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fix(hy-check): prevent option[T] TypeShape erasure on pointers, sends, receives, and range loops (Fixes #753) #755

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fix(hy-check): prevent option[T] TypeShape erasure on pointers, sends, receives, and range loops (Fixes #753) #755

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ff7f319
fix(hy-check): prevent option[T] TypeShape erasure on pointers, sends…
aazminu Oct 19, 2026
1fa49e8
fix(hy-check): preserve option TypeExpr across receive, select, range…
aazminu Oct 19, 2026
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14 changes: 11 additions & 3 deletions compiler/crates/hy-check/src/closures.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -908,14 +908,21 @@ fn check_stmt_boundaries<'a>(ck: &mut Checker<'_>, st: &mut FnState, stmt: &'a S
TypeShape::Chan(e) => *e,
_ => TypeShape::Unknown,
};
let elem_ty = ck.ty_of_expr(st, chan).and_then(|ct| {
match ck.resolve_type_alias(&ct) {
hy_syntax::TypeExpr::Chan { elem, .. } => Some(*elem),
_ => None,
}
});
for (i, n) in names.iter().enumerate() {
let shape = if i == 0 {
elem.clone()
} else {
TypeShape::Primitive
};
let ty = if i == 0 { elem_ty.clone() } else { None };
mark_nested_overwritten(st, n, nested);
ck.define_binding(st, n, shape, None, false, managed, false);
ck.define_binding(st, n, shape, ty, false, managed, false);
}
sync_nested_moves(st, nested);
}
Expand Down Expand Up @@ -987,11 +994,12 @@ fn check_stmt_boundaries<'a>(ck: &mut Checker<'_>, st: &mut FnState, stmt: &'a S
collect_expr_direct_fnlits(expr, st, nested);
let is_chan = matches!(ck.shape_of_expr(st, expr), TypeShape::Chan(_));
let shapes = ck.iterate_var_shapes(st, expr, vars.len());
for (name, shape) in vars.iter().zip(shapes) {
let tys = ck.iterate_var_tys(st, expr, vars.len());
for ((name, shape), ty) in vars.iter().zip(shapes).zip(tys) {
let is_ref = shape.is_reference_alias();
let may_share = ck.shape_may_share(&shape);
mark_nested_overwritten(st, name, nested);
ck.define_binding(st, name, shape, None, false, managed, false);
ck.define_binding(st, name, shape, ty, false, managed, false);
if !is_chan {
if may_share {
ck.record_may_share(st, name, expr);
Expand Down
20 changes: 17 additions & 3 deletions compiler/crates/hy-check/src/emit_guard.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -219,8 +219,9 @@ impl<'a> Checker<'a> {
self.check_expr_emit_guard(st, expr);
if deep {
let shapes = self.iterate_var_shapes(st, expr, vars.len());
for (name, shape) in vars.iter().zip(shapes) {
self.define_binding(st, name, shape, None, false, false, false);
let tys = self.iterate_var_tys(st, expr, vars.len());
for ((name, shape), ty) in vars.iter().zip(shapes).zip(tys) {
self.define_binding(st, name, shape, ty, false, false, false);
}
}
}
Expand Down Expand Up @@ -321,13 +322,20 @@ impl<'a> Checker<'a> {
TypeShape::Chan(e) => *e,
_ => TypeShape::Unknown,
};
let elem_ty = self.ty_of_expr(st, chan).and_then(|ct| {
match self.resolve_type_alias(&ct) {
TypeExpr::Chan { elem, .. } => Some(*elem),
_ => None,
}
});
for (i, n) in names.iter().enumerate() {
let shape = if i == 0 {
elem.clone()
} else {
TypeShape::Primitive
};
self.define_binding(st, n, shape, None, false, false, false);
let ty = if i == 0 { elem_ty.clone() } else { None };
self.define_binding(st, n, shape, ty, false, false, false);
}
}
}
Expand Down Expand Up @@ -367,6 +375,12 @@ impl<'a> Checker<'a> {
let ty = l.ty.clone().or_else(|| self.ty_of_expr(st, val));
self.define_binding(st, name, shape, ty, immutable, false, is_let);
}
} else if l.values.len() == 1 && l.names.len() > 1 {
let shapes = self.multi_value_shapes(st, &l.values[0], l.names.len());
let tys = self.multi_value_tys(st, &l.values[0], l.names.len());
for ((name, shape), ty) in l.names.iter().zip(shapes).zip(tys) {
self.define_binding(st, name, shape, ty, immutable, false, is_let);
}
}
}

Expand Down
14 changes: 11 additions & 3 deletions compiler/crates/hy-check/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -452,13 +452,20 @@ fn check_fn(ck: &mut Checker<'_>, f: &FnDecl) {
TypeShape::Chan(e) => *e,
_ => TypeShape::Unknown,
};
let elem_ty = ck.ty_of_expr(&st, chan).and_then(|ct| {
match ck.resolve_type_alias(&ct) {
hy_syntax::TypeExpr::Chan { elem, .. } => Some(*elem),
_ => None,
}
});
for (i, n) in names.iter().enumerate() {
let shape = if i == 0 {
elem.clone()
} else {
TypeShape::Primitive
};
ck.define_binding(&mut st, n, shape, None, false, managed, false);
let ty = if i == 0 { elem_ty.clone() } else { None };
ck.define_binding(&mut st, n, shape, ty, false, managed, false);
}
}
walk::ScopeEvent::MatchBind { name, subject } => {
Expand Down Expand Up @@ -699,10 +706,11 @@ fn check_fn(ck: &mut Checker<'_>, f: &FnDecl) {
);
let is_chan = matches!(ck.shape_of_expr(&st, expr), TypeShape::Chan(_));
let shapes = ck.iterate_var_shapes(&st, expr, vars.len());
for (name, shape) in vars.iter().zip(shapes) {
let tys = ck.iterate_var_tys(&st, expr, vars.len());
for ((name, shape), ty) in vars.iter().zip(shapes).zip(tys) {
let is_ref = shape.is_reference_alias();
let may_share = ck.shape_may_share(&shape);
ck.define_binding(&mut st, name, shape, None, false, managed, false);
ck.define_binding(&mut st, name, shape, ty, false, managed, false);
if !is_chan {
if may_share {
ck.record_may_share(&mut st, name, expr);
Expand Down
28 changes: 19 additions & 9 deletions compiler/crates/hy-check/src/loans.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2067,7 +2067,9 @@ impl<'a> Checker<'a> {
if let Some(ty) = &b.ty {
let resolved = self.resolve_type_alias(ty);
match &resolved {
hy_syntax::TypeExpr::Array { .. } => return true,
hy_syntax::TypeExpr::Array { .. } | hy_syntax::TypeExpr::Option { .. } => {
return true
}
hy_syntax::TypeExpr::Named { name: tname, .. } => {
let base = Self::base_named_type_str(tname);
if self.structs.contains_key(base) {
Expand Down Expand Up @@ -5133,7 +5135,10 @@ impl<'a> Checker<'a> {
managed: bool,
) {
let shape = self.shape_of_expr(st, subject);
let ty = match self.ty_of_expr(st, subject) {
let ty = match self
.ty_of_expr(st, subject)
.map(|t| self.resolve_type_alias(&t))
{
Some(hy_syntax::TypeExpr::Option { elem, .. }) => Some(*elem),
other => other,
};
Expand Down Expand Up @@ -5551,15 +5556,18 @@ impl<'a> Checker<'a> {
}

if let Some(b) = st.env_lookup_mut(name) {
let keep_existing_option_ty = matches!(info.shape, TypeShape::Unknown)
&& b.ty.as_ref().is_some_and(|t| self.ty_is_option(t));
if !matches!(info.shape, TypeShape::Unknown) || b.ty.is_none() {
b.shape = info.shape;
}
if info.ty.is_some()
|| b.ty.is_none()
|| matches!(
b.ty.as_ref().map(|t| self.resolve_type_alias(t)),
Some(hy_syntax::TypeExpr::Fn { .. })
)
if !keep_existing_option_ty
&& (info.ty.is_some()
|| b.ty.is_none()
|| matches!(
b.ty.as_ref().map(|t| self.resolve_type_alias(t)),
Some(hy_syntax::TypeExpr::Fn { .. })
))
{
b.ty = info.ty;
}
Expand Down Expand Up @@ -5674,10 +5682,12 @@ impl<'a> Checker<'a> {
self.preserve_peers_before_sever(st, name, false);
}
if let Some(b) = st.env_lookup_mut(name) {
let keep_existing_option_ty = matches!(shape, TypeShape::Unknown)
&& b.ty.as_ref().is_some_and(|t| self.ty_is_option(t));
if !matches!(shape, TypeShape::Unknown) || b.ty.is_none() {
b.shape = shape.clone();
}
if ty.is_some() || b.ty.is_none() {
if !keep_existing_option_ty && (ty.is_some() || b.ty.is_none()) {
b.ty = ty;
}
b.moved = None;
Expand Down
19 changes: 19 additions & 0 deletions compiler/crates/hy-check/src/range_iter.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -388,6 +388,25 @@ impl<'a> Checker<'a> {
/// sides treat an unknown operand. A TYPE contract, not a sendability
/// doubt — `managed` does not suppress it.
pub(crate) fn check_range_iterable(&mut self, st: &FnState, expr: &Expr, span: Span) {
if self.expr_is_option(st, expr) {
let ty_str = self
.ty_of_expr(st, expr)
.map(|t| t.render())
.unwrap_or_else(|| "option".to_string());
let msg = format!(
"cannot range over `{}` (`{}`) — `for x in e` needs a slice, array, string, map, or channel, not an `option` wrapper (LX13)",
expr.render(),
ty_str
);
let notes = vec![
"why: `option[T]` lowers to a value struct in Go (`hyb_opt`), which Go cannot range over".to_string(),
"fix: unwrap the `option` with `match` (`match opt { some(xs) => for x in xs { ... }, none => {} }`) before ranging".to_string(),
];
self.diags.push(
Diagnostic::error("HYB-E2009", self.path.clone(), span, msg).with_notes(notes),
);
return;
}
// Go: "array, pointer to array, slice, string, map, or channel" —
// only pointer-to-ARRAY is rangeable (`*struct` / `*slice` /
// `*string` are not), so normalize exactly one Pointer level for
Expand Down
19 changes: 19 additions & 0 deletions compiler/crates/hy-check/src/recv.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -340,6 +340,25 @@ impl<'a> Checker<'a> {
/// side, an ill-typed source is not a sendability doubt — `managed`
/// does not suppress it.
pub(crate) fn check_recv_operand(&mut self, st: &FnState, chan: &Expr, span: Span) -> bool {
if self.expr_is_option(st, chan) {
let ty_str = self
.ty_of_expr(st, chan)
.map(|t| t.render())
.unwrap_or_else(|| "option".to_string());
let msg = format!(
"cannot receive from `{}` (`{}`) — a receive source must be a channel, not an `option` wrapper (O4)",
chan.render(),
ty_str
);
let notes = vec![
"why: `option[chan T]` lowers to a value struct in Go (`hyb_opt`), not a channel; receiving directly from an `option` fails `go build`".to_string(),
"fix: unwrap the `option` with `match` (`match opt { some(ch) => <-ch, none => {} }`) before receiving".to_string(),
];
self.diags.push(
Diagnostic::error("HYB-E2008", self.path.clone(), span, msg).with_notes(notes),
);
return false;
}
match self.shape_of_expr(st, chan) {
TypeShape::Chan(_) => {
if let Some(ty) = self.recv_chan_type_expr(st, chan) {
Expand Down
29 changes: 29 additions & 0 deletions compiler/crates/hy-check/src/sendability.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -434,6 +434,16 @@ impl<'a> Checker<'a> {
}),
});
}
if self.expr_is_option(st, operand) {
return Outcome::Rejected(RejectInfo {
value: expr.render(),
ty: format!("*{}", self.binding_ty_str(b)),
notes: vec![format!(
"`&{}` lends a mutable `option` wrapper — a live borrow of mutable shared state, which is not one of the sendable classes (O4)",
root
)],
});
}
match &b.shape {
// `&hits` where hits is atomic-typed — the mediated route (OQ6)
TypeShape::Atomic => Outcome::Ok,
Expand Down Expand Up @@ -832,6 +842,25 @@ impl<'a> Checker<'a> {
/// usual); false emits the diagnostic and the caller skips the value
/// check (the site is ill-typed — no cascade).
pub(crate) fn check_send_target(&mut self, st: &FnState, chan: &Expr, span: Span) -> bool {
if self.expr_is_option(st, chan) {
let ty_str = self
.ty_of_expr(st, chan)
.map(|t| t.render())
.unwrap_or_else(|| "option".to_string());
let msg = format!(
"cannot send to `{}` (`{}`) — a send target must be a channel, not an `option` wrapper (O4)",
chan.render(),
ty_str
);
let notes = vec![
"why: `option[chan T]` lowers to a value struct in Go (`hyb_opt`), not a channel; sending directly to an `option` fails `go build`".to_string(),
"fix: unwrap the `option` with `match` (`match opt { some(ch) => ch <- v, none => {} }`) before sending".to_string(),
];
self.diags.push(
Diagnostic::error("HYB-E3007", self.path.clone(), span, msg).with_notes(notes),
);
return false;
}
match self.shape_of_expr(st, chan) {
TypeShape::Chan(_) => {
if let Some(ty) = self.ty_of_expr(st, chan) {
Expand Down
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