d66daee849
'Unknown' int/float types actually never exist as such, they get replaced by type variables immediately. So the whole `Uncertain<IntTy>` thing was unnecessary and just led to a bunch of match branches that were never hit.
811 lines
36 KiB
Rust
811 lines
36 KiB
Rust
//! Type inference for expressions.
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use std::iter::{repeat, repeat_with};
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use std::{mem, sync::Arc};
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use hir_def::{
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builtin_type::Signedness,
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expr::{Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
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path::{GenericArg, GenericArgs},
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resolver::resolver_for_expr,
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AdtId, AssocContainerId, FieldId, Lookup,
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};
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use hir_expand::name::Name;
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use ra_syntax::ast::RangeOp;
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use crate::{
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autoderef, method_resolution, op,
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traits::InEnvironment,
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utils::{generics, variant_data, Generics},
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ApplicationTy, Binders, CallableDef, InferTy, IntTy, Mutability, Obligation, Rawness, Substs,
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TraitRef, Ty, TypeCtor,
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};
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use super::{
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find_breakable, BindingMode, BreakableContext, Diverges, Expectation, InferenceContext,
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InferenceDiagnostic, TypeMismatch,
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};
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impl<'a> InferenceContext<'a> {
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pub(super) fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
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let ty = self.infer_expr_inner(tgt_expr, expected);
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if ty.is_never() {
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// Any expression that produces a value of type `!` must have diverged
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self.diverges = Diverges::Always;
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}
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let could_unify = self.unify(&ty, &expected.ty);
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if !could_unify {
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self.result.type_mismatches.insert(
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tgt_expr,
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TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() },
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);
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}
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self.resolve_ty_as_possible(ty)
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}
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/// Infer type of expression with possibly implicit coerce to the expected type.
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/// Return the type after possible coercion.
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pub(super) fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
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let ty = self.infer_expr_inner(expr, &expected);
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let ty = if !self.coerce(&ty, &expected.coercion_target()) {
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self.result
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.type_mismatches
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.insert(expr, TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() });
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// Return actual type when type mismatch.
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// This is needed for diagnostic when return type mismatch.
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ty
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} else if expected.coercion_target() == &Ty::Unknown {
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ty
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} else {
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expected.ty.clone()
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};
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self.resolve_ty_as_possible(ty)
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}
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fn infer_expr_inner(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
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let body = Arc::clone(&self.body); // avoid borrow checker problem
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let ty = match &body[tgt_expr] {
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Expr::Missing => Ty::Unknown,
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Expr::If { condition, then_branch, else_branch } => {
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// if let is desugared to match, so this is always simple if
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self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
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let condition_diverges = mem::replace(&mut self.diverges, Diverges::Maybe);
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let mut both_arms_diverge = Diverges::Always;
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let then_ty = self.infer_expr_inner(*then_branch, &expected);
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both_arms_diverge &= mem::replace(&mut self.diverges, Diverges::Maybe);
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let else_ty = match else_branch {
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Some(else_branch) => self.infer_expr_inner(*else_branch, &expected),
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None => Ty::unit(),
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};
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both_arms_diverge &= self.diverges;
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self.diverges = condition_diverges | both_arms_diverge;
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self.coerce_merge_branch(&then_ty, &else_ty)
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}
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Expr::Block { statements, tail, .. } => {
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// FIXME: Breakable block inference
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self.infer_block(statements, *tail, expected)
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}
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Expr::TryBlock { body } => {
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let _inner = self.infer_expr(*body, expected);
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// FIXME should be std::result::Result<{inner}, _>
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Ty::Unknown
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}
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Expr::Loop { body, label } => {
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self.breakables.push(BreakableContext {
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may_break: false,
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break_ty: self.table.new_type_var(),
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label: label.clone(),
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});
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self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
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let ctxt = self.breakables.pop().expect("breakable stack broken");
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if ctxt.may_break {
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self.diverges = Diverges::Maybe;
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}
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if ctxt.may_break {
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ctxt.break_ty
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} else {
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Ty::simple(TypeCtor::Never)
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}
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}
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Expr::While { condition, body, label } => {
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self.breakables.push(BreakableContext {
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may_break: false,
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break_ty: Ty::Unknown,
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label: label.clone(),
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});
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// while let is desugared to a match loop, so this is always simple while
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self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
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self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
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let _ctxt = self.breakables.pop().expect("breakable stack broken");
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// the body may not run, so it diverging doesn't mean we diverge
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self.diverges = Diverges::Maybe;
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Ty::unit()
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}
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Expr::For { iterable, body, pat, label } => {
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let iterable_ty = self.infer_expr(*iterable, &Expectation::none());
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self.breakables.push(BreakableContext {
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may_break: false,
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break_ty: Ty::Unknown,
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label: label.clone(),
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});
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let pat_ty =
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self.resolve_associated_type(iterable_ty, self.resolve_into_iter_item());
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self.infer_pat(*pat, &pat_ty, BindingMode::default());
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self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
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let _ctxt = self.breakables.pop().expect("breakable stack broken");
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// the body may not run, so it diverging doesn't mean we diverge
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self.diverges = Diverges::Maybe;
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Ty::unit()
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}
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Expr::Lambda { body, args, ret_type, arg_types } => {
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assert_eq!(args.len(), arg_types.len());
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let mut sig_tys = Vec::new();
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// collect explicitly written argument types
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for arg_type in arg_types.iter() {
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let arg_ty = if let Some(type_ref) = arg_type {
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self.make_ty(type_ref)
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} else {
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self.table.new_type_var()
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};
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sig_tys.push(arg_ty);
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}
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// add return type
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let ret_ty = match ret_type {
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Some(type_ref) => self.make_ty(type_ref),
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None => self.table.new_type_var(),
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};
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sig_tys.push(ret_ty.clone());
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let sig_ty = Ty::apply(
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TypeCtor::FnPtr { num_args: sig_tys.len() as u16 - 1 },
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Substs(sig_tys.clone().into()),
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);
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let closure_ty =
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Ty::apply_one(TypeCtor::Closure { def: self.owner, expr: tgt_expr }, sig_ty);
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// Eagerly try to relate the closure type with the expected
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// type, otherwise we often won't have enough information to
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// infer the body.
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self.coerce(&closure_ty, &expected.ty);
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// Now go through the argument patterns
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for (arg_pat, arg_ty) in args.iter().zip(sig_tys) {
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let resolved = self.resolve_ty_as_possible(arg_ty);
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self.infer_pat(*arg_pat, &resolved, BindingMode::default());
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}
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let prev_diverges = mem::replace(&mut self.diverges, Diverges::Maybe);
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let prev_ret_ty = mem::replace(&mut self.return_ty, ret_ty.clone());
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self.infer_expr_coerce(*body, &Expectation::has_type(ret_ty));
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self.diverges = prev_diverges;
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self.return_ty = prev_ret_ty;
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closure_ty
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}
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Expr::Call { callee, args } => {
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let callee_ty = self.infer_expr(*callee, &Expectation::none());
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let (param_tys, ret_ty) = match callee_ty.callable_sig(self.db) {
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Some(sig) => (sig.params().to_vec(), sig.ret().clone()),
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None => {
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// Not callable
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// FIXME: report an error
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(Vec::new(), Ty::Unknown)
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}
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};
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self.register_obligations_for_call(&callee_ty);
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self.check_call_arguments(args, ¶m_tys);
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self.normalize_associated_types_in(ret_ty)
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}
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Expr::MethodCall { receiver, args, method_name, generic_args } => self
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.infer_method_call(tgt_expr, *receiver, &args, &method_name, generic_args.as_ref()),
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Expr::Match { expr, arms } => {
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let input_ty = self.infer_expr(*expr, &Expectation::none());
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let mut result_ty = if arms.is_empty() {
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Ty::simple(TypeCtor::Never)
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} else {
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self.table.new_type_var()
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};
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let matchee_diverges = self.diverges;
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let mut all_arms_diverge = Diverges::Always;
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for arm in arms {
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self.diverges = Diverges::Maybe;
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let _pat_ty = self.infer_pat(arm.pat, &input_ty, BindingMode::default());
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if let Some(guard_expr) = arm.guard {
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self.infer_expr(
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guard_expr,
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&Expectation::has_type(Ty::simple(TypeCtor::Bool)),
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);
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}
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let arm_ty = self.infer_expr_inner(arm.expr, &expected);
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all_arms_diverge &= self.diverges;
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result_ty = self.coerce_merge_branch(&result_ty, &arm_ty);
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}
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self.diverges = matchee_diverges | all_arms_diverge;
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result_ty
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}
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Expr::Path(p) => {
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// FIXME this could be more efficient...
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let resolver = resolver_for_expr(self.db.upcast(), self.owner, tgt_expr);
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self.infer_path(&resolver, p, tgt_expr.into()).unwrap_or(Ty::Unknown)
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}
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Expr::Continue { .. } => Ty::simple(TypeCtor::Never),
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Expr::Break { expr, label } => {
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let val_ty = if let Some(expr) = expr {
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self.infer_expr(*expr, &Expectation::none())
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} else {
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Ty::unit()
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};
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let last_ty =
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if let Some(ctxt) = find_breakable(&mut self.breakables, label.as_ref()) {
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ctxt.break_ty.clone()
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} else {
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Ty::Unknown
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};
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let merged_type = self.coerce_merge_branch(&last_ty, &val_ty);
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if let Some(ctxt) = find_breakable(&mut self.breakables, label.as_ref()) {
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ctxt.break_ty = merged_type;
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ctxt.may_break = true;
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} else {
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self.push_diagnostic(InferenceDiagnostic::BreakOutsideOfLoop {
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expr: tgt_expr,
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});
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}
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Ty::simple(TypeCtor::Never)
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}
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Expr::Return { expr } => {
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if let Some(expr) = expr {
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self.infer_expr_coerce(*expr, &Expectation::has_type(self.return_ty.clone()));
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} else {
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let unit = Ty::unit();
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self.coerce(&unit, &self.return_ty.clone());
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}
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Ty::simple(TypeCtor::Never)
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}
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Expr::RecordLit { path, fields, spread } => {
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let (ty, def_id) = self.resolve_variant(path.as_ref());
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if let Some(variant) = def_id {
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self.write_variant_resolution(tgt_expr.into(), variant);
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}
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self.unify(&ty, &expected.ty);
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let substs = ty.substs().unwrap_or_else(Substs::empty);
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let field_types = def_id.map(|it| self.db.field_types(it)).unwrap_or_default();
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let variant_data = def_id.map(|it| variant_data(self.db.upcast(), it));
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for (field_idx, field) in fields.iter().enumerate() {
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let field_def =
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variant_data.as_ref().and_then(|it| match it.field(&field.name) {
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Some(local_id) => Some(FieldId { parent: def_id.unwrap(), local_id }),
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None => {
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self.push_diagnostic(InferenceDiagnostic::NoSuchField {
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expr: tgt_expr,
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field: field_idx,
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});
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None
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}
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});
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if let Some(field_def) = field_def {
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self.result.record_field_resolutions.insert(field.expr, field_def);
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}
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let field_ty = field_def
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.map_or(Ty::Unknown, |it| field_types[it.local_id].clone().subst(&substs));
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self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty));
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}
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if let Some(expr) = spread {
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self.infer_expr(*expr, &Expectation::has_type(ty.clone()));
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}
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ty
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}
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Expr::Field { expr, name } => {
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let receiver_ty = self.infer_expr_inner(*expr, &Expectation::none());
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let canonicalized = self.canonicalizer().canonicalize_ty(receiver_ty);
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let ty = autoderef::autoderef(
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self.db,
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self.resolver.krate(),
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InEnvironment {
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value: canonicalized.value.clone(),
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environment: self.trait_env.clone(),
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},
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)
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.find_map(|derefed_ty| match canonicalized.decanonicalize_ty(derefed_ty.value) {
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Ty::Apply(a_ty) => match a_ty.ctor {
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TypeCtor::Tuple { .. } => name
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.as_tuple_index()
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.and_then(|idx| a_ty.parameters.0.get(idx).cloned()),
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TypeCtor::Adt(AdtId::StructId(s)) => {
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self.db.struct_data(s).variant_data.field(name).map(|local_id| {
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let field = FieldId { parent: s.into(), local_id };
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self.write_field_resolution(tgt_expr, field);
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self.db.field_types(s.into())[field.local_id]
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.clone()
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.subst(&a_ty.parameters)
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})
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}
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// FIXME:
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TypeCtor::Adt(AdtId::UnionId(_)) => None,
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_ => None,
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},
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_ => None,
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})
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.unwrap_or(Ty::Unknown);
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let ty = self.insert_type_vars(ty);
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self.normalize_associated_types_in(ty)
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}
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Expr::Await { expr } => {
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let inner_ty = self.infer_expr_inner(*expr, &Expectation::none());
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self.resolve_associated_type(inner_ty, self.resolve_future_future_output())
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}
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Expr::Try { expr } => {
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let inner_ty = self.infer_expr_inner(*expr, &Expectation::none());
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self.resolve_associated_type(inner_ty, self.resolve_ops_try_ok())
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}
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Expr::Cast { expr, type_ref } => {
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let _inner_ty = self.infer_expr_inner(*expr, &Expectation::none());
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let cast_ty = self.make_ty(type_ref);
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// FIXME check the cast...
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cast_ty
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}
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Expr::Ref { expr, rawness, mutability } => {
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let expectation = if let Some((exp_inner, exp_rawness, exp_mutability)) =
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&expected.ty.as_reference_or_ptr()
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{
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if *exp_mutability == Mutability::Mut && *mutability == Mutability::Shared {
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// FIXME: throw type error - expected mut reference but found shared ref,
|
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// which cannot be coerced
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}
|
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if *exp_rawness == Rawness::Ref && *rawness == Rawness::RawPtr {
|
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// FIXME: throw type error - expected reference but found ptr,
|
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// which cannot be coerced
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}
|
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Expectation::rvalue_hint(Ty::clone(exp_inner))
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} else {
|
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Expectation::none()
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};
|
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let inner_ty = self.infer_expr_inner(*expr, &expectation);
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let ty = match rawness {
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Rawness::RawPtr => TypeCtor::RawPtr(*mutability),
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Rawness::Ref => TypeCtor::Ref(*mutability),
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};
|
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Ty::apply_one(ty, inner_ty)
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}
|
|
Expr::Box { expr } => {
|
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let inner_ty = self.infer_expr_inner(*expr, &Expectation::none());
|
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if let Some(box_) = self.resolve_boxed_box() {
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Ty::apply_one(TypeCtor::Adt(box_), inner_ty)
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} else {
|
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Ty::Unknown
|
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}
|
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}
|
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Expr::UnaryOp { expr, op } => {
|
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let inner_ty = self.infer_expr_inner(*expr, &Expectation::none());
|
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match op {
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|
UnaryOp::Deref => match self.resolver.krate() {
|
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Some(krate) => {
|
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let canonicalized = self.canonicalizer().canonicalize_ty(inner_ty);
|
|
match autoderef::deref(
|
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self.db,
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krate,
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InEnvironment {
|
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value: &canonicalized.value,
|
|
environment: self.trait_env.clone(),
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},
|
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) {
|
|
Some(derefed_ty) => {
|
|
canonicalized.decanonicalize_ty(derefed_ty.value)
|
|
}
|
|
None => Ty::Unknown,
|
|
}
|
|
}
|
|
None => Ty::Unknown,
|
|
},
|
|
UnaryOp::Neg => {
|
|
match &inner_ty {
|
|
// Fast path for builtins
|
|
Ty::Apply(ApplicationTy {
|
|
ctor: TypeCtor::Int(IntTy { signedness: Signedness::Signed, .. }),
|
|
..
|
|
})
|
|
| Ty::Apply(ApplicationTy { ctor: TypeCtor::Float(_), .. })
|
|
| Ty::Infer(InferTy::IntVar(..))
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| Ty::Infer(InferTy::FloatVar(..)) => inner_ty,
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// Otherwise we resolve via the std::ops::Neg trait
|
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_ => self
|
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.resolve_associated_type(inner_ty, self.resolve_ops_neg_output()),
|
|
}
|
|
}
|
|
UnaryOp::Not => {
|
|
match &inner_ty {
|
|
// Fast path for builtins
|
|
Ty::Apply(ApplicationTy { ctor: TypeCtor::Bool, .. })
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|
| Ty::Apply(ApplicationTy { ctor: TypeCtor::Int(_), .. })
|
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| Ty::Infer(InferTy::IntVar(..)) => inner_ty,
|
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// Otherwise we resolve via the std::ops::Not trait
|
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_ => self
|
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.resolve_associated_type(inner_ty, self.resolve_ops_not_output()),
|
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}
|
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}
|
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}
|
|
}
|
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Expr::BinaryOp { lhs, rhs, op } => match op {
|
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Some(op) => {
|
|
let lhs_expectation = match op {
|
|
BinaryOp::LogicOp(..) => 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.clone());
|
|
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, lhs_ty, rhs_ty)
|
|
}
|
|
_ => Ty::Unknown,
|
|
},
|
|
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) => Ty::simple(TypeCtor::Adt(adt)),
|
|
None => Ty::Unknown,
|
|
},
|
|
(RangeOp::Exclusive, None, Some(ty)) => match self.resolve_range_to() {
|
|
Some(adt) => Ty::apply_one(TypeCtor::Adt(adt), ty),
|
|
None => Ty::Unknown,
|
|
},
|
|
(RangeOp::Inclusive, None, Some(ty)) => {
|
|
match self.resolve_range_to_inclusive() {
|
|
Some(adt) => Ty::apply_one(TypeCtor::Adt(adt), ty),
|
|
None => Ty::Unknown,
|
|
}
|
|
}
|
|
(RangeOp::Exclusive, Some(_), Some(ty)) => match self.resolve_range() {
|
|
Some(adt) => Ty::apply_one(TypeCtor::Adt(adt), ty),
|
|
None => Ty::Unknown,
|
|
},
|
|
(RangeOp::Inclusive, Some(_), Some(ty)) => {
|
|
match self.resolve_range_inclusive() {
|
|
Some(adt) => Ty::apply_one(TypeCtor::Adt(adt), ty),
|
|
None => Ty::Unknown,
|
|
}
|
|
}
|
|
(RangeOp::Exclusive, Some(ty), None) => match self.resolve_range_from() {
|
|
Some(adt) => Ty::apply_one(TypeCtor::Adt(adt), ty),
|
|
None => Ty::Unknown,
|
|
},
|
|
(RangeOp::Inclusive, _, None) => Ty::Unknown,
|
|
}
|
|
}
|
|
Expr::Index { base, index } => {
|
|
let base_ty = self.infer_expr_inner(*base, &Expectation::none());
|
|
let index_ty = self.infer_expr(*index, &Expectation::none());
|
|
|
|
if let (Some(index_trait), Some(krate)) =
|
|
(self.resolve_ops_index(), self.resolver.krate())
|
|
{
|
|
let canonicalized = self.canonicalizer().canonicalize_ty(base_ty);
|
|
let self_ty = method_resolution::resolve_indexing_op(
|
|
self.db,
|
|
&canonicalized.value,
|
|
self.trait_env.clone(),
|
|
krate,
|
|
index_trait,
|
|
);
|
|
let self_ty =
|
|
self_ty.map_or(Ty::Unknown, |t| canonicalized.decanonicalize_ty(t.value));
|
|
self.resolve_associated_type_with_params(
|
|
self_ty,
|
|
self.resolve_ops_index_output(),
|
|
&[index_ty],
|
|
)
|
|
} else {
|
|
Ty::Unknown
|
|
}
|
|
}
|
|
Expr::Tuple { exprs } => {
|
|
let mut tys = match &expected.ty {
|
|
ty_app!(TypeCtor::Tuple { .. }, st) => st
|
|
.iter()
|
|
.cloned()
|
|
.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()));
|
|
}
|
|
|
|
Ty::apply(TypeCtor::Tuple { cardinality: tys.len() as u16 }, Substs(tys.into()))
|
|
}
|
|
Expr::Array(array) => {
|
|
let elem_ty = match &expected.ty {
|
|
ty_app!(TypeCtor::Array, st) | ty_app!(TypeCtor::Slice, st) => {
|
|
st.as_single().clone()
|
|
}
|
|
_ => self.table.new_type_var(),
|
|
};
|
|
|
|
match array {
|
|
Array::ElementList(items) => {
|
|
for expr in items.iter() {
|
|
self.infer_expr_coerce(*expr, &Expectation::has_type(elem_ty.clone()));
|
|
}
|
|
}
|
|
Array::Repeat { initializer, repeat } => {
|
|
self.infer_expr_coerce(
|
|
*initializer,
|
|
&Expectation::has_type(elem_ty.clone()),
|
|
);
|
|
self.infer_expr(
|
|
*repeat,
|
|
&Expectation::has_type(Ty::simple(TypeCtor::Int(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(IntTy::u8()));
|
|
let array_type = Ty::apply_one(TypeCtor::Array, byte_type);
|
|
Ty::apply_one(TypeCtor::Ref(Mutability::Shared), array_type)
|
|
}
|
|
Literal::Char(..) => Ty::simple(TypeCtor::Char),
|
|
Literal::Int(_v, ty) => match ty {
|
|
Some(int_ty) => Ty::simple(TypeCtor::Int((*int_ty).into())),
|
|
None => self.table.new_integer_var(),
|
|
},
|
|
Literal::Float(_v, ty) => match ty {
|
|
Some(float_ty) => Ty::simple(TypeCtor::Float((*float_ty).into())),
|
|
None => self.table.new_float_var(),
|
|
},
|
|
},
|
|
};
|
|
// use a new type variable if we got Ty::Unknown here
|
|
let ty = self.insert_type_vars_shallow(ty);
|
|
let ty = self.resolve_ty_as_possible(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);
|
|
|
|
// Always use the declared type when specified
|
|
let mut ty = decl_ty.clone();
|
|
|
|
if let Some(expr) = initializer {
|
|
let actual_ty =
|
|
self.infer_expr_coerce(*expr, &Expectation::has_type(decl_ty.clone()));
|
|
if decl_ty == Ty::Unknown {
|
|
ty = actual_ty;
|
|
}
|
|
}
|
|
|
|
let ty = self.resolve_ty_as_possible(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_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 self.diverges.is_always() {
|
|
// we don't even make an attempt at coercion
|
|
self.table.new_maybe_never_type_var()
|
|
} else {
|
|
self.coerce(&Ty::unit(), expected.coercion_target());
|
|
Ty::unit()
|
|
}
|
|
};
|
|
ty
|
|
}
|
|
|
|
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 traits_in_scope = self.resolver.traits_in_scope(self.db.upcast());
|
|
|
|
let resolved = self.resolver.krate().and_then(|krate| {
|
|
method_resolution::lookup_method(
|
|
&canonicalized_receiver.value,
|
|
self.db,
|
|
self.trait_env.clone(),
|
|
krate,
|
|
&traits_in_scope,
|
|
method_name,
|
|
)
|
|
});
|
|
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.value_ty(func.into()), Some(generics(self.db.upcast(), func.into())))
|
|
}
|
|
None => (receiver_ty, Binders::new(0, Ty::Unknown), None),
|
|
};
|
|
let substs = self.substs_for_method_call(def_generics, generic_args, &derefed_receiver_ty);
|
|
let method_ty = method_ty.subst(&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);
|
|
|
|
self.check_call_arguments(args, ¶m_tys);
|
|
self.normalize_associated_types_in(ret_ty)
|
|
}
|
|
|
|
fn check_call_arguments(&mut self, args: &[ExprId], param_tys: &[Ty]) {
|
|
// 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 param_iter = param_tys.iter().cloned().chain(repeat(Ty::Unknown));
|
|
for (&arg, param_ty) in args.iter().zip(param_iter) {
|
|
let is_closure = match &self.body[arg] {
|
|
Expr::Lambda { .. } => true,
|
|
_ => false,
|
|
};
|
|
|
|
if is_closure != check_closures {
|
|
continue;
|
|
}
|
|
|
|
let param_ty = self.normalize_associated_types_in(param_ty);
|
|
self.infer_expr_coerce(arg, &Expectation::has_type(param_ty.clone()));
|
|
}
|
|
}
|
|
}
|
|
|
|
fn substs_for_method_call(
|
|
&mut self,
|
|
def_generics: Option<Generics>,
|
|
generic_args: Option<&GenericArgs>,
|
|
receiver_ty: &Ty,
|
|
) -> Substs {
|
|
let (parent_params, self_params, type_params, impl_trait_params) =
|
|
def_generics.as_ref().map_or((0, 0, 0, 0), |g| g.provenance_split());
|
|
assert_eq!(self_params, 0); // method shouldn't have another Self param
|
|
let total_len = parent_params + type_params + impl_trait_params;
|
|
let mut substs = Vec::with_capacity(total_len);
|
|
// Parent arguments are unknown, except for the receiver type
|
|
if let Some(parent_generics) = def_generics.as_ref().map(|p| p.iter_parent()) {
|
|
for (_id, param) in parent_generics {
|
|
if param.provenance == hir_def::generics::TypeParamProvenance::TraitSelf {
|
|
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(type_params) {
|
|
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..total_len {
|
|
substs.push(Ty::Unknown);
|
|
}
|
|
assert_eq!(substs.len(), total_len);
|
|
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::FunctionId(f) => {
|
|
if let AssocContainerId::TraitId(trait_) =
|
|
f.lookup(self.db.upcast()).container
|
|
{
|
|
// construct a TraitDef
|
|
let substs = a_ty
|
|
.parameters
|
|
.prefix(generics(self.db.upcast(), trait_.into()).len());
|
|
self.obligations.push(Obligation::Trait(TraitRef { trait_, substs }));
|
|
}
|
|
}
|
|
CallableDef::StructId(_) | CallableDef::EnumVariantId(_) => {}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|