesEnvironment::new(param_env);
let _ = ocx.resolve_regions_and_report_errors(defining_use_anchor, &outlives_env);
}
}
// Clean up after ourselves
Expand Down
40 changes: 11 additions & 29 deletions compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -332,10 +332,6 @@ fn compare_method_predicate_entailment<'tcx>(
param_env,
infcx.implied_bounds_tys(param_env, impl_m_def_id, wf_tys.clone()),
);
infcx.process_registered_region_obligations(
outlives_env.region_bound_pairs(),
outlives_env.param_env,
);
let errors = infcx.resolve_regions(&outlives_env);
if !errors.is_empty() {
// FIXME(compiler-errors): This can be simplified when IMPLIED_BOUNDS_ENTAILMENT
Expand Down Expand Up @@ -722,18 +718,18 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
return Err(reported);
}

let collected_types = collector.types;

// Finally, resolve all regions. This catches wily misuses of
// lifetime parameters.
let outlives_environment = OutlivesEnvironment::with_bounds(
let outlives_env = OutlivesEnvironment::with_bounds(
param_env,
infcx.implied_bounds_tys(param_env, impl_m_def_id, wf_tys),
);
infcx
.err_ctxt()
.check_region_obligations_and_report_errors(impl_m_def_id, &outlives_environment)?;
ocx.resolve_regions_and_report_errors(impl_m_def_id, &outlives_env)?;

let mut collected_tys = FxHashMap::default();
for (def_id, (ty, substs)) in collector.types {
for (def_id, (ty, substs)) in collected_types {
match infcx.fully_resolve(ty) {
Ok(ty) => {
// `ty` contains free regions that we created earlier while liberating the
Expand Down Expand Up @@ -1742,11 +1738,8 @@ pub(super) fn compare_impl_const_raw(
return Err(infcx.err_ctxt().report_fulfillment_errors(&errors));
}

let outlives_environment = OutlivesEnvironment::new(param_env);
infcx
.err_ctxt()
.check_region_obligations_and_report_errors(impl_const_item_def, &outlives_environment)?;
Ok(())
let outlives_env = OutlivesEnvironment::new(param_env);
ocx.resolve_regions_and_report_errors(impl_const_item_def, &outlives_env)
}

pub(super) fn compare_impl_ty<'tcx>(
Expand Down Expand Up @@ -1845,13 +1838,8 @@ fn compare_type_predicate_entailment<'tcx>(

// Finally, resolve all regions. This catches wily misuses of
// lifetime parameters.
let outlives_environment = OutlivesEnvironment::new(param_env);
infcx.err_ctxt().check_region_obligations_and_report_errors(
impl_ty.def_id.expect_local(),
&outlives_environment,
)?;

Ok(())
let outlives_env = OutlivesEnvironment::new(param_env);
ocx.resolve_regions_and_report_errors(impl_ty_def_id, &outlives_env)
}

/// Validate that `ProjectionCandidate`s created for this associated type will
Expand Down Expand Up @@ -2063,14 +2051,8 @@ pub(super) fn check_type_bounds<'tcx>(
// Finally, resolve all regions. This catches wily misuses of
// lifetime parameters.
let implied_bounds = infcx.implied_bounds_tys(param_env, impl_ty_def_id, assumed_wf_types);
let outlives_environment = OutlivesEnvironment::with_bounds(param_env, implied_bounds);

infcx.err_ctxt().check_region_obligations_and_report_errors(
impl_ty.def_id.expect_local(),
&outlives_environment,
)?;

Ok(())
let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
ocx.resolve_regions_and_report_errors(impl_ty_def_id, &outlives_env)
}

fn assoc_item_kind_str(impl_item: &ty::AssocItem) -> &'static str {
Expand Down
11 changes: 2 additions & 9 deletions compiler/rustc_hir_analysis/src/check/wfcheck.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -114,11 +114,9 @@ pub(super) fn enter_wf_checking_ctxt<'tcx, F>(
return;
}

let outlives_environment = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);

let _ = infcx
.err_ctxt()
.check_region_obligations_and_report_errors(body_def_id, &outlives_environment);
let _ = wfcx.ocx.resolve_regions_and_report_errors(body_def_id, &outlives_env);
}

fn check_well_formed(tcx: TyCtxt<'_>, def_id: hir::OwnerId) {
Expand Down Expand Up @@ -680,12 +678,7 @@ fn resolve_regions_with_wf_tys<'tcx>(

add_constraints(&infcx, region_bound_pairs);

infcx.process_registered_region_obligations(
outlives_environment.region_bound_pairs(),
param_env,
);
let errors = infcx.resolve_regions(&outlives_environment);

debug!(?errors, "errors");

// If we were able to prove that the type outlives the region without
Expand Down
6 changes: 2 additions & 4 deletions compiler/rustc_hir_analysis/src/coherence/builtin.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -354,9 +354,7 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef

// Finally, resolve all regions.
let outlives_env = OutlivesEnvironment::new(param_env);
let _ = infcx
.err_ctxt()
.check_region_obligations_and_report_errors(impl_did, &outlives_env);
let _ = ocx.resolve_regions_and_report_errors(impl_did, &outlives_env);
}
}
_ => {
Expand Down Expand Up @@ -592,7 +590,7 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> Coe

// Finally, resolve all regions.
let outlives_env = OutlivesEnvironment::new(param_env);
let _ = infcx.err_ctxt().check_region_obligations_and_report_errors(impl_did, &outlives_env);
let _ = ocx.resolve_regions_and_report_errors(impl_did, &outlives_env);

CoerceUnsizedInfo { custom_kind: kind }
}
3 changes: 1 addition & 2 deletions compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -180,8 +180,7 @@ fn get_impl_substs(

let implied_bounds = infcx.implied_bounds_tys(param_env, impl1_def_id, assumed_wf_types);
let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
let _ =
infcx.err_ctxt().check_region_obligations_and_report_errors(impl1_def_id, &outlives_env);
let _ = ocx.resolve_regions_and_report_errors(impl1_def_id, &outlives_env);
let Ok(impl2_substs) = infcx.fully_resolve(impl2_substs) else {
let span = tcx.def_span(impl1_def_id);
tcx.sess.emit_err(SubstsOnOverriddenImpl { span });
Expand Down
30 changes: 28 additions & 2 deletions compiler/rustc_infer/src/infer/error_reporting/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,7 @@ use rustc_middle::ty::{
self, error::TypeError, List, Region, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable,
TypeVisitable, TypeVisitableExt,
};
use rustc_span::DUMMY_SP;
use rustc_span::{sym, symbol::kw, BytePos, DesugaringKind, Pos, Span};
use rustc_target::spec::abi;
use std::ops::{ControlFlow, Deref};
Expand Down Expand Up @@ -113,7 +114,11 @@ fn escape_literal(s: &str) -> String {

/// A helper for building type related errors. The `typeck_results`
/// field is only populated during an in-progress typeck.
/// Get an instance by calling `InferCtxt::err` or `FnCtxt::infer_err`.
/// Get an instance by calling `InferCtxt::err_ctxt` or `FnCtxt::err_ctxt`.
///
/// You must only create this if you intend to actually emit an error.
/// This provides a lot of utility methods which should not be used
/// during the happy path.
pub struct TypeErrCtxt<'a, 'tcx> {
pub infcx: &'a InferCtxt<'tcx>,
pub typeck_results: Option<std::cell::Ref<'a, ty::TypeckResults<'tcx>>>,
Expand All @@ -125,6 +130,19 @@ pub struct TypeErrCtxt<'a, 'tcx> {
Box<dyn Fn(Ty<'tcx>) -> Vec<(Ty<'tcx>, Vec<PredicateObligation<'tcx>>)> + 'a>,
}

impl Drop for TypeErrCtxt<'_, '_> {
fn drop(&mut self) {
if let Some(_) = self.infcx.tcx.sess.has_errors_or_delayed_span_bugs() {
// ok, emitted an error.
} else {
self.infcx
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This might create a problem if we create an error then cancel it, but I guess we can just wait until the ICE is filed :)

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yeah, imo that should not happen. Once you start using the err_ctxt() you should only cancel if we already emit an error somewhere else.

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I think this caused rust-lang/rust-clippy#10645 🙈

.tcx
.sess
.delay_span_bug(DUMMY_SP, "used a `TypeErrCtxt` without failing compilation");
}
}
}

impl TypeErrCtxt<'_, '_> {
/// This is just to avoid a potential footgun of accidentally
/// dropping `typeck_results` by calling `InferCtxt::err_ctxt`
Expand Down Expand Up @@ -419,7 +437,11 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
&self,
generic_param_scope: LocalDefId,
errors: &[RegionResolutionError<'tcx>],
) {
) -> ErrorGuaranteed {
if let Some(guaranteed) = self.infcx.tainted_by_errors() {
return guaranteed;
}

debug!("report_region_errors(): {} errors to start", errors.len());

// try to pre-process the errors, which will group some of them
Expand Down Expand Up @@ -499,6 +521,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
}
}
}

self.tcx
.sess
.delay_span_bug(self.tcx.def_span(generic_param_scope), "expected region errors")
}

// This method goes through all the errors and try to group certain types
Expand Down
142 changes: 1 addition & 141 deletions compiler/rustc_infer/src/infer/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -45,8 +45,7 @@ use self::combine::CombineFields;
use self::error_reporting::TypeErrCtxt;
use self::free_regions::RegionRelations;
use self::lexical_region_resolve::LexicalRegionResolutions;
use self::outlives::env::OutlivesEnvironment;
use self::region_constraints::{GenericKind, RegionConstraintData, VarInfos, VerifyBound};
use self::region_constraints::{GenericKind, VarInfos, VerifyBound};
use self::region_constraints::{
RegionConstraintCollector, RegionConstraintStorage, RegionSnapshot,
};
Expand Down Expand Up @@ -1213,95 +1212,6 @@ impl<'tcx> InferCtxt<'tcx> {
self.tainted_by_errors.set(Some(e));
}

pub fn skip_region_resolution(&self) {
let (var_infos, _) = {
let mut inner = self.inner.borrow_mut();
let inner = &mut *inner;
// Note: `inner.region_obligations` may not be empty, because we
// didn't necessarily call `process_registered_region_obligations`.
// This is okay, because that doesn't introduce new vars.
inner
.region_constraint_storage
.take()
.expect("regions already resolved")
.with_log(&mut inner.undo_log)
.into_infos_and_data()
};

let lexical_region_resolutions = LexicalRegionResolutions {
values: rustc_index::vec::IndexVec::from_elem_n(
crate::infer::lexical_region_resolve::VarValue::Value(self.tcx.lifetimes.re_erased),
var_infos.len(),
),
};

let old_value = self.lexical_region_resolutions.replace(Some(lexical_region_resolutions));
assert!(old_value.is_none());
}

/// Process the region constraints and return any errors that
/// result. After this, no more unification operations should be
/// done -- or the compiler will panic -- but it is legal to use
/// `resolve_vars_if_possible` as well as `fully_resolve`.
pub fn resolve_regions(
&self,
outlives_env: &OutlivesEnvironment<'tcx>,
) -> Vec<RegionResolutionError<'tcx>> {
let (var_infos, data) = {
let mut inner = self.inner.borrow_mut();
let inner = &mut *inner;
assert!(
self.tainted_by_errors().is_some() || inner.region_obligations.is_empty(),
"region_obligations not empty: {:#?}",
inner.region_obligations
);
inner
.region_constraint_storage
.take()
.expect("regions already resolved")
.with_log(&mut inner.undo_log)
.into_infos_and_data()
};

let region_rels = &RegionRelations::new(self.tcx, outlives_env.free_region_map());

let (lexical_region_resolutions, errors) =
lexical_region_resolve::resolve(outlives_env.param_env, region_rels, var_infos, data);

let old_value = self.lexical_region_resolutions.replace(Some(lexical_region_resolutions));
assert!(old_value.is_none());

errors
}
/// Obtains (and clears) the current set of region
/// constraints. The inference context is still usable: further
/// unifications will simply add new constraints.
///
/// This method is not meant to be used with normal lexical region
/// resolution. Rather, it is used in the NLL mode as a kind of
/// interim hack: basically we run normal type-check and generate
/// region constraints as normal, but then we take them and
/// translate them into the form that the NLL solver
/// understands. See the NLL module for mode details.
pub fn take_and_reset_region_constraints(&self) -> RegionConstraintData<'tcx> {
assert!(
self.inner.borrow().region_obligations.is_empty(),
"region_obligations not empty: {:#?}",
self.inner.borrow().region_obligations
);

self.inner.borrow_mut().unwrap_region_constraints().take_and_reset_data()
}

/// Gives temporary access to the region constraint data.
pub fn with_region_constraints<R>(
&self,
op: impl FnOnce(&RegionConstraintData<'tcx>) -> R,
) -> R {
let mut inner = self.inner.borrow_mut();
op(inner.unwrap_region_constraints().data())
}

pub fn region_var_origin(&self, vid: ty::RegionVid) -> RegionVariableOrigin {
let mut inner = self.inner.borrow_mut();
let inner = &mut *inner;
Expand Down Expand Up @@ -1754,56 +1664,6 @@ impl<'cx, 'tcx> Drop for CanonicalizationCtxtGuard<'cx, 'tcx> {
}

impl<'tcx> TypeErrCtxt<'_, 'tcx> {
/// Processes registered region obliations and resolves regions, reporting
/// any errors if any were raised. Prefer using this function over manually
/// calling `resolve_regions_and_report_errors`.
pub fn check_region_obligations_and_report_errors(
&self,
generic_param_scope: LocalDefId,
outlives_env: &OutlivesEnvironment<'tcx>,
) -> Result<(), ErrorGuaranteed> {
self.process_registered_region_obligations(
outlives_env.region_bound_pairs(),
outlives_env.param_env,
);

self.resolve_regions_and_report_errors(generic_param_scope, outlives_env)
}

/// Process the region constraints and report any errors that
/// result. After this, no more unification operations should be
/// done -- or the compiler will panic -- but it is legal to use
/// `resolve_vars_if_possible` as well as `fully_resolve`.
///
/// Make sure to call [`InferCtxt::process_registered_region_obligations`]
/// first, or preferably use [`TypeErrCtxt::check_region_obligations_and_report_errors`]
/// to do both of these operations together.
pub fn resolve_regions_and_report_errors(
&self,
generic_param_scope: LocalDefId,
outlives_env: &OutlivesEnvironment<'tcx>,
) -> Result<(), ErrorGuaranteed> {
let errors = self.resolve_regions(outlives_env);

if let None = self.tainted_by_errors() {
// As a heuristic, just skip reporting region errors
// altogether if other errors have been reported while
// this infcx was in use. This is totally hokey but
// otherwise we have a hard time separating legit region
// errors from silly ones.
self.report_region_errors(generic_param_scope, &errors);
}

if errors.is_empty() {
Ok(())
} else {
Err(self
.tcx
.sess
.delay_span_bug(rustc_span::DUMMY_SP, "error should have been emitted"))
}
}

// [Note-Type-error-reporting]
// An invariant is that anytime the expected or actual type is Error (the special
// error type, meaning that an error occurred when typechecking this expression),
Expand Down
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