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Some cleanup
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@jackh726
jackh726 committed Oct 16, 2021
1 parent 0bc340f commit a8c44d3
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Showing 3 changed files with 216 additions and 59 deletions.
164 changes: 105 additions & 59 deletions compiler/rustc_typeck/src/check/wfcheck.rs
View file
@@ -1,6 +1,7 @@
use crate::check::{FnCtxt, Inherited};
use crate::constrained_generic_params::{identify_constrained_generic_params, Parameter};

use crate::traits::query::type_op::{self, TypeOp, TypeOpOutput};
use rustc_ast as ast;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
Expand All @@ -15,13 +16,14 @@ use rustc_infer::infer::TyCtxtInferExt;
use rustc_middle::hir::map as hir_map;
use rustc_middle::ty::subst::{GenericArgKind, InternalSubsts, Subst};
use rustc_middle::ty::trait_def::TraitSpecializationKind;
use rustc_middle::ty::{self, AdtKind, GenericParamDefKind, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeVisitor, WithConstness};
use rustc_session::lint;
use rustc_middle::ty::{
self, AdtKind, GenericParamDefKind, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeVisitor,
WithConstness,
};
use rustc_session::parse::feature_err;
use rustc_span::symbol::{sym, Ident, Symbol};
use rustc_span::{DUMMY_SP, Span};
use rustc_trait_selection::traits::query::evaluate_obligation::{InferCtxtExt as _};
use rustc_trait_selection::traits::query::outlives_bounds::{InferCtxtExt as _};
use rustc_span::Span;
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode, WellFormedLoc};

use std::convert::TryInto;
Expand Down Expand Up @@ -255,75 +257,119 @@ pub fn check_trait_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
}
}

// Require that the user writes as where clauses on GATs the implicit
// outlives bounds involving trait parameters in trait functions and
// lifetimes passed as GAT substs. See `self-outlives-lint` test.
check_gat_where_clauses(tcx, trait_item, encl_trait_def_id);
}

/// Require that the user writes as where clauses on GATs the implicit
/// outlives bounds involving trait parameters in trait functions and
/// lifetimes passed as GAT substs. See `self-outlives-lint` test.
fn check_gat_where_clauses(
tcx: TyCtxt<'_>,
trait_item: &hir::TraitItem<'_>,
encl_trait_def_id: DefId,
) {
let item = tcx.associated_item(trait_item.def_id);
// If the current trait item isn't a type, it isn't a GAT
if !matches!(item.kind, ty::AssocKind::Type) {
return;
}
let generics: &ty::Generics = tcx.generics_of(trait_item.def_id);
if matches!(item.kind, ty::AssocKind::Type) && generics.params.len() > 0 {
let associated_items: &ty::AssocItems<'_> = tcx.associated_items(encl_trait_def_id);
associated_items
.in_definition_order()
.filter(|item| matches!(item.kind, ty::AssocKind::Fn))
.for_each(|item| {
tcx.infer_ctxt().enter(|infcx| {
let sig: ty::Binder<'_, ty::FnSig<'_>> = tcx.fn_sig(item.def_id);
let sig = infcx.replace_bound_vars_with_placeholders(sig);
let output = sig.output();
let mut visitor = RegionsInGATs {
tcx,
gat: trait_item.def_id.to_def_id(),
regions: FxHashSet::default(),
};
output.visit_with(&mut visitor);
for input in sig.inputs() {
let bounds = infcx.implied_outlives_bounds(ty::ParamEnv::empty(), hir_id, input, DUMMY_SP);
debug!(?bounds);
let mut clauses = FxHashSet::default();
for bound in bounds {
match bound {
traits::query::OutlivesBound::RegionSubParam(r, p) => {
for idx in visitor.regions.iter().filter(|(proj_r, _)| proj_r == &r).map(|r| r.1) {
let param_r = tcx.mk_region(ty::RegionKind::ReEarlyBound(ty::EarlyBoundRegion {
def_id: generics.params[idx].def_id,
index: idx as u32,
name: generics.params[idx].name,
}));
let clause = ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(tcx.mk_ty(ty::Param(p)), param_r));
let clause = tcx.mk_predicate(ty::Binder::dummy(clause));
clauses.insert(clause);
}
}
_ => {}
}
}
debug!(?clauses);
if !clauses.is_empty() {
let written_predicates: ty::GenericPredicates<'_> = tcx.predicates_of(trait_item.def_id);
for clause in clauses {
let found = written_predicates.predicates.iter().find(|p| p.0 == clause).is_some();
debug!(?clause, ?found);
let mut error = tcx.sess.struct_span_err(
trait_item.generics.span,
&format!("Missing bound: {}", clause),
// If the current associated type doesn't have any (own) params, it's not a GAT
if generics.params.len() == 0 {
return;
}
let associated_items: &ty::AssocItems<'_> = tcx.associated_items(encl_trait_def_id);
// For every function in this trait...
for item in
associated_items.in_definition_order().filter(|item| matches!(item.kind, ty::AssocKind::Fn))
{
tcx.infer_ctxt().enter(|infcx| {
let sig: ty::Binder<'_, ty::FnSig<'_>> = tcx.fn_sig(item.def_id);
let sig = infcx.replace_bound_vars_with_placeholders(sig);
// Find out what regions are passed as GAT substs
let mut visitor = GATSubstCollector {
tcx,
gat: trait_item.def_id.to_def_id(),
regions: FxHashSet::default(),
_types: FxHashSet::default(),
};
sig.output().visit_with(&mut visitor);
// If there are none, then it nothing to do
if visitor.regions.is_empty() {
return;
}
let mut clauses = FxHashSet::default();
// Otherwise, find the clauses required from implied bounds
for input in sig.inputs() {
// For a given input type, find the implied bounds
let TypeOpOutput { output: bounds, .. } = match ty::ParamEnv::empty()
.and(type_op::implied_outlives_bounds::ImpliedOutlivesBounds { ty: input })
.fully_perform(&infcx)
{
Ok(o) => o,
Err(_) => continue,
};
debug!(?bounds);
for bound in bounds {
match bound {
traits::query::OutlivesBound::RegionSubParam(r, p) => {
// If the implied bound is a `RegionSubParam` and
// the region is used a GAT subst...
for idx in visitor
.regions
.iter()
.filter(|(proj_r, _)| proj_r == &r)
.map(|r| r.1)
{
// Then create a clause that is required on the GAT
let param_r = tcx.mk_region(ty::RegionKind::ReEarlyBound(
ty::EarlyBoundRegion {
def_id: generics.params[idx].def_id,
index: idx as u32,
name: generics.params[idx].name,
},
));
let clause = ty::PredicateKind::TypeOutlives(
ty::OutlivesPredicate(tcx.mk_ty(ty::Param(p)), param_r),
);
error.emit();
let clause = tcx.mk_predicate(ty::Binder::dummy(clause));
clauses.insert(clause);
}
}
_ => {}
}
})
});
}
}
// If there are any missing clauses, emit an error
debug!(?clauses);
if !clauses.is_empty() {
let written_predicates: ty::GenericPredicates<'_> =
tcx.predicates_of(trait_item.def_id);
for clause in clauses {
let found =
written_predicates.predicates.iter().find(|p| p.0 == clause).is_some();
debug!(?clause, ?found);
let mut error = tcx.sess.struct_span_err(
trait_item.generics.span,
&format!("Missing bound: {}", clause),
);
error.emit();
}
}
})
}
}

struct RegionsInGATs<'tcx> {
struct GATSubstCollector<'tcx> {
tcx: TyCtxt<'tcx>,
gat: DefId,
// Which region appears and which parameter index its subsituted for
regions: FxHashSet<(ty::Region<'tcx>, usize)>,
// Which params appears and which parameter index its subsituted for
_types: FxHashSet<(Ty<'tcx>, usize)>,
}

impl<'tcx> TypeVisitor<'tcx> for RegionsInGATs<'tcx> {
impl<'tcx> TypeVisitor<'tcx> for GATSubstCollector<'tcx> {
type BreakTy = !;

fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
Expand Down
55 changes: 55 additions & 0 deletions src/test/ui/generic-associated-types/self-outlives-lint.rs
View file
Expand Up @@ -4,6 +4,7 @@

trait Iterable {
type Item<'x>;
//~^ Missing bound
fn iter<'a>(&'a self) -> Self::Item<'a>;
}

Expand All @@ -18,6 +19,7 @@ impl<T> Iterable for T {

trait Deserializer<T> {
type Out<'x>;
//~^ Missing bound
fn deserialize<'a>(&self, input: &'a T) -> Self::Out<'a>;
}

Expand All @@ -30,12 +32,65 @@ impl<T> Deserializer<T> for () {

trait Deserializer2<T> {
type Out<'x>;
//~^ Missing bound
fn deserialize2<'a, 'b: 'a>(&self, input: &'a T, input2: &'b T) -> Self::Out<'a>;
}

trait Deserializer3<T, U> {
type Out<'x, 'y>;
//~^ Missing bound
//~^^ Missing bound
fn deserialize2<'a, 'b>(&self, input: &'a T, input2: &'b U) -> Self::Out<'a, 'b>;
}

trait Deserializer4 {
type Out<'x>;
//~^ Missing bound
fn deserialize<'a, T>(&self, input: &'a T) -> Self::Out<'a>;
}

struct Wrap<T>(T);

trait Des {
type Out<'x, D>;
//~^ Missing bound
fn des<'z, T>(&self, data: &'z Wrap<T>) -> Self::Out<'z, Wrap<T>>;
}
/*
impl Des for () {
type Out<'x, D> = &'x D;
fn des<'a, T>(&self, data: &'a Wrap<T>) -> Self::Out<'a, Wrap<T>> {
data
}
}
*/

trait Des2 {
type Out<'x, D>;
//~^ Missing bound
fn des<'z, T>(&self, data: &'z Wrap<T>) -> Self::Out<'z, T>;
}
/*
impl Des2 for () {
type Out<'x, D> = &'x D;
fn des<'a, T>(&self, data: &'a Wrap<T>) -> Self::Out<'a, T> {
data
}
}
*/

trait Des3 {
type Out<'x, D>;
//~^ Missing bound
fn des<'z, T>(&self, data: &'z T) -> Self::Out<'z, T>;
}
/*
impl Des3 for () {
type Out<'x, D> = &'x D;
fn des<'a, T>(&self, data: &'a T) -> Self::Out<'a, T> {
data
}
}
*/

fn main() {}
56 changes: 56 additions & 0 deletions src/test/ui/generic-associated-types/self-outlives-lint.stderr
View file
@@ -0,0 +1,56 @@
error: Missing bound: Self: 'x
--> $DIR/self-outlives-lint.rs:6:14
|
LL | type Item<'x>;
| ^^^^

error: Missing bound: T: 'x
--> $DIR/self-outlives-lint.rs:21:13
|
LL | type Out<'x>;
| ^^^^

error: Missing bound: T: 'x
--> $DIR/self-outlives-lint.rs:34:13
|
LL | type Out<'x>;
| ^^^^

error: Missing bound: T: 'x
--> $DIR/self-outlives-lint.rs:40:13
|
LL | type Out<'x, 'y>;
| ^^^^^^^^

error: Missing bound: U: 'y
--> $DIR/self-outlives-lint.rs:40:13
|
LL | type Out<'x, 'y>;
| ^^^^^^^^

error: Missing bound: T: 'x
--> $DIR/self-outlives-lint.rs:47:13
|
LL | type Out<'x>;
| ^^^^

error: Missing bound: T: 'x
--> $DIR/self-outlives-lint.rs:55:13
|
LL | type Out<'x, D>;
| ^^^^^^^

error: Missing bound: T: 'x
--> $DIR/self-outlives-lint.rs:69:13
|
LL | type Out<'x, D>;
| ^^^^^^^

error: Missing bound: T: 'x
--> $DIR/self-outlives-lint.rs:83:13
|
LL | type Out<'x, D>;
| ^^^^^^^

error: aborting due to 9 previous errors

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