Module infer 

Type inference, i.e. the process of walking through the code and determining the type of each expression and pattern.

For type inference, compare the implementations in rustc (the various check_* methods in rustc_hir_typeck/check.rs are a good entry point) and IntelliJ-Rust (org.rust.lang.core.types.infer). Our entry point for inference here is the infer function, which infers the types of all expressions in a given function.

During inference, types (i.e. the Ty struct) can contain type ‘variables’ which represent currently unknown types; as we walk through the expressions, we might determine that certain variables need to be equal to each other, or to certain types. To record this, we use the union-find implementation from the ena crate, which is extracted from rustc.

Re-exports

pub use coerce::could_coerce;

pub use unify::could_unify;

pub use unify::could_unify_deeply;

Modules

autoderef 🔒

Autoderef helpers for inference.

callee 🔒

Inference of calls.

cast 🔒

Type cast logic. Basically coercion + additional casts.

closure 🔒

Inference of closure parameter types based on the closure’s expected type.

coerce 🔒

Type Coercion

diagnostics 🔒

This file contains the Diagnostics type used during inference, and a wrapper around TyLoweringContext (InferenceTyLoweringContext) that replaces it and takes care of diagnostics in inference.

expr 🔒

Type inference for expressions.

fallback 🔒

Fallback of infer vars to ! and i32/f64.

mutability 🔒

Finds if an expression is an immutable context or a mutable context, which is used in selecting between Deref and DerefMut or Index and IndexMut or similar.

op 🔒

Inference of binary and unary operators.

opaques 🔒

Defining opaque types via inference.

pat 🔒

Type inference for patterns.

path 🔒

Path expression resolution.

place_op 🔒

Inference of place operators: deref and indexing (operators that create places, as opposed to values).

unify 🔒

Unification and canonicalization logic.

Structs

Adjustment

Represents coercing a value to a different type of value.

BindingMode

The mode of a binding (mut, ref mut, etc). Used for both the explicit binding annotations given in the HIR for a binding and the final binding mode that we infer after type inference/match ergonomics. .0 is the by-reference mode (ref, ref mut, or by value), .1 is the mutability of the binding.

BreakableContext 🔒

CaptureInfo

Part of MinCaptureInformationMap; describes the capture kind (&, &mut, move) for a particular capture as well as identifying the part of the source code that triggered this capture to occur.

CaptureSourceStack

CapturedPlace

A composite describing a Place that is captured by a closure.

ClosureData

InferenceContext 🔒

The inference context contains all information needed during type inference.

InferenceResult

The result of type inference: A mapping from expressions and patterns to types.

OverloadedDeref

An overloaded autoderef step, representing a Deref(Mut)::deref(_mut) call, with the signature &'a T -> &'a U or &'a mut T -> &'a mut U. The target type is U in both cases, with the region and mutability being those shared by both the receiver and the returned reference.

PatAdjustment

Represents an implicit coercion applied to the scrutinee of a match before testing a pattern against it. Currently, this is used only for implicit dereferences.

Enums

Adjust

AllowTwoPhase

At least for initial deployment, we want to limit two-phase borrows to only a few specific cases. Right now, those are mostly “things that desugar” into method calls:

AutoBorrow

AutoBorrowMutability

BreakableKind 🔒

ByRef

CaptureSourceStackRepr 🔒

DerefPatBorrowMode 🔒

Diverges 🔒

Expectation 🔒

When inferring an expression, we propagate downward whatever type hint we are able in the form of an Expectation.

ExplicitDropMethodUseKind

InferenceDiagnostic

InferenceTyDiagnosticSource

PatAdjust

Represents implicit coercions of patterns’ types, rather than values’ types.

PointerCast

ReturnKind

UpvarCapture

Information describing the capture of an upvar. This is computed during typeck, specifically by regionck.

Functions

find_breakable 🔒

find_continuable 🔒

infer_anon_const_cycle_result 🔒

infer_anon_const_query 🔒

Infer types for an anonymous const expression.

infer_cycle_result 🔒

infer_finalize 🔒

infer_query 🔒

The entry point of type inference.

infer_query_with_inspect

Type Aliases

MinCaptureList 🔒

Part of MinCaptureInformationMap; List of CapturePlaces.

RootVariableMinCaptureList 🔒

Part of MinCaptureInformationMap; Maps a root variable to the list of CapturedPlace. Used to track the minimum set of Places that need to be captured to support all Places captured by the closure starting at a given root variable.