hir_ty/
lib.rs

1//! The type system. We currently use this to infer types for completion, hover
2//! information and various assists.
3
4#![cfg_attr(feature = "in-rust-tree", feature(rustc_private))]
5// It's useful to refer to code that is private in doc comments.
6#![allow(rustdoc::private_intra_doc_links)]
7
8// FIXME: We used to import `rustc_*` deps from `rustc_private` with `feature = "in-rust-tree" but
9// temporarily switched to crates.io versions due to hardships that working on them from rustc
10// demands corresponding changes on rust-analyzer at the same time.
11// For details, see the zulip discussion below:
12// https://rust-lang.zulipchat.com/#narrow/channel/185405-t-compiler.2Frust-analyzer/topic/relying.20on.20in-tree.20.60rustc_type_ir.60.2F.60rustc_next_trait_solver.60/with/541055689
13
14extern crate ra_ap_rustc_abi as rustc_abi;
15extern crate ra_ap_rustc_ast_ir as rustc_ast_ir;
16extern crate ra_ap_rustc_index as rustc_index;
17extern crate ra_ap_rustc_next_trait_solver as rustc_next_trait_solver;
18extern crate ra_ap_rustc_type_ir as rustc_type_ir;
19
20extern crate self as hir_ty;
21
22pub mod builtin_derive;
23pub mod generics;
24mod infer;
25pub mod inhabitedness;
26mod lower;
27pub mod next_solver;
28mod opaques;
29mod representability;
30mod specialization;
31mod target_feature;
32pub mod utils;
33mod variance;
34
35pub mod autoderef;
36pub mod consteval;
37pub mod db;
38pub mod drop;
39pub mod dyn_compatibility;
40pub mod lang_items;
41pub mod layout;
42pub mod method_resolution;
43pub mod mir;
44pub mod primitive;
45pub mod solver_errors;
46pub mod traits;
47
48use std::{hash::Hash, ops::ControlFlow};
49
50use base_db::SourceDatabase;
51use hir_def::{
52    CallableDefId, ConstId, DefWithBodyId, EnumVariantId, ExpressionStoreOwnerId, FunctionId,
53    GenericDefId, HasModule, LifetimeParamId, ModuleId, StaticId, TypeAliasId, TypeOrConstParamId,
54    TypeParamId,
55    expr_store::{Body, ExpressionStore},
56    hir::{BindingId, ExprId, ExprOrPatId, ExprOrPatIdPacked, PatId},
57    resolver::{HasResolver, Resolver, TypeNs},
58    type_ref::{Rawness, TypeRefId},
59};
60use hir_expand::name::Name;
61use indexmap::{IndexMap, map::Entry};
62use macros::GenericTypeVisitable;
63use mir::{MirEvalError, VTableMap};
64use rustc_abi::ExternAbi;
65use rustc_hash::{FxBuildHasher, FxHashMap, FxHashSet};
66use rustc_type_ir::{
67    BoundVarIndexKind, TypeSuperVisitable, TypeVisitableExt,
68    inherent::{IntoKind, Ty as _},
69};
70use salsa::SalsaValue;
71use stdx::impl_from;
72use traits::FnTrait;
73
74use crate::{
75    db::{AnonConstId, HirDatabase},
76    lower::SupertraitsInfo,
77    next_solver::{
78        AliasTy, Binder, BoundConst, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, Canonical,
79        CanonicalVarKind, CanonicalVarKinds, ClauseKind, Const, ConstKind, DbInterner, GenericArgs,
80        PolyFnSig, Region, RegionKind, TraitRef, Ty, TyKind, TypingMode,
81        abi::Safety,
82        infer::{
83            DbInternerInferExt,
84            traits::{Obligation, ObligationCause},
85        },
86        obligation_ctxt::ObligationCtxt,
87    },
88};
89
90pub use autoderef::autoderef;
91pub use infer::{
92    Adjust, Adjustment, AutoBorrow, BindingMode, ByRef, ExplicitDropMethodUseKind,
93    InferenceDiagnostic, InferenceResult, OverloadedDeref, PointerCast, ReturnKind,
94    cast::CastError, could_coerce, could_unify, could_unify_deeply, infer_query_with_inspect,
95};
96pub use lower::{
97    FieldType, GenericDefaults, GenericDefaultsRef, GenericPredicates, LifetimeElisionKind,
98    LifetimeLoweringMode, LoweringMode, TyDefId, TyLoweringContext, TyLoweringInferVarsCtx,
99    TyLoweringResult, ValueTyDefId, diagnostics::*,
100};
101pub use next_solver::interner::{attach_db, attach_db_allow_change, with_attached_db};
102pub use target_feature::TargetFeatures;
103pub use traits::{ParamEnvAndCrate, check_orphan_rules};
104pub use utils::{
105    TargetFeatureIsSafeInTarget, Unsafety, all_super_traits, direct_super_traits,
106    is_fn_unsafe_to_call, target_feature_is_safe_in_target,
107};
108
109pub mod closure_analysis {
110    pub use crate::infer::{
111        CaptureInfo, CaptureSourceStack, CapturedPlace, ClosureData, UpvarCapture,
112        closure::analysis::{
113            BorrowKind,
114            expr_use_visitor::{FakeReadCause, Place, PlaceBase, Projection, ProjectionKind},
115        },
116    };
117}
118
119/// A constant can have reference to other things. Memory map job is holding
120/// the necessary bits of memory of the const eval session to keep the constant
121/// meaningful.
122#[derive(Debug, Default, Clone, PartialEq, Eq, GenericTypeVisitable)]
123pub enum MemoryMap<'db> {
124    #[default]
125    Empty,
126    Simple(Box<[u8]>),
127    Complex(Box<ComplexMemoryMap<'db>>),
128}
129
130#[derive(Debug, Default, Clone, PartialEq, Eq, GenericTypeVisitable)]
131pub struct ComplexMemoryMap<'db> {
132    memory: IndexMap<usize, Box<[u8]>, FxBuildHasher>,
133    vtable: VTableMap<'db>,
134}
135
136impl ComplexMemoryMap<'_> {
137    fn insert(&mut self, addr: usize, val: Box<[u8]>) {
138        match self.memory.entry(addr) {
139            Entry::Occupied(mut e) => {
140                if e.get().len() < val.len() {
141                    e.insert(val);
142                }
143            }
144            Entry::Vacant(e) => {
145                e.insert(val);
146            }
147        }
148    }
149}
150
151impl<'db> MemoryMap<'db> {
152    pub fn vtable_ty(&self, id: usize) -> Result<Ty<'db>, MirEvalError<'db>> {
153        match self {
154            MemoryMap::Empty | MemoryMap::Simple(_) => Err(MirEvalError::InvalidVTableId(id)),
155            MemoryMap::Complex(cm) => cm.vtable.ty(id),
156        }
157    }
158
159    fn simple(v: Box<[u8]>) -> Self {
160        MemoryMap::Simple(v)
161    }
162
163    /// This functions convert each address by a function `f` which gets the byte intervals and assign an address
164    /// to them. It is useful when you want to load a constant with a memory map in a new memory. You can pass an
165    /// allocator function as `f` and it will return a mapping of old addresses to new addresses.
166    fn transform_addresses(
167        &self,
168        mut f: impl FnMut(&[u8], usize) -> Result<usize, MirEvalError<'db>>,
169    ) -> Result<FxHashMap<usize, usize>, MirEvalError<'db>> {
170        let mut transform = |(addr, val): (&usize, &[u8])| {
171            let addr = *addr;
172            let align = if addr == 0 { 64 } else { (addr - (addr & (addr - 1))).min(64) };
173            f(val, align).map(|it| (addr, it))
174        };
175        match self {
176            MemoryMap::Empty => Ok(Default::default()),
177            MemoryMap::Simple(m) => transform((&0, m)).map(|(addr, val)| {
178                let mut map = FxHashMap::with_capacity_and_hasher(1, rustc_hash::FxBuildHasher);
179                map.insert(addr, val);
180                map
181            }),
182            MemoryMap::Complex(cm) => {
183                cm.memory.iter().map(|(addr, val)| transform((addr, val))).collect()
184            }
185        }
186    }
187
188    pub fn get(&self, addr: usize, size: usize) -> Option<&[u8]> {
189        if size == 0 {
190            Some(&[])
191        } else {
192            match self {
193                MemoryMap::Empty => Some(&[]),
194                MemoryMap::Simple(m) if addr == 0 => m.get(0..size),
195                MemoryMap::Simple(_) => None,
196                MemoryMap::Complex(cm) => cm.memory.get(&addr)?.get(0..size),
197            }
198        }
199    }
200}
201
202/// Returns the index of a parameter in the generic type parameter list by its id.
203pub fn type_or_const_param_idx(db: &dyn HirDatabase, id: TypeOrConstParamId) -> u32 {
204    generics::generics(db, id.parent).type_or_const_param_idx(id)
205}
206
207pub fn lifetime_param_idx(db: &dyn HirDatabase, id: LifetimeParamId) -> u32 {
208    generics::generics(db, id.parent).lifetime_param_idx(id, false).0
209}
210
211#[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
212pub enum ImplTraitId {
213    ReturnTypeImplTrait(hir_def::FunctionId, next_solver::ImplTraitIdx),
214    TypeAliasImplTrait(hir_def::TypeAliasId, next_solver::ImplTraitIdx),
215}
216
217/// 'Canonicalizes' the `t` by replacing any errors with new variables. Also
218/// ensures there are no unbound variables or inference variables anywhere in
219/// the `t`.
220pub fn replace_errors_with_variables<'db, T>(interner: DbInterner<'db>, t: &T) -> Canonical<'db, T>
221where
222    T: rustc_type_ir::TypeFoldable<DbInterner<'db>> + Clone,
223{
224    use rustc_type_ir::{FallibleTypeFolder, TypeSuperFoldable};
225    struct ErrorReplacer<'db> {
226        interner: DbInterner<'db>,
227        vars: Vec<CanonicalVarKind<'db>>,
228        binder: rustc_type_ir::DebruijnIndex,
229    }
230    impl<'db> FallibleTypeFolder<DbInterner<'db>> for ErrorReplacer<'db> {
231        #[cfg(debug_assertions)]
232        type Error = ();
233        #[cfg(not(debug_assertions))]
234        type Error = std::convert::Infallible;
235
236        fn cx(&self) -> DbInterner<'db> {
237            self.interner
238        }
239
240        fn try_fold_binder<T>(&mut self, t: Binder<'db, T>) -> Result<Binder<'db, T>, Self::Error>
241        where
242            T: rustc_type_ir::TypeFoldable<DbInterner<'db>>,
243        {
244            self.binder.shift_in(1);
245            let result = t.try_super_fold_with(self);
246            self.binder.shift_out(1);
247            result
248        }
249
250        fn try_fold_ty(&mut self, t: Ty<'db>) -> Result<Ty<'db>, Self::Error> {
251            if !t.has_type_flags(
252                rustc_type_ir::TypeFlags::HAS_ERROR
253                    | rustc_type_ir::TypeFlags::HAS_TY_INFER
254                    | rustc_type_ir::TypeFlags::HAS_CT_INFER
255                    | rustc_type_ir::TypeFlags::HAS_RE_INFER,
256            ) {
257                return Ok(t);
258            }
259
260            #[cfg(debug_assertions)]
261            let error = || Err(());
262            #[cfg(not(debug_assertions))]
263            let error = || Ok(Ty::new_error(self.interner, crate::next_solver::ErrorGuaranteed));
264
265            match t.kind() {
266                TyKind::Error(_) => {
267                    let var = rustc_type_ir::BoundVar::from_usize(self.vars.len());
268                    self.vars.push(CanonicalVarKind::Ty {
269                        ui: rustc_type_ir::UniverseIndex::ZERO,
270                        sub_root: var,
271                    });
272                    Ok(Ty::new_bound(
273                        self.interner,
274                        self.binder,
275                        BoundTy { var, kind: BoundTyKind::Anon },
276                    ))
277                }
278                TyKind::Infer(_) => error(),
279                TyKind::Bound(BoundVarIndexKind::Bound(index), _) if index > self.binder => error(),
280                _ => t.try_super_fold_with(self),
281            }
282        }
283
284        fn try_fold_const(&mut self, ct: Const<'db>) -> Result<Const<'db>, Self::Error> {
285            if !ct.has_type_flags(
286                rustc_type_ir::TypeFlags::HAS_ERROR
287                    | rustc_type_ir::TypeFlags::HAS_TY_INFER
288                    | rustc_type_ir::TypeFlags::HAS_CT_INFER
289                    | rustc_type_ir::TypeFlags::HAS_RE_INFER,
290            ) {
291                return Ok(ct);
292            }
293
294            #[cfg(debug_assertions)]
295            let error = || Err(());
296            #[cfg(not(debug_assertions))]
297            let error = || Ok(Const::error(self.interner));
298
299            match ct.kind() {
300                ConstKind::Error(_) => {
301                    let var = rustc_type_ir::BoundVar::from_usize(self.vars.len());
302                    self.vars.push(CanonicalVarKind::Const(rustc_type_ir::UniverseIndex::ZERO));
303                    Ok(Const::new_bound(self.interner, self.binder, BoundConst::new(var)))
304                }
305                ConstKind::Infer(_) => error(),
306                ConstKind::Bound(BoundVarIndexKind::Bound(index), _) if index > self.binder => {
307                    error()
308                }
309                _ => ct.try_super_fold_with(self),
310            }
311        }
312
313        fn try_fold_region(&mut self, region: Region<'db>) -> Result<Region<'db>, Self::Error> {
314            #[cfg(debug_assertions)]
315            let error = || Err(());
316            #[cfg(not(debug_assertions))]
317            let error = || Ok(Region::error(self.interner));
318
319            match region.kind() {
320                RegionKind::ReError(_) => {
321                    let var = rustc_type_ir::BoundVar::from_usize(self.vars.len());
322                    self.vars.push(CanonicalVarKind::Region(rustc_type_ir::UniverseIndex::ZERO));
323                    Ok(Region::new_bound(
324                        self.interner,
325                        self.binder,
326                        BoundRegion { var, kind: BoundRegionKind::Anon },
327                    ))
328                }
329                RegionKind::ReVar(_) => error(),
330                RegionKind::ReBound(BoundVarIndexKind::Bound(index), _) if index > self.binder => {
331                    error()
332                }
333                _ => Ok(region),
334            }
335        }
336    }
337
338    let mut error_replacer =
339        ErrorReplacer { vars: Vec::new(), binder: rustc_type_ir::DebruijnIndex::ZERO, interner };
340    let value = match t.clone().try_fold_with(&mut error_replacer) {
341        Ok(t) => t,
342        Err(_) => panic!("Encountered unbound or inference vars in {t:?}"),
343    };
344    Canonical {
345        value,
346        max_universe: rustc_type_ir::UniverseIndex::ZERO,
347        var_kinds: CanonicalVarKinds::new_from_slice(&error_replacer.vars),
348    }
349}
350
351/// To be used from `hir` only.
352pub fn associated_type_shorthand_candidates(
353    db: &dyn HirDatabase,
354    def: GenericDefId,
355    res: TypeNs,
356    mut cb: impl FnMut(&Name, TypeAliasId) -> bool,
357) -> Option<TypeAliasId> {
358    let interner = DbInterner::new_no_crate(db);
359    let (def, param) = match res {
360        TypeNs::GenericParam(param) => (def, param),
361        TypeNs::SelfType(impl_) => {
362            let impl_trait = db.impl_trait(impl_)?.skip_binder().def_id.0;
363            let param = TypeParamId::trait_self(impl_trait);
364            (impl_trait.into(), param)
365        }
366        _ => return None,
367    };
368
369    let mut dedup_map = FxHashSet::default();
370    let param_ty = Ty::new_param(interner, param, type_or_const_param_idx(db, param.into()));
371    // We use the ParamEnv and not the predicates because the ParamEnv elaborates bounds.
372    let param_env = db.trait_environment(def);
373    for clause in param_env.clauses {
374        let ClauseKind::Trait(trait_clause) = clause.kind().skip_binder() else { continue };
375        if trait_clause.self_ty() != param_ty {
376            continue;
377        }
378        let trait_id = trait_clause.def_id().0;
379        dedup_map.extend(
380            SupertraitsInfo::query(db, trait_id)
381                .defined_assoc_types
382                .iter()
383                .map(|(name, id)| (name, *id)),
384        );
385    }
386
387    dedup_map
388        .into_iter()
389        .try_for_each(
390            |(name, id)| {
391                if cb(name, id) { ControlFlow::Break(id) } else { ControlFlow::Continue(()) }
392            },
393        )
394        .break_value()
395}
396
397/// To be used from `hir` only.
398pub fn callable_sig_from_fn_trait<'db>(
399    self_ty: Ty<'db>,
400    param_env: ParamEnvAndCrate<'db>,
401    db: &'db dyn HirDatabase,
402) -> Option<(FnTrait, PolyFnSig<'db>)> {
403    let ParamEnvAndCrate { param_env, krate } = param_env;
404    let interner = DbInterner::new_with(db, krate);
405    let infcx = interner.infer_ctxt().build(TypingMode::PostAnalysis);
406    let lang_items = interner.lang_items();
407    let cause = ObligationCause::dummy();
408
409    let impls_trait = |trait_: FnTrait| {
410        let mut ocx = ObligationCtxt::new(&infcx);
411        let tupled_args = infcx.next_ty_var(Span::Dummy);
412        let args = GenericArgs::new_from_slice(&[self_ty.into(), tupled_args.into()]);
413        let trait_id = trait_.get_id(lang_items)?;
414        let trait_ref = TraitRef::new_from_args(interner, trait_id.into(), args);
415        let obligation = Obligation::new(interner, cause, param_env, trait_ref);
416        ocx.register_obligation(obligation);
417        if !ocx.try_evaluate_obligations().is_empty() {
418            return None;
419        }
420        let tupled_args =
421            infcx.resolve_vars_if_possible(tupled_args).replace_infer_with_error(interner);
422        if tupled_args.is_tuple() { Some(tupled_args) } else { None }
423    };
424
425    let (trait_, args) = 'find_trait: {
426        for trait_ in [FnTrait::Fn, FnTrait::FnMut, FnTrait::FnOnce] {
427            if let Some(args) = impls_trait(trait_) {
428                break 'find_trait (trait_, args);
429            }
430        }
431        return None;
432    };
433
434    let output_assoc_type = lang_items.FnOnceOutput?;
435    let output_projection = Ty::new_alias(
436        interner,
437        AliasTy::new(
438            interner,
439            rustc_type_ir::Projection { def_id: output_assoc_type.into() },
440            [self_ty, args],
441        ),
442    );
443    let mut ocx = ObligationCtxt::new(&infcx);
444    let ret = ocx.structurally_normalize_ty(&cause, param_env, output_projection).ok()?;
445    let ret = ret.replace_infer_with_error(interner);
446
447    let sig = Binder::dummy(interner.mk_fn_sig(
448        args.tuple_fields(),
449        ret,
450        false,
451        // FIXME(splat): handle splatted arguments
452        Safety::Safe,
453        ExternAbi::Rust,
454    ));
455    Some((trait_, sig))
456}
457
458struct ParamCollector {
459    params: FxHashSet<TypeOrConstParamId>,
460}
461
462impl<'db> rustc_type_ir::TypeVisitor<DbInterner<'db>> for ParamCollector {
463    type Result = ();
464
465    fn visit_ty(&mut self, ty: Ty<'db>) -> Self::Result {
466        if let TyKind::Param(param) = ty.kind() {
467            self.params.insert(param.id.into());
468        }
469
470        ty.super_visit_with(self);
471    }
472
473    fn visit_const(&mut self, konst: Const<'db>) -> Self::Result {
474        if let ConstKind::Param(param) = konst.kind() {
475            self.params.insert(param.id.into());
476        }
477
478        konst.super_visit_with(self);
479    }
480}
481
482/// Returns unique params for types and consts contained in `value`.
483pub fn collect_params<'db, T>(value: &T) -> Vec<TypeOrConstParamId>
484where
485    T: ?Sized + rustc_type_ir::TypeVisitable<DbInterner<'db>>,
486{
487    let mut collector = ParamCollector { params: FxHashSet::default() };
488    value.visit_with(&mut collector);
489    Vec::from_iter(collector.params)
490}
491
492/// A `Span` represents some location in lowered code - a type, expression or pattern.
493///
494/// It has no meaning outside its body therefore it should not exit the pass it was created in
495/// (e.g. inference). It is usually associated with a solver obligation or an infer var, which
496/// should also not cross the pass they were created in.
497#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
498pub enum Span {
499    ExprId(ExprId),
500    PatId(PatId),
501    BindingId(BindingId),
502    TypeRefId(TypeRefId),
503    /// An unimportant location. Errors on this will be suppressed.
504    Dummy,
505}
506impl_from!(ExprId, PatId, BindingId, TypeRefId for Span);
507
508impl From<ExprOrPatIdPacked> for Span {
509    fn from(value: ExprOrPatIdPacked) -> Self {
510        match value.unpack() {
511            ExprOrPatId::ExprId(idx) => idx.into(),
512            ExprOrPatId::PatId(idx) => idx.into(),
513        }
514    }
515}
516
517impl Span {
518    pub(crate) fn pick_best(a: Span, b: Span) -> Span {
519        // We prefer dummy spans to minimize the risk of false errors.
520        if b.is_dummy() { b } else { a }
521    }
522
523    #[inline]
524    pub fn is_dummy(&self) -> bool {
525        matches!(self, Self::Dummy)
526    }
527}
528
529/// A [`DefWithBodyId`], or an anon const.
530#[derive(
531    Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord, salsa::Supertype, SalsaValue,
532)]
533pub enum InferBodyId<'db> {
534    DefWithBodyId(DefWithBodyId),
535    AnonConstId(AnonConstId<'db>),
536}
537impl_from!(
538    impl<'db>
539    DefWithBodyId(FunctionId, ConstId, StaticId),
540    AnonConstId<'db>
541    for InferBodyId<'db>
542);
543impl<'db> From<EnumVariantId> for InferBodyId<'db> {
544    fn from(id: EnumVariantId) -> Self {
545        InferBodyId::DefWithBodyId(DefWithBodyId::VariantId(id))
546    }
547}
548
549impl HasModule for InferBodyId<'_> {
550    fn module(&self, db: &dyn SourceDatabase) -> ModuleId {
551        match self {
552            InferBodyId::DefWithBodyId(id) => id.module(db),
553            InferBodyId::AnonConstId(id) => id.module(db),
554        }
555    }
556}
557
558impl HasResolver for InferBodyId<'_> {
559    fn resolver(self, db: &dyn SourceDatabase) -> Resolver<'_> {
560        match self {
561            InferBodyId::DefWithBodyId(id) => id.resolver(db),
562            InferBodyId::AnonConstId(id) => id.resolver(db),
563        }
564    }
565}
566
567impl InferBodyId<'_> {
568    pub fn expression_store_owner(self, db: &dyn HirDatabase) -> ExpressionStoreOwnerId {
569        match self {
570            InferBodyId::DefWithBodyId(id) => id.into(),
571            InferBodyId::AnonConstId(id) => id.loc(db).owner,
572        }
573    }
574
575    pub fn generic_def(self, db: &dyn HirDatabase) -> GenericDefId {
576        match self {
577            InferBodyId::DefWithBodyId(id) => id.generic_def(db),
578            InferBodyId::AnonConstId(id) => id.loc(db).owner.generic_def(db),
579        }
580    }
581
582    #[inline]
583    pub fn as_function(self) -> Option<FunctionId> {
584        match self {
585            InferBodyId::DefWithBodyId(DefWithBodyId::FunctionId(it)) => Some(it),
586            _ => None,
587        }
588    }
589
590    #[inline]
591    pub fn as_variant(self) -> Option<EnumVariantId> {
592        match self {
593            InferBodyId::DefWithBodyId(DefWithBodyId::VariantId(it)) => Some(it),
594            _ => None,
595        }
596    }
597
598    pub fn store_and_root_expr(self, db: &dyn HirDatabase) -> (&ExpressionStore, ExprId) {
599        match self {
600            InferBodyId::DefWithBodyId(id) => {
601                let body = Body::of(db, id);
602                (body, body.root_expr())
603            }
604            InferBodyId::AnonConstId(id) => {
605                let loc = id.loc(db);
606                let store = ExpressionStore::of(db, loc.owner);
607                (store, loc.expr)
608            }
609        }
610    }
611}
612
613pub fn setup_tracing() -> Option<tracing::subscriber::DefaultGuard> {
614    use std::env;
615    use tracing_subscriber::{Registry, layer::SubscriberExt};
616    use tracing_tree::HierarchicalLayer;
617
618    let filter: tracing_subscriber::filter::Targets =
619        env::var("SOLVER_DEBUG").ok().and_then(|it| it.parse().ok()).unwrap_or_default();
620    let layer = HierarchicalLayer::default()
621        .with_indent_lines(true)
622        .with_ansi(false)
623        .with_indent_amount(2)
624        .with_writer(std::io::stderr);
625    let subscriber = Registry::default().with(filter).with(layer);
626    Some(tracing::subscriber::set_default(subscriber))
627}
hir_ty/lib.rs

hir_ty/
lib.rs
