f59cd1a4a0
1515: Trait environment r=matklad a=flodiebold
This adds the environment, i.e. the set of `where` clauses in scope, when solving trait goals. That means that e.g. in
```rust
fn foo<T: SomeTrait>(t: T) {}
```
, we are able to complete methods of `SomeTrait` on the `t`. This affects the trait APIs quite a bit (since every method that needs to be able to solve for some trait needs to get this environment somehow), so I thought I'd do it rather sooner than later ;)
Co-authored-by: Florian Diebold <flodiebold@gmail.com>
1516 lines
59 KiB
Rust
1516 lines
59 KiB
Rust
//! Type inference, i.e. the process of walking through the code and determining
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//! the type of each expression and pattern.
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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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//! During inference, types (i.e. the `Ty` struct) can contain type 'variables'
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//! which represent currently unknown types; as we walk through the expressions,
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//! we might determine that certain variables need to be equal to each other, or
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//! to certain types. To record this, we use the union-find implementation from
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//! the `ena` crate, which is extracted from rustc.
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use std::borrow::Cow;
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use std::iter::repeat;
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use std::mem;
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use std::ops::Index;
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use std::sync::Arc;
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use ena::unify::{InPlaceUnificationTable, NoError, UnifyKey, UnifyValue};
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use rustc_hash::FxHashMap;
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use ra_arena::map::ArenaMap;
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use ra_prof::profile;
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use test_utils::tested_by;
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use super::{
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autoderef, lower, method_resolution, op, primitive,
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traits::{Guidance, Obligation, ProjectionPredicate, Solution},
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ApplicationTy, CallableDef, Environment, InEnvironment, ProjectionTy, Substs, TraitRef, Ty,
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TypableDef, TypeCtor,
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};
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use crate::{
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adt::VariantDef,
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code_model::{ModuleDef::Trait, TypeAlias},
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diagnostics::DiagnosticSink,
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expr::{
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self, Array, BinaryOp, BindingAnnotation, Body, Expr, ExprId, FieldPat, Literal, Pat,
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PatId, Statement, UnaryOp,
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},
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generics::{GenericParams, HasGenericParams},
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name,
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nameres::{Namespace, PerNs},
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path::{GenericArg, GenericArgs, PathKind, PathSegment},
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resolve::{
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Resolution::{self, Def},
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Resolver,
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},
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ty::infer::diagnostics::InferenceDiagnostic,
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type_ref::{Mutability, TypeRef},
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AdtDef, ConstData, DefWithBody, FnData, Function, HirDatabase, ImplItem, ModuleDef, Name, Path,
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StructField,
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};
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mod unify;
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/// The entry point of type inference.
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pub fn infer_query(db: &impl HirDatabase, def: DefWithBody) -> Arc<InferenceResult> {
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let _p = profile("infer_query");
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let body = def.body(db);
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let resolver = def.resolver(db);
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let mut ctx = InferenceContext::new(db, body, resolver);
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match def {
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DefWithBody::Const(ref c) => ctx.collect_const(&c.data(db)),
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DefWithBody::Function(ref f) => ctx.collect_fn(&f.data(db)),
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DefWithBody::Static(ref s) => ctx.collect_const(&s.data(db)),
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}
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ctx.infer_body();
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Arc::new(ctx.resolve_all())
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}
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#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
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enum ExprOrPatId {
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ExprId(ExprId),
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PatId(PatId),
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}
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impl_froms!(ExprOrPatId: ExprId, PatId);
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/// Binding modes inferred for patterns.
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/// https://doc.rust-lang.org/reference/patterns.html#binding-modes
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#[derive(Copy, Clone, Debug, Eq, PartialEq)]
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enum BindingMode {
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Move,
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Ref(Mutability),
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}
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impl BindingMode {
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pub fn convert(annotation: BindingAnnotation) -> BindingMode {
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match annotation {
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BindingAnnotation::Unannotated | BindingAnnotation::Mutable => BindingMode::Move,
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BindingAnnotation::Ref => BindingMode::Ref(Mutability::Shared),
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BindingAnnotation::RefMut => BindingMode::Ref(Mutability::Mut),
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}
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}
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}
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impl Default for BindingMode {
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fn default() -> Self {
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BindingMode::Move
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}
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}
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/// The result of type inference: A mapping from expressions and patterns to types.
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#[derive(Clone, PartialEq, Eq, Debug)]
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pub struct InferenceResult {
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/// For each method call expr, records the function it resolves to.
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method_resolutions: FxHashMap<ExprId, Function>,
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/// For each field access expr, records the field it resolves to.
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field_resolutions: FxHashMap<ExprId, StructField>,
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/// For each associated item record what it resolves to
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assoc_resolutions: FxHashMap<ExprOrPatId, ImplItem>,
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diagnostics: Vec<InferenceDiagnostic>,
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pub(super) type_of_expr: ArenaMap<ExprId, Ty>,
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pub(super) type_of_pat: ArenaMap<PatId, Ty>,
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}
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impl InferenceResult {
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pub fn method_resolution(&self, expr: ExprId) -> Option<Function> {
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self.method_resolutions.get(&expr).copied()
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}
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pub fn field_resolution(&self, expr: ExprId) -> Option<StructField> {
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self.field_resolutions.get(&expr).copied()
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}
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pub fn assoc_resolutions_for_expr(&self, id: ExprId) -> Option<ImplItem> {
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self.assoc_resolutions.get(&id.into()).copied()
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}
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pub fn assoc_resolutions_for_pat(&self, id: PatId) -> Option<ImplItem> {
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self.assoc_resolutions.get(&id.into()).copied()
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}
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pub(crate) fn add_diagnostics(
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&self,
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db: &impl HirDatabase,
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owner: Function,
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sink: &mut DiagnosticSink,
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) {
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self.diagnostics.iter().for_each(|it| it.add_to(db, owner, sink))
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}
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}
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impl Index<ExprId> for InferenceResult {
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type Output = Ty;
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fn index(&self, expr: ExprId) -> &Ty {
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self.type_of_expr.get(expr).unwrap_or(&Ty::Unknown)
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}
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}
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impl Index<PatId> for InferenceResult {
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type Output = Ty;
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fn index(&self, pat: PatId) -> &Ty {
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self.type_of_pat.get(pat).unwrap_or(&Ty::Unknown)
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}
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}
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/// The inference context contains all information needed during type inference.
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#[derive(Clone, Debug)]
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struct InferenceContext<'a, D: HirDatabase> {
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db: &'a D,
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body: Arc<Body>,
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resolver: Resolver,
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var_unification_table: InPlaceUnificationTable<TypeVarId>,
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trait_env: Arc<Environment>,
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obligations: Vec<Obligation>,
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method_resolutions: FxHashMap<ExprId, Function>,
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field_resolutions: FxHashMap<ExprId, StructField>,
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assoc_resolutions: FxHashMap<ExprOrPatId, ImplItem>,
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type_of_expr: ArenaMap<ExprId, Ty>,
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type_of_pat: ArenaMap<PatId, Ty>,
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diagnostics: Vec<InferenceDiagnostic>,
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/// The return type of the function being inferred.
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return_ty: Ty,
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}
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impl<'a, D: HirDatabase> InferenceContext<'a, D> {
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fn new(db: &'a D, body: Arc<Body>, resolver: Resolver) -> Self {
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InferenceContext {
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method_resolutions: FxHashMap::default(),
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field_resolutions: FxHashMap::default(),
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assoc_resolutions: FxHashMap::default(),
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type_of_expr: ArenaMap::default(),
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type_of_pat: ArenaMap::default(),
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diagnostics: Vec::default(),
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var_unification_table: InPlaceUnificationTable::new(),
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obligations: Vec::default(),
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return_ty: Ty::Unknown, // set in collect_fn_signature
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trait_env: lower::trait_env(db, &resolver),
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db,
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body,
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resolver,
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}
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}
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fn resolve_all(mut self) -> InferenceResult {
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// FIXME resolve obligations as well (use Guidance if necessary)
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let mut tv_stack = Vec::new();
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let mut expr_types = mem::replace(&mut self.type_of_expr, ArenaMap::default());
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for ty in expr_types.values_mut() {
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let resolved = self.resolve_ty_completely(&mut tv_stack, mem::replace(ty, Ty::Unknown));
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*ty = resolved;
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}
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let mut pat_types = mem::replace(&mut self.type_of_pat, ArenaMap::default());
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for ty in pat_types.values_mut() {
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let resolved = self.resolve_ty_completely(&mut tv_stack, mem::replace(ty, Ty::Unknown));
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*ty = resolved;
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}
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InferenceResult {
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method_resolutions: self.method_resolutions,
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field_resolutions: self.field_resolutions,
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assoc_resolutions: self.assoc_resolutions,
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type_of_expr: expr_types,
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type_of_pat: pat_types,
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diagnostics: self.diagnostics,
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}
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}
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fn write_expr_ty(&mut self, expr: ExprId, ty: Ty) {
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self.type_of_expr.insert(expr, ty);
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}
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fn write_method_resolution(&mut self, expr: ExprId, func: Function) {
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self.method_resolutions.insert(expr, func);
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}
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fn write_field_resolution(&mut self, expr: ExprId, field: StructField) {
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self.field_resolutions.insert(expr, field);
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}
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fn write_assoc_resolution(&mut self, id: ExprOrPatId, item: ImplItem) {
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self.assoc_resolutions.insert(id, item);
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}
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fn write_pat_ty(&mut self, pat: PatId, ty: Ty) {
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self.type_of_pat.insert(pat, ty);
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}
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fn make_ty(&mut self, type_ref: &TypeRef) -> Ty {
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let ty = Ty::from_hir(
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self.db,
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// FIXME use right resolver for block
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&self.resolver,
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type_ref,
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);
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self.insert_type_vars(ty)
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}
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fn unify_substs(&mut self, substs1: &Substs, substs2: &Substs, depth: usize) -> bool {
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substs1.0.iter().zip(substs2.0.iter()).all(|(t1, t2)| self.unify_inner(t1, t2, depth))
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}
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fn unify(&mut self, ty1: &Ty, ty2: &Ty) -> bool {
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self.unify_inner(ty1, ty2, 0)
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}
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fn unify_inner(&mut self, ty1: &Ty, ty2: &Ty, depth: usize) -> bool {
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if depth > 1000 {
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// prevent stackoverflows
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panic!("infinite recursion in unification");
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}
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if ty1 == ty2 {
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return true;
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}
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// try to resolve type vars first
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let ty1 = self.resolve_ty_shallow(ty1);
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let ty2 = self.resolve_ty_shallow(ty2);
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match (&*ty1, &*ty2) {
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(Ty::Unknown, ..) => true,
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(.., Ty::Unknown) => true,
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(Ty::Apply(a_ty1), Ty::Apply(a_ty2)) if a_ty1.ctor == a_ty2.ctor => {
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self.unify_substs(&a_ty1.parameters, &a_ty2.parameters, depth + 1)
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}
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(Ty::Infer(InferTy::TypeVar(tv1)), Ty::Infer(InferTy::TypeVar(tv2)))
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| (Ty::Infer(InferTy::IntVar(tv1)), Ty::Infer(InferTy::IntVar(tv2)))
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| (Ty::Infer(InferTy::FloatVar(tv1)), Ty::Infer(InferTy::FloatVar(tv2))) => {
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// both type vars are unknown since we tried to resolve them
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self.var_unification_table.union(*tv1, *tv2);
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true
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}
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(Ty::Infer(InferTy::TypeVar(tv)), other)
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| (other, Ty::Infer(InferTy::TypeVar(tv)))
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| (Ty::Infer(InferTy::IntVar(tv)), other)
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| (other, Ty::Infer(InferTy::IntVar(tv)))
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| (Ty::Infer(InferTy::FloatVar(tv)), other)
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| (other, Ty::Infer(InferTy::FloatVar(tv))) => {
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// the type var is unknown since we tried to resolve it
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self.var_unification_table.union_value(*tv, TypeVarValue::Known(other.clone()));
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true
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}
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_ => false,
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}
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}
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fn new_type_var(&mut self) -> Ty {
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Ty::Infer(InferTy::TypeVar(self.var_unification_table.new_key(TypeVarValue::Unknown)))
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}
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fn new_integer_var(&mut self) -> Ty {
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Ty::Infer(InferTy::IntVar(self.var_unification_table.new_key(TypeVarValue::Unknown)))
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}
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fn new_float_var(&mut self) -> Ty {
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Ty::Infer(InferTy::FloatVar(self.var_unification_table.new_key(TypeVarValue::Unknown)))
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}
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/// Replaces Ty::Unknown by a new type var, so we can maybe still infer it.
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fn insert_type_vars_shallow(&mut self, ty: Ty) -> Ty {
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match ty {
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Ty::Unknown => self.new_type_var(),
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Ty::Apply(ApplicationTy {
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ctor: TypeCtor::Int(primitive::UncertainIntTy::Unknown),
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..
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}) => self.new_integer_var(),
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Ty::Apply(ApplicationTy {
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ctor: TypeCtor::Float(primitive::UncertainFloatTy::Unknown),
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..
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}) => self.new_float_var(),
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_ => ty,
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}
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}
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fn insert_type_vars(&mut self, ty: Ty) -> Ty {
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ty.fold(&mut |ty| self.insert_type_vars_shallow(ty))
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}
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fn resolve_obligations_as_possible(&mut self) {
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let obligations = mem::replace(&mut self.obligations, Vec::new());
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for obligation in obligations {
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let in_env = InEnvironment::new(self.trait_env.clone(), obligation.clone());
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let canonicalized = self.canonicalizer().canonicalize_obligation(in_env);
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let solution =
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self.db.solve(self.resolver.krate().unwrap(), canonicalized.value.clone());
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|
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match solution {
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Some(Solution::Unique(substs)) => {
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canonicalized.apply_solution(self, substs.0);
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}
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Some(Solution::Ambig(Guidance::Definite(substs))) => {
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canonicalized.apply_solution(self, substs.0);
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self.obligations.push(obligation);
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}
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Some(_) => {
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// FIXME use this when trying to resolve everything at the end
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self.obligations.push(obligation);
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}
|
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None => {
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// FIXME obligation cannot be fulfilled => diagnostic
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}
|
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};
|
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}
|
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}
|
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|
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/// Resolves the type as far as currently possible, replacing type variables
|
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/// by their known types. All types returned by the infer_* functions should
|
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/// be resolved as far as possible, i.e. contain no type variables with
|
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/// known type.
|
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fn resolve_ty_as_possible(&mut self, tv_stack: &mut Vec<TypeVarId>, ty: Ty) -> Ty {
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self.resolve_obligations_as_possible();
|
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|
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ty.fold(&mut |ty| match ty {
|
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Ty::Infer(tv) => {
|
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let inner = tv.to_inner();
|
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if tv_stack.contains(&inner) {
|
||
tested_by!(type_var_cycles_resolve_as_possible);
|
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// recursive type
|
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return tv.fallback_value();
|
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}
|
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if let Some(known_ty) = self.var_unification_table.probe_value(inner).known() {
|
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// known_ty may contain other variables that are known by now
|
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tv_stack.push(inner);
|
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let result = self.resolve_ty_as_possible(tv_stack, known_ty.clone());
|
||
tv_stack.pop();
|
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result
|
||
} else {
|
||
ty
|
||
}
|
||
}
|
||
_ => ty,
|
||
})
|
||
}
|
||
|
||
/// If `ty` is a type variable with known type, returns that type;
|
||
/// otherwise, return ty.
|
||
fn resolve_ty_shallow<'b>(&mut self, ty: &'b Ty) -> Cow<'b, Ty> {
|
||
let mut ty = Cow::Borrowed(ty);
|
||
// The type variable could resolve to a int/float variable. Hence try
|
||
// resolving up to three times; each type of variable shouldn't occur
|
||
// more than once
|
||
for i in 0..3 {
|
||
if i > 0 {
|
||
tested_by!(type_var_resolves_to_int_var);
|
||
}
|
||
match &*ty {
|
||
Ty::Infer(tv) => {
|
||
let inner = tv.to_inner();
|
||
match self.var_unification_table.probe_value(inner).known() {
|
||
Some(known_ty) => {
|
||
// The known_ty can't be a type var itself
|
||
ty = Cow::Owned(known_ty.clone());
|
||
}
|
||
_ => return ty,
|
||
}
|
||
}
|
||
_ => return ty,
|
||
}
|
||
}
|
||
log::error!("Inference variable still not resolved: {:?}", ty);
|
||
ty
|
||
}
|
||
|
||
/// Resolves the type completely; type variables without known type are
|
||
/// replaced by Ty::Unknown.
|
||
fn resolve_ty_completely(&mut self, tv_stack: &mut Vec<TypeVarId>, ty: Ty) -> Ty {
|
||
ty.fold(&mut |ty| match ty {
|
||
Ty::Infer(tv) => {
|
||
let inner = tv.to_inner();
|
||
if tv_stack.contains(&inner) {
|
||
tested_by!(type_var_cycles_resolve_completely);
|
||
// recursive type
|
||
return tv.fallback_value();
|
||
}
|
||
if let Some(known_ty) = self.var_unification_table.probe_value(inner).known() {
|
||
// known_ty may contain other variables that are known by now
|
||
tv_stack.push(inner);
|
||
let result = self.resolve_ty_completely(tv_stack, known_ty.clone());
|
||
tv_stack.pop();
|
||
result
|
||
} else {
|
||
tv.fallback_value()
|
||
}
|
||
}
|
||
_ => ty,
|
||
})
|
||
}
|
||
|
||
fn infer_path_expr(&mut self, resolver: &Resolver, path: &Path, id: ExprOrPatId) -> Option<Ty> {
|
||
let resolved = resolver.resolve_path_segments(self.db, &path);
|
||
|
||
let (def, remaining_index) = resolved.into_inner();
|
||
|
||
log::debug!(
|
||
"path {:?} resolved to {:?} with remaining index {:?}",
|
||
path,
|
||
def,
|
||
remaining_index
|
||
);
|
||
|
||
// if the remaining_index is None, we expect the path
|
||
// to be fully resolved, in this case we continue with
|
||
// the default by attempting to `take_values´ from the resolution.
|
||
// Otherwise the path was partially resolved, which means
|
||
// we might have resolved into a type for which
|
||
// we may find some associated item starting at the
|
||
// path.segment pointed to by `remaining_index´
|
||
let mut resolved =
|
||
if remaining_index.is_none() { def.take_values()? } else { def.take_types()? };
|
||
|
||
let remaining_index = remaining_index.unwrap_or_else(|| path.segments.len());
|
||
let mut actual_def_ty: Option<Ty> = None;
|
||
|
||
let krate = resolver.krate()?;
|
||
// resolve intermediate segments
|
||
for (i, segment) in path.segments[remaining_index..].iter().enumerate() {
|
||
let ty = match resolved {
|
||
Resolution::Def(def) => {
|
||
// FIXME resolve associated items from traits as well
|
||
let typable: Option<TypableDef> = def.into();
|
||
let typable = typable?;
|
||
|
||
let ty = self.db.type_for_def(typable, Namespace::Types);
|
||
|
||
// For example, this substs will take `Gen::*<u32>*::make`
|
||
assert!(remaining_index > 0);
|
||
let substs = Ty::substs_from_path_segment(
|
||
self.db,
|
||
&self.resolver,
|
||
&path.segments[remaining_index + i - 1],
|
||
typable,
|
||
);
|
||
|
||
ty.subst(&substs)
|
||
}
|
||
Resolution::LocalBinding(_) => {
|
||
// can't have a local binding in an associated item path
|
||
return None;
|
||
}
|
||
Resolution::GenericParam(..) => {
|
||
// FIXME associated item of generic param
|
||
return None;
|
||
}
|
||
Resolution::SelfType(_) => {
|
||
// FIXME associated item of self type
|
||
return None;
|
||
}
|
||
};
|
||
|
||
// Attempt to find an impl_item for the type which has a name matching
|
||
// the current segment
|
||
log::debug!("looking for path segment: {:?}", segment);
|
||
|
||
actual_def_ty = Some(ty.clone());
|
||
|
||
let item: crate::ModuleDef = ty.iterate_impl_items(self.db, krate, |item| {
|
||
let matching_def: Option<crate::ModuleDef> = match item {
|
||
crate::ImplItem::Method(func) => {
|
||
if segment.name == func.name(self.db) {
|
||
Some(func.into())
|
||
} else {
|
||
None
|
||
}
|
||
}
|
||
|
||
crate::ImplItem::Const(konst) => {
|
||
let data = konst.data(self.db);
|
||
if segment.name == *data.name() {
|
||
Some(konst.into())
|
||
} else {
|
||
None
|
||
}
|
||
}
|
||
|
||
// FIXME: Resolve associated types
|
||
crate::ImplItem::TypeAlias(_) => None,
|
||
};
|
||
match matching_def {
|
||
Some(_) => {
|
||
self.write_assoc_resolution(id, item);
|
||
matching_def
|
||
}
|
||
None => None,
|
||
}
|
||
})?;
|
||
|
||
resolved = Resolution::Def(item);
|
||
}
|
||
|
||
match resolved {
|
||
Resolution::Def(def) => {
|
||
let typable: Option<TypableDef> = def.into();
|
||
let typable = typable?;
|
||
let mut ty = self.db.type_for_def(typable, Namespace::Values);
|
||
if let Some(sts) = self.find_self_types(&def, actual_def_ty) {
|
||
ty = ty.subst(&sts);
|
||
}
|
||
|
||
let substs = Ty::substs_from_path(self.db, &self.resolver, path, typable);
|
||
let ty = ty.subst(&substs);
|
||
let ty = self.insert_type_vars(ty);
|
||
Some(ty)
|
||
}
|
||
Resolution::LocalBinding(pat) => {
|
||
let ty = self.type_of_pat.get(pat)?.clone();
|
||
let ty = self.resolve_ty_as_possible(&mut vec![], ty);
|
||
Some(ty)
|
||
}
|
||
Resolution::GenericParam(..) => {
|
||
// generic params can't refer to values... yet
|
||
None
|
||
}
|
||
Resolution::SelfType(_) => {
|
||
log::error!("path expr {:?} resolved to Self type in values ns", path);
|
||
None
|
||
}
|
||
}
|
||
}
|
||
|
||
fn find_self_types(&self, def: &ModuleDef, actual_def_ty: Option<Ty>) -> Option<Substs> {
|
||
let actual_def_ty = actual_def_ty?;
|
||
|
||
if let crate::ModuleDef::Function(func) = def {
|
||
// We only do the infer if parent has generic params
|
||
let gen = func.generic_params(self.db);
|
||
if gen.count_parent_params() == 0 {
|
||
return None;
|
||
}
|
||
|
||
let impl_block = func.impl_block(self.db)?.target_ty(self.db);
|
||
let impl_block_substs = impl_block.substs()?;
|
||
let actual_substs = actual_def_ty.substs()?;
|
||
|
||
let mut new_substs = vec![Ty::Unknown; gen.count_parent_params()];
|
||
|
||
// The following code *link up* the function actual parma type
|
||
// and impl_block type param index
|
||
impl_block_substs.iter().zip(actual_substs.iter()).for_each(|(param, pty)| {
|
||
if let Ty::Param { idx, .. } = param {
|
||
if let Some(s) = new_substs.get_mut(*idx as usize) {
|
||
*s = pty.clone();
|
||
}
|
||
}
|
||
});
|
||
|
||
Some(Substs(new_substs.into()))
|
||
} else {
|
||
None
|
||
}
|
||
}
|
||
|
||
fn resolve_variant(&mut self, path: Option<&Path>) -> (Ty, Option<VariantDef>) {
|
||
let path = match path {
|
||
Some(path) => path,
|
||
None => return (Ty::Unknown, None),
|
||
};
|
||
let resolver = &self.resolver;
|
||
let typable: Option<TypableDef> =
|
||
// FIXME: this should resolve assoc items as well, see this example:
|
||
// https://play.rust-lang.org/?gist=087992e9e22495446c01c0d4e2d69521
|
||
match resolver.resolve_path_without_assoc_items(self.db, &path).take_types() {
|
||
Some(Resolution::Def(def)) => def.into(),
|
||
Some(Resolution::LocalBinding(..)) => {
|
||
// this cannot happen
|
||
log::error!("path resolved to local binding in type ns");
|
||
return (Ty::Unknown, None);
|
||
}
|
||
Some(Resolution::GenericParam(..)) => {
|
||
// generic params can't be used in struct literals
|
||
return (Ty::Unknown, None);
|
||
}
|
||
Some(Resolution::SelfType(..)) => {
|
||
// FIXME this is allowed in an impl for a struct, handle this
|
||
return (Ty::Unknown, None);
|
||
}
|
||
None => return (Ty::Unknown, None),
|
||
};
|
||
let def = match typable {
|
||
None => return (Ty::Unknown, None),
|
||
Some(it) => it,
|
||
};
|
||
// FIXME remove the duplication between here and `Ty::from_path`?
|
||
let substs = Ty::substs_from_path(self.db, resolver, path, def);
|
||
match def {
|
||
TypableDef::Struct(s) => {
|
||
let ty = s.ty(self.db);
|
||
let ty = self.insert_type_vars(ty.apply_substs(substs));
|
||
(ty, Some(s.into()))
|
||
}
|
||
TypableDef::EnumVariant(var) => {
|
||
let ty = var.parent_enum(self.db).ty(self.db);
|
||
let ty = self.insert_type_vars(ty.apply_substs(substs));
|
||
(ty, Some(var.into()))
|
||
}
|
||
TypableDef::Union(_)
|
||
| TypableDef::TypeAlias(_)
|
||
| TypableDef::Function(_)
|
||
| TypableDef::Enum(_)
|
||
| TypableDef::Const(_)
|
||
| TypableDef::Static(_)
|
||
| TypableDef::BuiltinType(_) => (Ty::Unknown, None),
|
||
}
|
||
}
|
||
|
||
fn infer_tuple_struct_pat(
|
||
&mut self,
|
||
path: Option<&Path>,
|
||
subpats: &[PatId],
|
||
expected: &Ty,
|
||
default_bm: BindingMode,
|
||
) -> Ty {
|
||
let (ty, def) = self.resolve_variant(path);
|
||
|
||
self.unify(&ty, expected);
|
||
|
||
let substs = ty.substs().unwrap_or_else(Substs::empty);
|
||
|
||
for (i, &subpat) in subpats.iter().enumerate() {
|
||
let expected_ty = def
|
||
.and_then(|d| d.field(self.db, &Name::tuple_field_name(i)))
|
||
.map_or(Ty::Unknown, |field| field.ty(self.db))
|
||
.subst(&substs);
|
||
self.infer_pat(subpat, &expected_ty, default_bm);
|
||
}
|
||
|
||
ty
|
||
}
|
||
|
||
fn infer_struct_pat(
|
||
&mut self,
|
||
path: Option<&Path>,
|
||
subpats: &[FieldPat],
|
||
expected: &Ty,
|
||
default_bm: BindingMode,
|
||
) -> Ty {
|
||
let (ty, def) = self.resolve_variant(path);
|
||
|
||
self.unify(&ty, expected);
|
||
|
||
let substs = ty.substs().unwrap_or_else(Substs::empty);
|
||
|
||
for subpat in subpats {
|
||
let matching_field = def.and_then(|it| it.field(self.db, &subpat.name));
|
||
let expected_ty =
|
||
matching_field.map_or(Ty::Unknown, |field| field.ty(self.db)).subst(&substs);
|
||
self.infer_pat(subpat.pat, &expected_ty, default_bm);
|
||
}
|
||
|
||
ty
|
||
}
|
||
|
||
fn infer_pat(&mut self, pat: PatId, mut expected: &Ty, mut default_bm: BindingMode) -> Ty {
|
||
let body = Arc::clone(&self.body); // avoid borrow checker problem
|
||
|
||
let is_non_ref_pat = match &body[pat] {
|
||
Pat::Tuple(..)
|
||
| Pat::TupleStruct { .. }
|
||
| Pat::Struct { .. }
|
||
| Pat::Range { .. }
|
||
| Pat::Slice { .. } => true,
|
||
// FIXME: Path/Lit might actually evaluate to ref, but inference is unimplemented.
|
||
Pat::Path(..) | Pat::Lit(..) => true,
|
||
Pat::Wild | Pat::Bind { .. } | Pat::Ref { .. } | Pat::Missing => false,
|
||
};
|
||
if is_non_ref_pat {
|
||
while let Some((inner, mutability)) = expected.as_reference() {
|
||
expected = inner;
|
||
default_bm = match default_bm {
|
||
BindingMode::Move => BindingMode::Ref(mutability),
|
||
BindingMode::Ref(Mutability::Shared) => BindingMode::Ref(Mutability::Shared),
|
||
BindingMode::Ref(Mutability::Mut) => BindingMode::Ref(mutability),
|
||
}
|
||
}
|
||
} else if let Pat::Ref { .. } = &body[pat] {
|
||
tested_by!(match_ergonomics_ref);
|
||
// When you encounter a `&pat` pattern, reset to Move.
|
||
// This is so that `w` is by value: `let (_, &w) = &(1, &2);`
|
||
default_bm = BindingMode::Move;
|
||
}
|
||
|
||
// Lose mutability.
|
||
let default_bm = default_bm;
|
||
let expected = expected;
|
||
|
||
let ty = match &body[pat] {
|
||
Pat::Tuple(ref args) => {
|
||
let expectations = match expected.as_tuple() {
|
||
Some(parameters) => &*parameters.0,
|
||
_ => &[],
|
||
};
|
||
let expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown));
|
||
|
||
let inner_tys: Substs = args
|
||
.iter()
|
||
.zip(expectations_iter)
|
||
.map(|(&pat, ty)| self.infer_pat(pat, ty, default_bm))
|
||
.collect::<Vec<_>>()
|
||
.into();
|
||
|
||
Ty::apply(TypeCtor::Tuple { cardinality: inner_tys.len() as u16 }, inner_tys)
|
||
}
|
||
Pat::Ref { pat, mutability } => {
|
||
let expectation = match expected.as_reference() {
|
||
Some((inner_ty, exp_mut)) => {
|
||
if *mutability != exp_mut {
|
||
// FIXME: emit type error?
|
||
}
|
||
inner_ty
|
||
}
|
||
_ => &Ty::Unknown,
|
||
};
|
||
let subty = self.infer_pat(*pat, expectation, default_bm);
|
||
Ty::apply_one(TypeCtor::Ref(*mutability), subty)
|
||
}
|
||
Pat::TupleStruct { path: ref p, args: ref subpats } => {
|
||
self.infer_tuple_struct_pat(p.as_ref(), subpats, expected, default_bm)
|
||
}
|
||
Pat::Struct { path: ref p, args: ref fields } => {
|
||
self.infer_struct_pat(p.as_ref(), fields, expected, default_bm)
|
||
}
|
||
Pat::Path(path) => {
|
||
// FIXME use correct resolver for the surrounding expression
|
||
let resolver = self.resolver.clone();
|
||
self.infer_path_expr(&resolver, &path, pat.into()).unwrap_or(Ty::Unknown)
|
||
}
|
||
Pat::Bind { mode, name: _name, subpat } => {
|
||
let mode = if mode == &BindingAnnotation::Unannotated {
|
||
default_bm
|
||
} else {
|
||
BindingMode::convert(*mode)
|
||
};
|
||
let inner_ty = if let Some(subpat) = subpat {
|
||
self.infer_pat(*subpat, expected, default_bm)
|
||
} else {
|
||
expected.clone()
|
||
};
|
||
let inner_ty = self.insert_type_vars_shallow(inner_ty);
|
||
|
||
let bound_ty = match mode {
|
||
BindingMode::Ref(mutability) => {
|
||
Ty::apply_one(TypeCtor::Ref(mutability), inner_ty.clone())
|
||
}
|
||
BindingMode::Move => inner_ty.clone(),
|
||
};
|
||
let bound_ty = self.resolve_ty_as_possible(&mut vec![], bound_ty);
|
||
self.write_pat_ty(pat, bound_ty);
|
||
return inner_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);
|
||
let ty = self.resolve_ty_as_possible(&mut vec![], ty);
|
||
self.write_pat_ty(pat, ty.clone());
|
||
ty
|
||
}
|
||
|
||
fn substs_for_method_call(
|
||
&mut self,
|
||
def_generics: Option<Arc<GenericParams>>,
|
||
generic_args: Option<&GenericArgs>,
|
||
receiver_ty: &Ty,
|
||
) -> Substs {
|
||
let (parent_param_count, param_count) =
|
||
def_generics.as_ref().map_or((0, 0), |g| (g.count_parent_params(), g.params.len()));
|
||
let mut substs = Vec::with_capacity(parent_param_count + param_count);
|
||
// Parent arguments are unknown, except for the receiver type
|
||
if let Some(parent_generics) = def_generics.and_then(|p| p.parent_params.clone()) {
|
||
for param in &parent_generics.params {
|
||
if param.name == name::SELF_TYPE {
|
||
substs.push(receiver_ty.clone());
|
||
} else {
|
||
substs.push(Ty::Unknown);
|
||
}
|
||
}
|
||
}
|
||
// handle provided type arguments
|
||
if let Some(generic_args) = generic_args {
|
||
// if args are provided, it should be all of them, but we can't rely on that
|
||
for arg in generic_args.args.iter().take(param_count) {
|
||
match arg {
|
||
GenericArg::Type(type_ref) => {
|
||
let ty = self.make_ty(type_ref);
|
||
substs.push(ty);
|
||
}
|
||
}
|
||
}
|
||
};
|
||
let supplied_params = substs.len();
|
||
for _ in supplied_params..parent_param_count + param_count {
|
||
substs.push(Ty::Unknown);
|
||
}
|
||
assert_eq!(substs.len(), parent_param_count + param_count);
|
||
Substs(substs.into())
|
||
}
|
||
|
||
fn register_obligations_for_call(&mut self, callable_ty: &Ty) {
|
||
if let Ty::Apply(a_ty) = callable_ty {
|
||
if let TypeCtor::FnDef(def) = a_ty.ctor {
|
||
let generic_predicates = self.db.generic_predicates(def.into());
|
||
for predicate in generic_predicates.iter() {
|
||
let predicate = predicate.clone().subst(&a_ty.parameters);
|
||
if let Some(obligation) = Obligation::from_predicate(predicate) {
|
||
self.obligations.push(obligation);
|
||
}
|
||
}
|
||
// add obligation for trait implementation, if this is a trait method
|
||
match def {
|
||
CallableDef::Function(f) => {
|
||
if let Some(trait_) = f.parent_trait(self.db) {
|
||
// construct a TraitDef
|
||
let substs = a_ty.parameters.prefix(
|
||
trait_.generic_params(self.db).count_params_including_parent(),
|
||
);
|
||
self.obligations.push(Obligation::Trait(TraitRef { trait_, substs }));
|
||
}
|
||
}
|
||
CallableDef::Struct(_) | CallableDef::EnumVariant(_) => {}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
fn infer_method_call(
|
||
&mut self,
|
||
tgt_expr: ExprId,
|
||
receiver: ExprId,
|
||
args: &[ExprId],
|
||
method_name: &Name,
|
||
generic_args: Option<&GenericArgs>,
|
||
) -> Ty {
|
||
let receiver_ty = self.infer_expr(receiver, &Expectation::none());
|
||
let canonicalized_receiver = self.canonicalizer().canonicalize_ty(receiver_ty.clone());
|
||
let resolved = method_resolution::lookup_method(
|
||
&canonicalized_receiver.value,
|
||
self.db,
|
||
method_name,
|
||
&self.resolver,
|
||
);
|
||
let (derefed_receiver_ty, method_ty, def_generics) = match resolved {
|
||
Some((ty, func)) => {
|
||
let ty = canonicalized_receiver.decanonicalize_ty(ty);
|
||
self.write_method_resolution(tgt_expr, func);
|
||
(
|
||
ty,
|
||
self.db.type_for_def(func.into(), Namespace::Values),
|
||
Some(func.generic_params(self.db)),
|
||
)
|
||
}
|
||
None => (receiver_ty, Ty::Unknown, None),
|
||
};
|
||
let substs = self.substs_for_method_call(def_generics, generic_args, &derefed_receiver_ty);
|
||
let method_ty = method_ty.apply_substs(substs);
|
||
let method_ty = self.insert_type_vars(method_ty);
|
||
self.register_obligations_for_call(&method_ty);
|
||
let (expected_receiver_ty, param_tys, ret_ty) = match method_ty.callable_sig(self.db) {
|
||
Some(sig) => {
|
||
if !sig.params().is_empty() {
|
||
(sig.params()[0].clone(), sig.params()[1..].to_vec(), sig.ret().clone())
|
||
} else {
|
||
(Ty::Unknown, Vec::new(), sig.ret().clone())
|
||
}
|
||
}
|
||
None => (Ty::Unknown, Vec::new(), Ty::Unknown),
|
||
};
|
||
// Apply autoref so the below unification works correctly
|
||
// FIXME: return correct autorefs from lookup_method
|
||
let actual_receiver_ty = match expected_receiver_ty.as_reference() {
|
||
Some((_, mutability)) => Ty::apply_one(TypeCtor::Ref(mutability), derefed_receiver_ty),
|
||
_ => derefed_receiver_ty,
|
||
};
|
||
self.unify(&expected_receiver_ty, &actual_receiver_ty);
|
||
|
||
let param_iter = param_tys.into_iter().chain(repeat(Ty::Unknown));
|
||
for (arg, param) in args.iter().zip(param_iter) {
|
||
self.infer_expr(*arg, &Expectation::has_type(param));
|
||
}
|
||
ret_ty
|
||
}
|
||
|
||
fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
|
||
let body = Arc::clone(&self.body); // avoid borrow checker problem
|
||
let ty = match &body[tgt_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::simple(TypeCtor::Bool)));
|
||
let then_ty = self.infer_expr(*then_branch, expected);
|
||
match else_branch {
|
||
Some(else_branch) => {
|
||
self.infer_expr(*else_branch, expected);
|
||
}
|
||
None => {
|
||
// no else branch -> unit
|
||
self.unify(&then_ty, &Ty::unit()); // actually coerce
|
||
}
|
||
};
|
||
then_ty
|
||
}
|
||
Expr::Block { statements, tail } => self.infer_block(statements, *tail, expected),
|
||
Expr::TryBlock { body } => {
|
||
let _inner = self.infer_expr(*body, expected);
|
||
// FIXME should be std::result::Result<{inner}, _>
|
||
Ty::Unknown
|
||
}
|
||
Expr::Loop { body } => {
|
||
self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
|
||
// FIXME handle break with value
|
||
Ty::simple(TypeCtor::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::simple(TypeCtor::Bool)));
|
||
self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
|
||
Ty::unit()
|
||
}
|
||
Expr::For { iterable, body, pat } => {
|
||
let iterable_ty = self.infer_expr(*iterable, &Expectation::none());
|
||
|
||
let pat_ty = match self.resolve_into_iter_item() {
|
||
Some(into_iter_item_alias) => {
|
||
let pat_ty = self.new_type_var();
|
||
let projection = ProjectionPredicate {
|
||
ty: pat_ty.clone(),
|
||
projection_ty: ProjectionTy {
|
||
associated_ty: into_iter_item_alias,
|
||
parameters: vec![iterable_ty].into(),
|
||
},
|
||
};
|
||
self.obligations.push(Obligation::Projection(projection));
|
||
self.resolve_ty_as_possible(&mut vec![], pat_ty)
|
||
}
|
||
None => Ty::Unknown,
|
||
};
|
||
|
||
self.infer_pat(*pat, &pat_ty, BindingMode::default());
|
||
self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
|
||
Ty::unit()
|
||
}
|
||
Expr::Lambda { body, args, arg_types } => {
|
||
assert_eq!(args.len(), arg_types.len());
|
||
|
||
for (arg_pat, arg_type) in args.iter().zip(arg_types.iter()) {
|
||
let expected = if let Some(type_ref) = arg_type {
|
||
self.make_ty(type_ref)
|
||
} else {
|
||
Ty::Unknown
|
||
};
|
||
self.infer_pat(*arg_pat, &expected, BindingMode::default());
|
||
}
|
||
|
||
// FIXME: 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 (param_tys, ret_ty) = match callee_ty.callable_sig(self.db) {
|
||
Some(sig) => (sig.params().to_vec(), sig.ret().clone()),
|
||
None => {
|
||
// Not callable
|
||
// FIXME: report an error
|
||
(Vec::new(), Ty::Unknown)
|
||
}
|
||
};
|
||
self.register_obligations_for_call(&callee_ty);
|
||
let param_iter = param_tys.into_iter().chain(repeat(Ty::Unknown));
|
||
for (arg, param) in args.iter().zip(param_iter) {
|
||
self.infer_expr(*arg, &Expectation::has_type(param));
|
||
}
|
||
ret_ty
|
||
}
|
||
Expr::MethodCall { receiver, args, method_name, generic_args } => self
|
||
.infer_method_call(tgt_expr, *receiver, &args, &method_name, generic_args.as_ref()),
|
||
Expr::Match { expr, arms } => {
|
||
let expected = if expected.ty == Ty::Unknown {
|
||
Expectation::has_type(self.new_type_var())
|
||
} else {
|
||
expected.clone()
|
||
};
|
||
let input_ty = self.infer_expr(*expr, &Expectation::none());
|
||
|
||
for arm in arms {
|
||
for &pat in &arm.pats {
|
||
let _pat_ty = self.infer_pat(pat, &input_ty, BindingMode::default());
|
||
}
|
||
if let Some(guard_expr) = arm.guard {
|
||
self.infer_expr(
|
||
guard_expr,
|
||
&Expectation::has_type(Ty::simple(TypeCtor::Bool)),
|
||
);
|
||
}
|
||
self.infer_expr(arm.expr, &expected);
|
||
}
|
||
|
||
expected.ty
|
||
}
|
||
Expr::Path(p) => {
|
||
// FIXME this could be more efficient...
|
||
let resolver = expr::resolver_for_expr(self.body.clone(), self.db, tgt_expr);
|
||
self.infer_path_expr(&resolver, p, tgt_expr.into()).unwrap_or(Ty::Unknown)
|
||
}
|
||
Expr::Continue => Ty::simple(TypeCtor::Never),
|
||
Expr::Break { expr } => {
|
||
if let Some(expr) = expr {
|
||
// FIXME handle break with value
|
||
self.infer_expr(*expr, &Expectation::none());
|
||
}
|
||
Ty::simple(TypeCtor::Never)
|
||
}
|
||
Expr::Return { expr } => {
|
||
if let Some(expr) = expr {
|
||
self.infer_expr(*expr, &Expectation::has_type(self.return_ty.clone()));
|
||
}
|
||
Ty::simple(TypeCtor::Never)
|
||
}
|
||
Expr::StructLit { path, fields, spread } => {
|
||
let (ty, def_id) = self.resolve_variant(path.as_ref());
|
||
let substs = ty.substs().unwrap_or_else(Substs::empty);
|
||
for (field_idx, field) in fields.iter().enumerate() {
|
||
let field_ty = def_id
|
||
.and_then(|it| match it.field(self.db, &field.name) {
|
||
Some(field) => Some(field),
|
||
None => {
|
||
self.diagnostics.push(InferenceDiagnostic::NoSuchField {
|
||
expr: tgt_expr,
|
||
field: field_idx,
|
||
});
|
||
None
|
||
}
|
||
})
|
||
.map_or(Ty::Unknown, |field| field.ty(self.db))
|
||
.subst(&substs);
|
||
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 canonicalized = self.canonicalizer().canonicalize_ty(receiver_ty);
|
||
let ty = autoderef::autoderef(
|
||
self.db,
|
||
&self.resolver.clone(),
|
||
canonicalized.value.clone(),
|
||
)
|
||
.find_map(|derefed_ty| match canonicalized.decanonicalize_ty(derefed_ty.value) {
|
||
Ty::Apply(a_ty) => match a_ty.ctor {
|
||
TypeCtor::Tuple { .. } => {
|
||
let i = name.to_string().parse::<usize>().ok();
|
||
i.and_then(|i| a_ty.parameters.0.get(i).cloned())
|
||
}
|
||
TypeCtor::Adt(AdtDef::Struct(s)) => s.field(self.db, name).map(|field| {
|
||
self.write_field_resolution(tgt_expr, field);
|
||
field.ty(self.db).subst(&a_ty.parameters)
|
||
}),
|
||
_ => None,
|
||
},
|
||
_ => None,
|
||
})
|
||
.unwrap_or(Ty::Unknown);
|
||
self.insert_type_vars(ty)
|
||
}
|
||
Expr::Try { expr } => {
|
||
let inner_ty = self.infer_expr(*expr, &Expectation::none());
|
||
let ty = match self.resolve_ops_try_ok() {
|
||
Some(ops_try_ok_alias) => {
|
||
let ty = self.new_type_var();
|
||
let projection = ProjectionPredicate {
|
||
ty: ty.clone(),
|
||
projection_ty: ProjectionTy {
|
||
associated_ty: ops_try_ok_alias,
|
||
parameters: vec![inner_ty].into(),
|
||
},
|
||
};
|
||
self.obligations.push(Obligation::Projection(projection));
|
||
self.resolve_ty_as_possible(&mut vec![], ty)
|
||
}
|
||
None => Ty::Unknown,
|
||
};
|
||
ty
|
||
}
|
||
Expr::Cast { expr, type_ref } => {
|
||
let _inner_ty = self.infer_expr(*expr, &Expectation::none());
|
||
let cast_ty = self.make_ty(type_ref);
|
||
// FIXME check the cast...
|
||
cast_ty
|
||
}
|
||
Expr::Ref { expr, mutability } => {
|
||
let expectation =
|
||
if let Some((exp_inner, exp_mutability)) = &expected.ty.as_reference() {
|
||
if *exp_mutability == Mutability::Mut && *mutability == Mutability::Shared {
|
||
// FIXME: throw type error - expected mut reference but found shared ref,
|
||
// which cannot be coerced
|
||
}
|
||
Expectation::has_type(Ty::clone(exp_inner))
|
||
} else {
|
||
Expectation::none()
|
||
};
|
||
// FIXME reference coercions etc.
|
||
let inner_ty = self.infer_expr(*expr, &expectation);
|
||
Ty::apply_one(TypeCtor::Ref(*mutability), inner_ty)
|
||
}
|
||
Expr::UnaryOp { expr, op } => {
|
||
let inner_ty = self.infer_expr(*expr, &Expectation::none());
|
||
match op {
|
||
UnaryOp::Deref => {
|
||
let canonicalized = self.canonicalizer().canonicalize_ty(inner_ty);
|
||
if let Some(derefed_ty) =
|
||
autoderef::deref(self.db, &self.resolver, &canonicalized.value)
|
||
{
|
||
canonicalized.decanonicalize_ty(derefed_ty.value)
|
||
} else {
|
||
Ty::Unknown
|
||
}
|
||
}
|
||
UnaryOp::Neg => {
|
||
match &inner_ty {
|
||
Ty::Apply(a_ty) => match a_ty.ctor {
|
||
TypeCtor::Int(primitive::UncertainIntTy::Unknown)
|
||
| TypeCtor::Int(primitive::UncertainIntTy::Known(
|
||
primitive::IntTy {
|
||
signedness: primitive::Signedness::Signed,
|
||
..
|
||
},
|
||
))
|
||
| TypeCtor::Float(..) => inner_ty,
|
||
_ => Ty::Unknown,
|
||
},
|
||
Ty::Infer(InferTy::IntVar(..)) | Ty::Infer(InferTy::FloatVar(..)) => {
|
||
inner_ty
|
||
}
|
||
// FIXME: resolve ops::Neg trait
|
||
_ => Ty::Unknown,
|
||
}
|
||
}
|
||
UnaryOp::Not => {
|
||
match &inner_ty {
|
||
Ty::Apply(a_ty) => match a_ty.ctor {
|
||
TypeCtor::Bool | TypeCtor::Int(_) => inner_ty,
|
||
_ => Ty::Unknown,
|
||
},
|
||
Ty::Infer(InferTy::IntVar(..)) => inner_ty,
|
||
// FIXME: resolve ops::Not trait for inner_ty
|
||
_ => Ty::Unknown,
|
||
}
|
||
}
|
||
}
|
||
}
|
||
Expr::BinaryOp { lhs, rhs, op } => match op {
|
||
Some(op) => {
|
||
let lhs_expectation = match op {
|
||
BinaryOp::BooleanAnd | BinaryOp::BooleanOr => {
|
||
Expectation::has_type(Ty::simple(TypeCtor::Bool))
|
||
}
|
||
_ => Expectation::none(),
|
||
};
|
||
let lhs_ty = self.infer_expr(*lhs, &lhs_expectation);
|
||
// FIXME: find implementation of trait corresponding to operation
|
||
// symbol and resolve associated `Output` type
|
||
let rhs_expectation = op::binary_op_rhs_expectation(*op, lhs_ty);
|
||
let rhs_ty = self.infer_expr(*rhs, &Expectation::has_type(rhs_expectation));
|
||
|
||
// FIXME: similar as above, return ty is often associated trait type
|
||
op::binary_op_return_ty(*op, rhs_ty)
|
||
}
|
||
_ => Ty::Unknown,
|
||
},
|
||
Expr::Tuple { exprs } => {
|
||
let mut ty_vec = Vec::with_capacity(exprs.len());
|
||
for arg in exprs.iter() {
|
||
ty_vec.push(self.infer_expr(*arg, &Expectation::none()));
|
||
}
|
||
|
||
Ty::apply(
|
||
TypeCtor::Tuple { cardinality: ty_vec.len() as u16 },
|
||
Substs(ty_vec.into()),
|
||
)
|
||
}
|
||
Expr::Array(array) => {
|
||
let elem_ty = match &expected.ty {
|
||
Ty::Apply(a_ty) => match a_ty.ctor {
|
||
TypeCtor::Slice | TypeCtor::Array => {
|
||
Ty::clone(&a_ty.parameters.as_single())
|
||
}
|
||
_ => self.new_type_var(),
|
||
},
|
||
_ => self.new_type_var(),
|
||
};
|
||
|
||
match array {
|
||
Array::ElementList(items) => {
|
||
for expr in items.iter() {
|
||
self.infer_expr(*expr, &Expectation::has_type(elem_ty.clone()));
|
||
}
|
||
}
|
||
Array::Repeat { initializer, repeat } => {
|
||
self.infer_expr(*initializer, &Expectation::has_type(elem_ty.clone()));
|
||
self.infer_expr(
|
||
*repeat,
|
||
&Expectation::has_type(Ty::simple(TypeCtor::Int(
|
||
primitive::UncertainIntTy::Known(primitive::IntTy::usize()),
|
||
))),
|
||
);
|
||
}
|
||
}
|
||
|
||
Ty::apply_one(TypeCtor::Array, elem_ty)
|
||
}
|
||
Expr::Literal(lit) => match lit {
|
||
Literal::Bool(..) => Ty::simple(TypeCtor::Bool),
|
||
Literal::String(..) => {
|
||
Ty::apply_one(TypeCtor::Ref(Mutability::Shared), Ty::simple(TypeCtor::Str))
|
||
}
|
||
Literal::ByteString(..) => {
|
||
let byte_type = Ty::simple(TypeCtor::Int(primitive::UncertainIntTy::Known(
|
||
primitive::IntTy::u8(),
|
||
)));
|
||
let slice_type = Ty::apply_one(TypeCtor::Slice, byte_type);
|
||
Ty::apply_one(TypeCtor::Ref(Mutability::Shared), slice_type)
|
||
}
|
||
Literal::Char(..) => Ty::simple(TypeCtor::Char),
|
||
Literal::Int(_v, ty) => Ty::simple(TypeCtor::Int(*ty)),
|
||
Literal::Float(_v, ty) => Ty::simple(TypeCtor::Float(*ty)),
|
||
},
|
||
};
|
||
// 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(&mut vec![], ty);
|
||
self.write_expr_ty(tgt_expr, ty.clone());
|
||
ty
|
||
}
|
||
|
||
fn infer_block(
|
||
&mut self,
|
||
statements: &[Statement],
|
||
tail: Option<ExprId>,
|
||
expected: &Expectation,
|
||
) -> Ty {
|
||
for stmt in statements {
|
||
match stmt {
|
||
Statement::Let { pat, type_ref, initializer } => {
|
||
let decl_ty =
|
||
type_ref.as_ref().map(|tr| self.make_ty(tr)).unwrap_or(Ty::Unknown);
|
||
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.infer_pat(*pat, &ty, BindingMode::default());
|
||
}
|
||
Statement::Expr(expr) => {
|
||
self.infer_expr(*expr, &Expectation::none());
|
||
}
|
||
}
|
||
}
|
||
let ty = if let Some(expr) = tail { self.infer_expr(expr, expected) } else { Ty::unit() };
|
||
ty
|
||
}
|
||
|
||
fn collect_const(&mut self, data: &ConstData) {
|
||
self.return_ty = self.make_ty(data.type_ref());
|
||
}
|
||
|
||
fn collect_fn(&mut self, data: &FnData) {
|
||
let body = Arc::clone(&self.body); // avoid borrow checker problem
|
||
for (type_ref, pat) in data.params().iter().zip(body.params()) {
|
||
let ty = self.make_ty(type_ref);
|
||
|
||
self.infer_pat(*pat, &ty, BindingMode::default());
|
||
}
|
||
self.return_ty = self.make_ty(data.ret_type());
|
||
}
|
||
|
||
fn infer_body(&mut self) {
|
||
self.infer_expr(self.body.body_expr(), &Expectation::has_type(self.return_ty.clone()));
|
||
}
|
||
|
||
fn resolve_into_iter_item(&self) -> Option<TypeAlias> {
|
||
let into_iter_path = Path {
|
||
kind: PathKind::Abs,
|
||
segments: vec![
|
||
PathSegment { name: name::STD, args_and_bindings: None },
|
||
PathSegment { name: name::ITER, args_and_bindings: None },
|
||
PathSegment { name: name::INTO_ITERATOR, args_and_bindings: None },
|
||
],
|
||
};
|
||
|
||
match self.resolver.resolve_path_segments(self.db, &into_iter_path).into_fully_resolved() {
|
||
PerNs { types: Some(Def(Trait(trait_))), .. } => {
|
||
Some(trait_.associated_type_by_name(self.db, name::ITEM)?)
|
||
}
|
||
_ => None,
|
||
}
|
||
}
|
||
|
||
fn resolve_ops_try_ok(&self) -> Option<TypeAlias> {
|
||
let ops_try_path = Path {
|
||
kind: PathKind::Abs,
|
||
segments: vec![
|
||
PathSegment { name: name::STD, args_and_bindings: None },
|
||
PathSegment { name: name::OPS, args_and_bindings: None },
|
||
PathSegment { name: name::TRY, args_and_bindings: None },
|
||
],
|
||
};
|
||
|
||
match self.resolver.resolve_path_segments(self.db, &ops_try_path).into_fully_resolved() {
|
||
PerNs { types: Some(Def(Trait(trait_))), .. } => {
|
||
Some(trait_.associated_type_by_name(self.db, name::OK)?)
|
||
}
|
||
_ => None,
|
||
}
|
||
}
|
||
}
|
||
|
||
/// The ID of a type variable.
|
||
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
|
||
pub struct TypeVarId(pub(super) 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(t1), TypeVarValue::Known(t2)) => panic!(
|
||
"equating two type variables, both of which have known types: {:?} and {:?}",
|
||
t1, t2
|
||
),
|
||
|
||
// 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. There's separate
|
||
/// values for general types, and for integer and float variables. The latter
|
||
/// two are used for inference of literal values (e.g. `100` could be one of
|
||
/// several integer types).
|
||
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
|
||
pub enum InferTy {
|
||
TypeVar(TypeVarId),
|
||
IntVar(TypeVarId),
|
||
FloatVar(TypeVarId),
|
||
}
|
||
|
||
impl InferTy {
|
||
fn to_inner(self) -> TypeVarId {
|
||
match self {
|
||
InferTy::TypeVar(ty) | InferTy::IntVar(ty) | InferTy::FloatVar(ty) => ty,
|
||
}
|
||
}
|
||
|
||
fn fallback_value(self) -> Ty {
|
||
match self {
|
||
InferTy::TypeVar(..) => Ty::Unknown,
|
||
InferTy::IntVar(..) => {
|
||
Ty::simple(TypeCtor::Int(primitive::UncertainIntTy::Known(primitive::IntTy::i32())))
|
||
}
|
||
InferTy::FloatVar(..) => Ty::simple(TypeCtor::Float(
|
||
primitive::UncertainFloatTy::Known(primitive::FloatTy::f64()),
|
||
)),
|
||
}
|
||
}
|
||
}
|
||
|
||
/// 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,
|
||
// FIXME: 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 }
|
||
}
|
||
}
|
||
|
||
mod diagnostics {
|
||
use crate::{
|
||
diagnostics::{DiagnosticSink, NoSuchField},
|
||
expr::ExprId,
|
||
Function, HasSource, HirDatabase,
|
||
};
|
||
|
||
#[derive(Debug, PartialEq, Eq, Clone)]
|
||
pub(super) enum InferenceDiagnostic {
|
||
NoSuchField { expr: ExprId, field: usize },
|
||
}
|
||
|
||
impl InferenceDiagnostic {
|
||
pub(super) fn add_to(
|
||
&self,
|
||
db: &impl HirDatabase,
|
||
owner: Function,
|
||
sink: &mut DiagnosticSink,
|
||
) {
|
||
match self {
|
||
InferenceDiagnostic::NoSuchField { expr, field } => {
|
||
let file = owner.source(db).file_id;
|
||
let field = owner.body_source_map(db).field_syntax(*expr, *field);
|
||
sink.push(NoSuchField { file, field })
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|