1079 lines
38 KiB
Rust
1079 lines
38 KiB
Rust
//! The type system. We currently use this to infer types for completion.
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//!
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//! For type inference, compare the implementations in rustc (the various
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//! check_* methods in librustc_typeck/check/mod.rs are a good entry point) and
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//! IntelliJ-Rust (org.rust.lang.core.types.infer). Our entry point for
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//! inference here is the `infer` function, which infers the types of all
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//! expressions in a given function.
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//!
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//! The central struct here is `Ty`, which represents a type. During inference,
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//! it can contain type 'variables' which represent currently unknown types; as
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//! we walk through the expressions, we might determine that certain variables
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//! need to be equal to each other, or to certain types. To record this, we use
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//! the union-find implementation from the `ena` crate, which is extracted from
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//! rustc.
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mod autoderef;
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mod primitive;
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#[cfg(test)]
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mod tests;
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use std::ops::Index;
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use std::sync::Arc;
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use std::{fmt, mem};
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use log;
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use ena::unify::{InPlaceUnificationTable, UnifyKey, UnifyValue, NoError};
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use ra_arena::map::ArenaMap;
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use join_to_string::join;
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use ra_db::Cancelable;
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use crate::{
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Def, DefId, Module, Function, Struct, Enum, EnumVariant, Path, Name, ImplBlock,
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FnSignature, FnScopes,
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db::HirDatabase,
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type_ref::{TypeRef, Mutability},
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name::KnownName,
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expr::{Body, Expr, ExprId, PatId, UnaryOp, BinaryOp, Statement},
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};
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fn transpose<T>(x: Cancelable<Option<T>>) -> Option<Cancelable<T>> {
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match x {
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Ok(Some(t)) => Some(Ok(t)),
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Ok(None) => None,
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Err(e) => Some(Err(e)),
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}
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}
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/// The ID of a type variable.
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#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
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pub struct TypeVarId(u32);
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impl UnifyKey for TypeVarId {
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type Value = TypeVarValue;
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fn index(&self) -> u32 {
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self.0
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}
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fn from_index(i: u32) -> Self {
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TypeVarId(i)
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}
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fn tag() -> &'static str {
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"TypeVarId"
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}
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}
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/// The value of a type variable: either we already know the type, or we don't
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/// know it yet.
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#[derive(Clone, PartialEq, Eq, Debug)]
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pub enum TypeVarValue {
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Known(Ty),
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Unknown,
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}
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impl TypeVarValue {
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fn known(&self) -> Option<&Ty> {
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match self {
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TypeVarValue::Known(ty) => Some(ty),
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TypeVarValue::Unknown => None,
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}
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}
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}
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impl UnifyValue for TypeVarValue {
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type Error = NoError;
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fn unify_values(value1: &Self, value2: &Self) -> Result<Self, NoError> {
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match (value1, value2) {
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// We should never equate two type variables, both of which have
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// known types. Instead, we recursively equate those types.
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(TypeVarValue::Known(t1), TypeVarValue::Known(t2)) => panic!(
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"equating two type variables, both of which have known types: {:?} and {:?}",
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t1, t2
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),
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// If one side is known, prefer that one.
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(TypeVarValue::Known(..), TypeVarValue::Unknown) => Ok(value1.clone()),
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(TypeVarValue::Unknown, TypeVarValue::Known(..)) => Ok(value2.clone()),
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(TypeVarValue::Unknown, TypeVarValue::Unknown) => Ok(TypeVarValue::Unknown),
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}
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}
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}
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/// The kinds of placeholders we need during type inference. Currently, we only
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/// have type variables; in the future, we will probably also need int and float
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/// variables, for inference of literal values (e.g. `100` could be one of
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/// several integer types).
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#[derive(Clone, PartialEq, Eq, Hash, Debug)]
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pub enum InferTy {
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TypeVar(TypeVarId),
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}
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/// When inferring an expression, we propagate downward whatever type hint we
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/// are able in the form of an `Expectation`.
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#[derive(Clone, PartialEq, Eq, Debug)]
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struct Expectation {
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ty: Ty,
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// TODO: In some cases, we need to be aware whether the expectation is that
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// the type match exactly what we passed, or whether it just needs to be
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// coercible to the expected type. See Expectation::rvalue_hint in rustc.
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}
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impl Expectation {
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/// The expectation that the type of the expression needs to equal the given
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/// type.
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fn has_type(ty: Ty) -> Self {
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Expectation { ty }
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}
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/// This expresses no expectation on the type.
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fn none() -> Self {
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Expectation { ty: Ty::Unknown }
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}
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}
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/// A type. This is based on the `TyKind` enum in rustc (librustc/ty/sty.rs).
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///
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/// This should be cheap to clone.
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#[derive(Clone, PartialEq, Eq, Hash, Debug)]
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pub enum Ty {
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/// The primitive boolean type. Written as `bool`.
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Bool,
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/// The primitive character type; holds a Unicode scalar value
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/// (a non-surrogate code point). Written as `char`.
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Char,
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/// A primitive signed integer type. For example, `i32`.
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Int(primitive::IntTy),
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/// A primitive unsigned integer type. For example, `u32`.
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Uint(primitive::UintTy),
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/// A primitive floating-point type. For example, `f64`.
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Float(primitive::FloatTy),
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/// Structures, enumerations and unions.
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Adt {
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/// The DefId of the struct/enum.
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def_id: DefId,
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/// The name, for displaying.
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name: Name,
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// later we'll need generic substitutions here
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},
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/// The pointee of a string slice. Written as `str`.
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Str,
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// An array with the given length. Written as `[T; n]`.
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// Array(Ty, ty::Const),
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/// The pointee of an array slice. Written as `[T]`.
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Slice(Arc<Ty>),
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/// A raw pointer. Written as `*mut T` or `*const T`
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RawPtr(Arc<Ty>, Mutability),
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/// A reference; a pointer with an associated lifetime. Written as
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/// `&'a mut T` or `&'a T`.
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Ref(Arc<Ty>, Mutability),
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/// A pointer to a function. Written as `fn() -> i32`.
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///
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/// For example the type of `bar` here:
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///
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/// ```rust
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/// fn foo() -> i32 { 1 }
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/// let bar: fn() -> i32 = foo;
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/// ```
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FnPtr(Arc<FnSig>),
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// rustc has a separate type for each function, which just coerces to the
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// above function pointer type. Once we implement generics, we will probably
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// need this as well.
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// A trait, defined with `dyn trait`.
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// Dynamic(),
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// The anonymous type of a closure. Used to represent the type of
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// `|a| a`.
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// Closure(DefId, ClosureSubsts<'tcx>),
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// The anonymous type of a generator. Used to represent the type of
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// `|a| yield a`.
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// Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
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// A type representing the types stored inside a generator.
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// This should only appear in GeneratorInteriors.
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// GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
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/// The never type `!`.
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Never,
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/// A tuple type. For example, `(i32, bool)`.
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Tuple(Arc<[Ty]>),
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// The projection of an associated type. For example,
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// `<T as Trait<..>>::N`.pub
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// Projection(ProjectionTy),
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// Opaque (`impl Trait`) type found in a return type.
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// Opaque(DefId, Substs),
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// A type parameter; for example, `T` in `fn f<T>(x: T) {}
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// Param(ParamTy),
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/// A type variable used during type checking. Not to be confused with a
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/// type parameter.
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Infer(InferTy),
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/// A placeholder for a type which could not be computed; this is propagated
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/// to avoid useless error messages. Doubles as a placeholder where type
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/// variables are inserted before type checking, since we want to try to
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/// infer a better type here anyway -- for the IDE use case, we want to try
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/// to infer as much as possible even in the presence of type errors.
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Unknown,
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}
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/// A function signature.
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#[derive(Clone, PartialEq, Eq, Hash, Debug)]
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pub struct FnSig {
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input: Vec<Ty>,
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output: Ty,
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}
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impl Ty {
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pub(crate) fn from_hir(
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db: &impl HirDatabase,
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module: &Module,
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impl_block: Option<&ImplBlock>,
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type_ref: &TypeRef,
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) -> Cancelable<Self> {
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Ok(match type_ref {
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TypeRef::Never => Ty::Never,
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TypeRef::Tuple(inner) => {
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let inner_tys = inner
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.iter()
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.map(|tr| Ty::from_hir(db, module, impl_block, tr))
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.collect::<Cancelable<Vec<_>>>()?;
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Ty::Tuple(inner_tys.into())
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}
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TypeRef::Path(path) => Ty::from_hir_path(db, module, impl_block, path)?,
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TypeRef::RawPtr(inner, mutability) => {
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let inner_ty = Ty::from_hir(db, module, impl_block, inner)?;
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Ty::RawPtr(Arc::new(inner_ty), *mutability)
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}
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TypeRef::Array(_inner) => Ty::Unknown, // TODO
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TypeRef::Slice(inner) => {
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let inner_ty = Ty::from_hir(db, module, impl_block, inner)?;
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Ty::Slice(Arc::new(inner_ty))
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}
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TypeRef::Reference(inner, mutability) => {
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let inner_ty = Ty::from_hir(db, module, impl_block, inner)?;
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Ty::Ref(Arc::new(inner_ty), *mutability)
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}
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TypeRef::Placeholder => Ty::Unknown,
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TypeRef::Fn(params) => {
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let mut inner_tys = params
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.iter()
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.map(|tr| Ty::from_hir(db, module, impl_block, tr))
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.collect::<Cancelable<Vec<_>>>()?;
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let return_ty = inner_tys
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.pop()
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.expect("TypeRef::Fn should always have at least return type");
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let sig = FnSig {
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input: inner_tys,
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output: return_ty,
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};
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Ty::FnPtr(Arc::new(sig))
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}
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TypeRef::Error => Ty::Unknown,
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})
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}
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pub(crate) fn from_hir_opt(
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db: &impl HirDatabase,
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module: &Module,
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impl_block: Option<&ImplBlock>,
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type_ref: Option<&TypeRef>,
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) -> Cancelable<Self> {
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type_ref
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.map(|t| Ty::from_hir(db, module, impl_block, t))
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.unwrap_or(Ok(Ty::Unknown))
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}
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pub(crate) fn from_hir_path(
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db: &impl HirDatabase,
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module: &Module,
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impl_block: Option<&ImplBlock>,
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path: &Path,
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) -> Cancelable<Self> {
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if let Some(name) = path.as_ident() {
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if let Some(KnownName::Bool) = name.as_known_name() {
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return Ok(Ty::Bool);
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} else if let Some(KnownName::Char) = name.as_known_name() {
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return Ok(Ty::Char);
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} else if let Some(KnownName::Str) = name.as_known_name() {
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return Ok(Ty::Str);
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} else if let Some(int_ty) = primitive::IntTy::from_name(name) {
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return Ok(Ty::Int(int_ty));
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} else if let Some(uint_ty) = primitive::UintTy::from_name(name) {
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return Ok(Ty::Uint(uint_ty));
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} else if let Some(float_ty) = primitive::FloatTy::from_name(name) {
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return Ok(Ty::Float(float_ty));
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} else if name.as_known_name() == Some(KnownName::SelfType) {
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return Ty::from_hir_opt(db, module, None, impl_block.map(|i| i.target_type()));
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}
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}
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// Resolve in module (in type namespace)
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let resolved = if let Some(r) = module.resolve_path(db, path)?.take_types() {
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r
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} else {
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return Ok(Ty::Unknown);
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};
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let ty = db.type_for_def(resolved)?;
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Ok(ty)
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}
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pub fn unit() -> Self {
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Ty::Tuple(Arc::new([]))
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}
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fn walk_mut(&mut self, f: &mut impl FnMut(&mut Ty)) {
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f(self);
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match self {
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Ty::Slice(t) => Arc::make_mut(t).walk_mut(f),
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Ty::RawPtr(t, _) => Arc::make_mut(t).walk_mut(f),
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Ty::Ref(t, _) => Arc::make_mut(t).walk_mut(f),
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Ty::Tuple(ts) => {
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// Without an Arc::make_mut_slice, we can't avoid the clone here:
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let mut v: Vec<_> = ts.iter().cloned().collect();
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for t in &mut v {
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t.walk_mut(f);
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}
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*ts = v.into();
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}
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Ty::FnPtr(sig) => {
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let sig_mut = Arc::make_mut(sig);
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for input in &mut sig_mut.input {
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input.walk_mut(f);
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}
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sig_mut.output.walk_mut(f);
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}
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Ty::Adt { .. } => {} // need to walk type parameters later
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_ => {}
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}
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}
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fn fold(mut self, f: &mut impl FnMut(Ty) -> Ty) -> Ty {
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self.walk_mut(&mut |ty_mut| {
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let ty = mem::replace(ty_mut, Ty::Unknown);
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*ty_mut = f(ty);
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});
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self
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}
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fn builtin_deref(&self) -> Option<Ty> {
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match self {
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Ty::Ref(t, _) => Some(Ty::clone(t)),
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Ty::RawPtr(t, _) => Some(Ty::clone(t)),
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_ => None,
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}
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}
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}
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impl fmt::Display for Ty {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match self {
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Ty::Bool => write!(f, "bool"),
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Ty::Char => write!(f, "char"),
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Ty::Int(t) => write!(f, "{}", t.ty_to_string()),
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Ty::Uint(t) => write!(f, "{}", t.ty_to_string()),
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Ty::Float(t) => write!(f, "{}", t.ty_to_string()),
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Ty::Str => write!(f, "str"),
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Ty::Slice(t) => write!(f, "[{}]", t),
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Ty::RawPtr(t, m) => write!(f, "*{}{}", m.as_keyword_for_ptr(), t),
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Ty::Ref(t, m) => write!(f, "&{}{}", m.as_keyword_for_ref(), t),
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Ty::Never => write!(f, "!"),
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Ty::Tuple(ts) => {
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if ts.len() == 1 {
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write!(f, "({},)", ts[0])
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} else {
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join(ts.iter())
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.surround_with("(", ")")
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.separator(", ")
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.to_fmt(f)
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}
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}
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Ty::FnPtr(sig) => {
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join(sig.input.iter())
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.surround_with("fn(", ")")
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.separator(", ")
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.to_fmt(f)?;
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write!(f, " -> {}", sig.output)
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}
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Ty::Adt { name, .. } => write!(f, "{}", name),
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Ty::Unknown => write!(f, "[unknown]"),
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Ty::Infer(..) => write!(f, "_"),
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}
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}
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}
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|
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// Functions returning declared types for items
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|
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/// Compute the declared type of a function. This should not need to look at the
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/// function body.
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fn type_for_fn(db: &impl HirDatabase, f: Function) -> Cancelable<Ty> {
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let signature = f.signature(db);
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let module = f.module(db)?;
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|
let impl_block = f.impl_block(db)?;
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// TODO we ignore type parameters for now
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let input = signature
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.args()
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.iter()
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.map(|tr| Ty::from_hir(db, &module, impl_block.as_ref(), tr))
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.collect::<Cancelable<Vec<_>>>()?;
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let output = Ty::from_hir(db, &module, impl_block.as_ref(), signature.ret_type())?;
|
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let sig = FnSig { input, output };
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Ok(Ty::FnPtr(Arc::new(sig)))
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}
|
|
|
|
fn type_for_struct(db: &impl HirDatabase, s: Struct) -> Cancelable<Ty> {
|
|
Ok(Ty::Adt {
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|
def_id: s.def_id(),
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name: s.name(db)?.unwrap_or_else(Name::missing),
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})
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}
|
|
|
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pub fn type_for_enum(db: &impl HirDatabase, s: Enum) -> Cancelable<Ty> {
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Ok(Ty::Adt {
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def_id: s.def_id(),
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name: s.name(db)?.unwrap_or_else(Name::missing),
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})
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}
|
|
|
|
pub fn type_for_enum_variant(db: &impl HirDatabase, ev: EnumVariant) -> Cancelable<Ty> {
|
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let enum_parent = ev.parent_enum(db)?;
|
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|
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type_for_enum(db, enum_parent)
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}
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|
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pub(super) fn type_for_def(db: &impl HirDatabase, def_id: DefId) -> Cancelable<Ty> {
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let def = def_id.resolve(db)?;
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match def {
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Def::Module(..) => {
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log::debug!("trying to get type for module {:?}", def_id);
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Ok(Ty::Unknown)
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}
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Def::Function(f) => type_for_fn(db, f),
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Def::Struct(s) => type_for_struct(db, s),
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Def::Enum(e) => type_for_enum(db, e),
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Def::EnumVariant(ev) => type_for_enum_variant(db, ev),
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|
Def::Item => {
|
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log::debug!("trying to get type for item of unknown type {:?}", def_id);
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Ok(Ty::Unknown)
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}
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}
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}
|
|
|
|
pub(super) fn type_for_field(
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db: &impl HirDatabase,
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def_id: DefId,
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field: Name,
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) -> Cancelable<Option<Ty>> {
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|
let def = def_id.resolve(db)?;
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|
let variant_data = match def {
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|
Def::Struct(s) => s.variant_data(db)?,
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|
Def::EnumVariant(ev) => ev.variant_data(db)?,
|
|
// TODO: unions
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|
_ => panic!(
|
|
"trying to get type for field in non-struct/variant {:?}",
|
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def_id
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),
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|
};
|
|
let module = def_id.module(db)?;
|
|
let impl_block = def_id.impl_block(db)?;
|
|
let type_ref = ctry!(variant_data.get_field_type_ref(&field));
|
|
Ok(Some(Ty::from_hir(
|
|
db,
|
|
&module,
|
|
impl_block.as_ref(),
|
|
&type_ref,
|
|
)?))
|
|
}
|
|
|
|
/// The result of type inference: A mapping from expressions and patterns to types.
|
|
#[derive(Clone, PartialEq, Eq, Debug)]
|
|
pub struct InferenceResult {
|
|
type_of_expr: ArenaMap<ExprId, Ty>,
|
|
type_of_pat: ArenaMap<PatId, Ty>,
|
|
}
|
|
|
|
impl Index<ExprId> for InferenceResult {
|
|
type Output = Ty;
|
|
|
|
fn index(&self, expr: ExprId) -> &Ty {
|
|
self.type_of_expr.get(expr).unwrap_or(&Ty::Unknown)
|
|
}
|
|
}
|
|
|
|
impl Index<PatId> for InferenceResult {
|
|
type Output = Ty;
|
|
|
|
fn index(&self, pat: PatId) -> &Ty {
|
|
self.type_of_pat.get(pat).unwrap_or(&Ty::Unknown)
|
|
}
|
|
}
|
|
|
|
/// The inference context contains all information needed during type inference.
|
|
#[derive(Clone, Debug)]
|
|
struct InferenceContext<'a, D: HirDatabase> {
|
|
db: &'a D,
|
|
body: Arc<Body>,
|
|
scopes: Arc<FnScopes>,
|
|
module: Module,
|
|
impl_block: Option<ImplBlock>,
|
|
var_unification_table: InPlaceUnificationTable<TypeVarId>,
|
|
type_of_expr: ArenaMap<ExprId, Ty>,
|
|
type_of_pat: ArenaMap<PatId, Ty>,
|
|
/// The return type of the function being inferred.
|
|
return_ty: Ty,
|
|
}
|
|
|
|
fn binary_op_return_ty(op: BinaryOp, rhs_ty: Ty) -> Ty {
|
|
match op {
|
|
BinaryOp::BooleanOr
|
|
| BinaryOp::BooleanAnd
|
|
| BinaryOp::EqualityTest
|
|
| BinaryOp::LesserEqualTest
|
|
| BinaryOp::GreaterEqualTest
|
|
| BinaryOp::LesserTest
|
|
| BinaryOp::GreaterTest => Ty::Bool,
|
|
BinaryOp::Assignment
|
|
| BinaryOp::AddAssign
|
|
| BinaryOp::SubAssign
|
|
| BinaryOp::DivAssign
|
|
| BinaryOp::MulAssign
|
|
| BinaryOp::RemAssign
|
|
| BinaryOp::ShrAssign
|
|
| BinaryOp::ShlAssign
|
|
| BinaryOp::BitAndAssign
|
|
| BinaryOp::BitOrAssign
|
|
| BinaryOp::BitXorAssign => Ty::unit(),
|
|
BinaryOp::Addition
|
|
| BinaryOp::Subtraction
|
|
| BinaryOp::Multiplication
|
|
| BinaryOp::Division
|
|
| BinaryOp::Remainder
|
|
| BinaryOp::LeftShift
|
|
| BinaryOp::RightShift
|
|
| BinaryOp::BitwiseAnd
|
|
| BinaryOp::BitwiseOr
|
|
| BinaryOp::BitwiseXor => match rhs_ty {
|
|
Ty::Uint(..) | Ty::Int(..) | Ty::Float(..) => rhs_ty,
|
|
_ => Ty::Unknown,
|
|
},
|
|
BinaryOp::RangeRightOpen | BinaryOp::RangeRightClosed => Ty::Unknown,
|
|
}
|
|
}
|
|
|
|
fn binary_op_rhs_expectation(op: BinaryOp, lhs_ty: Ty) -> Ty {
|
|
match op {
|
|
BinaryOp::BooleanAnd | BinaryOp::BooleanOr => Ty::Bool,
|
|
BinaryOp::Assignment | BinaryOp::EqualityTest => match lhs_ty {
|
|
Ty::Uint(..) | Ty::Int(..) | Ty::Float(..) | Ty::Str | Ty::Char | Ty::Bool => lhs_ty,
|
|
_ => Ty::Unknown,
|
|
},
|
|
BinaryOp::LesserEqualTest
|
|
| BinaryOp::GreaterEqualTest
|
|
| BinaryOp::LesserTest
|
|
| BinaryOp::GreaterTest
|
|
| BinaryOp::AddAssign
|
|
| BinaryOp::SubAssign
|
|
| BinaryOp::DivAssign
|
|
| BinaryOp::MulAssign
|
|
| BinaryOp::RemAssign
|
|
| BinaryOp::ShrAssign
|
|
| BinaryOp::ShlAssign
|
|
| BinaryOp::BitAndAssign
|
|
| BinaryOp::BitOrAssign
|
|
| BinaryOp::BitXorAssign
|
|
| BinaryOp::Addition
|
|
| BinaryOp::Subtraction
|
|
| BinaryOp::Multiplication
|
|
| BinaryOp::Division
|
|
| BinaryOp::Remainder
|
|
| BinaryOp::LeftShift
|
|
| BinaryOp::RightShift
|
|
| BinaryOp::BitwiseAnd
|
|
| BinaryOp::BitwiseOr
|
|
| BinaryOp::BitwiseXor => match lhs_ty {
|
|
Ty::Uint(..) | Ty::Int(..) | Ty::Float(..) => lhs_ty,
|
|
_ => Ty::Unknown,
|
|
},
|
|
_ => Ty::Unknown,
|
|
}
|
|
}
|
|
|
|
impl<'a, D: HirDatabase> InferenceContext<'a, D> {
|
|
fn new(
|
|
db: &'a D,
|
|
body: Arc<Body>,
|
|
scopes: Arc<FnScopes>,
|
|
module: Module,
|
|
impl_block: Option<ImplBlock>,
|
|
) -> Self {
|
|
InferenceContext {
|
|
type_of_expr: ArenaMap::default(),
|
|
type_of_pat: ArenaMap::default(),
|
|
var_unification_table: InPlaceUnificationTable::new(),
|
|
return_ty: Ty::Unknown, // set in collect_fn_signature
|
|
db,
|
|
body,
|
|
scopes,
|
|
module,
|
|
impl_block,
|
|
}
|
|
}
|
|
|
|
fn resolve_all(mut self) -> InferenceResult {
|
|
let mut expr_types = mem::replace(&mut self.type_of_expr, ArenaMap::default());
|
|
for ty in expr_types.values_mut() {
|
|
let resolved = self.resolve_ty_completely(mem::replace(ty, Ty::Unknown));
|
|
*ty = resolved;
|
|
}
|
|
let mut pat_types = mem::replace(&mut self.type_of_pat, ArenaMap::default());
|
|
for ty in pat_types.values_mut() {
|
|
let resolved = self.resolve_ty_completely(mem::replace(ty, Ty::Unknown));
|
|
*ty = resolved;
|
|
}
|
|
InferenceResult {
|
|
type_of_expr: expr_types,
|
|
type_of_pat: pat_types,
|
|
}
|
|
}
|
|
|
|
fn write_expr_ty(&mut self, expr: ExprId, ty: Ty) {
|
|
self.type_of_expr.insert(expr, ty);
|
|
}
|
|
|
|
fn write_pat_ty(&mut self, pat: PatId, ty: Ty) {
|
|
self.type_of_pat.insert(pat, ty);
|
|
}
|
|
|
|
fn make_ty(&self, type_ref: &TypeRef) -> Cancelable<Ty> {
|
|
Ty::from_hir(self.db, &self.module, self.impl_block.as_ref(), type_ref)
|
|
}
|
|
|
|
fn unify(&mut self, ty1: &Ty, ty2: &Ty) -> bool {
|
|
match (ty1, ty2) {
|
|
(Ty::Unknown, ..) => true,
|
|
(.., Ty::Unknown) => true,
|
|
(Ty::Bool, _)
|
|
| (Ty::Str, _)
|
|
| (Ty::Never, _)
|
|
| (Ty::Char, _)
|
|
| (Ty::Int(..), Ty::Int(..))
|
|
| (Ty::Uint(..), Ty::Uint(..))
|
|
| (Ty::Float(..), Ty::Float(..)) => ty1 == ty2,
|
|
(
|
|
Ty::Adt {
|
|
def_id: def_id1, ..
|
|
},
|
|
Ty::Adt {
|
|
def_id: def_id2, ..
|
|
},
|
|
) if def_id1 == def_id2 => true,
|
|
(Ty::Slice(t1), Ty::Slice(t2)) => self.unify(t1, t2),
|
|
(Ty::RawPtr(t1, m1), Ty::RawPtr(t2, m2)) if m1 == m2 => self.unify(t1, t2),
|
|
(Ty::Ref(t1, m1), Ty::Ref(t2, m2)) if m1 == m2 => self.unify(t1, t2),
|
|
(Ty::FnPtr(sig1), Ty::FnPtr(sig2)) if sig1 == sig2 => true,
|
|
(Ty::Tuple(ts1), Ty::Tuple(ts2)) if ts1.len() == ts2.len() => ts1
|
|
.iter()
|
|
.zip(ts2.iter())
|
|
.all(|(t1, t2)| self.unify(t1, t2)),
|
|
(Ty::Infer(InferTy::TypeVar(tv1)), Ty::Infer(InferTy::TypeVar(tv2))) => {
|
|
self.var_unification_table.union(*tv1, *tv2);
|
|
true
|
|
}
|
|
(Ty::Infer(InferTy::TypeVar(tv)), other) | (other, Ty::Infer(InferTy::TypeVar(tv))) => {
|
|
self.var_unification_table
|
|
.union_value(*tv, TypeVarValue::Known(other.clone()));
|
|
true
|
|
}
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
fn new_type_var(&mut self) -> Ty {
|
|
Ty::Infer(InferTy::TypeVar(
|
|
self.var_unification_table.new_key(TypeVarValue::Unknown),
|
|
))
|
|
}
|
|
|
|
/// Replaces Ty::Unknown by a new type var, so we can maybe still infer it.
|
|
fn insert_type_vars_shallow(&mut self, ty: Ty) -> Ty {
|
|
match ty {
|
|
Ty::Unknown => self.new_type_var(),
|
|
_ => ty,
|
|
}
|
|
}
|
|
|
|
fn insert_type_vars(&mut self, ty: Ty) -> Ty {
|
|
ty.fold(&mut |ty| self.insert_type_vars_shallow(ty))
|
|
}
|
|
|
|
/// Resolves the type as far as currently possible, replacing type variables
|
|
/// by their known types. All types returned by the infer_* functions should
|
|
/// be resolved as far as possible, i.e. contain no type variables with
|
|
/// known type.
|
|
fn resolve_ty_as_possible(&mut self, ty: Ty) -> Ty {
|
|
ty.fold(&mut |ty| match ty {
|
|
Ty::Infer(InferTy::TypeVar(tv)) => {
|
|
if let Some(known_ty) = self.var_unification_table.probe_value(tv).known() {
|
|
// known_ty may contain other variables that are known by now
|
|
self.resolve_ty_as_possible(known_ty.clone())
|
|
} else {
|
|
Ty::Infer(InferTy::TypeVar(tv))
|
|
}
|
|
}
|
|
_ => ty,
|
|
})
|
|
}
|
|
|
|
/// Resolves the type completely; type variables without known type are
|
|
/// replaced by Ty::Unknown.
|
|
fn resolve_ty_completely(&mut self, ty: Ty) -> Ty {
|
|
ty.fold(&mut |ty| match ty {
|
|
Ty::Infer(InferTy::TypeVar(tv)) => {
|
|
if let Some(known_ty) = self.var_unification_table.probe_value(tv).known() {
|
|
// known_ty may contain other variables that are known by now
|
|
self.resolve_ty_completely(known_ty.clone())
|
|
} else {
|
|
Ty::Unknown
|
|
}
|
|
}
|
|
_ => ty,
|
|
})
|
|
}
|
|
|
|
fn infer_path_expr(&mut self, expr: ExprId, path: &Path) -> Cancelable<Option<Ty>> {
|
|
if path.is_ident() || path.is_self() {
|
|
// resolve locally
|
|
let name = path.as_ident().cloned().unwrap_or_else(Name::self_param);
|
|
if let Some(scope_entry) = self.scopes.resolve_local_name(expr, name) {
|
|
let ty = ctry!(self.type_of_pat.get(scope_entry.pat()));
|
|
let ty = self.resolve_ty_as_possible(ty.clone());
|
|
return Ok(Some(ty));
|
|
};
|
|
};
|
|
|
|
// resolve in module
|
|
let resolved = ctry!(self.module.resolve_path(self.db, &path)?.take_values());
|
|
let ty = self.db.type_for_def(resolved)?;
|
|
let ty = self.insert_type_vars(ty);
|
|
Ok(Some(ty))
|
|
}
|
|
|
|
fn resolve_variant(&self, path: Option<&Path>) -> Cancelable<(Ty, Option<DefId>)> {
|
|
let path = if let Some(path) = path {
|
|
path
|
|
} else {
|
|
return Ok((Ty::Unknown, None));
|
|
};
|
|
let def_id = if let Some(def_id) = self.module.resolve_path(self.db, &path)?.take_types() {
|
|
def_id
|
|
} else {
|
|
return Ok((Ty::Unknown, None));
|
|
};
|
|
Ok(match def_id.resolve(self.db)? {
|
|
Def::Struct(s) => {
|
|
let ty = type_for_struct(self.db, s)?;
|
|
(ty, Some(def_id))
|
|
}
|
|
Def::EnumVariant(ev) => {
|
|
let ty = type_for_enum_variant(self.db, ev)?;
|
|
(ty, Some(def_id))
|
|
}
|
|
_ => (Ty::Unknown, None),
|
|
})
|
|
}
|
|
|
|
fn infer_expr(&mut self, expr: ExprId, expected: &Expectation) -> Cancelable<Ty> {
|
|
let body = Arc::clone(&self.body); // avoid borrow checker problem
|
|
let ty = match &body[expr] {
|
|
Expr::Missing => Ty::Unknown,
|
|
Expr::If {
|
|
condition,
|
|
then_branch,
|
|
else_branch,
|
|
} => {
|
|
// if let is desugared to match, so this is always simple if
|
|
self.infer_expr(*condition, &Expectation::has_type(Ty::Bool))?;
|
|
let then_ty = self.infer_expr(*then_branch, expected)?;
|
|
if let Some(else_branch) = else_branch {
|
|
self.infer_expr(*else_branch, expected)?;
|
|
} else {
|
|
// no else branch -> unit
|
|
self.unify(&expected.ty, &Ty::unit()); // actually coerce
|
|
}
|
|
then_ty
|
|
}
|
|
Expr::Block { statements, tail } => self.infer_block(statements, *tail, expected)?,
|
|
Expr::Loop { body } => {
|
|
self.infer_expr(*body, &Expectation::has_type(Ty::unit()))?;
|
|
// TODO handle break with value
|
|
Ty::Never
|
|
}
|
|
Expr::While { condition, body } => {
|
|
// while let is desugared to a match loop, so this is always simple while
|
|
self.infer_expr(*condition, &Expectation::has_type(Ty::Bool))?;
|
|
self.infer_expr(*body, &Expectation::has_type(Ty::unit()))?;
|
|
Ty::unit()
|
|
}
|
|
Expr::For { iterable, body, .. } => {
|
|
let _iterable_ty = self.infer_expr(*iterable, &Expectation::none());
|
|
// TODO write type for pat
|
|
self.infer_expr(*body, &Expectation::has_type(Ty::unit()))?;
|
|
Ty::unit()
|
|
}
|
|
Expr::Lambda { body, .. } => {
|
|
// TODO write types for args, infer lambda type etc.
|
|
let _body_ty = self.infer_expr(*body, &Expectation::none())?;
|
|
Ty::Unknown
|
|
}
|
|
Expr::Call { callee, args } => {
|
|
let callee_ty = self.infer_expr(*callee, &Expectation::none())?;
|
|
let (arg_tys, ret_ty) = match &callee_ty {
|
|
Ty::FnPtr(sig) => (&sig.input[..], sig.output.clone()),
|
|
_ => {
|
|
// not callable
|
|
// TODO report an error?
|
|
(&[][..], Ty::Unknown)
|
|
}
|
|
};
|
|
for (i, arg) in args.iter().enumerate() {
|
|
self.infer_expr(
|
|
*arg,
|
|
&Expectation::has_type(arg_tys.get(i).cloned().unwrap_or(Ty::Unknown)),
|
|
)?;
|
|
}
|
|
ret_ty
|
|
}
|
|
Expr::MethodCall { receiver, args, .. } => {
|
|
let _receiver_ty = self.infer_expr(*receiver, &Expectation::none())?;
|
|
// TODO resolve method...
|
|
for (_i, arg) in args.iter().enumerate() {
|
|
// TODO unify / expect argument type
|
|
self.infer_expr(*arg, &Expectation::none())?;
|
|
}
|
|
Ty::Unknown
|
|
}
|
|
Expr::Match { expr, arms } => {
|
|
let _ty = self.infer_expr(*expr, &Expectation::none())?;
|
|
for arm in arms {
|
|
// TODO type the bindings in pats
|
|
// TODO type the guard
|
|
let _ty = self.infer_expr(arm.expr, &Expectation::none())?;
|
|
}
|
|
// TODO unify all the match arm types
|
|
Ty::Unknown
|
|
}
|
|
Expr::Path(p) => self.infer_path_expr(expr, p)?.unwrap_or(Ty::Unknown),
|
|
Expr::Continue => Ty::Never,
|
|
Expr::Break { expr } => {
|
|
if let Some(expr) = expr {
|
|
// TODO handle break with value
|
|
self.infer_expr(*expr, &Expectation::none())?;
|
|
}
|
|
Ty::Never
|
|
}
|
|
Expr::Return { expr } => {
|
|
if let Some(expr) = expr {
|
|
self.infer_expr(*expr, &Expectation::has_type(self.return_ty.clone()))?;
|
|
}
|
|
Ty::Never
|
|
}
|
|
Expr::StructLit {
|
|
path,
|
|
fields,
|
|
spread,
|
|
} => {
|
|
let (ty, def_id) = self.resolve_variant(path.as_ref())?;
|
|
for field in fields {
|
|
let field_ty = if let Some(def_id) = def_id {
|
|
self.db
|
|
.type_for_field(def_id, field.name.clone())?
|
|
.unwrap_or(Ty::Unknown)
|
|
} else {
|
|
Ty::Unknown
|
|
};
|
|
self.infer_expr(field.expr, &Expectation::has_type(field_ty))?;
|
|
}
|
|
if let Some(expr) = spread {
|
|
self.infer_expr(*expr, &Expectation::has_type(ty.clone()))?;
|
|
}
|
|
ty
|
|
}
|
|
Expr::Field { expr, name } => {
|
|
let receiver_ty = self.infer_expr(*expr, &Expectation::none())?;
|
|
let ty = receiver_ty
|
|
.autoderef(self.db)
|
|
.find_map(|derefed_ty| match derefed_ty {
|
|
// this is more complicated than necessary because type_for_field is cancelable
|
|
Ty::Tuple(fields) => {
|
|
let i = name.to_string().parse::<usize>().ok();
|
|
i.and_then(|i| fields.get(i).cloned()).map(Ok)
|
|
}
|
|
Ty::Adt { def_id, .. } => {
|
|
transpose(self.db.type_for_field(def_id, name.clone()))
|
|
}
|
|
_ => None,
|
|
})
|
|
.unwrap_or(Ok(Ty::Unknown))?;
|
|
self.insert_type_vars(ty)
|
|
}
|
|
Expr::Try { expr } => {
|
|
let _inner_ty = self.infer_expr(*expr, &Expectation::none())?;
|
|
Ty::Unknown
|
|
}
|
|
Expr::Cast { expr, type_ref } => {
|
|
let _inner_ty = self.infer_expr(*expr, &Expectation::none())?;
|
|
let cast_ty =
|
|
Ty::from_hir(self.db, &self.module, self.impl_block.as_ref(), type_ref)?;
|
|
let cast_ty = self.insert_type_vars(cast_ty);
|
|
// TODO check the cast...
|
|
cast_ty
|
|
}
|
|
Expr::Ref { expr, mutability } => {
|
|
// TODO pass the expectation down
|
|
let inner_ty = self.infer_expr(*expr, &Expectation::none())?;
|
|
// TODO reference coercions etc.
|
|
Ty::Ref(Arc::new(inner_ty), *mutability)
|
|
}
|
|
Expr::UnaryOp { expr, op } => {
|
|
let inner_ty = self.infer_expr(*expr, &Expectation::none())?;
|
|
match op {
|
|
Some(UnaryOp::Deref) => {
|
|
if let Some(derefed_ty) = inner_ty.builtin_deref() {
|
|
derefed_ty
|
|
} else {
|
|
// TODO Deref::deref
|
|
Ty::Unknown
|
|
}
|
|
}
|
|
_ => Ty::Unknown,
|
|
}
|
|
}
|
|
Expr::BinaryOp { lhs, rhs, op } => match op {
|
|
Some(op) => {
|
|
let lhs_expectation = match op {
|
|
BinaryOp::BooleanAnd | BinaryOp::BooleanOr => {
|
|
Expectation::has_type(Ty::Bool)
|
|
}
|
|
_ => Expectation::none(),
|
|
};
|
|
let lhs_ty = self.infer_expr(*lhs, &lhs_expectation)?;
|
|
// TODO: find implementation of trait corresponding to operation
|
|
// symbol and resolve associated `Output` type
|
|
let rhs_expectation = binary_op_rhs_expectation(*op, lhs_ty);
|
|
let rhs_ty = self.infer_expr(*rhs, &Expectation::has_type(rhs_expectation))?;
|
|
|
|
// TODO: similar as above, return ty is often associated trait type
|
|
binary_op_return_ty(*op, rhs_ty)
|
|
}
|
|
_ => Ty::Unknown,
|
|
},
|
|
};
|
|
// use a new type variable if we got Ty::Unknown here
|
|
let ty = self.insert_type_vars_shallow(ty);
|
|
self.unify(&ty, &expected.ty);
|
|
let ty = self.resolve_ty_as_possible(ty);
|
|
self.write_expr_ty(expr, ty.clone());
|
|
Ok(ty)
|
|
}
|
|
|
|
fn infer_block(
|
|
&mut self,
|
|
statements: &[Statement],
|
|
tail: Option<ExprId>,
|
|
expected: &Expectation,
|
|
) -> Cancelable<Ty> {
|
|
for stmt in statements {
|
|
match stmt {
|
|
Statement::Let {
|
|
pat,
|
|
type_ref,
|
|
initializer,
|
|
} => {
|
|
let decl_ty = Ty::from_hir_opt(
|
|
self.db,
|
|
&self.module,
|
|
self.impl_block.as_ref(),
|
|
type_ref.as_ref(),
|
|
)?;
|
|
let decl_ty = self.insert_type_vars(decl_ty);
|
|
let ty = if let Some(expr) = initializer {
|
|
let expr_ty = self.infer_expr(*expr, &Expectation::has_type(decl_ty))?;
|
|
expr_ty
|
|
} else {
|
|
decl_ty
|
|
};
|
|
|
|
self.write_pat_ty(*pat, ty);
|
|
}
|
|
Statement::Expr(expr) => {
|
|
self.infer_expr(*expr, &Expectation::none())?;
|
|
}
|
|
}
|
|
}
|
|
let ty = if let Some(expr) = tail {
|
|
self.infer_expr(expr, expected)?
|
|
} else {
|
|
Ty::unit()
|
|
};
|
|
Ok(ty)
|
|
}
|
|
|
|
fn collect_fn_signature(&mut self, signature: &FnSignature) -> Cancelable<()> {
|
|
let body = Arc::clone(&self.body); // avoid borrow checker problem
|
|
for (type_ref, pat) in signature.args().iter().zip(body.args()) {
|
|
let ty = self.make_ty(type_ref)?;
|
|
let ty = self.insert_type_vars(ty);
|
|
self.write_pat_ty(*pat, ty);
|
|
}
|
|
self.return_ty = {
|
|
let ty = self.make_ty(signature.ret_type())?;
|
|
let ty = self.insert_type_vars(ty);
|
|
ty
|
|
};
|
|
Ok(())
|
|
}
|
|
|
|
fn infer_body(&mut self) -> Cancelable<()> {
|
|
self.infer_expr(
|
|
self.body.body_expr(),
|
|
&Expectation::has_type(self.return_ty.clone()),
|
|
)?;
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
pub fn infer(db: &impl HirDatabase, def_id: DefId) -> Cancelable<Arc<InferenceResult>> {
|
|
db.check_canceled()?;
|
|
let function = Function::new(def_id); // TODO: consts also need inference
|
|
let body = function.body(db)?;
|
|
let scopes = db.fn_scopes(def_id)?;
|
|
let module = function.module(db)?;
|
|
let impl_block = function.impl_block(db)?;
|
|
let mut ctx = InferenceContext::new(db, body, scopes, module, impl_block);
|
|
|
|
let signature = function.signature(db);
|
|
ctx.collect_fn_signature(&signature)?;
|
|
|
|
ctx.infer_body()?;
|
|
|
|
Ok(Arc::new(ctx.resolve_all()))
|
|
}
|