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Correctly handle non-semi statement expressions for never coercions

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This commit is contained in:
Lukas Wirth 2023-03-04 19:39:00 +01:00
parent 95c4cb991f
commit b85e2af898
3 changed files with 37 additions and 14 deletions
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45
crates/hir-ty/src/infer/expr.rs
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@ -84,6 +84,30 @@ impl<'a> InferenceContext<'a> {
}
}
pub(super) 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()
};
}
let adj_ty = self.table.new_type_var();
self.write_expr_adj(
expr,
vec![Adjustment { kind: Adjust::NeverToAny, target: adj_ty.clone() }],
);
adj_ty
} else {
ty
}
}
fn infer_expr_inner(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
self.db.unwind_if_cancelled();
@ -91,7 +115,7 @@ impl<'a> InferenceContext<'a> {
Expr::Missing => self.err_ty(),
&Expr::If { condition, then_branch, else_branch } => {
let expected = &expected.adjust_for_branches(&mut self.table);
self.infer_expr(
self.infer_expr_coerce_never(
condition,
&Expectation::HasType(self.result.standard_types.bool_.clone()),
);
@ -415,7 +439,7 @@ impl<'a> InferenceContext<'a> {
for arm in arms.iter() {
if let Some(guard_expr) = arm.guard {
self.diverges = Diverges::Maybe;
self.infer_expr(
self.infer_expr_coerce_never(
guard_expr,
&Expectation::HasType(self.result.standard_types.bool_.clone()),
);
@ -1146,7 +1170,6 @@ impl<'a> InferenceContext<'a> {
let coerce_ty = expected.coercion_target_type(&mut self.table);
let old_resolver =
mem::replace(&mut self.resolver, resolver_for_expr(self.db.upcast(), self.owner, expr));
let (break_ty, ty) =
self.with_breakable_ctx(BreakableKind::Block, Some(coerce_ty.clone()), label, |this| {
for stmt in statements {
@ -1188,14 +1211,14 @@ impl<'a> InferenceContext<'a> {
}
}
&Statement::Expr { expr, has_semi } => {
this.infer_expr(
expr,
&if has_semi {
Expectation::none()
} else {
Expectation::HasType(this.result.standard_types.unit.clone())
},
);
if has_semi {
this.infer_expr(expr, &Expectation::none());
} else {
this.infer_expr_coerce(
expr,
&Expectation::HasType(this.result.standard_types.unit.clone()),
);
}
}
}
}