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Refactor & improve handling of overloaded binary operators

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Fixes #9971. Also records them as method resolutions, which we could use
later.
This commit is contained in:
Florian Diebold 2021-08-22 17:21:47 +02:00
parent c8fd4fd410
commit 424dda8113
11 changed files with 317 additions and 261 deletions
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243
crates/hir_ty/src/infer/expr.rs
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@ -8,10 +8,13 @@ use std::{
use chalk_ir::{cast::Cast, fold::Shift, Mutability, TyVariableKind};
use hir_def::{
expr::{Array, BinaryOp, Expr, ExprId, Literal, MatchGuard, Statement, UnaryOp},
expr::{
ArithOp, Array, BinaryOp, CmpOp, Expr, ExprId, Literal, MatchGuard, Ordering, Statement,
UnaryOp,
},
path::{GenericArg, GenericArgs},
resolver::resolver_for_expr,
AssocContainerId, FieldId, Lookup,
AssocContainerId, FieldId, FunctionId, Lookup,
};
use hir_expand::name::{name, Name};
use stdx::always;
@ -23,7 +26,7 @@ use crate::{
infer::coerce::CoerceMany,
lower::lower_to_chalk_mutability,
mapping::from_chalk,
method_resolution, op,
method_resolution,
primitive::{self, UintTy},
static_lifetime, to_chalk_trait_id,
traits::FnTrait,
@ -669,34 +672,21 @@ impl<'a> InferenceContext<'a> {
}
}
Expr::BinaryOp { lhs, rhs, op } => match op {
Some(op) => {
let lhs_expectation = match op {
BinaryOp::LogicOp(..) => {
Expectation::has_type(TyKind::Scalar(Scalar::Bool).intern(&Interner))
}
_ => Expectation::none(),
};
let lhs_ty = self.infer_expr(*lhs, &lhs_expectation);
let lhs_ty = self.resolve_ty_shallow(&lhs_ty);
let rhs_expectation = op::binary_op_rhs_expectation(*op, lhs_ty.clone());
let rhs_ty =
self.infer_expr_coerce(*rhs, &Expectation::has_type(rhs_expectation));
let rhs_ty = self.resolve_ty_shallow(&rhs_ty);
let ret = op::binary_op_return_ty(*op, lhs_ty.clone(), rhs_ty.clone());
if ret.is_unknown() {
cov_mark::hit!(infer_expr_inner_binary_operator_overload);
self.resolve_associated_type_with_params(
lhs_ty,
self.resolve_binary_op_output(op),
&[rhs_ty],
)
} else {
ret
}
Some(BinaryOp::Assignment { op: None }) => {
let lhs_ty = self.infer_expr(*lhs, &Expectation::none());
self.infer_expr_coerce(*rhs, &Expectation::has_type(lhs_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 } => {
@ -862,6 +852,62 @@ impl<'a> InferenceContext<'a> {
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 func = self.resolve_binop_method(op);
let func = match func {
Some(func) => func,
None => {
let rhs_ty = self.builtin_binary_op_rhs_expectation(op, lhs_ty.clone());
let rhs_ty = self.infer_expr_coerce(rhs, &Expectation::from_option(rhs_ty));
return self
.builtin_binary_op_return_ty(op, lhs_ty, rhs_ty)
.unwrap_or_else(|| self.err_ty());
}
};
let subst = TyBuilder::subst_for_def(self.db, func)
.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) => sig.ret().clone(),
None => self.err_ty(),
};
let ret_ty = self.normalize_associated_types_in(ret_ty);
// FIXME: record autoref adjustments
// use knowledge of built-in binary ops, which can sometimes help inference
if let Some(builtin_rhs) = self.builtin_binary_op_rhs_expectation(op, lhs_ty.clone()) {
self.unify(&builtin_rhs, &rhs_ty);
}
if let Some(builtin_ret) =
self.builtin_binary_op_return_ty(op, lhs_ty.clone(), rhs_ty.clone())
{
self.unify(&builtin_ret, &ret_ty);
}
ret_ty
}
fn infer_block(
&mut self,
expr: ExprId,
@ -1136,4 +1182,141 @@ impl<'a> InferenceContext<'a> {
}
}
}
fn builtin_binary_op_return_ty(&mut self, op: BinaryOp, lhs_ty: Ty, rhs_ty: Ty) -> Option<Ty> {
let lhs_ty = self.resolve_ty_shallow(&lhs_ty);
let rhs_ty = self.resolve_ty_shallow(&rhs_ty);
match op {
BinaryOp::LogicOp(_) | BinaryOp::CmpOp(_) => {
Some(TyKind::Scalar(Scalar::Bool).intern(&Interner))
}
BinaryOp::Assignment { .. } => Some(TyBuilder::unit()),
BinaryOp::ArithOp(ArithOp::Shl | ArithOp::Shr) => {
// all integer combinations are valid here
if matches!(
lhs_ty.kind(&Interner),
TyKind::Scalar(Scalar::Int(_) | Scalar::Uint(_))
| TyKind::InferenceVar(_, TyVariableKind::Integer)
) && matches!(
rhs_ty.kind(&Interner),
TyKind::Scalar(Scalar::Int(_) | Scalar::Uint(_))
| TyKind::InferenceVar(_, TyVariableKind::Integer)
) {
Some(lhs_ty)
} else {
None
}
}
BinaryOp::ArithOp(_) => match (lhs_ty.kind(&Interner), rhs_ty.kind(&Interner)) {
// (int, int) | (uint, uint) | (float, float)
(TyKind::Scalar(Scalar::Int(_)), TyKind::Scalar(Scalar::Int(_)))
| (TyKind::Scalar(Scalar::Uint(_)), TyKind::Scalar(Scalar::Uint(_)))
| (TyKind::Scalar(Scalar::Float(_)), TyKind::Scalar(Scalar::Float(_))) => {
Some(rhs_ty)
}
// ({int}, int) | ({int}, uint)
(
TyKind::InferenceVar(_, TyVariableKind::Integer),
TyKind::Scalar(Scalar::Int(_) | Scalar::Uint(_)),
) => Some(rhs_ty),
// (int, {int}) | (uint, {int})
(
TyKind::Scalar(Scalar::Int(_) | Scalar::Uint(_)),
TyKind::InferenceVar(_, TyVariableKind::Integer),
) => Some(lhs_ty),
// ({float} | float)
(
TyKind::InferenceVar(_, TyVariableKind::Float),
TyKind::Scalar(Scalar::Float(_)),
) => Some(rhs_ty),
// (float, {float})
(
TyKind::Scalar(Scalar::Float(_)),
TyKind::InferenceVar(_, TyVariableKind::Float),
) => Some(lhs_ty),
// ({int}, {int}) | ({float}, {float})
(
TyKind::InferenceVar(_, TyVariableKind::Integer),
TyKind::InferenceVar(_, TyVariableKind::Integer),
)
| (
TyKind::InferenceVar(_, TyVariableKind::Float),
TyKind::InferenceVar(_, TyVariableKind::Float),
) => Some(rhs_ty),
_ => None,
},
}
}
fn builtin_binary_op_rhs_expectation(&mut self, op: BinaryOp, lhs_ty: Ty) -> Option<Ty> {
Some(match op {
BinaryOp::LogicOp(..) => TyKind::Scalar(Scalar::Bool).intern(&Interner),
BinaryOp::Assignment { op: None } => lhs_ty,
BinaryOp::CmpOp(CmpOp::Eq { .. }) => match self
.resolve_ty_shallow(&lhs_ty)
.kind(&Interner)
{
TyKind::Scalar(_) | TyKind::Str => lhs_ty,
TyKind::InferenceVar(_, TyVariableKind::Integer | TyVariableKind::Float) => lhs_ty,
_ => return None,
},
BinaryOp::ArithOp(ArithOp::Shl | ArithOp::Shr) => return None,
BinaryOp::CmpOp(CmpOp::Ord { .. })
| BinaryOp::Assignment { op: Some(_) }
| BinaryOp::ArithOp(_) => match self.resolve_ty_shallow(&lhs_ty).kind(&Interner) {
TyKind::Scalar(Scalar::Int(_) | Scalar::Uint(_) | Scalar::Float(_)) => lhs_ty,
TyKind::InferenceVar(_, TyVariableKind::Integer | TyVariableKind::Float) => lhs_ty,
_ => return None,
},
})
}
fn resolve_binop_method(&self, op: BinaryOp) -> Option<FunctionId> {
let (name, lang_item) = match op {
BinaryOp::LogicOp(_) => return None,
BinaryOp::ArithOp(aop) => match aop {
ArithOp::Add => (name!(add), "add"),
ArithOp::Mul => (name!(mul), "mul"),
ArithOp::Sub => (name!(sub), "sub"),
ArithOp::Div => (name!(div), "div"),
ArithOp::Rem => (name!(rem), "rem"),
ArithOp::Shl => (name!(shl), "shl"),
ArithOp::Shr => (name!(shr), "shr"),
ArithOp::BitXor => (name!(bitxor), "bitxor"),
ArithOp::BitOr => (name!(bitor), "bitor"),
ArithOp::BitAnd => (name!(bitand), "bitand"),
},
BinaryOp::Assignment { op: Some(aop) } => match aop {
ArithOp::Add => (name!(add_assign), "add_assign"),
ArithOp::Mul => (name!(mul_assign), "mul_assign"),
ArithOp::Sub => (name!(sub_assign), "sub_assign"),
ArithOp::Div => (name!(div_assign), "div_assign"),
ArithOp::Rem => (name!(rem_assign), "rem_assign"),
ArithOp::Shl => (name!(shl_assign), "shl_assign"),
ArithOp::Shr => (name!(shr_assign), "shr_assign"),
ArithOp::BitXor => (name!(bitxor_assign), "bitxor_assign"),
ArithOp::BitOr => (name!(bitor_assign), "bitor_assign"),
ArithOp::BitAnd => (name!(bitand_assign), "bitand_assign"),
},
BinaryOp::CmpOp(cop) => match cop {
CmpOp::Eq { negated: false } => (name!(eq), "eq"),
CmpOp::Eq { negated: true } => (name!(ne), "eq"),
CmpOp::Ord { ordering: Ordering::Less, strict: false } => {
(name!(le), "partial_ord")
}
CmpOp::Ord { ordering: Ordering::Less, strict: true } => (name!(lt), "partial_ord"),
CmpOp::Ord { ordering: Ordering::Greater, strict: false } => {
(name!(ge), "partial_ord")
}
CmpOp::Ord { ordering: Ordering::Greater, strict: true } => {
(name!(gt), "partial_ord")
}
},
BinaryOp::Assignment { op: None } => return None,
};
let trait_ = self.resolve_lang_item(lang_item)?.as_trait()?;
self.db.trait_data(trait_).method_by_name(&name)
}
}