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iter 22b.2.9: fix — superclass-walk tests, simplify class_superclasses map shape

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Brummel
2026-05-09 18:59:15 +02:00
parent 7cff741632
commit b741a8ba05
4 changed files with 165 additions and 16 deletions
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crates/ail/tests/typeclass_22b2.rs
+43
View File
@@ -169,3 +169,46 @@ fn fn_with_correct_constraint_typechecks_green() {
diagnostics
);
}
/// Property protected: superclass-walk in `expand_declared_constraints`
/// covers the residual class produced by calling a superclass's method
/// from within a function constrained on the subclass. Concretely: the
/// fn declares `Ord a =>` and calls `eq` (an `Eq` method); the residual
/// `(Eq, a)` is satisfied because `Ord` extends `Eq`, so the expanded
/// declared set must include `(Eq, a)`. Without the superclass walk the
/// fn would spuriously fire `missing-constraint`. This is the positive
/// fixture for Decision 11's one-step superclass closure.
#[test]
fn fn_calling_superclass_method_via_subclass_constraint_typechecks_green() {
let entry = examples_dir()
.join("test_22b2_constraint_declared_via_superclass.ail.json");
let ws = ailang_core::workspace::load_workspace(&entry)
.expect("workspace loads");
let diagnostics = ailang_check::check_workspace(&ws);
assert!(
diagnostics.is_empty(),
"expected no diagnostics; superclass walk should have covered Eq via Ord; got: {:?}",
diagnostics
);
}
/// Property protected: the superclass walk goes from subclass to
/// superclass only — never the other direction. A fn that declares
/// `Eq a =>` and calls `lt` (an `Ord` method) must still fire
/// `missing-constraint` because `Ord` is a *sub*class of `Eq`, not a
/// superclass; the declared `(Eq, a)` does not cover the residual
/// `(Ord, a)`. Without this asymmetry, declaring the superclass would
/// spuriously satisfy any subclass residual.
#[test]
fn fn_with_superclass_constraint_calling_subclass_method_fires_missing_constraint() {
let entry = examples_dir()
.join("test_22b2_missing_constraint_subclass.ail.json");
let ws = ailang_core::workspace::load_workspace(&entry)
.expect("workspace loads");
let diagnostics = ailang_check::check_workspace(&ws);
assert!(
diagnostics.iter().any(|d| d.code == "missing-constraint"),
"expected missing-constraint; superclass walk should NOT cover sub-direction; got: {:?}",
diagnostics.iter().map(|d| &d.code).collect::<Vec<_>>()
);
}
crates/ailang-check/src/lib.rs
+16 -16
View File
@@ -1139,14 +1139,13 @@ fn check_in_workspace(
}
}
env.class_methods = class_methods;
let mut class_superclasses: BTreeMap<String, Option<String>> = BTreeMap::new();
let mut class_superclasses: BTreeMap<String, String> = BTreeMap::new();
for module in ws.modules.values() {
for def in &module.defs {
if let Def::Class(cd) = def {
class_superclasses.insert(
cd.name.clone(),
cd.superclass.as_ref().map(|s| s.class.clone()),
);
if let Some(sc) = &cd.superclass {
class_superclasses.insert(cd.name.clone(), sc.class.clone());
}
}
}
}
@@ -1321,10 +1320,9 @@ fn check_fn(f: &FnDef, env: &Env) -> Result<()> {
let mut effects = BTreeSet::new();
let mut subst = Subst::default();
let mut counter: u32 = 0;
// Iter 22b.2 (Task 9): per-fn residual class constraints. Every
// call to a class method inside the body pushes a
// [`ResidualConstraint`] here; after the body finishes, we
// compare against the expanded declared set.
// Per-fn residual class constraints. Every call to a class method
// inside the body pushes a [`ResidualConstraint`] here; after the
// body finishes, we compare against the expanded declared set.
let mut residuals: Vec<ResidualConstraint> = Vec::new();
let body_ty = synth(&f.body, &env, &mut locals, &mut effects, &f.name, &mut subst, &mut counter, &mut residuals)?;
unify(&ret_ty, &body_ty, &mut subst)?;
@@ -1407,11 +1405,11 @@ pub(crate) struct ResidualConstraint {
/// residual is satisfied.
fn expand_declared_constraints(
declared: &[Constraint],
class_superclasses: &BTreeMap<String, Option<String>>,
class_superclasses: &BTreeMap<String, String>,
) -> Vec<Constraint> {
let mut out: Vec<Constraint> = declared.to_vec();
for c in declared {
if let Some(Some(sc)) = class_superclasses.get(&c.class) {
if let Some(sc) = class_superclasses.get(&c.class) {
out.push(Constraint {
class: sc.clone(),
type_: c.type_.clone(),
@@ -2413,11 +2411,13 @@ pub struct Env {
/// safe (no overwrites). Read in [`synth`]'s `Term::Var` arm.
pub class_methods: BTreeMap<String, ClassMethodEntry>,
/// Iter 22b.2 (Task 9): one-step superclass expansion table.
/// Maps each class name to its (optional) superclass class name.
/// Used by [`check_fn`] to expand `Forall.constraints` for the
/// missing-constraint check (Decision 11: max one step). The
/// schema permits at most one superclass per class.
pub class_superclasses: BTreeMap<String, Option<String>>,
/// Maps each class name to its superclass class name. Absence from
/// the map means the class has no superclass — populated only for
/// classes that declare one. Used by [`check_fn`] to expand
/// `Forall.constraints` for the missing-constraint check
/// (Decision 11: max one step). The schema permits at most one
/// superclass per class.
pub class_superclasses: BTreeMap<String, String>,
}
/// Back-pointer from a ctor name to the ADT that declared it. Stored
examples/test_22b2_constraint_declared_via_superclass.ail.json
+53
View File
@@ -0,0 +1,53 @@
{
"schema": "ailang/v0",
"name": "test_22b2_constraint_declared_via_superclass",
"imports": [],
"defs": [
{
"kind": "class", "name": "Eq", "param": "a",
"methods": [{
"name": "eq",
"type": {
"k": "fn",
"params": [{ "k": "var", "name": "a" }, { "k": "var", "name": "a" }],
"ret": { "k": "con", "name": "Bool" }, "effects": []
}
}]
},
{
"kind": "class", "name": "Ord", "param": "a",
"superclass": { "class": "Eq", "type": "a" },
"methods": [{
"name": "lt",
"type": {
"k": "fn",
"params": [{ "k": "var", "name": "a" }, { "k": "var", "name": "a" }],
"ret": { "k": "con", "name": "Bool" }, "effects": []
}
}]
},
{
"kind": "fn",
"name": "uses_eq_via_ord",
"type": {
"k": "forall",
"vars": ["a"],
"constraints": [
{ "class": "Ord", "type": { "k": "var", "name": "a" } }
],
"body": {
"k": "fn",
"params": [{ "k": "var", "name": "a" }, { "k": "var", "name": "a" }],
"ret": { "k": "con", "name": "Bool" },
"effects": []
}
},
"params": ["x", "y"],
"body": {
"t": "app",
"fn": { "t": "var", "name": "eq" },
"args": [{ "t": "var", "name": "x" }, { "t": "var", "name": "y" }]
}
}
]
}
examples/test_22b2_missing_constraint_subclass.ail.json
+53
View File
@@ -0,0 +1,53 @@
{
"schema": "ailang/v0",
"name": "test_22b2_missing_constraint_subclass",
"imports": [],
"defs": [
{
"kind": "class", "name": "Eq", "param": "a",
"methods": [{
"name": "eq",
"type": {
"k": "fn",
"params": [{ "k": "var", "name": "a" }, { "k": "var", "name": "a" }],
"ret": { "k": "con", "name": "Bool" }, "effects": []
}
}]
},
{
"kind": "class", "name": "Ord", "param": "a",
"superclass": { "class": "Eq", "type": "a" },
"methods": [{
"name": "lt",
"type": {
"k": "fn",
"params": [{ "k": "var", "name": "a" }, { "k": "var", "name": "a" }],
"ret": { "k": "con", "name": "Bool" }, "effects": []
}
}]
},
{
"kind": "fn",
"name": "needs_ord_but_only_has_eq",
"type": {
"k": "forall",
"vars": ["a"],
"constraints": [
{ "class": "Eq", "type": { "k": "var", "name": "a" } }
],
"body": {
"k": "fn",
"params": [{ "k": "var", "name": "a" }, { "k": "var", "name": "a" }],
"ret": { "k": "con", "name": "Bool" },
"effects": []
}
},
"params": ["x", "y"],
"body": {
"t": "app",
"fn": { "t": "var", "name": "lt" },
"args": [{ "t": "var", "name": "x" }, { "t": "var", "name": "y" }]
}
}
]
}