Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-ty/src/next_solver/infer/at.rs')
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diff --git a/crates/hir-ty/src/next_solver/infer/at.rs b/crates/hir-ty/src/next_solver/infer/at.rs new file mode 100644 index 0000000000..8dfffe0d36 --- /dev/null +++ b/crates/hir-ty/src/next_solver/infer/at.rs @@ -0,0 +1,363 @@ +//! A nice interface for working with the infcx. The basic idea is to +//! do `infcx.at(cause, param_env)`, which sets the "cause" of the +//! operation as well as the surrounding parameter environment. Then +//! you can do something like `.sub(a, b)` or `.eq(a, b)` to create a +//! subtype or equality relationship respectively. The first argument +//! is always the "expected" output from the POV of diagnostics. +//! +//! Examples: +//! ```ignore (fragment) +//! infcx.at(cause, param_env).sub(a, b) +//! // requires that `a <: b`, with `a` considered the "expected" type +//! +//! infcx.at(cause, param_env).sup(a, b) +//! // requires that `b <: a`, with `a` considered the "expected" type +//! +//! infcx.at(cause, param_env).eq(a, b) +//! // requires that `a == b`, with `a` considered the "expected" type +//! ``` +//! For finer-grained control, you can also do use `trace`: +//! ```ignore (fragment) +//! infcx.at(...).trace(a, b).sub(&c, &d) +//! ``` +//! This will set `a` and `b` as the "root" values for +//! error-reporting, but actually operate on `c` and `d`. This is +//! sometimes useful when the types of `c` and `d` are not traceable +//! things. (That system should probably be refactored.) + +use rustc_type_ir::{ + FnSig, GenericArgKind, TypeFoldable, TypingMode, Variance, + error::ExpectedFound, + inherent::{IntoKind, Span as _}, + relate::{Relate, TypeRelation, solver_relating::RelateExt}, +}; + +use crate::next_solver::{ + AliasTerm, AliasTy, Binder, Const, DbInterner, GenericArg, Goal, ParamEnv, + PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, Predicate, Region, Span, Term, + TraitRef, Ty, + fulfill::{FulfillmentCtxt, NextSolverError}, + infer::relate::lattice::{LatticeOp, LatticeOpKind}, +}; + +use super::{ + InferCtxt, InferOk, InferResult, TypeTrace, ValuePairs, + traits::{Obligation, ObligationCause}, +}; + +/// Whether we should define opaque types or just treat them opaquely. +/// +/// Currently only used to prevent predicate matching from matching anything +/// against opaque types. +#[derive(Debug, PartialEq, Eq, Clone, Copy)] +pub enum DefineOpaqueTypes { + Yes, + No, +} + +#[derive(Clone, Copy)] +pub struct At<'a, 'db> { + pub infcx: &'a InferCtxt<'db>, + pub cause: &'a ObligationCause, + pub param_env: ParamEnv<'db>, +} + +impl<'db> InferCtxt<'db> { + #[inline] + pub fn at<'a>(&'a self, cause: &'a ObligationCause, param_env: ParamEnv<'db>) -> At<'a, 'db> { + At { infcx: self, cause, param_env } + } + + /// Forks the inference context, creating a new inference context with the same inference + /// variables in the same state. This can be used to "branch off" many tests from the same + /// common state. + pub fn fork(&self) -> Self { + Self { + interner: self.interner, + typing_mode: self.typing_mode, + inner: self.inner.clone(), + tainted_by_errors: self.tainted_by_errors.clone(), + universe: self.universe.clone(), + } + } + + /// Forks the inference context, creating a new inference context with the same inference + /// variables in the same state, except possibly changing the intercrate mode. This can be + /// used to "branch off" many tests from the same common state. Used in negative coherence. + pub fn fork_with_typing_mode(&self, typing_mode: TypingMode<DbInterner<'db>>) -> Self { + // Unlike `fork`, this invalidates all cache entries as they may depend on the + // typing mode. + + Self { + interner: self.interner, + typing_mode, + inner: self.inner.clone(), + tainted_by_errors: self.tainted_by_errors.clone(), + universe: self.universe.clone(), + } + } +} + +pub trait ToTrace<'db>: Relate<DbInterner<'db>> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db>; +} + +impl<'a, 'db> At<'a, 'db> { + /// Makes `actual <: expected`. For example, if type-checking a + /// call like `foo(x)`, where `foo: fn(i32)`, you might have + /// `sup(i32, x)`, since the "expected" type is the type that + /// appears in the signature. + pub fn sup<T>( + self, + define_opaque_types: DefineOpaqueTypes, + expected: T, + actual: T, + ) -> InferResult<'db, ()> + where + T: ToTrace<'db>, + { + RelateExt::relate( + self.infcx, + self.param_env, + expected, + Variance::Contravariant, + actual, + Span::dummy(), + ) + .map(|goals| self.goals_to_obligations(goals)) + } + + /// Makes `expected <: actual`. + pub fn sub<T>( + self, + define_opaque_types: DefineOpaqueTypes, + expected: T, + actual: T, + ) -> InferResult<'db, ()> + where + T: ToTrace<'db>, + { + RelateExt::relate( + self.infcx, + self.param_env, + expected, + Variance::Covariant, + actual, + Span::dummy(), + ) + .map(|goals| self.goals_to_obligations(goals)) + } + + /// Makes `expected == actual`. + pub fn eq<T>( + self, + define_opaque_types: DefineOpaqueTypes, + expected: T, + actual: T, + ) -> InferResult<'db, ()> + where + T: ToTrace<'db>, + { + self.eq_trace( + define_opaque_types, + ToTrace::to_trace(self.cause, expected, actual), + expected, + actual, + ) + } + + /// Makes `expected == actual`. + pub fn eq_trace<T>( + self, + define_opaque_types: DefineOpaqueTypes, + trace: TypeTrace<'db>, + expected: T, + actual: T, + ) -> InferResult<'db, ()> + where + T: Relate<DbInterner<'db>>, + { + RelateExt::relate( + self.infcx, + self.param_env, + expected, + Variance::Invariant, + actual, + Span::dummy(), + ) + .map(|goals| self.goals_to_obligations(goals)) + } + + pub fn relate<T>( + self, + define_opaque_types: DefineOpaqueTypes, + expected: T, + variance: Variance, + actual: T, + ) -> InferResult<'db, ()> + where + T: ToTrace<'db>, + { + match variance { + Variance::Covariant => self.sub(define_opaque_types, expected, actual), + Variance::Invariant => self.eq(define_opaque_types, expected, actual), + Variance::Contravariant => self.sup(define_opaque_types, expected, actual), + + // We could make this make sense but it's not readily + // exposed and I don't feel like dealing with it. Note + // that bivariance in general does a bit more than just + // *nothing*, it checks that the types are the same + // "modulo variance" basically. + Variance::Bivariant => panic!("Bivariant given to `relate()`"), + } + } + + /// Deeply normalizes `value`, replacing all aliases which can by normalized in + /// the current environment. This errors in case normalization fails or is ambiguous. + pub fn deeply_normalize<T>(self, value: T) -> Result<T, Vec<NextSolverError<'db>>> + where + T: TypeFoldable<DbInterner<'db>>, + { + crate::next_solver::normalize::deeply_normalize(self, value) + } + + /// Computes the least-upper-bound, or mutual supertype, of two + /// values. The order of the arguments doesn't matter, but since + /// this can result in an error (e.g., if asked to compute LUB of + /// u32 and i32), it is meaningful to call one of them the + /// "expected type". + pub fn lub<T>(self, expected: T, actual: T) -> InferResult<'db, T> + where + T: ToTrace<'db>, + { + let mut op = LatticeOp::new( + self.infcx, + ToTrace::to_trace(self.cause, expected, actual), + self.param_env, + LatticeOpKind::Lub, + ); + let value = op.relate(expected, actual)?; + Ok(InferOk { value, obligations: op.into_obligations() }) + } + + fn goals_to_obligations(&self, goals: Vec<Goal<'db, Predicate<'db>>>) -> InferOk<'db, ()> { + InferOk { + value: (), + obligations: goals + .into_iter() + .map(|goal| { + Obligation::new( + self.infcx.interner, + self.cause.clone(), + goal.param_env, + goal.predicate, + ) + }) + .collect(), + } + } +} + +impl<'db> ToTrace<'db> for Ty<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { + cause: cause.clone(), + values: ValuePairs::Terms(ExpectedFound::new(a.into(), b.into())), + } + } +} + +impl<'db> ToTrace<'db> for Region<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { cause: cause.clone(), values: ValuePairs::Regions(ExpectedFound::new(a, b)) } + } +} + +impl<'db> ToTrace<'db> for Const<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { + cause: cause.clone(), + values: ValuePairs::Terms(ExpectedFound::new(a.into(), b.into())), + } + } +} + +impl<'db> ToTrace<'db> for GenericArg<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { + cause: cause.clone(), + values: match (a.kind(), b.kind()) { + (GenericArgKind::Lifetime(a), GenericArgKind::Lifetime(b)) => { + ValuePairs::Regions(ExpectedFound::new(a, b)) + } + (GenericArgKind::Type(a), GenericArgKind::Type(b)) => { + ValuePairs::Terms(ExpectedFound::new(a.into(), b.into())) + } + (GenericArgKind::Const(a), GenericArgKind::Const(b)) => { + ValuePairs::Terms(ExpectedFound::new(a.into(), b.into())) + } + _ => panic!("relating different kinds: {a:?} {b:?}"), + }, + } + } +} + +impl<'db> ToTrace<'db> for Term<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { cause: cause.clone(), values: ValuePairs::Terms(ExpectedFound::new(a, b)) } + } +} + +impl<'db> ToTrace<'db> for TraitRef<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { cause: cause.clone(), values: ValuePairs::TraitRefs(ExpectedFound::new(a, b)) } + } +} + +impl<'db> ToTrace<'db> for AliasTy<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { + cause: cause.clone(), + values: ValuePairs::Aliases(ExpectedFound::new(a.into(), b.into())), + } + } +} + +impl<'db> ToTrace<'db> for AliasTerm<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { cause: cause.clone(), values: ValuePairs::Aliases(ExpectedFound::new(a, b)) } + } +} + +impl<'db> ToTrace<'db> for FnSig<DbInterner<'db>> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { + cause: cause.clone(), + values: ValuePairs::PolySigs(ExpectedFound::new(Binder::dummy(a), Binder::dummy(b))), + } + } +} + +impl<'db> ToTrace<'db> for PolyFnSig<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { cause: cause.clone(), values: ValuePairs::PolySigs(ExpectedFound::new(a, b)) } + } +} + +impl<'db> ToTrace<'db> for PolyExistentialTraitRef<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { + cause: cause.clone(), + values: ValuePairs::ExistentialTraitRef(ExpectedFound::new(a, b)), + } + } +} + +impl<'db> ToTrace<'db> for PolyExistentialProjection<'db> { + fn to_trace(cause: &ObligationCause, a: Self, b: Self) -> TypeTrace<'db> { + TypeTrace { + cause: cause.clone(), + values: ValuePairs::ExistentialProjection(ExpectedFound::new(a, b)), + } + } +} |