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Rollup merge of #89561 - nbdd0121:const_typeck, r=nikomatsakis

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Type inference for inline consts

Fixes #78132
Fixes #78174
Fixes #81857
Fixes #89964

Perform type checking/inference of inline consts in the same context as the outer def, similar to what is currently done to closure.

Doing so would require `closure_base_def_id` of the inline const to return the outer def, and since `closure_base_def_id` can be called on non-local crate (and thus have no HIR available), a new `DefKind` is created for inline consts.

The type of the generated anon const can capture lifetime of outer def, so we couldn't just use the typeck result as the type of the inline const's def. Closure has a similar issue, and it uses extra type params `CK, CS, U` to capture closure kind, input/output signature and upvars. I use a similar approach for inline consts, letting it have an extra type param `R`, and then `typeof(InlineConst<[paremt generics], R>)` would just be `R`. In borrowck region requirements are also propagated to the outer MIR body just like it's currently done for closure.

With this PR, inline consts in expression position are quitely usable now; however the usage in pattern position is still incomplete -- since those does not remain in the MIR borrowck couldn't verify the lifetime there. I have left an ignored test as a FIXME.

Some disucssions can be found on [this Zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/inline.20consts.20typeck).
cc `````@spastorino````` `````@lcnr`````
r? `````@nikomatsakis`````

`````@rustbot````` label A-inference F-inline_const T-compiler
This commit is contained in:
Matthias Krüger 2021-11-09 19:00:40 +01:00 • committed by GitHub
commit fd74c93403
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49 changed files with 656 additions and 119 deletions
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2
compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
View file

@ -408,7 +408,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
let param = generics.type_param(&param_ty, tcx);
if let Some(generics) = tcx
.hir()
.get_generics(tcx.closure_base_def_id(self.mir_def_id().to_def_id()))
.get_generics(tcx.typeck_root_def_id(self.mir_def_id().to_def_id()))
{
suggest_constraining_type_param(
tcx,

2
compiler/rustc_borrowck/src/nll.rs
View file

@ -376,7 +376,7 @@ pub(super) fn dump_annotation<'a, 'tcx>(
errors_buffer: &mut Vec<Diagnostic>,
) {
let tcx = infcx.tcx;
let base_def_id = tcx.closure_base_def_id(body.source.def_id());
let base_def_id = tcx.typeck_root_def_id(body.source.def_id());
if !tcx.has_attr(base_def_id, sym::rustc_regions) {
return;
}

4
compiler/rustc_borrowck/src/region_infer/mod.rs
View file

@ -569,7 +569,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
// to store those. Otherwise, we'll pass in `None` to the
// functions below, which will trigger them to report errors
// eagerly.
let mut outlives_requirements = infcx.tcx.is_closure(mir_def_id).then(Vec::new);
let mut outlives_requirements = infcx.tcx.is_typeck_child(mir_def_id).then(Vec::new);
self.check_type_tests(infcx, body, outlives_requirements.as_mut(), &mut errors_buffer);
@ -2229,7 +2229,7 @@ impl<'tcx> ClosureRegionRequirementsExt<'tcx> for ClosureRegionRequirements<'tcx
tcx,
closure_substs,
self.num_external_vids,
tcx.closure_base_def_id(closure_def_id),
tcx.typeck_root_def_id(closure_def_id),
);
debug!("apply_requirements: closure_mapping={:?}", closure_mapping);

101
compiler/rustc_borrowck/src/type_check/mod.rs
View file

@ -10,6 +10,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::vec_map::VecMap;
use rustc_errors::struct_span_err;
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::lang_items::LangItem;
use rustc_index::vec::{Idx, IndexVec};
@ -1343,13 +1344,9 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
// though.
let category = match place.as_local() {
Some(RETURN_PLACE) => {
if let BorrowCheckContext {
universal_regions:
UniversalRegions { defining_ty: DefiningTy::Const(def_id, _), .. },
..
} = self.borrowck_context
{
if tcx.is_static(*def_id) {
let defining_ty = &self.borrowck_context.universal_regions.defining_ty;
if defining_ty.is_const() {
if tcx.is_static(defining_ty.def_id()) {
ConstraintCategory::UseAsStatic
} else {
ConstraintCategory::UseAsConst
@ -1527,6 +1524,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
}
TerminatorKind::SwitchInt { ref discr, switch_ty, .. } => {
self.check_operand(discr, term_location);
let discr_ty = discr.ty(body, tcx);
if let Err(terr) = self.sub_types(
discr_ty,
@ -1549,6 +1548,11 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
// FIXME: check the values
}
TerminatorKind::Call { ref func, ref args, ref destination, from_hir_call, .. } => {
self.check_operand(func, term_location);
for arg in args {
self.check_operand(arg, term_location);
}
let func_ty = func.ty(body, tcx);
debug!("check_terminator: call, func_ty={:?}", func_ty);
let sig = match func_ty.kind() {
@ -1593,6 +1597,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
self.check_call_inputs(body, term, &sig, args, term_location, from_hir_call);
}
TerminatorKind::Assert { ref cond, ref msg, .. } => {
self.check_operand(cond, term_location);
let cond_ty = cond.ty(body, tcx);
if cond_ty != tcx.types.bool {
span_mirbug!(self, term, "bad Assert ({:?}, not bool", cond_ty);
@ -1608,6 +1614,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
}
TerminatorKind::Yield { ref value, .. } => {
self.check_operand(value, term_location);
let value_ty = value.ty(body, tcx);
match body.yield_ty() {
None => span_mirbug!(self, term, "yield in non-generator"),
@ -1650,7 +1658,12 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
Some(RETURN_PLACE) => {
if let BorrowCheckContext {
universal_regions:
UniversalRegions { defining_ty: DefiningTy::Const(def_id, _), .. },
UniversalRegions {
defining_ty:
DefiningTy::Const(def_id, _)
| DefiningTy::InlineConst(def_id, _),
..
},
..
} = self.borrowck_context
{
@ -1931,15 +1944,51 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
}
fn check_operand(&mut self, op: &Operand<'tcx>, location: Location) {
if let Operand::Constant(constant) = op {
let maybe_uneval = match constant.literal {
ConstantKind::Ty(ct) => match ct.val {
ty::ConstKind::Unevaluated(uv) => Some(uv),
_ => None,
},
_ => None,
};
if let Some(uv) = maybe_uneval {
if uv.promoted.is_none() {
let tcx = self.tcx();
let def_id = uv.def.def_id_for_type_of();
if tcx.def_kind(def_id) == DefKind::InlineConst {
let predicates = self.prove_closure_bounds(
tcx,
def_id.expect_local(),
uv.substs(tcx),
location,
);
self.normalize_and_prove_instantiated_predicates(
def_id,
predicates,
location.to_locations(),
);
}
}
}
}
}
fn check_rvalue(&mut self, body: &Body<'tcx>, rvalue: &Rvalue<'tcx>, location: Location) {
let tcx = self.tcx();
match rvalue {
Rvalue::Aggregate(ak, ops) => {
for op in ops {
self.check_operand(op, location);
}
self.check_aggregate_rvalue(&body, rvalue, ak, ops, location)
}
Rvalue::Repeat(operand, len) => {
self.check_operand(operand, location);
// If the length cannot be evaluated we must assume that the length can be larger
// than 1.
// If the length is larger than 1, the repeat expression will need to copy the
@ -1990,7 +2039,22 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
}
Rvalue::NullaryOp(_, ty) | Rvalue::ShallowInitBox(_, ty) => {
Rvalue::NullaryOp(_, ty) => {
let trait_ref = ty::TraitRef {
def_id: tcx.require_lang_item(LangItem::Sized, Some(self.last_span)),
substs: tcx.mk_substs_trait(ty, &[]),
};
self.prove_trait_ref(
trait_ref,
location.to_locations(),
ConstraintCategory::SizedBound,
);
}
Rvalue::ShallowInitBox(operand, ty) => {
self.check_operand(operand, location);
let trait_ref = ty::TraitRef {
def_id: tcx.require_lang_item(LangItem::Sized, Some(self.last_span)),
substs: tcx.mk_substs_trait(ty, &[]),
@ -2004,6 +2068,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
Rvalue::Cast(cast_kind, op, ty) => {
self.check_operand(op, location);
match cast_kind {
CastKind::Pointer(PointerCast::ReifyFnPointer) => {
let fn_sig = op.ty(body, tcx).fn_sig(tcx);
@ -2250,6 +2316,9 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
BinOp::Eq | BinOp::Ne | BinOp::Lt | BinOp::Le | BinOp::Gt | BinOp::Ge,
box (left, right),
) => {
self.check_operand(left, location);
self.check_operand(right, location);
let ty_left = left.ty(body, tcx);
match ty_left.kind() {
// Types with regions are comparable if they have a common super-type.
@ -2300,13 +2369,19 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
}
Rvalue::Use(operand) | Rvalue::UnaryOp(_, operand) => {
self.check_operand(operand, location);
}
Rvalue::BinaryOp(_, box (left, right))
| Rvalue::CheckedBinaryOp(_, box (left, right)) => {
self.check_operand(left, location);
self.check_operand(right, location);
}
Rvalue::AddressOf(..)
| Rvalue::ThreadLocalRef(..)
| Rvalue::Use(..)
| Rvalue::Len(..)
| Rvalue::BinaryOp(..)
| Rvalue::CheckedBinaryOp(..)
| Rvalue::UnaryOp(..)
| Rvalue::Discriminant(..) => {}
}
}

87
compiler/rustc_borrowck/src/universal_regions.rs
View file

@ -23,7 +23,7 @@ use rustc_index::vec::{Idx, IndexVec};
use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin};
use rustc_middle::ty::fold::TypeFoldable;
use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};
use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt};
use rustc_middle::ty::{self, InlineConstSubsts, InlineConstSubstsParts, RegionVid, Ty, TyCtxt};
use std::iter;
use crate::nll::ToRegionVid;
@ -108,6 +108,10 @@ pub enum DefiningTy<'tcx> {
/// is that it has no inputs and a single return value, which is
/// the value of the constant.
Const(DefId, SubstsRef<'tcx>),
/// The MIR represents an inline const. The signature has no inputs and a
/// single return value found via `InlineConstSubsts::ty`.
InlineConst(DefId, SubstsRef<'tcx>),
}
impl<'tcx> DefiningTy<'tcx> {
@ -121,7 +125,7 @@ impl<'tcx> DefiningTy<'tcx> {
DefiningTy::Generator(_, substs, _) => {
Either::Right(Either::Left(substs.as_generator().upvar_tys()))
}
DefiningTy::FnDef(..) | DefiningTy::Const(..) => {
DefiningTy::FnDef(..) | DefiningTy::Const(..) | DefiningTy::InlineConst(..) => {
Either::Right(Either::Right(iter::empty()))
}
}
@ -133,7 +137,7 @@ impl<'tcx> DefiningTy<'tcx> {
pub fn implicit_inputs(self) -> usize {
match self {
DefiningTy::Closure(..) | DefiningTy::Generator(..) => 1,
DefiningTy::FnDef(..) | DefiningTy::Const(..) => 0,
DefiningTy::FnDef(..) | DefiningTy::Const(..) | DefiningTy::InlineConst(..) => 0,
}
}
@ -142,7 +146,7 @@ impl<'tcx> DefiningTy<'tcx> {
}
pub fn is_const(&self) -> bool {
matches!(*self, DefiningTy::Const(..))
matches!(*self, DefiningTy::Const(..) | DefiningTy::InlineConst(..))
}
pub fn def_id(&self) -> DefId {
@ -150,7 +154,8 @@ impl<'tcx> DefiningTy<'tcx> {
DefiningTy::Closure(def_id, ..)
| DefiningTy::Generator(def_id, ..)
| DefiningTy::FnDef(def_id, ..)
| DefiningTy::Const(def_id, ..) => def_id,
| DefiningTy::Const(def_id, ..)
| DefiningTy::InlineConst(def_id, ..) => def_id,
}
}
}
@ -242,7 +247,7 @@ impl<'tcx> UniversalRegions<'tcx> {
tcx: TyCtxt<'tcx>,
closure_substs: SubstsRef<'tcx>,
expected_num_vars: usize,
closure_base_def_id: DefId,
typeck_root_def_id: DefId,
) -> IndexVec<RegionVid, ty::Region<'tcx>> {
let mut region_mapping = IndexVec::with_capacity(expected_num_vars);
region_mapping.push(tcx.lifetimes.re_static);
@ -250,7 +255,7 @@ impl<'tcx> UniversalRegions<'tcx> {
region_mapping.push(fr);
});
for_each_late_bound_region_defined_on(tcx, closure_base_def_id, |r| {
for_each_late_bound_region_defined_on(tcx, typeck_root_def_id, |r| {
region_mapping.push(r);
});
@ -344,8 +349,8 @@ impl<'tcx> UniversalRegions<'tcx> {
// tests, and the resulting print-outs include def-ids
// and other things that are not stable across tests!
// So we just include the region-vid. Annoying.
let closure_base_def_id = tcx.closure_base_def_id(def_id);
for_each_late_bound_region_defined_on(tcx, closure_base_def_id, |r| {
let typeck_root_def_id = tcx.typeck_root_def_id(def_id);
for_each_late_bound_region_defined_on(tcx, typeck_root_def_id, |r| {
err.note(&format!("late-bound region is {:?}", self.to_region_vid(r),));
});
}
@ -359,8 +364,8 @@ impl<'tcx> UniversalRegions<'tcx> {
// FIXME: As above, we'd like to print out the region
// `r` but doing so is not stable across architectures
// and so forth.
let closure_base_def_id = tcx.closure_base_def_id(def_id);
for_each_late_bound_region_defined_on(tcx, closure_base_def_id, |r| {
let typeck_root_def_id = tcx.typeck_root_def_id(def_id);
for_each_late_bound_region_defined_on(tcx, typeck_root_def_id, |r| {
err.note(&format!("late-bound region is {:?}", self.to_region_vid(r),));
});
}
@ -376,6 +381,12 @@ impl<'tcx> UniversalRegions<'tcx> {
tcx.def_path_str_with_substs(def_id, substs),
));
}
DefiningTy::InlineConst(def_id, substs) => {
err.note(&format!(
"defining inline constant type: {}",
tcx.def_path_str_with_substs(def_id, substs),
));
}
}
}
}
@ -411,7 +422,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
let mut indices = self.compute_indices(fr_static, defining_ty);
debug!("build: indices={:?}", indices);
let closure_base_def_id = self.infcx.tcx.closure_base_def_id(self.mir_def.did.to_def_id());
let typeck_root_def_id = self.infcx.tcx.typeck_root_def_id(self.mir_def.did.to_def_id());
// If this is a closure or generator, then the late-bound regions from the enclosing
// function are actually external regions to us. For example, here, 'a is not local
@ -419,7 +430,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
// fn foo<'a>() {
// let c = || { let x: &'a u32 = ...; }
// }
if self.mir_def.did.to_def_id() != closure_base_def_id {
if self.mir_def.did.to_def_id() != typeck_root_def_id {
self.infcx
.replace_late_bound_regions_with_nll_infer_vars(self.mir_def.did, &mut indices)
}
@ -437,7 +448,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
);
// Converse of above, if this is a function then the late-bound regions declared on its
// signature are local to the fn.
if self.mir_def.did.to_def_id() == closure_base_def_id {
if self.mir_def.did.to_def_id() == typeck_root_def_id {
self.infcx
.replace_late_bound_regions_with_nll_infer_vars(self.mir_def.did, &mut indices);
}
@ -502,12 +513,12 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
/// see `DefiningTy` for details.
fn defining_ty(&self) -> DefiningTy<'tcx> {
let tcx = self.infcx.tcx;
let closure_base_def_id = tcx.closure_base_def_id(self.mir_def.did.to_def_id());
let typeck_root_def_id = tcx.typeck_root_def_id(self.mir_def.did.to_def_id());
match tcx.hir().body_owner_kind(self.mir_hir_id) {
BodyOwnerKind::Closure | BodyOwnerKind::Fn => {
let defining_ty = if self.mir_def.did.to_def_id() == closure_base_def_id {
tcx.type_of(closure_base_def_id)
let defining_ty = if self.mir_def.did.to_def_id() == typeck_root_def_id {
tcx.type_of(typeck_root_def_id)
} else {
let tables = tcx.typeck(self.mir_def.did);
tables.node_type(self.mir_hir_id)
@ -534,11 +545,21 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
}
BodyOwnerKind::Const | BodyOwnerKind::Static(..) => {
assert_eq!(self.mir_def.did.to_def_id(), closure_base_def_id);
let identity_substs = InternalSubsts::identity_for_item(tcx, closure_base_def_id);
let substs =
self.infcx.replace_free_regions_with_nll_infer_vars(FR, identity_substs);
DefiningTy::Const(self.mir_def.did.to_def_id(), substs)
let identity_substs = InternalSubsts::identity_for_item(tcx, typeck_root_def_id);
if self.mir_def.did.to_def_id() == typeck_root_def_id {
let substs =
self.infcx.replace_free_regions_with_nll_infer_vars(FR, identity_substs);
DefiningTy::Const(self.mir_def.did.to_def_id(), substs)
} else {
let ty = tcx.typeck(self.mir_def.did).node_type(self.mir_hir_id);
let substs = InlineConstSubsts::new(
tcx,
InlineConstSubstsParts { parent_substs: identity_substs, ty },
)
.substs;
let substs = self.infcx.replace_free_regions_with_nll_infer_vars(FR, substs);
DefiningTy::InlineConst(self.mir_def.did.to_def_id(), substs)
}
}
}
}
@ -553,17 +574,19 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
defining_ty: DefiningTy<'tcx>,
) -> UniversalRegionIndices<'tcx> {
let tcx = self.infcx.tcx;
let closure_base_def_id = tcx.closure_base_def_id(self.mir_def.did.to_def_id());
let identity_substs = InternalSubsts::identity_for_item(tcx, closure_base_def_id);
let typeck_root_def_id = tcx.typeck_root_def_id(self.mir_def.did.to_def_id());
let identity_substs = InternalSubsts::identity_for_item(tcx, typeck_root_def_id);
let fr_substs = match defining_ty {
DefiningTy::Closure(_, ref substs) | DefiningTy::Generator(_, ref substs, _) => {
DefiningTy::Closure(_, ref substs)
| DefiningTy::Generator(_, ref substs, _)
| DefiningTy::InlineConst(_, ref substs) => {
// In the case of closures, we rely on the fact that
// the first N elements in the ClosureSubsts are
// inherited from the `closure_base_def_id`.
// inherited from the `typeck_root_def_id`.
// Therefore, when we zip together (below) with
// `identity_substs`, we will get only those regions
// that correspond to early-bound regions declared on
// the `closure_base_def_id`.
// the `typeck_root_def_id`.
assert!(substs.len() >= identity_substs.len());
assert_eq!(substs.regions().count(), identity_substs.regions().count());
substs
@ -648,6 +671,12 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
let ty = indices.fold_to_region_vids(tcx, ty);
ty::Binder::dummy(tcx.intern_type_list(&[ty]))
}
DefiningTy::InlineConst(def_id, substs) => {
assert_eq!(self.mir_def.did.to_def_id(), def_id);
let ty = substs.as_inline_const().ty();
ty::Binder::dummy(tcx.intern_type_list(&[ty]))
}
}
}
}
@ -736,8 +765,8 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'cx, 'tcx> {
indices: &mut UniversalRegionIndices<'tcx>,
) {
debug!("replace_late_bound_regions_with_nll_infer_vars(mir_def_id={:?})", mir_def_id);
let closure_base_def_id = self.tcx.closure_base_def_id(mir_def_id.to_def_id());
for_each_late_bound_region_defined_on(self.tcx, closure_base_def_id, |r| {
let typeck_root_def_id = self.tcx.typeck_root_def_id(mir_def_id.to_def_id());
for_each_late_bound_region_defined_on(self.tcx, typeck_root_def_id, |r| {
debug!("replace_late_bound_regions_with_nll_infer_vars: r={:?}", r);
if !indices.indices.contains_key(&r) {
let region_vid = self.next_nll_region_var(FR);