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Check that TAIT generics are fully generic in mir typeck instead of wf-check, as wf-check can by definition only check TAIT in return position and not account for TAITs defined in the body of the function

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This commit is contained in:
Oli Scherer 2021-09-16 19:08:25 +00:00
parent 15d9ba0133
commit 6067eadb65
33 changed files with 433 additions and 272 deletions
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109
compiler/rustc_borrowck/src/region_infer/opaque_types.rs
View file

@ -1,5 +1,9 @@
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::vec_map::VecMap;
use rustc_hir::OpaqueTyOrigin;
use rustc_infer::infer::opaque_types::OpaqueTypeDecl;
use rustc_infer::infer::InferCtxt;
use rustc_middle::ty::subst::GenericArgKind;
use rustc_middle::ty::{self, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable};
use rustc_span::Span;
use rustc_trait_selection::opaque_types::InferCtxtExt;
@ -50,13 +54,14 @@ impl<'tcx> RegionInferenceContext<'tcx> {
pub(crate) fn infer_opaque_types(
&self,
infcx: &InferCtxt<'_, 'tcx>,
opaque_ty_decls: VecMap<OpaqueTypeKey<'tcx>, Ty<'tcx>>,
opaque_ty_decls: VecMap<OpaqueTypeKey<'tcx>, OpaqueTypeDecl<'tcx>>,
span: Span,
) -> VecMap<OpaqueTypeKey<'tcx>, Ty<'tcx>> {
opaque_ty_decls
.into_iter()
.map(|(opaque_type_key, concrete_type)| {
.filter_map(|(opaque_type_key, decl)| {
let substs = opaque_type_key.substs;
let concrete_type = decl.concrete_ty;
debug!(?concrete_type, ?substs);
let mut subst_regions = vec![self.universal_regions.fr_static];
@ -94,7 +99,13 @@ impl<'tcx> RegionInferenceContext<'tcx> {
universal_concrete_type,
span,
);
(opaque_type_key, remapped_type)
check_opaque_type_parameter_valid(
infcx.tcx,
opaque_type_key,
OpaqueTypeDecl { concrete_ty: remapped_type, ..decl },
)
.then_some((opaque_type_key, remapped_type))
})
.collect()
}
@ -119,3 +130,95 @@ impl<'tcx> RegionInferenceContext<'tcx> {
})
}
}
fn check_opaque_type_parameter_valid(
tcx: TyCtxt<'_>,
opaque_type_key: OpaqueTypeKey<'_>,
decl: OpaqueTypeDecl<'_>,
) -> bool {
match decl.origin {
// No need to check return position impl trait (RPIT)
// because for type and const parameters they are correct
// by construction: we convert
//
// fn foo<P0..Pn>() -> impl Trait
//
// into
//
// type Foo<P0...Pn>
// fn foo<P0..Pn>() -> Foo<P0...Pn>.
//
// For lifetime parameters we convert
//
// fn foo<'l0..'ln>() -> impl Trait<'l0..'lm>
//
// into
//
// type foo::<'p0..'pn>::Foo<'q0..'qm>
// fn foo<l0..'ln>() -> foo::<'static..'static>::Foo<'l0..'lm>.
//
// which would error here on all of the `'static` args.
OpaqueTyOrigin::FnReturn | OpaqueTyOrigin::AsyncFn => return true,
// Check these
OpaqueTyOrigin::TyAlias => {}
}
let span = decl.definition_span;
let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
let mut seen_params: FxHashMap<_, Vec<_>> = FxHashMap::default();
for (i, arg) in opaque_type_key.substs.iter().enumerate() {
let arg_is_param = match arg.unpack() {
GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Param(_)),
GenericArgKind::Lifetime(ty::ReStatic) => {
tcx.sess
.struct_span_err(span, "non-defining opaque type use in defining scope")
.span_label(
tcx.def_span(opaque_generics.param_at(i, tcx).def_id),
"cannot use static lifetime; use a bound lifetime \
instead or remove the lifetime parameter from the \
opaque type",
)
.emit();
return false;
}
GenericArgKind::Lifetime(lt) => {
matches!(lt, ty::ReEarlyBound(_) | ty::ReFree(_))
}
GenericArgKind::Const(ct) => matches!(ct.val, ty::ConstKind::Param(_)),
};
if arg_is_param {
seen_params.entry(arg).or_default().push(i);
} else {
// Prevent `fn foo() -> Foo<u32>` from being defining.
let opaque_param = opaque_generics.param_at(i, tcx);
tcx.sess
.struct_span_err(span, "non-defining opaque type use in defining scope")
.span_note(
tcx.def_span(opaque_param.def_id),
&format!(
"used non-generic {} `{}` for generic parameter",
opaque_param.kind.descr(),
arg,
),
)
.emit();
return false;
}
}
for (_, indices) in seen_params {
if indices.len() > 1 {
let descr = opaque_generics.param_at(indices[0], tcx).kind.descr();
let spans: Vec<_> = indices
.into_iter()
.map(|i| tcx.def_span(opaque_generics.param_at(i, tcx).def_id))
.collect();
tcx.sess
.struct_span_err(span, "non-defining opaque type use in defining scope")
.span_note(spans, &format!("{} used multiple times", descr))
.emit();
return false;
}
}
true
}

18
compiler/rustc_borrowck/src/type_check/mod.rs
View file

@ -14,6 +14,7 @@ use rustc_hir::def_id::LocalDefId;
use rustc_hir::lang_items::LangItem;
use rustc_index::vec::{Idx, IndexVec};
use rustc_infer::infer::canonical::QueryRegionConstraints;
use rustc_infer::infer::opaque_types::OpaqueTypeDecl;
use rustc_infer::infer::outlives::env::RegionBoundPairs;
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use rustc_infer::infer::{
@ -193,16 +194,17 @@ pub(crate) fn type_check<'mir, 'tcx>(
opaque_type_values
.into_iter()
.filter_map(|(opaque_type_key, decl)| {
let mut revealed_ty = infcx.resolve_vars_if_possible(decl.concrete_ty);
if revealed_ty.has_infer_types_or_consts() {
.filter_map(|(opaque_type_key, mut decl)| {
decl.concrete_ty = infcx.resolve_vars_if_possible(decl.concrete_ty);
if decl.concrete_ty.has_infer_types_or_consts() {
infcx.tcx.sess.delay_span_bug(
body.span,
&format!("could not resolve {:#?}", revealed_ty.kind()),
&format!("could not resolve {:#?}", decl.concrete_ty.kind()),
);
revealed_ty = infcx.tcx.ty_error();
decl.concrete_ty = infcx.tcx.ty_error();
}
let concrete_is_opaque = if let ty::Opaque(def_id, _) = revealed_ty.kind() {
let concrete_is_opaque = if let ty::Opaque(def_id, _) = decl.concrete_ty.kind()
{
*def_id == opaque_type_key.def_id
} else {
false
@ -234,7 +236,7 @@ pub(crate) fn type_check<'mir, 'tcx>(
);
None
} else {
Some((opaque_type_key, revealed_ty))
Some((opaque_type_key, decl))
}
})
.collect()
@ -890,7 +892,7 @@ struct BorrowCheckContext<'a, 'tcx> {
crate struct MirTypeckResults<'tcx> {
crate constraints: MirTypeckRegionConstraints<'tcx>,
crate universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
crate opaque_type_values: VecMap<OpaqueTypeKey<'tcx>, Ty<'tcx>>,
crate opaque_type_values: VecMap<OpaqueTypeKey<'tcx>, OpaqueTypeDecl<'tcx>>,
}
/// A collection of region constraints that must be satisfied for the