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|
//! The type system. We currently use this to infer types for completion.
//!
//! For type inference, compare the implementations in rustc (the various
//! check_* methods in librustc_typeck/check/mod.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.
//!
//! The central struct here is `Ty`, which represents a type. During inference,
//! it 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.
mod primitive;
#[cfg(test)]
mod tests;
use std::sync::Arc;
use std::{fmt, mem};
use log;
use rustc_hash::FxHashMap;
use ena::unify::{InPlaceUnificationTable, UnifyKey, UnifyValue, NoError};
use ra_db::{LocalSyntaxPtr, Cancelable};
use ra_syntax::{
ast::{self, AstNode, LoopBodyOwner, ArgListOwner, PrefixOp},
SyntaxNodeRef
};
use crate::{
Def, DefId, FnScopes, Module, Function, Struct, Enum, Path, Name, AsName, ImplBlock,
db::HirDatabase,
type_ref::{TypeRef, Mutability},
name::KnownName,
};
/// The ID of a type variable.
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
pub struct TypeVarId(u32);
impl UnifyKey for TypeVarId {
type Value = TypeVarValue;
fn index(&self) -> u32 {
self.0
}
fn from_index(i: u32) -> Self {
TypeVarId(i)
}
fn tag() -> &'static str {
"TypeVarId"
}
}
/// The value of a type variable: either we already know the type, or we don't
/// know it yet.
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum TypeVarValue {
Known(Ty),
Unknown,
}
impl TypeVarValue {
fn known(&self) -> Option<&Ty> {
match self {
TypeVarValue::Known(ty) => Some(ty),
TypeVarValue::Unknown => None,
}
}
}
impl UnifyValue for TypeVarValue {
type Error = NoError;
fn unify_values(value1: &Self, value2: &Self) -> Result<Self, NoError> {
match (value1, value2) {
// We should never equate two type variables, both of which have
// known types. Instead, we recursively equate those types.
(TypeVarValue::Known(..), TypeVarValue::Known(..)) => {
panic!("equating two type variables, both of which have known types")
}
// If one side is known, prefer that one.
(TypeVarValue::Known(..), TypeVarValue::Unknown) => Ok(value1.clone()),
(TypeVarValue::Unknown, TypeVarValue::Known(..)) => Ok(value2.clone()),
(TypeVarValue::Unknown, TypeVarValue::Unknown) => Ok(TypeVarValue::Unknown),
}
}
}
/// The kinds of placeholders we need during type inference. Currently, we only
/// have type variables; in the future, we will probably also need int and float
/// variables, for inference of literal values (e.g. `100` could be one of
/// several integer types).
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub enum InferTy {
TypeVar(TypeVarId),
}
/// When inferring an expression, we propagate downward whatever type hint we
/// are able in the form of an `Expectation`.
#[derive(Clone, PartialEq, Eq, Debug)]
struct Expectation {
ty: Ty,
// TODO: In some cases, we need to be aware whether the expectation is that
// the type match exactly what we passed, or whether it just needs to be
// coercible to the expected type. See Expectation::rvalue_hint in rustc.
}
impl Expectation {
/// The expectation that the type of the expression needs to equal the given
/// type.
fn has_type(ty: Ty) -> Self {
Expectation { ty }
}
/// This expresses no expectation on the type.
fn none() -> Self {
Expectation { ty: Ty::Unknown }
}
}
/// A type. This is based on the `TyKind` enum in rustc (librustc/ty/sty.rs).
///
/// This should be cheap to clone.
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub enum Ty {
/// The primitive boolean type. Written as `bool`.
Bool,
/// The primitive character type; holds a Unicode scalar value
/// (a non-surrogate code point). Written as `char`.
Char,
/// A primitive signed integer type. For example, `i32`.
Int(primitive::IntTy),
/// A primitive unsigned integer type. For example, `u32`.
Uint(primitive::UintTy),
/// A primitive floating-point type. For example, `f64`.
Float(primitive::FloatTy),
/// Structures, enumerations and unions.
Adt {
/// The DefId of the struct/enum.
def_id: DefId,
/// The name, for displaying.
name: Name,
// later we'll need generic substitutions here
},
/// The pointee of a string slice. Written as `str`.
Str,
// An array with the given length. Written as `[T; n]`.
// Array(Ty, ty::Const),
/// The pointee of an array slice. Written as `[T]`.
Slice(Arc<Ty>),
/// A raw pointer. Written as `*mut T` or `*const T`
RawPtr(Arc<Ty>, Mutability),
/// A reference; a pointer with an associated lifetime. Written as
/// `&'a mut T` or `&'a T`.
Ref(Arc<Ty>, Mutability),
/// A pointer to a function. Written as `fn() -> i32`.
///
/// For example the type of `bar` here:
///
/// ```rust
/// fn foo() -> i32 { 1 }
/// let bar: fn() -> i32 = foo;
/// ```
FnPtr(Arc<FnSig>),
// rustc has a separate type for each function, which just coerces to the
// above function pointer type. Once we implement generics, we will probably
// need this as well.
// A trait, defined with `dyn trait`.
// Dynamic(),
// The anonymous type of a closure. Used to represent the type of
// `|a| a`.
// Closure(DefId, ClosureSubsts<'tcx>),
// The anonymous type of a generator. Used to represent the type of
// `|a| yield a`.
// Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
// A type representin the types stored inside a generator.
// This should only appear in GeneratorInteriors.
// GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
/// The never type `!`.
Never,
/// A tuple type. For example, `(i32, bool)`.
Tuple(Arc<[Ty]>),
// The projection of an associated type. For example,
// `<T as Trait<..>>::N`.pub
// Projection(ProjectionTy),
// Opaque (`impl Trait`) type found in a return type.
// Opaque(DefId, Substs),
// A type parameter; for example, `T` in `fn f<T>(x: T) {}
// Param(ParamTy),
/// A type variable used during type checking. Not to be confused with a
/// type parameter.
Infer(InferTy),
/// A placeholder for a type which could not be computed; this is propagated
/// to avoid useless error messages. Doubles as a placeholder where type
/// variables are inserted before type checking, since we want to try to
/// infer a better type here anyway -- for the IDE use case, we want to try
/// to infer as much as possible even in the presence of type errors.
Unknown,
}
/// A function signature.
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub struct FnSig {
input: Vec<Ty>,
output: Ty,
}
impl Ty {
pub(crate) fn from_hir(
db: &impl HirDatabase,
module: &Module,
impl_block: Option<&ImplBlock>,
type_ref: &TypeRef,
) -> Cancelable<Self> {
Ok(match type_ref {
TypeRef::Never => Ty::Never,
TypeRef::Tuple(inner) => {
let inner_tys = inner
.iter()
.map(|tr| Ty::from_hir(db, module, impl_block, tr))
.collect::<Cancelable<Vec<_>>>()?;
Ty::Tuple(inner_tys.into())
}
TypeRef::Path(path) => Ty::from_hir_path(db, module, impl_block, path)?,
TypeRef::RawPtr(inner, mutability) => {
let inner_ty = Ty::from_hir(db, module, impl_block, inner)?;
Ty::RawPtr(Arc::new(inner_ty), *mutability)
}
TypeRef::Array(_inner) => Ty::Unknown, // TODO
TypeRef::Slice(inner) => {
let inner_ty = Ty::from_hir(db, module, impl_block, inner)?;
Ty::Slice(Arc::new(inner_ty))
}
TypeRef::Reference(inner, mutability) => {
let inner_ty = Ty::from_hir(db, module, impl_block, inner)?;
Ty::Ref(Arc::new(inner_ty), *mutability)
}
TypeRef::Placeholder => Ty::Unknown,
TypeRef::Fn(params) => {
let mut inner_tys = params
.iter()
.map(|tr| Ty::from_hir(db, module, impl_block, tr))
.collect::<Cancelable<Vec<_>>>()?;
let return_ty = inner_tys
.pop()
.expect("TypeRef::Fn should always have at least return type");
let sig = FnSig {
input: inner_tys,
output: return_ty,
};
Ty::FnPtr(Arc::new(sig))
}
TypeRef::Error => Ty::Unknown,
})
}
pub(crate) fn from_hir_opt(
db: &impl HirDatabase,
module: &Module,
impl_block: Option<&ImplBlock>,
type_ref: Option<&TypeRef>,
) -> Cancelable<Self> {
type_ref
.map(|t| Ty::from_hir(db, module, impl_block, t))
.unwrap_or(Ok(Ty::Unknown))
}
pub(crate) fn from_hir_path(
db: &impl HirDatabase,
module: &Module,
impl_block: Option<&ImplBlock>,
path: &Path,
) -> Cancelable<Self> {
if let Some(name) = path.as_ident() {
if let Some(int_ty) = primitive::IntTy::from_name(name) {
return Ok(Ty::Int(int_ty));
} else if let Some(uint_ty) = primitive::UintTy::from_name(name) {
return Ok(Ty::Uint(uint_ty));
} else if let Some(float_ty) = primitive::FloatTy::from_name(name) {
return Ok(Ty::Float(float_ty));
} else if name.as_known_name() == Some(KnownName::Self_) {
return Ty::from_hir_opt(db, module, None, impl_block.map(|i| i.target()));
}
}
// Resolve in module (in type namespace)
let resolved = if let Some(r) = module.resolve_path(db, path)?.take_types() {
r
} else {
return Ok(Ty::Unknown);
};
let ty = db.type_for_def(resolved)?;
Ok(ty)
}
// TODO: These should not be necessary long-term, since everything will work on HIR
pub(crate) fn from_ast_opt(
db: &impl HirDatabase,
module: &Module,
impl_block: Option<&ImplBlock>,
node: Option<ast::TypeRef>,
) -> Cancelable<Self> {
node.map(|n| Ty::from_ast(db, module, impl_block, n))
.unwrap_or(Ok(Ty::Unknown))
}
pub(crate) fn from_ast(
db: &impl HirDatabase,
module: &Module,
impl_block: Option<&ImplBlock>,
node: ast::TypeRef,
) -> Cancelable<Self> {
Ty::from_hir(db, module, impl_block, &TypeRef::from_ast(node))
}
pub fn unit() -> Self {
Ty::Tuple(Arc::new([]))
}
fn walk_mut(&mut self, f: &mut impl FnMut(&mut Ty)) {
f(self);
match self {
Ty::Slice(t) => Arc::make_mut(t).walk_mut(f),
Ty::RawPtr(t, _) => Arc::make_mut(t).walk_mut(f),
Ty::Ref(t, _) => Arc::make_mut(t).walk_mut(f),
Ty::Tuple(ts) => {
// Without an Arc::make_mut_slice, we can't avoid the clone here:
let mut v: Vec<_> = ts.iter().cloned().collect();
for t in &mut v {
t.walk_mut(f);
}
*ts = v.into();
}
Ty::FnPtr(sig) => {
let sig_mut = Arc::make_mut(sig);
for input in &mut sig_mut.input {
input.walk_mut(f);
}
sig_mut.output.walk_mut(f);
}
Ty::Adt { .. } => {} // need to walk type parameters later
_ => {}
}
}
fn fold(mut self, f: &mut impl FnMut(Ty) -> Ty) -> Ty {
self.walk_mut(&mut |ty_mut| {
let ty = mem::replace(ty_mut, Ty::Unknown);
*ty_mut = f(ty);
});
self
}
}
impl fmt::Display for Ty {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
Ty::Bool => write!(f, "bool"),
Ty::Char => write!(f, "char"),
Ty::Int(t) => write!(f, "{}", t.ty_to_string()),
Ty::Uint(t) => write!(f, "{}", t.ty_to_string()),
Ty::Float(t) => write!(f, "{}", t.ty_to_string()),
Ty::Str => write!(f, "str"),
Ty::Slice(t) => write!(f, "[{}]", t),
Ty::RawPtr(t, m) => write!(f, "*{}{}", m.as_keyword_for_ptr(), t),
Ty::Ref(t, m) => write!(f, "&{}{}", m.as_keyword_for_ref(), t),
Ty::Never => write!(f, "!"),
Ty::Tuple(ts) => {
write!(f, "(")?;
for t in ts.iter() {
write!(f, "{},", t)?;
}
write!(f, ")")
}
Ty::FnPtr(sig) => {
write!(f, "fn(")?;
for t in &sig.input {
write!(f, "{},", t)?;
}
write!(f, ") -> {}", sig.output)
}
Ty::Adt { name, .. } => write!(f, "{}", name),
Ty::Unknown => write!(f, "[unknown]"),
Ty::Infer(..) => write!(f, "_"),
}
}
}
// Functions returning declared types for items
/// Compute the declared type of a function. This should not need to look at the
/// function body (but currently uses the function AST, so does anyway - TODO).
fn type_for_fn(db: &impl HirDatabase, f: Function) -> Cancelable<Ty> {
let syntax = f.syntax(db);
let module = f.module(db)?;
let impl_block = f.impl_block(db)?;
let node = syntax.borrowed();
// TODO we ignore type parameters for now
let input = node
.param_list()
.map(|pl| {
pl.params()
.map(|p| Ty::from_ast_opt(db, &module, impl_block.as_ref(), p.type_ref()))
.collect()
})
.unwrap_or_else(|| Ok(Vec::new()))?;
let output = if let Some(type_ref) = node.ret_type().and_then(|rt| rt.type_ref()) {
Ty::from_ast(db, &module, impl_block.as_ref(), type_ref)?
} else {
Ty::unit()
};
let sig = FnSig { input, output };
Ok(Ty::FnPtr(Arc::new(sig)))
}
fn type_for_struct(db: &impl HirDatabase, s: Struct) -> Cancelable<Ty> {
Ok(Ty::Adt {
def_id: s.def_id(),
name: s.name(db)?.unwrap_or_else(Name::missing),
})
}
pub fn type_for_enum(db: &impl HirDatabase, s: Enum) -> Cancelable<Ty> {
Ok(Ty::Adt {
def_id: s.def_id(),
name: s.name(db)?.unwrap_or_else(Name::missing),
})
}
pub(super) fn type_for_def(db: &impl HirDatabase, def_id: DefId) -> Cancelable<Ty> {
let def = def_id.resolve(db)?;
match def {
Def::Module(..) => {
log::debug!("trying to get type for module {:?}", def_id);
Ok(Ty::Unknown)
}
Def::Function(f) => type_for_fn(db, f),
Def::Struct(s) => type_for_struct(db, s),
Def::Enum(e) => type_for_enum(db, e),
Def::Item => {
log::debug!("trying to get type for item of unknown type {:?}", def_id);
Ok(Ty::Unknown)
}
}
}
pub(super) fn type_for_field(db: &impl HirDatabase, def_id: DefId, field: Name) -> Cancelable<Ty> {
let def = def_id.resolve(db)?;
let variant_data = match def {
Def::Struct(s) => {
let variant_data = s.variant_data(db)?;
variant_data
}
// TODO: unions
// TODO: enum variants
_ => panic!(
"trying to get type for field in non-struct/variant {:?}",
def_id
),
};
let module = def_id.module(db)?;
let impl_block = def_id.impl_block(db)?;
let type_ref = if let Some(tr) = variant_data.get_field_type_ref(&field) {
tr
} else {
return Ok(Ty::Unknown);
};
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: FxHashMap<LocalSyntaxPtr, Ty>,
}
impl InferenceResult {
/// Returns the type of the given syntax node, if it was inferred. Will
/// return `None` for syntax nodes not in the inferred function or not
/// pointing to an expression/pattern, `Some(Ty::Unknown)` for
/// expressions/patterns that could not be inferred.
pub fn type_of_node(&self, node: SyntaxNodeRef) -> Option<Ty> {
self.type_of.get(&LocalSyntaxPtr::new(node)).cloned()
}
}
/// The inference context contains all information needed during type inference.
#[derive(Clone, Debug)]
struct InferenceContext<'a, D: HirDatabase> {
db: &'a D,
scopes: Arc<FnScopes>,
/// The self param for the current method, if it exists.
self_param: Option<LocalSyntaxPtr>,
module: Module,
impl_block: Option<ImplBlock>,
var_unification_table: InPlaceUnificationTable<TypeVarId>,
type_of: FxHashMap<LocalSyntaxPtr, Ty>,
}
impl<'a, D: HirDatabase> InferenceContext<'a, D> {
fn new(
db: &'a D,
scopes: Arc<FnScopes>,
module: Module,
impl_block: Option<ImplBlock>,
) -> Self {
InferenceContext {
type_of: FxHashMap::default(),
var_unification_table: InPlaceUnificationTable::new(),
self_param: None, // set during parameter typing
db,
scopes,
module,
impl_block,
}
}
fn resolve_all(mut self) -> InferenceResult {
let mut types = mem::replace(&mut self.type_of, FxHashMap::default());
for ty in types.values_mut() {
let resolved = self.resolve_ty_completely(mem::replace(ty, Ty::Unknown));
*ty = resolved;
}
InferenceResult { type_of: types }
}
fn write_ty(&mut self, node: SyntaxNodeRef, ty: Ty) {
self.type_of.insert(LocalSyntaxPtr::new(node), ty);
}
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: ast::PathExpr) -> Cancelable<Option<Ty>> {
let ast_path = ctry!(expr.path());
let path = ctry!(Path::from_ast(ast_path));
if path.is_ident() {
// resolve locally
let name = ctry!(ast_path.segment().and_then(|s| s.name_ref()));
if let Some(scope_entry) = self.scopes.resolve_local_name(name) {
let ty = ctry!(self.type_of.get(&scope_entry.ptr()));
let ty = self.resolve_ty_as_possible(ty.clone());
return Ok(Some(ty));
};
} else if path.is_self() {
// resolve `self` param
let self_param = ctry!(self.self_param);
let ty = ctry!(self.type_of.get(&self_param));
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<ast::Path>) -> Cancelable<(Ty, Option<DefId>)> {
let path = if let Some(path) = path.and_then(Path::from_ast) {
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))
}
_ => (Ty::Unknown, None),
})
}
fn infer_expr_opt(
&mut self,
expr: Option<ast::Expr>,
expected: &Expectation,
) -> Cancelable<Ty> {
if let Some(e) = expr {
self.infer_expr(e, expected)
} else {
Ok(Ty::Unknown)
}
}
fn infer_expr(&mut self, expr: ast::Expr, expected: &Expectation) -> Cancelable<Ty> {
let ty = match expr {
ast::Expr::IfExpr(e) => {
if let Some(condition) = e.condition() {
let expected = if condition.pat().is_none() {
Expectation::has_type(Ty::Bool)
} else {
Expectation::none()
};
self.infer_expr_opt(condition.expr(), &expected)?;
// TODO write type for pat
};
let if_ty = self.infer_block_opt(e.then_branch(), expected)?;
if let Some(else_branch) = e.else_branch() {
self.infer_block(else_branch, expected)?;
} else {
// no else branch -> unit
self.unify(&expected.ty, &Ty::unit()); // actually coerce
}
if_ty
}
ast::Expr::BlockExpr(e) => self.infer_block_opt(e.block(), expected)?,
ast::Expr::LoopExpr(e) => {
self.infer_block_opt(e.loop_body(), &Expectation::has_type(Ty::unit()))?;
// TODO never, or the type of the break param
Ty::Unknown
}
ast::Expr::WhileExpr(e) => {
if let Some(condition) = e.condition() {
let expected = if condition.pat().is_none() {
Expectation::has_type(Ty::Bool)
} else {
Expectation::none()
};
self.infer_expr_opt(condition.expr(), &expected)?;
// TODO write type for pat
};
self.infer_block_opt(e.loop_body(), &Expectation::has_type(Ty::unit()))?;
// TODO always unit?
Ty::unit()
}
ast::Expr::ForExpr(e) => {
let _iterable_ty = self.infer_expr_opt(e.iterable(), &Expectation::none());
if let Some(_pat) = e.pat() {
// TODO write type for pat
}
self.infer_block_opt(e.loop_body(), &Expectation::has_type(Ty::unit()))?;
// TODO always unit?
Ty::unit()
}
ast::Expr::LambdaExpr(e) => {
let _body_ty = self.infer_expr_opt(e.body(), &Expectation::none())?;
Ty::Unknown
}
ast::Expr::CallExpr(e) => {
let callee_ty = self.infer_expr_opt(e.expr(), &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)
}
};
if let Some(arg_list) = e.arg_list() {
for (i, arg) in arg_list.args().enumerate() {
self.infer_expr(
arg,
&Expectation::has_type(arg_tys.get(i).cloned().unwrap_or(Ty::Unknown)),
)?;
}
}
ret_ty
}
ast::Expr::MethodCallExpr(e) => {
let _receiver_ty = self.infer_expr_opt(e.expr(), &Expectation::none())?;
if let Some(arg_list) = e.arg_list() {
for arg in arg_list.args() {
// TODO unify / expect argument type
self.infer_expr(arg, &Expectation::none())?;
}
}
Ty::Unknown
}
ast::Expr::MatchExpr(e) => {
let _ty = self.infer_expr_opt(e.expr(), &Expectation::none())?;
if let Some(match_arm_list) = e.match_arm_list() {
for arm in match_arm_list.arms() {
// TODO type the bindings in pat
// TODO type the guard
let _ty = self.infer_expr_opt(arm.expr(), &Expectation::none())?;
}
// TODO unify all the match arm types
Ty::Unknown
} else {
Ty::Unknown
}
}
ast::Expr::TupleExpr(_e) => Ty::Unknown,
ast::Expr::ArrayExpr(_e) => Ty::Unknown,
ast::Expr::PathExpr(e) => self.infer_path_expr(e)?.unwrap_or(Ty::Unknown),
ast::Expr::ContinueExpr(_e) => Ty::Never,
ast::Expr::BreakExpr(_e) => Ty::Never,
ast::Expr::ParenExpr(e) => self.infer_expr_opt(e.expr(), expected)?,
ast::Expr::Label(_e) => Ty::Unknown,
ast::Expr::ReturnExpr(e) => {
// TODO expect return type of function
self.infer_expr_opt(e.expr(), &Expectation::none())?;
Ty::Never
}
ast::Expr::MatchArmList(_) | ast::Expr::MatchArm(_) | ast::Expr::MatchGuard(_) => {
// Can this even occur outside of a match expression?
Ty::Unknown
}
ast::Expr::StructLit(e) => {
let (ty, def_id) = self.resolve_variant(e.path())?;
if let Some(nfl) = e.named_field_list() {
for field in nfl.fields() {
let field_ty = if let (Some(def_id), Some(nr)) = (def_id, field.name_ref())
{
self.db.type_for_field(def_id, nr.as_name())?
} else {
Ty::Unknown
};
self.infer_expr_opt(field.expr(), &Expectation::has_type(field_ty))?;
}
}
ty
}
ast::Expr::NamedFieldList(_) | ast::Expr::NamedField(_) => {
// Can this even occur outside of a struct literal?
Ty::Unknown
}
ast::Expr::IndexExpr(_e) => Ty::Unknown,
ast::Expr::FieldExpr(e) => {
let receiver_ty = self.infer_expr_opt(e.expr(), &Expectation::none())?;
if let Some(nr) = e.name_ref() {
let ty = match receiver_ty {
Ty::Tuple(fields) => {
let i = nr.text().parse::<usize>().ok();
i.and_then(|i| fields.get(i).cloned())
.unwrap_or(Ty::Unknown)
}
Ty::Adt { def_id, .. } => self.db.type_for_field(def_id, nr.as_name())?,
_ => Ty::Unknown,
};
self.insert_type_vars(ty)
} else {
Ty::Unknown
}
}
ast::Expr::TryExpr(e) => {
let _inner_ty = self.infer_expr_opt(e.expr(), &Expectation::none())?;
Ty::Unknown
}
ast::Expr::CastExpr(e) => {
let _inner_ty = self.infer_expr_opt(e.expr(), &Expectation::none())?;
let cast_ty = Ty::from_ast_opt(
self.db,
&self.module,
self.impl_block.as_ref(),
e.type_ref(),
)?;
let cast_ty = self.insert_type_vars(cast_ty);
// TODO do the coercion...
cast_ty
}
ast::Expr::RefExpr(e) => {
// TODO pass the expectation down
let inner_ty = self.infer_expr_opt(e.expr(), &Expectation::none())?;
let m = Mutability::from_mutable(e.is_mut());
// TODO reference coercions etc.
Ty::Ref(Arc::new(inner_ty), m)
}
ast::Expr::PrefixExpr(e) => {
let inner_ty = self.infer_expr_opt(e.expr(), &Expectation::none())?;
match e.op() {
Some(PrefixOp::Deref) => {
match inner_ty {
// builtin deref:
Ty::Ref(ref_inner, _) => (*ref_inner).clone(),
Ty::RawPtr(ptr_inner, _) => (*ptr_inner).clone(),
// TODO Deref::deref
_ => Ty::Unknown,
}
}
_ => Ty::Unknown,
}
}
ast::Expr::RangeExpr(_e) => Ty::Unknown,
ast::Expr::BinExpr(_e) => Ty::Unknown,
ast::Expr::Literal(_e) => 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);
self.write_ty(expr.syntax(), ty.clone());
Ok(ty)
}
fn infer_block_opt(
&mut self,
node: Option<ast::Block>,
expected: &Expectation,
) -> Cancelable<Ty> {
if let Some(b) = node {
self.infer_block(b, expected)
} else {
Ok(Ty::Unknown)
}
}
fn infer_block(&mut self, node: ast::Block, expected: &Expectation) -> Cancelable<Ty> {
for stmt in node.statements() {
match stmt {
ast::Stmt::LetStmt(stmt) => {
let decl_ty = Ty::from_ast_opt(
self.db,
&self.module,
self.impl_block.as_ref(),
stmt.type_ref(),
)?;
let decl_ty = self.insert_type_vars(decl_ty);
let ty = if let Some(expr) = stmt.initializer() {
let expr_ty = self.infer_expr(expr, &Expectation::has_type(decl_ty))?;
expr_ty
} else {
decl_ty
};
if let Some(pat) = stmt.pat() {
self.write_ty(pat.syntax(), ty);
};
}
ast::Stmt::ExprStmt(expr_stmt) => {
self.infer_expr_opt(expr_stmt.expr(), &Expectation::none())?;
}
}
}
let ty = if let Some(expr) = node.expr() {
self.infer_expr(expr, expected)?
} else {
Ty::unit()
};
self.write_ty(node.syntax(), ty.clone());
Ok(ty)
}
}
pub fn infer(db: &impl HirDatabase, def_id: DefId) -> Cancelable<Arc<InferenceResult>> {
let function = Function::new(def_id); // TODO: consts also need inference
let scopes = function.scopes(db);
let module = function.module(db)?;
let impl_block = function.impl_block(db)?;
let mut ctx = InferenceContext::new(db, scopes, module, impl_block);
let syntax = function.syntax(db);
let node = syntax.borrowed();
if let Some(param_list) = node.param_list() {
if let Some(self_param) = param_list.self_param() {
let self_type = if let Some(impl_block) = &ctx.impl_block {
if let Some(type_ref) = self_param.type_ref() {
let ty = Ty::from_ast(db, &ctx.module, ctx.impl_block.as_ref(), type_ref)?;
ctx.insert_type_vars(ty)
} else {
// TODO this should be handled by desugaring during HIR conversion
let ty = Ty::from_hir(
db,
&ctx.module,
ctx.impl_block.as_ref(),
impl_block.target(),
)?;
let ty = match self_param.flavor() {
ast::SelfParamFlavor::Owned => ty,
ast::SelfParamFlavor::Ref => Ty::Ref(Arc::new(ty), Mutability::Shared),
ast::SelfParamFlavor::MutRef => Ty::Ref(Arc::new(ty), Mutability::Mut),
};
ctx.insert_type_vars(ty)
}
} else {
log::debug!(
"No impl block found, but self param for function {:?}",
def_id
);
ctx.new_type_var()
};
if let Some(self_kw) = self_param.self_kw() {
let self_param = LocalSyntaxPtr::new(self_kw.syntax());
ctx.self_param = Some(self_param);
ctx.type_of.insert(self_param, self_type);
}
}
for param in param_list.params() {
let pat = if let Some(pat) = param.pat() {
pat
} else {
continue;
};
let ty = if let Some(type_ref) = param.type_ref() {
let ty = Ty::from_ast(db, &ctx.module, ctx.impl_block.as_ref(), type_ref)?;
ctx.insert_type_vars(ty)
} else {
// missing type annotation
ctx.new_type_var()
};
ctx.type_of.insert(LocalSyntaxPtr::new(pat.syntax()), ty);
}
}
let ret_ty = if let Some(type_ref) = node.ret_type().and_then(|n| n.type_ref()) {
let ty = Ty::from_ast(db, &ctx.module, ctx.impl_block.as_ref(), type_ref)?;
ctx.insert_type_vars(ty)
} else {
Ty::unit()
};
if let Some(block) = node.body() {
ctx.infer_block(block, &Expectation::has_type(ret_ty))?;
}
Ok(Arc::new(ctx.resolve_all()))
}
|