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Dejargnonize subst

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Shoyu Vanilla
2024-02-12 15:39:32 +09:00
parent 084ce5bdb5
commit 3856df059e
128 changed files with 574 additions and 541 deletions
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42
compiler/rustc_hir_analysis/src/check/wfcheck.rs
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@@ -618,7 +618,7 @@ fn gather_gat_bounds<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>(
// The bounds we that we would require from `to_check`
let mut bounds = FxHashSet::default();
let (regions, types) = GATSubstCollector::visit(gat_def_id.to_def_id(), to_check);
let (regions, types) = GATArgsCollector::visit(gat_def_id.to_def_id(), to_check);
// If both regions and types are empty, then this GAT isn't in the
// set of types we are checking, and we shouldn't try to do clause analysis
@@ -787,34 +787,34 @@ fn test_region_obligations<'tcx>(
/// `<P0 as Trait<P1..Pn>>::GAT<Pn..Pm>` and adds the arguments `P0..Pm` into
/// the two vectors, `regions` and `types` (depending on their kind). For each
/// parameter `Pi` also track the index `i`.
struct GATSubstCollector<'tcx> {
struct GATArgsCollector<'tcx> {
gat: DefId,
// Which region appears and which parameter index its substituted for
// Which region appears and which parameter index its instantiated with
regions: FxHashSet<(ty::Region<'tcx>, usize)>,
// Which params appears and which parameter index its substituted for
// Which params appears and which parameter index its instantiated with
types: FxHashSet<(Ty<'tcx>, usize)>,
}
impl<'tcx> GATSubstCollector<'tcx> {
impl<'tcx> GATArgsCollector<'tcx> {
fn visit<T: TypeFoldable<TyCtxt<'tcx>>>(
gat: DefId,
t: T,
) -> (FxHashSet<(ty::Region<'tcx>, usize)>, FxHashSet<(Ty<'tcx>, usize)>) {
let mut visitor =
GATSubstCollector { gat, regions: FxHashSet::default(), types: FxHashSet::default() };
GATArgsCollector { gat, regions: FxHashSet::default(), types: FxHashSet::default() };
t.visit_with(&mut visitor);
(visitor.regions, visitor.types)
}
}
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for GATSubstCollector<'tcx> {
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for GATArgsCollector<'tcx> {
type BreakTy = !;
fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
match t.kind() {
ty::Alias(ty::Projection, p) if p.def_id == self.gat => {
for (idx, subst) in p.args.iter().enumerate() {
match subst.unpack() {
for (idx, arg) in p.args.iter().enumerate() {
match arg.unpack() {
GenericArgKind::Lifetime(lt) if !lt.is_bound() => {
self.regions.insert((lt, idx));
}
@@ -1407,14 +1407,14 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
}
}
// Check that trait predicates are WF when params are substituted by their defaults.
// Check that trait predicates are WF when params are instantiated with their defaults.
// We don't want to overly constrain the predicates that may be written but we want to
// catch cases where a default my never be applied such as `struct Foo<T: Copy = String>`.
// Therefore we check if a predicate which contains a single type param
// with a concrete default is WF with that default substituted.
// with a concrete default is WF with that default instantiated.
// For more examples see tests `defaults-well-formedness.rs` and `type-check-defaults.rs`.
//
// First we build the defaulted substitution.
// First we build the defaulted generic parameters.
let args = GenericArgs::for_item(tcx, def_id.to_def_id(), |param, _| {
match param.kind {
GenericParamDefKind::Lifetime => {
@@ -1428,7 +1428,7 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
let default_ty = tcx.type_of(param.def_id).instantiate_identity();
// ... and it's not a dependent default, ...
if !default_ty.has_param() {
// ... then substitute it with the default.
// ... then instantiate it with the default.
return default_ty.into();
}
}
@@ -1441,7 +1441,7 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
let default_ct = tcx.const_param_default(param.def_id).instantiate_identity();
// ... and it's not a dependent default, ...
if !default_ct.has_param() {
// ... then substitute it with the default.
// ... then instantiate it with the default.
return default_ct.into();
}
}
@@ -1451,7 +1451,7 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
}
});
// Now we build the substituted predicates.
// Now we build the instantiated predicates.
let default_obligations = predicates
.predicates
.iter()
@@ -1483,23 +1483,25 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
}
let mut param_count = CountParams::default();
let has_region = pred.visit_with(&mut param_count).is_break();
let substituted_pred = ty::EarlyBinder::bind(pred).instantiate(tcx, args);
let instantiated_pred = ty::EarlyBinder::bind(pred).instantiate(tcx, args);
// Don't check non-defaulted params, dependent defaults (including lifetimes)
// or preds with multiple params.
if substituted_pred.has_non_region_param() || param_count.params.len() > 1 || has_region
if instantiated_pred.has_non_region_param()
|| param_count.params.len() > 1
|| has_region
{
None
} else if predicates.predicates.iter().any(|&(p, _)| p == substituted_pred) {
} else if predicates.predicates.iter().any(|&(p, _)| p == instantiated_pred) {
// Avoid duplication of predicates that contain no parameters, for example.
None
} else {
Some((substituted_pred, sp))
Some((instantiated_pred, sp))
}
})
.map(|(pred, sp)| {
// Convert each of those into an obligation. So if you have
// something like `struct Foo<T: Copy = String>`, we would
// take that predicate `T: Copy`, substitute to `String: Copy`
// take that predicate `T: Copy`, instantiated with `String: Copy`
// (actually that happens in the previous `flat_map` call),
// and then try to prove it (in this case, we'll fail).
//