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rust/crates/hir-ty/src/infer/expr.rs

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//! Type inference for expressions.
use std::{
iter::{repeat, repeat_with},
mem,
};
use chalk_ir::{cast::Cast, fold::Shift, DebruijnIndex, Mutability, TyVariableKind};
use either::Either;
use hir_def::{
generics::TypeOrConstParamData,
hir::{
ArithOp, Array, BinaryOp, ClosureKind, Expr, ExprId, LabelId, Literal, Statement, UnaryOp,
},
lang_item::{LangItem, LangItemTarget},
path::{GenericArg, GenericArgs},
BlockId, ConstParamId, FieldId, ItemContainerId, Lookup, TupleFieldId, TupleId,
};
use hir_expand::name::{name, Name};
use stdx::always;
use syntax::ast::RangeOp;
use crate::{
autoderef::{builtin_deref, deref_by_trait, Autoderef},
consteval,
infer::{
coerce::{CoerceMany, CoercionCause},
find_continuable,
pat::contains_explicit_ref_binding,
BreakableKind,
},
lang_items::lang_items_for_bin_op,
lower::{
const_or_path_to_chalk, generic_arg_to_chalk, lower_to_chalk_mutability, ParamLoweringMode,
},
mapping::{from_chalk, ToChalk},
method_resolution::{self, VisibleFromModule},
primitive::{self, UintTy},
static_lifetime, to_chalk_trait_id,
traits::FnTrait,
utils::{generics, Generics},
Adjust, Adjustment, AdtId, AutoBorrow, Binders, CallableDefId, FnPointer, FnSig, FnSubst,
Interner, Rawness, Scalar, Substitution, TraitEnvironment, TraitRef, Ty, TyBuilder, TyExt,
TyKind,
};
use super::{
cast::CastCheck, coerce::auto_deref_adjust_steps, find_breakable, BreakableContext, Diverges,
Expectation, InferenceContext, InferenceDiagnostic, TypeMismatch,
};
impl InferenceContext<'_> {
pub(crate) fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
let ty = self.infer_expr_inner(tgt_expr, expected);
if let Some(expected_ty) = expected.only_has_type(&mut self.table) {
let could_unify = self.unify(&ty, &expected_ty);
if !could_unify {
self.result.type_mismatches.insert(
tgt_expr.into(),
TypeMismatch { expected: expected_ty, actual: ty.clone() },
);
}
}
ty
}
pub(crate) fn infer_expr_no_expect(&mut self, tgt_expr: ExprId) -> Ty {
self.infer_expr_inner(tgt_expr, &Expectation::None)
}
/// Infer type of expression with possibly implicit coerce to the expected type.
/// Return the type after possible coercion.
pub(super) fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
let ty = self.infer_expr_inner(expr, expected);
if let Some(target) = expected.only_has_type(&mut self.table) {
match self.coerce(Some(expr), &ty, &target) {
Ok(res) => res,
Err(_) => {
self.result.type_mismatches.insert(
expr.into(),
TypeMismatch { expected: target.clone(), actual: ty.clone() },
);
target
}
}
} else {
ty
}
}
fn infer_expr_coerce_never(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
let ty = self.infer_expr_inner(expr, expected);
// While we don't allow *arbitrary* coercions here, we *do* allow
// coercions from `!` to `expected`.
if ty.is_never() {
if let Some(adjustments) = self.result.expr_adjustments.get(&expr) {
return if let [Adjustment { kind: Adjust::NeverToAny, target }] = &**adjustments {
target.clone()
} else {
self.err_ty()
};
}
if let Some(target) = expected.only_has_type(&mut self.table) {
self.coerce(Some(expr), &ty, &target)
.expect("never-to-any coercion should always succeed")
} else {
ty
}
} else {
if let Some(expected_ty) = expected.only_has_type(&mut self.table) {
let could_unify = self.unify(&ty, &expected_ty);
if !could_unify {
self.result.type_mismatches.insert(
expr.into(),
TypeMismatch { expected: expected_ty, actual: ty.clone() },
);
}
}
ty
}
}
fn infer_expr_inner(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
self.db.unwind_if_cancelled();
let ty = match &self.body[tgt_expr] {
Expr::Missing => self.err_ty(),
&Expr::If { condition, then_branch, else_branch } => {
let expected = &expected.adjust_for_branches(&mut self.table);
self.infer_expr_coerce_never(
condition,
&Expectation::HasType(self.result.standard_types.bool_.clone()),
);
let condition_diverges = mem::replace(&mut self.diverges, Diverges::Maybe);
let then_ty = self.infer_expr_inner(then_branch, expected);
let then_diverges = mem::replace(&mut self.diverges, Diverges::Maybe);
let mut coerce = CoerceMany::new(expected.coercion_target_type(&mut self.table));
coerce.coerce(self, Some(then_branch), &then_ty, CoercionCause::Expr(then_branch));
match else_branch {
Some(else_branch) => {
let else_ty = self.infer_expr_inner(else_branch, expected);
let else_diverges = mem::replace(&mut self.diverges, Diverges::Maybe);
coerce.coerce(
self,
Some(else_branch),
&else_ty,
CoercionCause::Expr(else_branch),
);
self.diverges = condition_diverges | then_diverges & else_diverges;
}
None => {
coerce.coerce_forced_unit(self, CoercionCause::Expr(tgt_expr));
self.diverges = condition_diverges;
}
}
coerce.complete(self)
}
&Expr::Let { pat, expr } => {
let input_ty = self.infer_expr(expr, &Expectation::none());
self.infer_top_pat(pat, &input_ty);
self.result.standard_types.bool_.clone()
}
Expr::Block { statements, tail, label, id } => {
self.infer_block(tgt_expr, *id, statements, *tail, *label, expected)
}
Expr::Unsafe { id, statements, tail } => {
self.infer_block(tgt_expr, *id, statements, *tail, None, expected)
}
Expr::Const(id) => {
self.with_breakable_ctx(BreakableKind::Border, None, None, |this| {
let loc = this.db.lookup_intern_anonymous_const(*id);
this.infer_expr(loc.root, expected)
})
.1
}
Expr::Async { id, statements, tail } => {
self.infer_async_block(tgt_expr, id, statements, tail)
}
&Expr::Loop { body, label } => {
// FIXME: should be:
// let ty = expected.coercion_target_type(&mut self.table);
let ty = self.table.new_type_var();
let (breaks, ()) =
self.with_breakable_ctx(BreakableKind::Loop, Some(ty), label, |this| {
this.infer_expr(body, &Expectation::HasType(TyBuilder::unit()));
});
match breaks {
Some(breaks) => {
self.diverges = Diverges::Maybe;
breaks
}
None => self.result.standard_types.never.clone(),
}
}
Expr::Closure { body, args, ret_type, arg_types, closure_kind, capture_by: _ } => {
assert_eq!(args.len(), arg_types.len());
let mut sig_tys = Vec::with_capacity(arg_types.len() + 1);
// collect explicitly written argument types
for arg_type in arg_types.iter() {
let arg_ty = match arg_type {
Some(type_ref) => self.make_ty(type_ref),
None => self.table.new_type_var(),
};
sig_tys.push(arg_ty);
}
// add return type
let ret_ty = match ret_type {
Some(type_ref) => self.make_ty(type_ref),
None => self.table.new_type_var(),
};
if let ClosureKind::Async = closure_kind {
sig_tys.push(self.lower_async_block_type_impl_trait(ret_ty.clone(), *body));
} else {
sig_tys.push(ret_ty.clone());
}
let sig_ty = TyKind::Function(FnPointer {
num_binders: 0,
sig: FnSig { abi: (), safety: chalk_ir::Safety::Safe, variadic: false },
substitution: FnSubst(
Substitution::from_iter(Interner, sig_tys.iter().cloned())
.shifted_in(Interner),
),
})
.intern(Interner);
let (id, ty, resume_yield_tys) = match closure_kind {
ClosureKind::Generator(_) => {
// FIXME: report error when there are more than 1 parameter.
let resume_ty = match sig_tys.first() {
// When `sig_tys.len() == 1` the first type is the return type, not the
// first parameter type.
Some(ty) if sig_tys.len() > 1 => ty.clone(),
_ => self.result.standard_types.unit.clone(),
};
let yield_ty = self.table.new_type_var();
let subst = TyBuilder::subst_for_generator(self.db, self.owner)
.push(resume_ty.clone())
.push(yield_ty.clone())
.push(ret_ty.clone())
.build();
let generator_id = self.db.intern_generator((self.owner, tgt_expr)).into();
let generator_ty = TyKind::Generator(generator_id, subst).intern(Interner);
(None, generator_ty, Some((resume_ty, yield_ty)))
}
ClosureKind::Closure | ClosureKind::Async => {
let closure_id = self.db.intern_closure((self.owner, tgt_expr)).into();
let closure_ty = TyKind::Closure(
closure_id,
TyBuilder::subst_for_closure(self.db, self.owner, sig_ty.clone()),
)
.intern(Interner);
self.deferred_closures.entry(closure_id).or_default();
if let Some(c) = self.current_closure {
self.closure_dependencies.entry(c).or_default().push(closure_id);
}
(Some(closure_id), closure_ty, None)
}
};
// Eagerly try to relate the closure type with the expected
// type, otherwise we often won't have enough information to
// infer the body.
self.deduce_closure_type_from_expectations(tgt_expr, &ty, &sig_ty, expected);
// Now go through the argument patterns
for (arg_pat, arg_ty) in args.iter().zip(&sig_tys) {
self.infer_top_pat(*arg_pat, &arg_ty);
}
// FIXME: lift these out into a struct
let prev_diverges = mem::replace(&mut self.diverges, Diverges::Maybe);
let prev_closure = mem::replace(&mut self.current_closure, id);
let prev_ret_ty = mem::replace(&mut self.return_ty, ret_ty.clone());
let prev_ret_coercion =
mem::replace(&mut self.return_coercion, Some(CoerceMany::new(ret_ty)));
let prev_resume_yield_tys =
mem::replace(&mut self.resume_yield_tys, resume_yield_tys);
self.with_breakable_ctx(BreakableKind::Border, None, None, |this| {
this.infer_return(*body);
});
self.diverges = prev_diverges;
self.return_ty = prev_ret_ty;
self.return_coercion = prev_ret_coercion;
self.current_closure = prev_closure;
self.resume_yield_tys = prev_resume_yield_tys;
ty
}
Expr::Call { callee, args, .. } => {
let callee_ty = self.infer_expr(*callee, &Expectation::none());
let mut derefs = Autoderef::new(&mut self.table, callee_ty.clone(), false);
let (res, derefed_callee) = 'b: {
// manual loop to be able to access `derefs.table`
while let Some((callee_deref_ty, _)) = derefs.next() {
let res = derefs.table.callable_sig(&callee_deref_ty, args.len());
if res.is_some() {
break 'b (res, callee_deref_ty);
}
}
(None, callee_ty.clone())
};
// if the function is unresolved, we use is_varargs=true to
// suppress the arg count diagnostic here
let is_varargs =
derefed_callee.callable_sig(self.db).map_or(false, |sig| sig.is_varargs)
|| res.is_none();
let (param_tys, ret_ty) = match res {
Some((func, params, ret_ty)) => {
let mut adjustments = auto_deref_adjust_steps(&derefs);
if let TyKind::Closure(c, _) =
self.table.resolve_completely(callee_ty.clone()).kind(Interner)
{
if let Some(par) = self.current_closure {
self.closure_dependencies.entry(par).or_default().push(*c);
}
self.deferred_closures.entry(*c).or_default().push((
derefed_callee.clone(),
callee_ty.clone(),
params.clone(),
tgt_expr,
));
}
if let Some(fn_x) = func {
self.write_fn_trait_method_resolution(
fn_x,
&derefed_callee,
&mut adjustments,
&callee_ty,
&params,
tgt_expr,
);
}
self.write_expr_adj(*callee, adjustments);
(params, ret_ty)
}
None => {
self.result.diagnostics.push(InferenceDiagnostic::ExpectedFunction {
call_expr: tgt_expr,
found: callee_ty.clone(),
});
(Vec::new(), self.err_ty())
}
};
let indices_to_skip = self.check_legacy_const_generics(derefed_callee, args);
self.register_obligations_for_call(&callee_ty);
let expected_inputs = self.expected_inputs_for_expected_output(
expected,
ret_ty.clone(),
param_tys.clone(),
);
self.check_call_arguments(
tgt_expr,
args,
&expected_inputs,
&param_tys,
&indices_to_skip,
is_varargs,
);
self.normalize_associated_types_in(ret_ty)
}
Expr::MethodCall { receiver, args, method_name, generic_args } => self
.infer_method_call(
tgt_expr,
*receiver,
args,
method_name,
generic_args.as_deref(),
expected,
),
Expr::Match { expr, arms } => {
let input_ty = self.infer_expr(*expr, &Expectation::none());
if arms.is_empty() {
self.diverges = Diverges::Always;
self.result.standard_types.never.clone()
} else {
let matchee_diverges = mem::replace(&mut self.diverges, Diverges::Maybe);
let mut all_arms_diverge = Diverges::Always;
for arm in arms.iter() {
let input_ty = self.resolve_ty_shallow(&input_ty);
self.infer_top_pat(arm.pat, &input_ty);
}
let expected = expected.adjust_for_branches(&mut self.table);
let result_ty = match &expected {
// We don't coerce to `()` so that if the match expression is a
// statement it's branches can have any consistent type.
Expectation::HasType(ty) if *ty != self.result.standard_types.unit => {
ty.clone()
}
_ => self.table.new_type_var(),
};
let mut coerce = CoerceMany::new(result_ty);
for arm in arms.iter() {
if let Some(guard_expr) = arm.guard {
self.diverges = Diverges::Maybe;
self.infer_expr_coerce_never(
guard_expr,
&Expectation::HasType(self.result.standard_types.bool_.clone()),
);
}
self.diverges = Diverges::Maybe;
let arm_ty = self.infer_expr_inner(arm.expr, &expected);
all_arms_diverge &= self.diverges;
coerce.coerce(self, Some(arm.expr), &arm_ty, CoercionCause::Expr(arm.expr));
}
self.diverges = matchee_diverges | all_arms_diverge;
coerce.complete(self)
}
}
Expr::Path(p) => {
let g = self.resolver.update_to_inner_scope(self.db.upcast(), self.owner, tgt_expr);
let ty = self.infer_path(p, tgt_expr.into()).unwrap_or_else(|| self.err_ty());
self.resolver.reset_to_guard(g);
ty
}
&Expr::Continue { label } => {
if let None = find_continuable(&mut self.breakables, label) {
self.push_diagnostic(InferenceDiagnostic::BreakOutsideOfLoop {
expr: tgt_expr,
is_break: false,
bad_value_break: false,
});
};
self.result.standard_types.never.clone()
}
&Expr::Break { expr, label } => {
let val_ty = if let Some(expr) = expr {
let opt_coerce_to = match find_breakable(&mut self.breakables, label) {
Some(ctxt) => match &ctxt.coerce {
Some(coerce) => coerce.expected_ty(),
None => {
self.push_diagnostic(InferenceDiagnostic::BreakOutsideOfLoop {
expr: tgt_expr,
is_break: true,
bad_value_break: true,
});
self.err_ty()
}
},
None => self.err_ty(),
};
self.infer_expr_inner(expr, &Expectation::HasType(opt_coerce_to))
} else {
TyBuilder::unit()
};
match find_breakable(&mut self.breakables, label) {
Some(ctxt) => match ctxt.coerce.take() {
Some(mut coerce) => {
let cause = match expr {
Some(expr) => CoercionCause::Expr(expr),
None => CoercionCause::Expr(tgt_expr),
};
coerce.coerce(self, expr, &val_ty, cause);
// Avoiding borrowck
let ctxt = find_breakable(&mut self.breakables, label)
.expect("breakable stack changed during coercion");
ctxt.may_break = true;
ctxt.coerce = Some(coerce);
}
None => ctxt.may_break = true,
},
None => {
self.push_diagnostic(InferenceDiagnostic::BreakOutsideOfLoop {
expr: tgt_expr,
is_break: true,
bad_value_break: false,
});
}
}
self.result.standard_types.never.clone()
}
&Expr::Return { expr } => self.infer_expr_return(tgt_expr, expr),
Expr::Yield { expr } => {
if let Some((resume_ty, yield_ty)) = self.resume_yield_tys.clone() {
if let Some(expr) = expr {
self.infer_expr_coerce(*expr, &Expectation::has_type(yield_ty));
} else {
let unit = self.result.standard_types.unit.clone();
let _ = self.coerce(Some(tgt_expr), &unit, &yield_ty);
}
resume_ty
} else {
// FIXME: report error (yield expr in non-generator)
self.result.standard_types.unknown.clone()
}
}
Expr::Yeet { expr } => {
if let &Some(expr) = expr {
self.infer_expr_no_expect(expr);
}
self.result.standard_types.never.clone()
}
Expr::RecordLit { path, fields, spread, .. } => {
let (ty, def_id) = self.resolve_variant(path.as_deref(), false);
if let Some(t) = expected.only_has_type(&mut self.table) {
self.unify(&ty, &t);
}
let substs = ty
.as_adt()
.map(|(_, s)| s.clone())
.unwrap_or_else(|| Substitution::empty(Interner));
if let Some(variant) = def_id {
self.write_variant_resolution(tgt_expr.into(), variant);
}
match def_id {
_ if fields.is_empty() => {}
Some(def) => {
let field_types = self.db.field_types(def);
let variant_data = def.variant_data(self.db.upcast());
let visibilities = self.db.field_visibilities(def);
for field in fields.iter() {
let field_def = {
match variant_data.field(&field.name) {
Some(local_id) => {
if !visibilities[local_id].is_visible_from(
self.db.upcast(),
self.resolver.module(),
) {
self.push_diagnostic(
InferenceDiagnostic::NoSuchField {
field: field.expr.into(),
private: true,
},
);
}
Some(local_id)
}
None => {
self.push_diagnostic(InferenceDiagnostic::NoSuchField {
field: field.expr.into(),
private: false,
});
None
}
}
};
let field_ty = field_def.map_or(self.err_ty(), |it| {
field_types[it].clone().substitute(Interner, &substs)
});
// Field type might have some unknown types
// FIXME: we may want to emit a single type variable for all instance of type fields?
let field_ty = self.insert_type_vars(field_ty);
self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty));
}
}
None => {
for field in fields.iter() {
self.infer_expr_coerce(field.expr, &Expectation::None);
}
}
}
if let Some(expr) = spread {
self.infer_expr(*expr, &Expectation::has_type(ty.clone()));
}
ty
}
Expr::Field { expr, name } => self.infer_field_access(tgt_expr, *expr, name, expected),
Expr::Await { expr } => {
let inner_ty = self.infer_expr_inner(*expr, &Expectation::none());
self.resolve_associated_type(inner_ty, self.resolve_future_future_output())
}
Expr::Cast { expr, type_ref } => {
let cast_ty = self.make_ty(type_ref);
let expr_ty = self.infer_expr(*expr, &Expectation::Castable(cast_ty.clone()));
self.deferred_cast_checks.push(CastCheck::new(expr_ty, cast_ty.clone()));
cast_ty
}
Expr::Ref { expr, rawness, mutability } => {
let mutability = lower_to_chalk_mutability(*mutability);
let expectation = if let Some((exp_inner, exp_rawness, exp_mutability)) = expected
.only_has_type(&mut self.table)
.as_ref()
.and_then(|t| t.as_reference_or_ptr())
{
if exp_mutability == Mutability::Mut && mutability == Mutability::Not {
// FIXME: record type error - expected mut reference but found shared ref,
// which cannot be coerced
}
if exp_rawness == Rawness::Ref && *rawness == Rawness::RawPtr {
// FIXME: record type error - expected reference but found ptr,
// which cannot be coerced
}
Expectation::rvalue_hint(self, Ty::clone(exp_inner))
} else {
Expectation::none()
};
let inner_ty = self.infer_expr_inner(*expr, &expectation);
match rawness {
Rawness::RawPtr => TyKind::Raw(mutability, inner_ty),
Rawness::Ref => TyKind::Ref(mutability, static_lifetime(), inner_ty),
}
.intern(Interner)
}
&Expr::Box { expr } => self.infer_expr_box(expr, expected),
Expr::UnaryOp { expr, op } => {
let inner_ty = self.infer_expr_inner(*expr, &Expectation::none());
let inner_ty = self.resolve_ty_shallow(&inner_ty);
// FIXME: Note down method resolution her
match op {
UnaryOp::Deref => {
if let Some(deref_trait) = self.resolve_lang_trait(LangItem::Deref) {
if let Some(deref_fn) =
self.db.trait_data(deref_trait).method_by_name(&name![deref])
{
// FIXME: this is wrong in multiple ways, subst is empty, and we emit it even for builtin deref (note that
// the mutability is not wrong, and will be fixed in `self.infer_mut`).
self.write_method_resolution(
tgt_expr,
deref_fn,
Substitution::empty(Interner),
);
}
}
if let Some(derefed) = builtin_deref(&mut self.table, &inner_ty, true) {
self.resolve_ty_shallow(derefed)
} else {
deref_by_trait(&mut self.table, inner_ty)
.unwrap_or_else(|| self.err_ty())
}
}
UnaryOp::Neg => {
match inner_ty.kind(Interner) {
// Fast path for builtins
TyKind::Scalar(Scalar::Int(_) | Scalar::Uint(_) | Scalar::Float(_))
| TyKind::InferenceVar(
_,
TyVariableKind::Integer | TyVariableKind::Float,
) => inner_ty,
// Otherwise we resolve via the std::ops::Neg trait
_ => self
.resolve_associated_type(inner_ty, self.resolve_ops_neg_output()),
}
}
UnaryOp::Not => {
match inner_ty.kind(Interner) {
// Fast path for builtins
TyKind::Scalar(Scalar::Bool | Scalar::Int(_) | Scalar::Uint(_))
| TyKind::InferenceVar(_, TyVariableKind::Integer) => inner_ty,
// Otherwise we resolve via the std::ops::Not trait
_ => self
.resolve_associated_type(inner_ty, self.resolve_ops_not_output()),
}
}
}
}
Expr::BinaryOp { lhs, rhs, op } => match op {
Some(BinaryOp::Assignment { op: None }) => {
let lhs = *lhs;
let is_ordinary = match &self.body[lhs] {
Expr::Array(_)
| Expr::RecordLit { .. }
| Expr::Tuple { .. }
| Expr::Underscore => false,
Expr::Call { callee, .. } => !matches!(&self.body[*callee], Expr::Path(_)),
_ => true,
};
// In ordinary (non-destructuring) assignments, the type of
// `lhs` must be inferred first so that the ADT fields
// instantiations in RHS can be coerced to it. Note that this
// cannot happen in destructuring assignments because of how
// they are desugared.
if is_ordinary {
let lhs_ty = self.infer_expr(lhs, &Expectation::none());
self.infer_expr_coerce(*rhs, &Expectation::has_type(lhs_ty));
} else {
let rhs_ty = self.infer_expr(*rhs, &Expectation::none());
self.infer_assignee_expr(lhs, &rhs_ty);
}
self.result.standard_types.unit.clone()
}
Some(BinaryOp::LogicOp(_)) => {
let bool_ty = self.result.standard_types.bool_.clone();
self.infer_expr_coerce(*lhs, &Expectation::HasType(bool_ty.clone()));
let lhs_diverges = self.diverges;
self.infer_expr_coerce(*rhs, &Expectation::HasType(bool_ty.clone()));
// Depending on the LHS' value, the RHS can never execute.
self.diverges = lhs_diverges;
bool_ty
}
Some(op) => self.infer_overloadable_binop(*lhs, *op, *rhs, tgt_expr),
_ => self.err_ty(),
},
Expr::Range { lhs, rhs, range_type } => {
let lhs_ty = lhs.map(|e| self.infer_expr_inner(e, &Expectation::none()));
let rhs_expect = lhs_ty
.as_ref()
.map_or_else(Expectation::none, |ty| Expectation::has_type(ty.clone()));
let rhs_ty = rhs.map(|e| self.infer_expr(e, &rhs_expect));
match (range_type, lhs_ty, rhs_ty) {
(RangeOp::Exclusive, None, None) => match self.resolve_range_full() {
Some(adt) => TyBuilder::adt(self.db, adt).build(),
None => self.err_ty(),
},
(RangeOp::Exclusive, None, Some(ty)) => match self.resolve_range_to() {
Some(adt) => TyBuilder::adt(self.db, adt).push(ty).build(),
None => self.err_ty(),
},
(RangeOp::Inclusive, None, Some(ty)) => {
match self.resolve_range_to_inclusive() {
Some(adt) => TyBuilder::adt(self.db, adt).push(ty).build(),
None => self.err_ty(),
}
}
(RangeOp::Exclusive, Some(_), Some(ty)) => match self.resolve_range() {
Some(adt) => TyBuilder::adt(self.db, adt).push(ty).build(),
None => self.err_ty(),
},
(RangeOp::Inclusive, Some(_), Some(ty)) => {
match self.resolve_range_inclusive() {
Some(adt) => TyBuilder::adt(self.db, adt).push(ty).build(),
None => self.err_ty(),
}
}
(RangeOp::Exclusive, Some(ty), None) => match self.resolve_range_from() {
Some(adt) => TyBuilder::adt(self.db, adt).push(ty).build(),
None => self.err_ty(),
},
(RangeOp::Inclusive, _, None) => self.err_ty(),
}
}
Expr::Index { base, index, is_assignee_expr } => {
let base_ty = self.infer_expr_inner(*base, &Expectation::none());
let index_ty = self.infer_expr(*index, &Expectation::none());
if let Some(index_trait) = self.resolve_lang_trait(LangItem::Index) {
let canonicalized = self.canonicalize(base_ty.clone());
let receiver_adjustments = method_resolution::resolve_indexing_op(
self.db,
self.table.trait_env.clone(),
canonicalized.value,
index_trait,
);
let (self_ty, mut adj) = receiver_adjustments
.map_or((self.err_ty(), Vec::new()), |adj| {
adj.apply(&mut self.table, base_ty)
});
// mutability will be fixed up in `InferenceContext::infer_mut`;
adj.push(Adjustment::borrow(Mutability::Not, self_ty.clone()));
self.write_expr_adj(*base, adj);
if let Some(func) =
self.db.trait_data(index_trait).method_by_name(&name!(index))
{
let substs = TyBuilder::subst_for_def(self.db, index_trait, None)
.push(self_ty.clone())
.push(index_ty.clone())
.build();
self.write_method_resolution(tgt_expr, func, substs);
}
let assoc = self.resolve_ops_index_output();
let res = self.resolve_associated_type_with_params(
self_ty.clone(),
assoc,
&[index_ty.clone().cast(Interner)],
);
if *is_assignee_expr {
if let Some(index_trait) = self.resolve_lang_trait(LangItem::IndexMut) {
let trait_ref = TyBuilder::trait_ref(self.db, index_trait)
.push(self_ty)
.fill(|_| index_ty.clone().cast(Interner))
.build();
self.push_obligation(trait_ref.cast(Interner));
}
}
res
} else {
self.err_ty()
}
}
Expr::Tuple { exprs, .. } => {
let mut tys = match expected
.only_has_type(&mut self.table)
.as_ref()
.map(|t| t.kind(Interner))
{
Some(TyKind::Tuple(_, substs)) => substs
.iter(Interner)
.map(|a| a.assert_ty_ref(Interner).clone())
.chain(repeat_with(|| self.table.new_type_var()))
.take(exprs.len())
.collect::<Vec<_>>(),
_ => (0..exprs.len()).map(|_| self.table.new_type_var()).collect(),
};
for (expr, ty) in exprs.iter().zip(tys.iter_mut()) {
self.infer_expr_coerce(*expr, &Expectation::has_type(ty.clone()));
}
TyKind::Tuple(tys.len(), Substitution::from_iter(Interner, tys)).intern(Interner)
}
Expr::Array(array) => self.infer_expr_array(array, expected),
Expr::Literal(lit) => match lit {
Literal::Bool(..) => self.result.standard_types.bool_.clone(),
Literal::String(..) => {
TyKind::Ref(Mutability::Not, static_lifetime(), TyKind::Str.intern(Interner))
.intern(Interner)
}
Literal::ByteString(bs) => {
let byte_type = TyKind::Scalar(Scalar::Uint(UintTy::U8)).intern(Interner);
let len = consteval::usize_const(
self.db,
Some(bs.len() as u128),
self.resolver.krate(),
);
let array_type = TyKind::Array(byte_type, len).intern(Interner);
TyKind::Ref(Mutability::Not, static_lifetime(), array_type).intern(Interner)
}
Literal::CString(..) => TyKind::Ref(
Mutability::Not,
static_lifetime(),
self.resolve_lang_item(LangItem::CStr)
.and_then(LangItemTarget::as_struct)
.map_or_else(
|| self.err_ty(),
|strukt| {
TyKind::Adt(AdtId(strukt.into()), Substitution::empty(Interner))
.intern(Interner)
},
),
)
.intern(Interner),
Literal::Char(..) => TyKind::Scalar(Scalar::Char).intern(Interner),
Literal::Int(_v, ty) => match ty {
Some(int_ty) => {
TyKind::Scalar(Scalar::Int(primitive::int_ty_from_builtin(*int_ty)))
.intern(Interner)
}
None => self.table.new_integer_var(),
},
Literal::Uint(_v, ty) => match ty {
Some(int_ty) => {
TyKind::Scalar(Scalar::Uint(primitive::uint_ty_from_builtin(*int_ty)))
.intern(Interner)
}
None => self.table.new_integer_var(),
},
Literal::Float(_v, ty) => match ty {
Some(float_ty) => {
TyKind::Scalar(Scalar::Float(primitive::float_ty_from_builtin(*float_ty)))
.intern(Interner)
}
None => self.table.new_float_var(),
},
},
Expr::Underscore => {
// Underscore expressions may only appear in assignee expressions,
// which are handled by `infer_assignee_expr()`.
// Any other underscore expression is an error, we render a specialized diagnostic
// to let the user know what type is expected though.
let expected = expected.to_option(&mut self.table).unwrap_or_else(|| self.err_ty());
self.push_diagnostic(InferenceDiagnostic::TypedHole {
expr: tgt_expr,
expected: expected.clone(),
});
expected
}
Expr::OffsetOf(_) => TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(Interner),
Expr::InlineAsm(it) => {
self.infer_expr_no_expect(it.e);
self.result.standard_types.unit.clone()
}
};
// use a new type variable if we got unknown here
let ty = self.insert_type_vars_shallow(ty);
self.write_expr_ty(tgt_expr, ty.clone());
if self.resolve_ty_shallow(&ty).is_never() {
// Any expression that produces a value of type `!` must have diverged
self.diverges = Diverges::Always;
}
ty
}
fn infer_async_block(
&mut self,
tgt_expr: ExprId,
id: &Option<BlockId>,
statements: &[Statement],
tail: &Option<ExprId>,
) -> Ty {
let ret_ty = self.table.new_type_var();
let prev_diverges = mem::replace(&mut self.diverges, Diverges::Maybe);
let prev_ret_ty = mem::replace(&mut self.return_ty, ret_ty.clone());
let prev_ret_coercion =
mem::replace(&mut self.return_coercion, Some(CoerceMany::new(ret_ty.clone())));
let (_, inner_ty) = self.with_breakable_ctx(BreakableKind::Border, None, None, |this| {
this.infer_block(tgt_expr, *id, statements, *tail, None, &Expectation::has_type(ret_ty))
});
self.diverges = prev_diverges;
self.return_ty = prev_ret_ty;
self.return_coercion = prev_ret_coercion;
self.lower_async_block_type_impl_trait(inner_ty, tgt_expr)
}
pub(crate) fn lower_async_block_type_impl_trait(
&mut self,
inner_ty: Ty,
tgt_expr: ExprId,
) -> Ty {
// Use the first type parameter as the output type of future.
// existential type AsyncBlockImplTrait<InnerType>: Future<Output = InnerType>
let impl_trait_id = crate::ImplTraitId::AsyncBlockTypeImplTrait(self.owner, tgt_expr);
let opaque_ty_id = self.db.intern_impl_trait_id(impl_trait_id).into();
TyKind::OpaqueType(opaque_ty_id, Substitution::from1(Interner, inner_ty)).intern(Interner)
}
pub(crate) fn write_fn_trait_method_resolution(
&mut self,
fn_x: FnTrait,
derefed_callee: &Ty,
adjustments: &mut Vec<Adjustment>,
callee_ty: &Ty,
params: &Vec<Ty>,
tgt_expr: ExprId,
) {
match fn_x {
FnTrait::FnOnce => (),
FnTrait::FnMut => {
if let TyKind::Ref(Mutability::Mut, _, inner) = derefed_callee.kind(Interner) {
if adjustments
.last()
.map(|it| matches!(it.kind, Adjust::Borrow(_)))
.unwrap_or(true)
{
// prefer reborrow to move
adjustments
.push(Adjustment { kind: Adjust::Deref(None), target: inner.clone() });
adjustments.push(Adjustment::borrow(Mutability::Mut, inner.clone()))
}
} else {
adjustments.push(Adjustment::borrow(Mutability::Mut, derefed_callee.clone()));
}
}
FnTrait::Fn => {
if !matches!(derefed_callee.kind(Interner), TyKind::Ref(Mutability::Not, _, _)) {
adjustments.push(Adjustment::borrow(Mutability::Not, derefed_callee.clone()));
}
}
}
let Some(trait_) = fn_x.get_id(self.db, self.table.trait_env.krate) else {
return;
};
let trait_data = self.db.trait_data(trait_);
if let Some(func) = trait_data.method_by_name(&fn_x.method_name()) {
let subst = TyBuilder::subst_for_def(self.db, trait_, None)
.push(callee_ty.clone())
.push(TyBuilder::tuple_with(params.iter().cloned()))
.build();
self.write_method_resolution(tgt_expr, func, subst);
}
}
fn infer_expr_array(
&mut self,
array: &Array,
expected: &Expectation,
) -> chalk_ir::Ty<Interner> {
let elem_ty = match expected.to_option(&mut self.table).as_ref().map(|t| t.kind(Interner)) {
Some(TyKind::Array(st, _) | TyKind::Slice(st)) => st.clone(),
_ => self.table.new_type_var(),
};
let krate = self.resolver.krate();
let expected = Expectation::has_type(elem_ty.clone());
let (elem_ty, len) = match array {
Array::ElementList { elements, .. } if elements.is_empty() => {
(elem_ty, consteval::usize_const(self.db, Some(0), krate))
}
Array::ElementList { elements, .. } => {
let mut coerce = CoerceMany::new(elem_ty);
for &expr in elements.iter() {
let cur_elem_ty = self.infer_expr_inner(expr, &expected);
coerce.coerce(self, Some(expr), &cur_elem_ty, CoercionCause::Expr(expr));
}
(
coerce.complete(self),
consteval::usize_const(self.db, Some(elements.len() as u128), krate),
)
}
&Array::Repeat { initializer, repeat } => {
self.infer_expr_coerce(initializer, &Expectation::has_type(elem_ty.clone()));
let usize = TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(Interner);
match self.body[repeat] {
Expr::Underscore => {
self.write_expr_ty(repeat, usize);
}
_ => _ = self.infer_expr(repeat, &Expectation::HasType(usize)),
}
(
elem_ty,
if let Some(g_def) = self.owner.as_generic_def_id() {
let generics = generics(self.db.upcast(), g_def);
consteval::eval_to_const(
repeat,
ParamLoweringMode::Placeholder,
self,
|| generics,
DebruijnIndex::INNERMOST,
)
} else {
consteval::usize_const(self.db, None, krate)
},
)
}
};
// Try to evaluate unevaluated constant, and insert variable if is not possible.
let len = self.table.insert_const_vars_shallow(len);
TyKind::Array(elem_ty, len).intern(Interner)
}
pub(super) fn infer_return(&mut self, expr: ExprId) {
let ret_ty = self
.return_coercion
.as_mut()
.expect("infer_return called outside function body")
.expected_ty();
let return_expr_ty = self.infer_expr_inner(expr, &Expectation::HasType(ret_ty));
let mut coerce_many = self.return_coercion.take().unwrap();
coerce_many.coerce(self, Some(expr), &return_expr_ty, CoercionCause::Expr(expr));
self.return_coercion = Some(coerce_many);
}
fn infer_expr_return(&mut self, ret: ExprId, expr: Option<ExprId>) -> Ty {
match self.return_coercion {
Some(_) => {
if let Some(expr) = expr {
self.infer_return(expr);
} else {
let mut coerce = self.return_coercion.take().unwrap();
coerce.coerce_forced_unit(self, CoercionCause::Expr(ret));
self.return_coercion = Some(coerce);
}
}
None => {
// FIXME: diagnose return outside of function
if let Some(expr) = expr {
self.infer_expr_no_expect(expr);
}
}
}
self.result.standard_types.never.clone()
}
fn infer_expr_box(&mut self, inner_expr: ExprId, expected: &Expectation) -> Ty {
if let Some(box_id) = self.resolve_boxed_box() {
let table = &mut self.table;
let inner_exp = expected
.to_option(table)
.as_ref()
.map(|e| e.as_adt())
.flatten()
.filter(|(e_adt, _)| e_adt == &box_id)
.map(|(_, subts)| {
let g = subts.at(Interner, 0);
Expectation::rvalue_hint(self, Ty::clone(g.assert_ty_ref(Interner)))
})
.unwrap_or_else(Expectation::none);
let inner_ty = self.infer_expr_inner(inner_expr, &inner_exp);
TyBuilder::adt(self.db, box_id)
.push(inner_ty)
.fill_with_defaults(self.db, || self.table.new_type_var())
.build()
} else {
self.err_ty()
}
}
pub(super) fn infer_assignee_expr(&mut self, lhs: ExprId, rhs_ty: &Ty) -> Ty {
let is_rest_expr = |expr| {
matches!(
&self.body[expr],
Expr::Range { lhs: None, rhs: None, range_type: RangeOp::Exclusive },
)
};
let rhs_ty = self.resolve_ty_shallow(rhs_ty);
let ty = match &self.body[lhs] {
Expr::Tuple { exprs, .. } => {
// We don't consider multiple ellipses. This is analogous to
// `hir_def::body::lower::ExprCollector::collect_tuple_pat()`.
let ellipsis = exprs.iter().position(|e| is_rest_expr(*e));
let exprs: Vec<_> = exprs.iter().filter(|e| !is_rest_expr(**e)).copied().collect();
self.infer_tuple_pat_like(&rhs_ty, (), ellipsis, &exprs)
}
Expr::Call { callee, args, .. } => {
// Tuple structs
let path = match &self.body[*callee] {
Expr::Path(path) => Some(path),
_ => None,
};
// We don't consider multiple ellipses. This is analogous to
// `hir_def::body::lower::ExprCollector::collect_tuple_pat()`.
let ellipsis = args.iter().position(|e| is_rest_expr(*e));
let args: Vec<_> = args.iter().filter(|e| !is_rest_expr(**e)).copied().collect();
self.infer_tuple_struct_pat_like(path, &rhs_ty, (), lhs, ellipsis, &args)
}
Expr::Array(Array::ElementList { elements, .. }) => {
let elem_ty = match rhs_ty.kind(Interner) {
TyKind::Array(st, _) => st.clone(),
_ => self.err_ty(),
};
// There's no need to handle `..` as it cannot be bound.
let sub_exprs = elements.iter().filter(|e| !is_rest_expr(**e));
for e in sub_exprs {
self.infer_assignee_expr(*e, &elem_ty);
}
match rhs_ty.kind(Interner) {
TyKind::Array(_, _) => rhs_ty.clone(),
// Even when `rhs_ty` is not an array type, this assignee
// expression is inferred to be an array (of unknown element
// type and length). This should not be just an error type,
// because we are to compute the unifiability of this type and
// `rhs_ty` in the end of this function to issue type mismatches.
_ => TyKind::Array(
self.err_ty(),
crate::consteval::usize_const(self.db, None, self.resolver.krate()),
)
.intern(Interner),
}
}
Expr::RecordLit { path, fields, .. } => {
let subs = fields.iter().map(|f| (f.name.clone(), f.expr));
self.infer_record_pat_like(path.as_deref(), &rhs_ty, (), lhs, subs)
}
Expr::Underscore => rhs_ty.clone(),
_ => {
// `lhs` is a place expression, a unit struct, or an enum variant.
let lhs_ty = self.infer_expr_inner(lhs, &Expectation::none());
// This is the only branch where this function may coerce any type.
// We are returning early to avoid the unifiability check below.
let lhs_ty = self.insert_type_vars_shallow(lhs_ty);
let ty = match self.coerce(None, &rhs_ty, &lhs_ty) {
Ok(ty) => ty,
Err(_) => {
self.result.type_mismatches.insert(
lhs.into(),
TypeMismatch { expected: rhs_ty.clone(), actual: lhs_ty.clone() },
);
// `rhs_ty` is returned so no further type mismatches are
// reported because of this mismatch.
rhs_ty
}
};
self.write_expr_ty(lhs, ty.clone());
return ty;
}
};
let ty = self.insert_type_vars_shallow(ty);
if !self.unify(&ty, &rhs_ty) {
self.result
.type_mismatches
.insert(lhs.into(), TypeMismatch { expected: rhs_ty.clone(), actual: ty.clone() });
}
self.write_expr_ty(lhs, ty.clone());
ty
}
fn infer_overloadable_binop(
&mut self,
lhs: ExprId,
op: BinaryOp,
rhs: ExprId,
tgt_expr: ExprId,
) -> Ty {
let lhs_expectation = Expectation::none();
let lhs_ty = self.infer_expr(lhs, &lhs_expectation);
let rhs_ty = self.table.new_type_var();
let trait_func = lang_items_for_bin_op(op).and_then(|(name, lang_item)| {
let trait_id = self.resolve_lang_item(lang_item)?.as_trait()?;
let func = self.db.trait_data(trait_id).method_by_name(&name)?;
Some((trait_id, func))
});
let (trait_, func) = match trait_func {
Some(it) => it,
None => {
// HACK: `rhs_ty` is a general inference variable with no clue at all at this
// point. Passing `lhs_ty` as both operands just to check if `lhs_ty` is a builtin
// type applicable to `op`.
let ret_ty = if self.is_builtin_binop(&lhs_ty, &lhs_ty, op) {
// Assume both operands are builtin so we can continue inference. No guarantee
// on the correctness, rustc would complain as necessary lang items don't seem
// to exist anyway.
self.enforce_builtin_binop_types(&lhs_ty, &rhs_ty, op)
} else {
self.err_ty()
};
self.infer_expr_coerce(rhs, &Expectation::has_type(rhs_ty));
return ret_ty;
}
};
// HACK: We can use this substitution for the function because the function itself doesn't
// have its own generic parameters.
let subst = TyBuilder::subst_for_def(self.db, trait_, None)
.push(lhs_ty.clone())
.push(rhs_ty.clone())
.build();
self.write_method_resolution(tgt_expr, func, subst.clone());
let method_ty = self.db.value_ty(func.into()).substitute(Interner, &subst);
self.register_obligations_for_call(&method_ty);
self.infer_expr_coerce(rhs, &Expectation::has_type(rhs_ty.clone()));
let ret_ty = match method_ty.callable_sig(self.db) {
Some(sig) => {
let p_left = &sig.params()[0];
if matches!(op, BinaryOp::CmpOp(..) | BinaryOp::Assignment { .. }) {
if let &TyKind::Ref(mtbl, _, _) = p_left.kind(Interner) {
self.write_expr_adj(
lhs,
vec![Adjustment {
kind: Adjust::Borrow(AutoBorrow::Ref(mtbl)),
target: p_left.clone(),
}],
);
}
}
let p_right = &sig.params()[1];
if matches!(op, BinaryOp::CmpOp(..)) {
if let &TyKind::Ref(mtbl, _, _) = p_right.kind(Interner) {
self.write_expr_adj(
rhs,
vec![Adjustment {
kind: Adjust::Borrow(AutoBorrow::Ref(mtbl)),
target: p_right.clone(),
}],
);
}
}
sig.ret().clone()
}
None => self.err_ty(),
};
let ret_ty = self.normalize_associated_types_in(ret_ty);
if self.is_builtin_binop(&lhs_ty, &rhs_ty, op) {
// use knowledge of built-in binary ops, which can sometimes help inference
let builtin_ret = self.enforce_builtin_binop_types(&lhs_ty, &rhs_ty, op);
self.unify(&builtin_ret, &ret_ty);
}
ret_ty
}
fn infer_block(
&mut self,
expr: ExprId,
block_id: Option<BlockId>,
statements: &[Statement],
tail: Option<ExprId>,
label: Option<LabelId>,
expected: &Expectation,
) -> Ty {
let coerce_ty = expected.coercion_target_type(&mut self.table);
let g = self.resolver.update_to_inner_scope(self.db.upcast(), self.owner, expr);
let prev_env = block_id.map(|block_id| {
let prev_env = self.table.trait_env.clone();
TraitEnvironment::with_block(&mut self.table.trait_env, block_id);
prev_env
});
let (break_ty, ty) =
self.with_breakable_ctx(BreakableKind::Block, Some(coerce_ty), label, |this| {
for stmt in statements {
match stmt {
Statement::Let { pat, type_ref, initializer, else_branch } => {
let decl_ty = type_ref
.as_ref()
.map(|tr| this.make_ty(tr))
.unwrap_or_else(|| this.table.new_type_var());
let ty = if let Some(expr) = initializer {
let ty = if contains_explicit_ref_binding(&this.body, *pat) {
this.infer_expr(*expr, &Expectation::has_type(decl_ty.clone()))
} else {
this.infer_expr_coerce(
*expr,
&Expectation::has_type(decl_ty.clone()),
)
};
if type_ref.is_some() {
decl_ty
} else {
ty
}
} else {
decl_ty
};
this.infer_top_pat(*pat, &ty);
if let Some(expr) = else_branch {
let previous_diverges =
mem::replace(&mut this.diverges, Diverges::Maybe);
this.infer_expr_coerce(
*expr,
&Expectation::HasType(this.result.standard_types.never.clone()),
);
this.diverges = previous_diverges;
}
}
&Statement::Expr { expr, has_semi } => {
if has_semi {
this.infer_expr(expr, &Expectation::none());
} else {
this.infer_expr_coerce(
expr,
&Expectation::HasType(this.result.standard_types.unit.clone()),
);
}
}
}
}
// FIXME: This should make use of the breakable CoerceMany
if let Some(expr) = tail {
this.infer_expr_coerce(expr, expected)
} else {
// Citing rustc: if there is no explicit tail expression,
// that is typically equivalent to a tail expression
// of `()` -- except if the block diverges. In that
// case, there is no value supplied from the tail
// expression (assuming there are no other breaks,
// this implies that the type of the block will be
// `!`).
if this.diverges.is_always() {
// we don't even make an attempt at coercion
this.table.new_maybe_never_var()
} else if let Some(t) = expected.only_has_type(&mut this.table) {
if this
.coerce(Some(expr), &this.result.standard_types.unit.clone(), &t)
.is_err()
{
this.result.type_mismatches.insert(
expr.into(),
TypeMismatch {
expected: t.clone(),
actual: this.result.standard_types.unit.clone(),
},
);
}
t
} else {
this.result.standard_types.unit.clone()
}
}
});
self.resolver.reset_to_guard(g);
if let Some(prev_env) = prev_env {
self.table.trait_env = prev_env;
}
break_ty.unwrap_or(ty)
}
fn lookup_field(
&mut self,
receiver_ty: &Ty,
name: &Name,
) -> Option<(Ty, Either<FieldId, TupleFieldId>, Vec<Adjustment>, bool)> {
let mut autoderef = Autoderef::new(&mut self.table, receiver_ty.clone(), false);
let mut private_field = None;
let res = autoderef.by_ref().find_map(|(derefed_ty, _)| {
let (field_id, parameters) = match derefed_ty.kind(Interner) {
TyKind::Tuple(_, substs) => {
return name.as_tuple_index().and_then(|idx| {
substs
.as_slice(Interner)
.get(idx)
.map(|a| a.assert_ty_ref(Interner))
.cloned()
.map(|ty| {
(
Either::Right(TupleFieldId {
tuple: TupleId(
self.tuple_field_accesses_rev
.insert_full(substs.clone())
.0
as u32,
),
index: idx as u32,
}),
ty,
)
})
});
}
TyKind::Adt(AdtId(hir_def::AdtId::StructId(s)), parameters) => {
let local_id = self.db.struct_data(*s).variant_data.field(name)?;
let field = FieldId { parent: (*s).into(), local_id };
(field, parameters.clone())
}
TyKind::Adt(AdtId(hir_def::AdtId::UnionId(u)), parameters) => {
let local_id = self.db.union_data(*u).variant_data.field(name)?;
let field = FieldId { parent: (*u).into(), local_id };
(field, parameters.clone())
}
_ => return None,
};
let is_visible = self.db.field_visibilities(field_id.parent)[field_id.local_id]
.is_visible_from(self.db.upcast(), self.resolver.module());
if !is_visible {
if private_field.is_none() {
private_field = Some((field_id, parameters));
}
return None;
}
let ty = self.db.field_types(field_id.parent)[field_id.local_id]
.clone()
.substitute(Interner, &parameters);
Some((Either::Left(field_id), ty))
});
Some(match res {
Some((field_id, ty)) => {
let adjustments = auto_deref_adjust_steps(&autoderef);
let ty = self.insert_type_vars(ty);
let ty = self.normalize_associated_types_in(ty);
(ty, field_id, adjustments, true)
}
None => {
let (field_id, subst) = private_field?;
let adjustments = auto_deref_adjust_steps(&autoderef);
let ty = self.db.field_types(field_id.parent)[field_id.local_id]
.clone()
.substitute(Interner, &subst);
let ty = self.insert_type_vars(ty);
let ty = self.normalize_associated_types_in(ty);
(ty, Either::Left(field_id), adjustments, false)
}
})
}
fn infer_field_access(
&mut self,
tgt_expr: ExprId,
receiver: ExprId,
name: &Name,
expected: &Expectation,
) -> Ty {
let receiver_ty = self.infer_expr_inner(receiver, &Expectation::none());
if name.is_missing() {
// Bail out early, don't even try to look up field. Also, we don't issue an unresolved
// field diagnostic because this is a syntax error rather than a semantic error.
return self.err_ty();
}
match self.lookup_field(&receiver_ty, name) {
Some((ty, field_id, adjustments, is_public)) => {
self.write_expr_adj(receiver, adjustments);
self.result.field_resolutions.insert(tgt_expr, field_id);
if !is_public {
if let Either::Left(field) = field_id {
// FIXME: Merge this diagnostic into UnresolvedField?
self.result
.diagnostics
.push(InferenceDiagnostic::PrivateField { expr: tgt_expr, field });
}
}
ty
}
None => {
// no field found, lets attempt to resolve it like a function so that IDE things
// work out while people are typing
let canonicalized_receiver = self.canonicalize(receiver_ty.clone());
let resolved = method_resolution::lookup_method(
self.db,
&canonicalized_receiver.value,
self.table.trait_env.clone(),
self.get_traits_in_scope().as_ref().left_or_else(|&it| it),
VisibleFromModule::Filter(self.resolver.module()),
name,
);
self.result.diagnostics.push(InferenceDiagnostic::UnresolvedField {
expr: tgt_expr,
receiver: receiver_ty.clone(),
name: name.clone(),
method_with_same_name_exists: resolved.is_some(),
});
match resolved {
Some((adjust, func, _)) => {
let (ty, adjustments) = adjust.apply(&mut self.table, receiver_ty);
let generics = generics(self.db.upcast(), func.into());
let substs = self.substs_for_method_call(generics, None);
self.write_expr_adj(receiver, adjustments);
self.write_method_resolution(tgt_expr, func, substs.clone());
self.check_method_call(
tgt_expr,
&[],
self.db.value_ty(func.into()),
substs,
ty,
expected,
)
}
None => self.err_ty(),
}
}
}
}
fn infer_method_call(
&mut self,
tgt_expr: ExprId,
receiver: ExprId,
args: &[ExprId],
method_name: &Name,
generic_args: Option<&GenericArgs>,
expected: &Expectation,
) -> Ty {
let receiver_ty = self.infer_expr_inner(receiver, &Expectation::none());
let canonicalized_receiver = self.canonicalize(receiver_ty.clone());
let resolved = method_resolution::lookup_method(
self.db,
&canonicalized_receiver.value,
self.table.trait_env.clone(),
self.get_traits_in_scope().as_ref().left_or_else(|&it| it),
VisibleFromModule::Filter(self.resolver.module()),
method_name,
);
let (receiver_ty, method_ty, substs) = match resolved {
Some((adjust, func, visible)) => {
let (ty, adjustments) = adjust.apply(&mut self.table, receiver_ty);
let generics = generics(self.db.upcast(), func.into());
let substs = self.substs_for_method_call(generics, generic_args);
self.write_expr_adj(receiver, adjustments);
self.write_method_resolution(tgt_expr, func, substs.clone());
if !visible {
self.push_diagnostic(InferenceDiagnostic::PrivateAssocItem {
id: tgt_expr.into(),
item: func.into(),
})
}
(ty, self.db.value_ty(func.into()), substs)
}
None => {
let field_with_same_name_exists = match self.lookup_field(&receiver_ty, method_name)
{
Some((ty, field_id, adjustments, _public)) => {
self.write_expr_adj(receiver, adjustments);
self.result.field_resolutions.insert(tgt_expr, field_id);
Some(ty)
}
None => None,
};
let assoc_func_with_same_name = method_resolution::iterate_method_candidates(
&canonicalized_receiver.value,
self.db,
self.table.trait_env.clone(),
self.get_traits_in_scope().as_ref().left_or_else(|&it| it),
VisibleFromModule::Filter(self.resolver.module()),
Some(method_name),
method_resolution::LookupMode::Path,
|_ty, item, visible| {
if visible {
Some(item)
} else {
None
}
},
);
self.result.diagnostics.push(InferenceDiagnostic::UnresolvedMethodCall {
expr: tgt_expr,
receiver: receiver_ty.clone(),
name: method_name.clone(),
field_with_same_name: field_with_same_name_exists,
assoc_func_with_same_name,
});
(
receiver_ty,
Binders::empty(Interner, self.err_ty()),
Substitution::empty(Interner),
)
}
};
self.check_method_call(tgt_expr, args, method_ty, substs, receiver_ty, expected)
}
fn check_method_call(
&mut self,
tgt_expr: ExprId,
args: &[ExprId],
method_ty: Binders<Ty>,
substs: Substitution,
receiver_ty: Ty,
expected: &Expectation,
) -> Ty {
let method_ty = method_ty.substitute(Interner, &substs);
self.register_obligations_for_call(&method_ty);
let ((formal_receiver_ty, param_tys), ret_ty, is_varargs) =
match method_ty.callable_sig(self.db) {
Some(sig) => (
if !sig.params().is_empty() {
(sig.params()[0].clone(), sig.params()[1..].to_vec())
} else {
(self.err_ty(), Vec::new())
},
sig.ret().clone(),
sig.is_varargs,
),
None => ((self.err_ty(), Vec::new()), self.err_ty(), true),
};
self.unify(&formal_receiver_ty, &receiver_ty);
let expected_inputs =
self.expected_inputs_for_expected_output(expected, ret_ty.clone(), param_tys.clone());
self.check_call_arguments(tgt_expr, args, &expected_inputs, &param_tys, &[], is_varargs);
self.normalize_associated_types_in(ret_ty)
}
fn expected_inputs_for_expected_output(
&mut self,
expected_output: &Expectation,
output: Ty,
inputs: Vec<Ty>,
) -> Vec<Ty> {
if let Some(expected_ty) = expected_output.only_has_type(&mut self.table) {
self.table.fudge_inference(|table| {
if table.try_unify(&expected_ty, &output).is_ok() {
table.resolve_with_fallback(inputs, &|var, kind, _, _| match kind {
chalk_ir::VariableKind::Ty(tk) => var.to_ty(Interner, tk).cast(Interner),
chalk_ir::VariableKind::Lifetime => {
var.to_lifetime(Interner).cast(Interner)
}
chalk_ir::VariableKind::Const(ty) => {
var.to_const(Interner, ty).cast(Interner)
}
})
} else {
Vec::new()
}
})
} else {
Vec::new()
}
}
fn check_call_arguments(
&mut self,
expr: ExprId,
args: &[ExprId],
expected_inputs: &[Ty],
param_tys: &[Ty],
skip_indices: &[u32],
is_varargs: bool,
) {
if args.len() != param_tys.len() + skip_indices.len() && !is_varargs {
self.push_diagnostic(InferenceDiagnostic::MismatchedArgCount {
call_expr: expr,
expected: param_tys.len() + skip_indices.len(),
found: args.len(),
});
}
// Quoting https://github.com/rust-lang/rust/blob/6ef275e6c3cb1384ec78128eceeb4963ff788dca/src/librustc_typeck/check/mod.rs#L3325 --
// We do this in a pretty awful way: first we type-check any arguments
// that are not closures, then we type-check the closures. This is so
// that we have more information about the types of arguments when we
// type-check the functions. This isn't really the right way to do this.
for check_closures in [false, true] {
let mut skip_indices = skip_indices.into_iter().copied().fuse().peekable();
let param_iter = param_tys.iter().cloned().chain(repeat(self.err_ty()));
let expected_iter = expected_inputs
.iter()
.cloned()
.chain(param_iter.clone().skip(expected_inputs.len()));
for (idx, ((&arg, param_ty), expected_ty)) in
args.iter().zip(param_iter).zip(expected_iter).enumerate()
{
let is_closure = matches!(&self.body[arg], Expr::Closure { .. });
if is_closure != check_closures {
continue;
}
while skip_indices.peek().map_or(false, |i| *i < idx as u32) {
skip_indices.next();
}
if skip_indices.peek().copied() == Some(idx as u32) {
continue;
}
// the difference between param_ty and expected here is that
// expected is the parameter when the expected *return* type is
// taken into account. So in `let _: &[i32] = identity(&[1, 2])`
// the expected type is already `&[i32]`, whereas param_ty is
// still an unbound type variable. We don't always want to force
// the parameter to coerce to the expected type (for example in
// `coerce_unsize_expected_type_4`).
let param_ty = self.normalize_associated_types_in(param_ty);
let expected_ty = self.normalize_associated_types_in(expected_ty);
let expected = Expectation::rvalue_hint(self, expected_ty);
// infer with the expected type we have...
let ty = self.infer_expr_inner(arg, &expected);
// then coerce to either the expected type or just the formal parameter type
let coercion_target = if let Some(ty) = expected.only_has_type(&mut self.table) {
// if we are coercing to the expectation, unify with the
// formal parameter type to connect everything
self.unify(&ty, &param_ty);
ty
} else {
param_ty
};
// The function signature may contain some unknown types, so we need to insert
// type vars here to avoid type mismatch false positive.
let coercion_target = self.insert_type_vars(coercion_target);
if self.coerce(Some(arg), &ty, &coercion_target).is_err() {
self.result.type_mismatches.insert(
arg.into(),
TypeMismatch { expected: coercion_target, actual: ty.clone() },
);
}
}
}
}
fn substs_for_method_call(
&mut self,
def_generics: Generics,
generic_args: Option<&GenericArgs>,
) -> Substitution {
let (parent_params, self_params, type_params, const_params, impl_trait_params) =
def_generics.provenance_split();
assert_eq!(self_params, 0); // method shouldn't have another Self param
let total_len = parent_params + type_params + const_params + impl_trait_params;
let mut substs = Vec::with_capacity(total_len);
// handle provided 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, kind_id) in generic_args
.args
.iter()
.filter(|arg| !matches!(arg, GenericArg::Lifetime(_)))
.take(type_params + const_params)
.zip(def_generics.iter_id())
{
if let Some(g) = generic_arg_to_chalk(
self.db,
kind_id,
arg,
self,
|this, type_ref| this.make_ty(type_ref),
|this, c, ty| {
const_or_path_to_chalk(
this.db,
&this.resolver,
this.owner.into(),
ty,
c,
ParamLoweringMode::Placeholder,
|| generics(this.db.upcast(), this.resolver.generic_def().unwrap()),
DebruijnIndex::INNERMOST,
)
},
) {
substs.push(g);
}
}
};
// Handle everything else as unknown. This also handles generic arguments for the method's
// parent (impl or trait), which should come after those for the method.
for (id, data) in def_generics.iter().skip(substs.len()) {
match data {
TypeOrConstParamData::TypeParamData(_) => {
substs.push(self.table.new_type_var().cast(Interner))
}
TypeOrConstParamData::ConstParamData(_) => substs.push(
self.table
.new_const_var(self.db.const_param_ty(ConstParamId::from_unchecked(id)))
.cast(Interner),
),
}
}
assert_eq!(substs.len(), total_len);
Substitution::from_iter(Interner, substs)
}
fn register_obligations_for_call(&mut self, callable_ty: &Ty) {
let callable_ty = self.resolve_ty_shallow(callable_ty);
if let TyKind::FnDef(fn_def, parameters) = callable_ty.kind(Interner) {
let def: CallableDefId = from_chalk(self.db, *fn_def);
let generic_predicates = self.db.generic_predicates(def.into());
for predicate in generic_predicates.iter() {
let (predicate, binders) = predicate
.clone()
.substitute(Interner, parameters)
.into_value_and_skipped_binders();
always!(binders.len(Interner) == 0); // quantified where clauses not yet handled
self.push_obligation(predicate.cast(Interner));
}
// add obligation for trait implementation, if this is a trait method
match def {
CallableDefId::FunctionId(f) => {
if let ItemContainerId::TraitId(trait_) = f.lookup(self.db.upcast()).container {
// construct a TraitRef
let params_len = parameters.len(Interner);
let trait_params_len = generics(self.db.upcast(), trait_.into()).len();
let substs = Substitution::from_iter(
Interner,
// The generic parameters for the trait come after those for the
// function.
&parameters.as_slice(Interner)[params_len - trait_params_len..],
);
self.push_obligation(
TraitRef { trait_id: to_chalk_trait_id(trait_), substitution: substs }
.cast(Interner),
);
}
}
CallableDefId::StructId(_) | CallableDefId::EnumVariantId(_) => {}
}
}
}
/// Returns the argument indices to skip.
fn check_legacy_const_generics(&mut self, callee: Ty, args: &[ExprId]) -> Box<[u32]> {
let (func, subst) = match callee.kind(Interner) {
TyKind::FnDef(fn_id, subst) => {
let callable = CallableDefId::from_chalk(self.db, *fn_id);
let func = match callable {
CallableDefId::FunctionId(f) => f,
_ => return Default::default(),
};
(func, subst)
}
_ => return Default::default(),
};
let data = self.db.function_data(func);
if data.legacy_const_generics_indices.is_empty() {
return Default::default();
}
// only use legacy const generics if the param count matches with them
if data.params.len() + data.legacy_const_generics_indices.len() != args.len() {
if args.len() <= data.params.len() {
return Default::default();
} else {
// there are more parameters than there should be without legacy
// const params; use them
let mut indices = data.legacy_const_generics_indices.clone();
indices.sort();
return indices;
}
}
// check legacy const parameters
for (subst_idx, arg_idx) in data.legacy_const_generics_indices.iter().copied().enumerate() {
let arg = match subst.at(Interner, subst_idx).constant(Interner) {
Some(c) => c,
None => continue, // not a const parameter?
};
if arg_idx >= args.len() as u32 {
continue;
}
let _ty = arg.data(Interner).ty.clone();
let expected = Expectation::none(); // FIXME use actual const ty, when that is lowered correctly
self.infer_expr(args[arg_idx as usize], &expected);
// FIXME: evaluate and unify with the const
}
let mut indices = data.legacy_const_generics_indices.clone();
indices.sort();
indices
}
/// Dereferences a single level of immutable referencing.
fn deref_ty_if_possible(&mut self, ty: &Ty) -> Ty {
let ty = self.resolve_ty_shallow(ty);
match ty.kind(Interner) {
TyKind::Ref(Mutability::Not, _, inner) => self.resolve_ty_shallow(inner),
_ => ty,
}
}
/// Enforces expectations on lhs type and rhs type depending on the operator and returns the
/// output type of the binary op.
fn enforce_builtin_binop_types(&mut self, lhs: &Ty, rhs: &Ty, op: BinaryOp) -> Ty {
// Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work (See rust-lang/rust#57447).
let lhs = self.deref_ty_if_possible(lhs);
let rhs = self.deref_ty_if_possible(rhs);
let (op, is_assign) = match op {
BinaryOp::Assignment { op: Some(inner) } => (BinaryOp::ArithOp(inner), true),
_ => (op, false),
};
let output_ty = match op {
BinaryOp::LogicOp(_) => {
let bool_ = self.result.standard_types.bool_.clone();
self.unify(&lhs, &bool_);
self.unify(&rhs, &bool_);
bool_
}
BinaryOp::ArithOp(ArithOp::Shl | ArithOp::Shr) => {
// result type is same as LHS always
lhs
}
BinaryOp::ArithOp(_) => {
// LHS, RHS, and result will have the same type
self.unify(&lhs, &rhs);
lhs
}
BinaryOp::CmpOp(_) => {
// LHS and RHS will have the same type
self.unify(&lhs, &rhs);
self.result.standard_types.bool_.clone()
}
BinaryOp::Assignment { op: None } => {
stdx::never!("Simple assignment operator is not binary op.");
lhs
}
BinaryOp::Assignment { .. } => unreachable!("handled above"),
};
if is_assign {
self.result.standard_types.unit.clone()
} else {
output_ty
}
}
fn is_builtin_binop(&mut self, lhs: &Ty, rhs: &Ty, op: BinaryOp) -> bool {
// Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work (See rust-lang/rust#57447).
let lhs = self.deref_ty_if_possible(lhs);
let rhs = self.deref_ty_if_possible(rhs);
let op = match op {
BinaryOp::Assignment { op: Some(inner) } => BinaryOp::ArithOp(inner),
_ => op,
};
match op {
BinaryOp::LogicOp(_) => true,
BinaryOp::ArithOp(ArithOp::Shl | ArithOp::Shr) => {
lhs.is_integral() && rhs.is_integral()
}
BinaryOp::ArithOp(
ArithOp::Add | ArithOp::Sub | ArithOp::Mul | ArithOp::Div | ArithOp::Rem,
) => {
lhs.is_integral() && rhs.is_integral()
|| lhs.is_floating_point() && rhs.is_floating_point()
}
BinaryOp::ArithOp(ArithOp::BitAnd | ArithOp::BitOr | ArithOp::BitXor) => {
lhs.is_integral() && rhs.is_integral()
|| lhs.is_floating_point() && rhs.is_floating_point()
|| matches!(
(lhs.kind(Interner), rhs.kind(Interner)),
(TyKind::Scalar(Scalar::Bool), TyKind::Scalar(Scalar::Bool))
)
}
BinaryOp::CmpOp(_) => {
let is_scalar = |kind| {
matches!(
kind,
&TyKind::Scalar(_)
| TyKind::FnDef(..)
| TyKind::Function(_)
| TyKind::Raw(..)
| TyKind::InferenceVar(
_,
TyVariableKind::Integer | TyVariableKind::Float
)
)
};
is_scalar(lhs.kind(Interner)) && is_scalar(rhs.kind(Interner))
}
BinaryOp::Assignment { op: None } => {
stdx::never!("Simple assignment operator is not binary op.");
false
}
BinaryOp::Assignment { .. } => unreachable!("handled above"),
}
}
fn with_breakable_ctx<T>(
&mut self,
kind: BreakableKind,
ty: Option<Ty>,
label: Option<LabelId>,
cb: impl FnOnce(&mut Self) -> T,
) -> (Option<Ty>, T) {
self.breakables.push({
BreakableContext { kind, may_break: false, coerce: ty.map(CoerceMany::new), label }
});
let res = cb(self);
let ctx = self.breakables.pop().expect("breakable stack broken");
(if ctx.may_break { ctx.coerce.map(|ctx| ctx.complete(self)) } else { None }, res)
}
}
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