diff options
Diffstat (limited to 'compiler/rustc_middle/src/mir/query.rs')
| -rw-r--r-- | compiler/rustc_middle/src/mir/query.rs | 476 |
1 files changed, 476 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs new file mode 100644 index 000000000..dd9f8795f --- /dev/null +++ b/compiler/rustc_middle/src/mir/query.rs @@ -0,0 +1,476 @@ +//! Values computed by queries that use MIR. + +use crate::mir::{Body, ConstantKind, Promoted}; +use crate::ty::{self, OpaqueHiddenType, Ty, TyCtxt}; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::vec_map::VecMap; +use rustc_errors::ErrorGuaranteed; +use rustc_hir as hir; +use rustc_hir::def_id::{DefId, LocalDefId}; +use rustc_index::bit_set::BitMatrix; +use rustc_index::vec::IndexVec; +use rustc_span::Span; +use rustc_target::abi::VariantIdx; +use smallvec::SmallVec; +use std::cell::Cell; +use std::fmt::{self, Debug}; + +use super::{Field, SourceInfo}; + +#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)] +pub enum UnsafetyViolationKind { + /// Unsafe operation outside `unsafe`. + General, + /// Unsafe operation in an `unsafe fn` but outside an `unsafe` block. + /// Has to be handled as a lint for backwards compatibility. + UnsafeFn, +} + +#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)] +pub enum UnsafetyViolationDetails { + CallToUnsafeFunction, + UseOfInlineAssembly, + InitializingTypeWith, + CastOfPointerToInt, + UseOfMutableStatic, + UseOfExternStatic, + DerefOfRawPointer, + AccessToUnionField, + MutationOfLayoutConstrainedField, + BorrowOfLayoutConstrainedField, + CallToFunctionWith, +} + +impl UnsafetyViolationDetails { + pub fn description_and_note(&self) -> (&'static str, &'static str) { + use UnsafetyViolationDetails::*; + match self { + CallToUnsafeFunction => ( + "call to unsafe function", + "consult the function's documentation for information on how to avoid undefined \ + behavior", + ), + UseOfInlineAssembly => ( + "use of inline assembly", + "inline assembly is entirely unchecked and can cause undefined behavior", + ), + InitializingTypeWith => ( + "initializing type with `rustc_layout_scalar_valid_range` attr", + "initializing a layout restricted type's field with a value outside the valid \ + range is undefined behavior", + ), + CastOfPointerToInt => { + ("cast of pointer to int", "casting pointers to integers in constants") + } + UseOfMutableStatic => ( + "use of mutable static", + "mutable statics can be mutated by multiple threads: aliasing violations or data \ + races will cause undefined behavior", + ), + UseOfExternStatic => ( + "use of extern static", + "extern statics are not controlled by the Rust type system: invalid data, \ + aliasing violations or data races will cause undefined behavior", + ), + DerefOfRawPointer => ( + "dereference of raw pointer", + "raw pointers may be null, dangling or unaligned; they can violate aliasing rules \ + and cause data races: all of these are undefined behavior", + ), + AccessToUnionField => ( + "access to union field", + "the field may not be properly initialized: using uninitialized data will cause \ + undefined behavior", + ), + MutationOfLayoutConstrainedField => ( + "mutation of layout constrained field", + "mutating layout constrained fields cannot statically be checked for valid values", + ), + BorrowOfLayoutConstrainedField => ( + "borrow of layout constrained field with interior mutability", + "references to fields of layout constrained fields lose the constraints. Coupled \ + with interior mutability, the field can be changed to invalid values", + ), + CallToFunctionWith => ( + "call to function with `#[target_feature]`", + "can only be called if the required target features are available", + ), + } + } +} + +#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)] +pub struct UnsafetyViolation { + pub source_info: SourceInfo, + pub lint_root: hir::HirId, + pub kind: UnsafetyViolationKind, + pub details: UnsafetyViolationDetails, +} + +#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)] +pub enum UnusedUnsafe { + /// `unsafe` block contains no unsafe operations + /// > ``unnecessary `unsafe` block`` + Unused, + /// `unsafe` block nested under another (used) `unsafe` block + /// > ``… because it's nested under this `unsafe` block`` + InUnsafeBlock(hir::HirId), + /// `unsafe` block nested under `unsafe fn` + /// > ``… because it's nested under this `unsafe fn` `` + /// + /// the second HirId here indicates the first usage of the `unsafe` block, + /// which allows retrieval of the LintLevelSource for why that operation would + /// have been permitted without the block + InUnsafeFn(hir::HirId, hir::HirId), +} + +#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)] +pub enum UsedUnsafeBlockData { + SomeDisallowedInUnsafeFn, + // the HirId here indicates the first usage of the `unsafe` block + // (i.e. the one that's first encountered in the MIR traversal of the unsafety check) + AllAllowedInUnsafeFn(hir::HirId), +} + +#[derive(TyEncodable, TyDecodable, HashStable, Debug)] +pub struct UnsafetyCheckResult { + /// Violations that are propagated *upwards* from this function. + pub violations: Vec<UnsafetyViolation>, + + /// Used `unsafe` blocks in this function. This is used for the "unused_unsafe" lint. + /// + /// The keys are the used `unsafe` blocks, the UnusedUnsafeKind indicates whether + /// or not any of the usages happen at a place that doesn't allow `unsafe_op_in_unsafe_fn`. + pub used_unsafe_blocks: FxHashMap<hir::HirId, UsedUnsafeBlockData>, + + /// This is `Some` iff the item is not a closure. + pub unused_unsafes: Option<Vec<(hir::HirId, UnusedUnsafe)>>, +} + +rustc_index::newtype_index! { + pub struct GeneratorSavedLocal { + derive [HashStable] + DEBUG_FORMAT = "_{}", + } +} + +/// The layout of generator state. +#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)] +pub struct GeneratorLayout<'tcx> { + /// The type of every local stored inside the generator. + pub field_tys: IndexVec<GeneratorSavedLocal, Ty<'tcx>>, + + /// Which of the above fields are in each variant. Note that one field may + /// be stored in multiple variants. + pub variant_fields: IndexVec<VariantIdx, IndexVec<Field, GeneratorSavedLocal>>, + + /// The source that led to each variant being created (usually, a yield or + /// await). + pub variant_source_info: IndexVec<VariantIdx, SourceInfo>, + + /// Which saved locals are storage-live at the same time. Locals that do not + /// have conflicts with each other are allowed to overlap in the computed + /// layout. + pub storage_conflicts: BitMatrix<GeneratorSavedLocal, GeneratorSavedLocal>, +} + +impl Debug for GeneratorLayout<'_> { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + /// Prints an iterator of (key, value) tuples as a map. + struct MapPrinter<'a, K, V>(Cell<Option<Box<dyn Iterator<Item = (K, V)> + 'a>>>); + impl<'a, K, V> MapPrinter<'a, K, V> { + fn new(iter: impl Iterator<Item = (K, V)> + 'a) -> Self { + Self(Cell::new(Some(Box::new(iter)))) + } + } + impl<'a, K: Debug, V: Debug> Debug for MapPrinter<'a, K, V> { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt.debug_map().entries(self.0.take().unwrap()).finish() + } + } + + /// Prints the generator variant name. + struct GenVariantPrinter(VariantIdx); + impl From<VariantIdx> for GenVariantPrinter { + fn from(idx: VariantIdx) -> Self { + GenVariantPrinter(idx) + } + } + impl Debug for GenVariantPrinter { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + let variant_name = ty::GeneratorSubsts::variant_name(self.0); + if fmt.alternate() { + write!(fmt, "{:9}({:?})", variant_name, self.0) + } else { + write!(fmt, "{}", variant_name) + } + } + } + + /// Forces its contents to print in regular mode instead of alternate mode. + struct OneLinePrinter<T>(T); + impl<T: Debug> Debug for OneLinePrinter<T> { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(fmt, "{:?}", self.0) + } + } + + fmt.debug_struct("GeneratorLayout") + .field("field_tys", &MapPrinter::new(self.field_tys.iter_enumerated())) + .field( + "variant_fields", + &MapPrinter::new( + self.variant_fields + .iter_enumerated() + .map(|(k, v)| (GenVariantPrinter(k), OneLinePrinter(v))), + ), + ) + .field("storage_conflicts", &self.storage_conflicts) + .finish() + } +} + +#[derive(Debug, TyEncodable, TyDecodable, HashStable)] +pub struct BorrowCheckResult<'tcx> { + /// All the opaque types that are restricted to concrete types + /// by this function. Unlike the value in `TypeckResults`, this has + /// unerased regions. + pub concrete_opaque_types: VecMap<LocalDefId, OpaqueHiddenType<'tcx>>, + pub closure_requirements: Option<ClosureRegionRequirements<'tcx>>, + pub used_mut_upvars: SmallVec<[Field; 8]>, + pub tainted_by_errors: Option<ErrorGuaranteed>, +} + +/// The result of the `mir_const_qualif` query. +/// +/// Each field (except `error_occurred`) corresponds to an implementer of the `Qualif` trait in +/// `rustc_const_eval/src/transform/check_consts/qualifs.rs`. See that file for more information on each +/// `Qualif`. +#[derive(Clone, Copy, Debug, Default, TyEncodable, TyDecodable, HashStable)] +pub struct ConstQualifs { + pub has_mut_interior: bool, + pub needs_drop: bool, + pub needs_non_const_drop: bool, + pub custom_eq: bool, + pub tainted_by_errors: Option<ErrorGuaranteed>, +} + +/// After we borrow check a closure, we are left with various +/// requirements that we have inferred between the free regions that +/// appear in the closure's signature or on its field types. These +/// requirements are then verified and proved by the closure's +/// creating function. This struct encodes those requirements. +/// +/// The requirements are listed as being between various `RegionVid`. The 0th +/// region refers to `'static`; subsequent region vids refer to the free +/// regions that appear in the closure (or generator's) type, in order of +/// appearance. (This numbering is actually defined by the `UniversalRegions` +/// struct in the NLL region checker. See for example +/// `UniversalRegions::closure_mapping`.) Note the free regions in the +/// closure's signature and captures are erased. +/// +/// Example: If type check produces a closure with the closure substs: +/// +/// ```text +/// ClosureSubsts = [ +/// 'a, // From the parent. +/// 'b, +/// i8, // the "closure kind" +/// for<'x> fn(&'<erased> &'x u32) -> &'x u32, // the "closure signature" +/// &'<erased> String, // some upvar +/// ] +/// ``` +/// +/// We would "renumber" each free region to a unique vid, as follows: +/// +/// ```text +/// ClosureSubsts = [ +/// '1, // From the parent. +/// '2, +/// i8, // the "closure kind" +/// for<'x> fn(&'3 &'x u32) -> &'x u32, // the "closure signature" +/// &'4 String, // some upvar +/// ] +/// ``` +/// +/// Now the code might impose a requirement like `'1: '2`. When an +/// instance of the closure is created, the corresponding free regions +/// can be extracted from its type and constrained to have the given +/// outlives relationship. +/// +/// In some cases, we have to record outlives requirements between types and +/// regions as well. In that case, if those types include any regions, those +/// regions are recorded using their external names (`ReStatic`, +/// `ReEarlyBound`, `ReFree`). We use these because in a query response we +/// cannot use `ReVar` (which is what we use internally within the rest of the +/// NLL code). +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct ClosureRegionRequirements<'tcx> { + /// The number of external regions defined on the closure. In our + /// example above, it would be 3 -- one for `'static`, then `'1` + /// and `'2`. This is just used for a sanity check later on, to + /// make sure that the number of regions we see at the callsite + /// matches. + pub num_external_vids: usize, + + /// Requirements between the various free regions defined in + /// indices. + pub outlives_requirements: Vec<ClosureOutlivesRequirement<'tcx>>, +} + +/// Indicates an outlives-constraint between a type or between two +/// free regions declared on the closure. +#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct ClosureOutlivesRequirement<'tcx> { + // This region or type ... + pub subject: ClosureOutlivesSubject<'tcx>, + + // ... must outlive this one. + pub outlived_free_region: ty::RegionVid, + + // If not, report an error here ... + pub blame_span: Span, + + // ... due to this reason. + pub category: ConstraintCategory<'tcx>, +} + +// Make sure this enum doesn't unintentionally grow +#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))] +rustc_data_structures::static_assert_size!(ConstraintCategory<'_>, 16); + +/// Outlives-constraints can be categorized to determine whether and why they +/// are interesting (for error reporting). Order of variants indicates sort +/// order of the category, thereby influencing diagnostic output. +/// +/// See also `rustc_const_eval::borrow_check::constraints`. +#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash)] +#[derive(TyEncodable, TyDecodable, HashStable)] +pub enum ConstraintCategory<'tcx> { + Return(ReturnConstraint), + Yield, + UseAsConst, + UseAsStatic, + TypeAnnotation, + Cast, + + /// A constraint that came from checking the body of a closure. + /// + /// We try to get the category that the closure used when reporting this. + ClosureBounds, + + /// Contains the function type if available. + CallArgument(Option<Ty<'tcx>>), + CopyBound, + SizedBound, + Assignment, + /// A constraint that came from a usage of a variable (e.g. in an ADT expression + /// like `Foo { field: my_val }`) + Usage, + OpaqueType, + ClosureUpvar(Field), + + /// A constraint from a user-written predicate + /// with the provided span, written on the item + /// with the given `DefId` + Predicate(Span), + + /// A "boring" constraint (caused by the given location) is one that + /// the user probably doesn't want to see described in diagnostics, + /// because it is kind of an artifact of the type system setup. + Boring, + // Boring and applicable everywhere. + BoringNoLocation, + + /// A constraint that doesn't correspond to anything the user sees. + Internal, +} + +#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash)] +#[derive(TyEncodable, TyDecodable, HashStable)] +pub enum ReturnConstraint { + Normal, + ClosureUpvar(Field), +} + +/// The subject of a `ClosureOutlivesRequirement` -- that is, the thing +/// that must outlive some region. +#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum ClosureOutlivesSubject<'tcx> { + /// Subject is a type, typically a type parameter, but could also + /// be a projection. Indicates a requirement like `T: 'a` being + /// passed to the caller, where the type here is `T`. + /// + /// The type here is guaranteed not to contain any free regions at + /// present. + Ty(Ty<'tcx>), + + /// Subject is a free region from the closure. Indicates a requirement + /// like `'a: 'b` being passed to the caller; the region here is `'a`. + Region(ty::RegionVid), +} + +/// The constituent parts of a type level constant of kind ADT or array. +#[derive(Copy, Clone, Debug, HashStable)] +pub struct DestructuredConst<'tcx> { + pub variant: Option<VariantIdx>, + pub fields: &'tcx [ty::Const<'tcx>], +} + +/// The constituent parts of a mir constant of kind ADT or array. +#[derive(Copy, Clone, Debug, HashStable)] +pub struct DestructuredMirConstant<'tcx> { + pub variant: Option<VariantIdx>, + pub fields: &'tcx [ConstantKind<'tcx>], +} + +/// Coverage information summarized from a MIR if instrumented for source code coverage (see +/// compiler option `-Cinstrument-coverage`). This information is generated by the +/// `InstrumentCoverage` MIR pass and can be retrieved via the `coverageinfo` query. +#[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable)] +pub struct CoverageInfo { + /// The total number of coverage region counters added to the MIR `Body`. + pub num_counters: u32, + + /// The total number of coverage region counter expressions added to the MIR `Body`. + pub num_expressions: u32, +} + +/// Shims which make dealing with `WithOptConstParam` easier. +/// +/// For more information on why this is needed, consider looking +/// at the docs for `WithOptConstParam` itself. +impl<'tcx> TyCtxt<'tcx> { + #[inline] + pub fn mir_const_qualif_opt_const_arg( + self, + def: ty::WithOptConstParam<LocalDefId>, + ) -> ConstQualifs { + if let Some(param_did) = def.const_param_did { + self.mir_const_qualif_const_arg((def.did, param_did)) + } else { + self.mir_const_qualif(def.did) + } + } + + #[inline] + pub fn promoted_mir_opt_const_arg( + self, + def: ty::WithOptConstParam<DefId>, + ) -> &'tcx IndexVec<Promoted, Body<'tcx>> { + if let Some((did, param_did)) = def.as_const_arg() { + self.promoted_mir_of_const_arg((did, param_did)) + } else { + self.promoted_mir(def.did) + } + } + + #[inline] + pub fn mir_for_ctfe_opt_const_arg(self, def: ty::WithOptConstParam<DefId>) -> &'tcx Body<'tcx> { + if let Some((did, param_did)) = def.as_const_arg() { + self.mir_for_ctfe_of_const_arg((did, param_did)) + } else { + self.mir_for_ctfe(def.did) + } + } +} |