iter 22b.3.6: fix — quality-review (shadow-aware walker, cross-mod test, Option-typed targets, const helper)

This commit is contained in:
2026-05-09 21:21:33 +02:00
parent d1b590ceab
commit 7f260b82ad
4 changed files with 408 additions and 68 deletions
+159
View File
@@ -443,6 +443,165 @@ fn fixpoint_handles_chained_class_method_calls() {
);
}
/// Property: when a fn's body locally shadows a class-method name
/// (here `show` is rebound by a `let`-binding), synth resolves the
/// shadowed `Var` against the local and pushes NO residual for it.
/// The rewrite walker must mirror that exact lookup-precedence rule
/// — when a `Term::Var { name }` is in the local scope, the walker
/// must NOT advance the per-callsite cursor. Otherwise a subsequent
/// (real) class-method call site is re-aligned to the wrong slot of
/// `ordered_targets`, and the user-visible diff is two corruptions:
/// the shadowed Var gets a wrong mono-symbol, and the next real call
/// site is left un-rewritten (or rewritten to yet another mismatched
/// target).
///
/// Body shape (`main`):
/// let _t = show 5 in -- residual #0: show@Int
/// let show = "shadow" in -- shadow `show`
/// let _u = show in -- shadowed Var (no residual)
/// foo 7 -- residual #1: foo@Int
///
/// `synth` pushes exactly two residuals (in order: show@Int, foo@Int).
/// The shadow-aware walker must:
/// - rewrite the outer `show` callee → `show#Int`,
/// - leave the inner shadowed `show` Var literally as `show`,
/// - rewrite the `foo` callee → `foo#Int`.
///
/// A shadow-blind walker would advance the cursor on the inner Var,
/// rewriting it to `foo#Int` (using residual #1) AND leaving the real
/// `foo 7` callee untouched (cursor walks off the end of the slice).
#[test]
fn rewrite_walker_skips_locally_shadowed_class_method() {
use ailang_core::ast::{Def, Term};
let entry = examples_dir().join("test_22b3_shadow_class_method.ail.json");
let ws = ailang_core::load_workspace(&entry).expect("load");
let diags = ailang_check::check_workspace(&ws);
assert!(diags.is_empty(), "fixture must typecheck: {:?}", diags);
let ws = ailang_check::monomorphise_workspace(&ws).expect("mono");
let main_module = ws.modules.get("test_22b3_shadow_class_method").unwrap();
let main_fn = main_module
.defs
.iter()
.find_map(|d| match d {
Def::Fn(f) if f.name == "main" => Some(f),
_ => None,
})
.expect("main");
// Body: Let _t (= App show 5) (Let show "shadow" (Let _u (Var show) (App foo 7)))
let (outer_value, outer_body): (&Term, &Term) = match &main_fn.body {
Term::Let { value, body, .. } => (value.as_ref(), body.as_ref()),
other => panic!("outer body is not Let: {:?}", other),
};
let outer_callee = match outer_value {
Term::App { callee, .. } => match callee.as_ref() {
Term::Var { name } => name.as_str(),
other => panic!("outer callee is not Var: {:?}", other),
},
other => panic!("outer value is not App: {:?}", other),
};
assert_eq!(
outer_callee, "show#Int",
"the outer class-method call site must be rewritten to show#Int"
);
// Step inside `let show = "shadow" in <body>`.
let shadow_let_body = match outer_body {
Term::Let { name, body, .. } => {
assert_eq!(name, "show", "expected shadowing let to bind `show`");
body.as_ref()
}
other => panic!("expected shadowing Let, got {:?}", other),
};
// Step inside `let _u = <Var show> in <foo-call>`.
let (inner_value, inner_body): (&Term, &Term) = match shadow_let_body {
Term::Let { value, body, .. } => (value.as_ref(), body.as_ref()),
other => panic!("expected inner Let, got {:?}", other),
};
let shadowed_var_name = match inner_value {
Term::Var { name } => name.as_str(),
other => panic!("inner value is not Var: {:?}", other),
};
// The locally-shadowed `show` Var must NOT be rewritten.
assert_eq!(
shadowed_var_name, "show",
"locally-shadowed `show` Var must remain literal `show`, \
not be re-aligned to a later residual slot"
);
// The real `foo 7` call site — the second residual — must be
// rewritten correctly to `foo#Int`. A shadow-blind walker would
// have spent residual #1 on the shadowed Var and left this Var
// untouched.
let foo_callee = match inner_body {
Term::App { callee, .. } => match callee.as_ref() {
Term::Var { name } => name.as_str(),
other => panic!("foo callee is not Var: {:?}", other),
},
other => panic!("expected App for `foo 7`, got {:?}", other),
};
assert_eq!(
foo_callee, "foo#Int",
"the post-shadow `foo` call site must align to residual #1"
);
}
/// Property: a class-method call site in module A whose `defining_module`
/// (per the registry's instance entry) is module B is rewritten to the
/// qualified name `<B>.<mono_symbol>` — defending the cross-module
/// resolution branch in the walker. Also asserts the synth-def
/// placement contract: the synthesised FnDef lives in B, not A.
#[test]
fn rewrite_uses_qualified_name_for_cross_module_call_site() {
let entry = examples_dir().join("test_22b2_xmod_instance_present.ail.json");
let ws = ailang_core::load_workspace(&entry).expect("load");
let diags = ailang_check::check_workspace(&ws);
assert!(diags.is_empty(), "fixture must typecheck: {:?}", diags);
let ws = ailang_check::monomorphise_workspace(&ws).expect("mono");
let main_module = ws.modules.get("test_22b2_xmod_instance_present").unwrap();
let main_fn = main_module
.defs
.iter()
.find_map(|d| match d {
ailang_core::ast::Def::Fn(f) if f.name == "main" => Some(f),
_ => None,
})
.expect("main");
let callee_name: &str = match &main_fn.body {
ailang_core::ast::Term::App { callee, .. } => match callee.as_ref() {
ailang_core::ast::Term::Var { name } => name.as_str(),
other => panic!("callee is not Var: {:?}", other),
},
other => panic!("body is not App: {:?}", other),
};
// class+instance live in test_22b2_xmod_classmod; caller in
// test_22b2_xmod_instance_present → qualified call.
assert_eq!(callee_name, "test_22b2_xmod_classmod.show#Int");
// Placement: the synthesised def must live in the defining module,
// not the caller's module.
let classmod = ws.modules.get("test_22b2_xmod_classmod").unwrap();
let has_synth = classmod.defs.iter().any(|d| {
matches!(d, ailang_core::ast::Def::Fn(f) if f.name == "show#Int")
});
assert!(
has_synth,
"show#Int must live in the instance's defining module"
);
let caller_has_synth = main_module.defs.iter().any(|d| {
matches!(d, ailang_core::ast::Def::Fn(f) if f.name == "show#Int")
});
assert!(
!caller_has_synth,
"show#Int must NOT live in the caller's module"
);
}
/// After the mono pass, the body of `main` in
/// test_22b2_instance_present must reference `show#Int` instead
/// of `show`.
+152 -67
View File
@@ -51,7 +51,7 @@
//! the implementation so the constraint is visible to anyone
//! extending the skeleton.
use ailang_core::ast::{Arm, ClassDef, Def, FnDef as AstFnDef, InstanceDef, Term, Type};
use ailang_core::ast::{Arm, ClassDef, ConstDef, Def, FnDef as AstFnDef, InstanceDef, Pattern, Term, Type};
use ailang_core::workspace::Workspace;
use crate::Result;
use indexmap::IndexMap;
@@ -156,47 +156,35 @@ pub fn monomorphise_workspace(ws: &Workspace) -> Result<Workspace> {
for mname in &module_names {
let n_defs = ws_owned.modules[mname].defs.len();
for i in 0..n_defs {
let (ordered, defining_module_name): (Vec<Option<MonoTarget>>, String) = {
let ordered: Vec<Option<MonoTarget>> = {
let m = &ws_owned.modules[mname];
let d = &m.defs[i];
match d {
Def::Fn(f) => (collect_residuals_ordered(f, mname, &env)?, mname.clone()),
Def::Fn(f) => collect_residuals_ordered(f, mname, &env)?,
Def::Const(c) => {
let pseudo = AstFnDef {
name: c.name.clone(),
ty: c.ty.clone(),
params: Vec::new(),
body: c.value.clone(),
doc: None,
suppress: Vec::new(),
};
(collect_residuals_ordered(&pseudo, mname, &env)?, mname.clone())
let pseudo = const_as_pseudo_fn(c);
collect_residuals_ordered(&pseudo, mname, &env)?
}
_ => continue,
}
};
let m = ws_owned.modules.get_mut(mname).unwrap();
let d = &mut m.defs[i];
let ordered_concrete: Vec<MonoTarget> = ordered
.into_iter()
.map(|o| {
o.unwrap_or_else(|| MonoTarget {
class: String::new(),
method: String::new(),
type_: Type::unit(),
defining_module: defining_module_name.clone(),
})
})
.collect();
let mut cursor = 0usize;
let mut locals: BTreeSet<String> = BTreeSet::new();
match d {
Def::Fn(f) => {
// Top-level fn params shadow class-method names too.
for p in &f.params {
locals.insert(p.clone());
}
rewrite_class_method_calls(
&mut f.body,
&env.class_methods,
mname,
&ordered_concrete,
&ordered,
&mut cursor,
&mut locals,
);
}
Def::Const(c) => {
@@ -204,8 +192,9 @@ pub fn monomorphise_workspace(ws: &Workspace) -> Result<Workspace> {
&mut c.value,
&env.class_methods,
mname,
&ordered_concrete,
&ordered,
&mut cursor,
&mut locals,
);
}
_ => {}
@@ -233,14 +222,7 @@ fn collect_targets_workspace_wide(
out.extend(collect_mono_targets(f, mname, env)?);
}
Def::Const(c) => {
let pseudo = AstFnDef {
name: c.name.clone(),
ty: c.ty.clone(),
params: Vec::new(),
body: c.value.clone(),
doc: None,
suppress: Vec::new(),
};
let pseudo = const_as_pseudo_fn(c);
out.extend(collect_mono_targets(&pseudo, mname, env)?);
}
_ => {}
@@ -250,6 +232,24 @@ fn collect_targets_workspace_wide(
Ok(out)
}
/// Iter 22b.3.6: wrap a [`ConstDef`] in a synthetic zero-arg
/// [`AstFnDef`] for residual-collection / rewrite purposes. Const
/// bodies have no parameter list, so the residual gathering only
/// depends on body shape — the wrapping is a structural adapter,
/// not a semantic conversion. Two callers (Phase 1 collection and
/// Phase 3 rewrite) need the same shape; sharing the constructor
/// keeps them in lockstep.
fn const_as_pseudo_fn(c: &ConstDef) -> AstFnDef {
AstFnDef {
name: c.name.clone(),
ty: c.ty.clone(),
params: Vec::new(),
body: c.value.clone(),
doc: None,
suppress: Vec::new(),
}
}
/// Iter 22b.3: workspace-wide `class-name -> ClassDef` index.
/// Used by the fixpoint to look up the matching class definition
/// when synthesising a fn.
@@ -574,30 +574,48 @@ pub fn synthesise_mono_fn(
/// synth-replay run on the same body.
///
/// The walker increments a positional counter at each
/// class-method-named `Term::Var` it encounters. The counter must
/// match the order in which `synth` pushes residuals (pre-order
/// AST walk; child evaluation order matches the `match` arms in
/// `crate::synth`). When this invariant holds, `ordered_targets[idx]`
/// is the target resolved at the i-th class-method call site.
/// class-method-named `Term::Var` it encounters that is NOT
/// shadowed by a local binding. The counter must match the order
/// in which `synth` pushes residuals (pre-order AST walk; child
/// evaluation order matches the `match` arms in [`crate::synth`]).
/// When this invariant holds, `ordered_targets[idx]` is the target
/// resolved at the i-th class-method call site.
///
/// `caller_module`: name of the module enclosing this body. If
/// the target's `defining_module` differs, the rewritten name is
/// qualified `<defining_module>.<mono_symbol>` (cross-module
/// resolution path); otherwise unqualified. Targets whose `class`
/// is empty are sentinel placeholders for non-concrete residuals
/// — the cursor advances over them and the name is left unchanged.
/// resolution path); otherwise unqualified.
///
/// `locals` mirrors `synth`'s lookup-precedence rule: a `Term::Var`
/// whose `name` is in `locals` resolves to the local binding and
/// `synth` pushes NO residual for it, so the walker must NOT
/// advance the cursor either. Each binding-form pushes its binders
/// before recursing into the relevant scope and pops them after.
///
/// `ordered_targets[idx]`:
/// - `Some(t)` — concrete instance found; rewrite the name.
/// - `None` — residual was non-concrete or had no instance; cursor
/// still advances (to keep alignment) but the name is left
/// unchanged.
fn rewrite_class_method_calls(
body: &mut Term,
class_methods: &BTreeMap<String, crate::ClassMethodEntry>,
caller_module: &str,
ordered_targets: &[MonoTarget],
ordered_targets: &[Option<MonoTarget>],
cursor: &mut usize,
locals: &mut BTreeSet<String>,
) {
match body {
Term::Var { name } => {
if class_methods.contains_key(name) {
if let Some(t) = ordered_targets.get(*cursor) {
if !t.class.is_empty() {
// Mirror synth's lookup-precedence rule: if `name` is
// shadowed by a local, synth resolves to the local
// and pushes no residual — we must not advance.
if locals.contains(name) {
return;
}
if let Some(slot) = ordered_targets.get(*cursor) {
if let Some(t) = slot {
let sym = mono_symbol(&t.method, &t.type_);
let new_name = if t.defining_module == caller_module {
sym
@@ -612,58 +630,125 @@ fn rewrite_class_method_calls(
}
}
Term::App { callee, args, .. } => {
rewrite_class_method_calls(callee, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(callee, class_methods, caller_module, ordered_targets, cursor, locals);
for a in args {
rewrite_class_method_calls(a, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(a, class_methods, caller_module, ordered_targets, cursor, locals);
}
}
Term::Let { value, body, .. } => {
rewrite_class_method_calls(value, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(body, class_methods, caller_module, ordered_targets, cursor);
Term::Let { name, value, body } => {
// synth: `value` is in the outer scope; `body` sees `name`.
rewrite_class_method_calls(value, class_methods, caller_module, ordered_targets, cursor, locals);
let inserted = locals.insert(name.clone());
rewrite_class_method_calls(body, class_methods, caller_module, ordered_targets, cursor, locals);
if inserted {
locals.remove(name);
}
}
Term::LetRec { body, in_term, .. } => {
rewrite_class_method_calls(body, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(in_term, class_methods, caller_module, ordered_targets, cursor);
Term::LetRec { name, params, body, in_term, .. } => {
// synth: `name` is in scope in BOTH `body` (with `params`
// also in scope) AND `in_term` (without `params`).
let name_inserted = locals.insert(name.clone());
// Body scope: name + params.
let mut params_inserted: Vec<String> = Vec::new();
for p in params {
if locals.insert(p.clone()) {
params_inserted.push(p.clone());
}
}
rewrite_class_method_calls(body, class_methods, caller_module, ordered_targets, cursor, locals);
for p in &params_inserted {
locals.remove(p);
}
// In-clause scope: name only.
rewrite_class_method_calls(in_term, class_methods, caller_module, ordered_targets, cursor, locals);
if name_inserted {
locals.remove(name);
}
}
Term::If { cond, then, else_ } => {
rewrite_class_method_calls(cond, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(then, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(else_, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(cond, class_methods, caller_module, ordered_targets, cursor, locals);
rewrite_class_method_calls(then, class_methods, caller_module, ordered_targets, cursor, locals);
rewrite_class_method_calls(else_, class_methods, caller_module, ordered_targets, cursor, locals);
}
Term::Do { args, .. } => {
for a in args {
rewrite_class_method_calls(a, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(a, class_methods, caller_module, ordered_targets, cursor, locals);
}
}
Term::Ctor { args, .. } => {
for a in args {
rewrite_class_method_calls(a, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(a, class_methods, caller_module, ordered_targets, cursor, locals);
}
}
Term::Match { scrutinee, arms } => {
rewrite_class_method_calls(scrutinee, class_methods, caller_module, ordered_targets, cursor);
for Arm { body, .. } in arms {
rewrite_class_method_calls(body, class_methods, caller_module, ordered_targets, cursor);
// synth: scrutinee is in outer scope; each arm's body sees
// its pattern's binders.
rewrite_class_method_calls(scrutinee, class_methods, caller_module, ordered_targets, cursor, locals);
for Arm { pat, body } in arms {
let binders = pattern_binders(pat);
let mut inserted: Vec<String> = Vec::new();
for b in &binders {
if locals.insert(b.clone()) {
inserted.push(b.clone());
}
}
rewrite_class_method_calls(body, class_methods, caller_module, ordered_targets, cursor, locals);
for b in &inserted {
locals.remove(b);
}
}
}
Term::Lam { body, .. } => {
rewrite_class_method_calls(body, class_methods, caller_module, ordered_targets, cursor);
Term::Lam { params, body, .. } => {
// synth: params are in scope in `body`.
let mut inserted: Vec<String> = Vec::new();
for p in params {
if locals.insert(p.clone()) {
inserted.push(p.clone());
}
}
rewrite_class_method_calls(body, class_methods, caller_module, ordered_targets, cursor, locals);
for p in &inserted {
locals.remove(p);
}
}
Term::Seq { lhs, rhs } => {
rewrite_class_method_calls(lhs, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(rhs, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(lhs, class_methods, caller_module, ordered_targets, cursor, locals);
rewrite_class_method_calls(rhs, class_methods, caller_module, ordered_targets, cursor, locals);
}
Term::Clone { value } => {
rewrite_class_method_calls(value, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(value, class_methods, caller_module, ordered_targets, cursor, locals);
}
Term::ReuseAs { source, body } => {
rewrite_class_method_calls(source, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(body, class_methods, caller_module, ordered_targets, cursor);
rewrite_class_method_calls(source, class_methods, caller_module, ordered_targets, cursor, locals);
rewrite_class_method_calls(body, class_methods, caller_module, ordered_targets, cursor, locals);
}
Term::Lit { .. } => {}
}
}
/// Iter 22b.3.6: collect the variable binders introduced by a
/// match pattern. Used by the walker's `Term::Match` arm to extend
/// `locals` for each arm body. Mirrors `Pattern`'s shape:
/// - [`Pattern::Wild`] / [`Pattern::Lit`] bind nothing,
/// - [`Pattern::Var`] binds its `name`,
/// - [`Pattern::Ctor`] recurses through its `fields`.
fn pattern_binders(pat: &Pattern) -> Vec<String> {
let mut out: Vec<String> = Vec::new();
fn rec(pat: &Pattern, out: &mut Vec<String>) {
match pat {
Pattern::Wild | Pattern::Lit { .. } => {}
Pattern::Var { name } => out.push(name.clone()),
Pattern::Ctor { fields, .. } => {
for f in fields {
rec(f, out);
}
}
}
}
rec(pat, &mut out);
out
}
/// Iter 22b.3: traversal-ordered residual collection — used by
/// the rewrite walker to align cursor positions. Unlike
/// [`collect_mono_targets`], this includes non-concrete residuals
+7 -1
View File
@@ -26,7 +26,13 @@
"methods": [
{
"name": "show",
"body": { "t": "lit", "lit": { "kind": "str", "value": "n" } }
"body": {
"t": "lam",
"params": ["x"],
"paramTypes": [{ "k": "var", "name": "a" }],
"retType": { "k": "con", "name": "Str" },
"body": { "t": "lit", "lit": { "kind": "str", "value": "n" } }
}
}
]
}
@@ -0,0 +1,90 @@
{
"schema": "ailang/v0",
"name": "test_22b3_shadow_class_method",
"imports": [],
"defs": [
{
"kind": "class", "name": "Show", "param": "a",
"methods": [{
"name": "show",
"type": {
"k": "fn", "params": [{ "k": "var", "name": "a" }],
"ret": { "k": "con", "name": "Str" }, "effects": []
}
}]
},
{
"kind": "class", "name": "Foo", "param": "a",
"methods": [{
"name": "foo",
"type": {
"k": "fn", "params": [{ "k": "var", "name": "a" }],
"ret": { "k": "con", "name": "Str" }, "effects": []
}
}]
},
{
"kind": "instance",
"class": "Show",
"type": { "k": "con", "name": "Int" },
"methods": [{
"name": "show",
"body": {
"t": "lam",
"params": ["x"],
"paramTypes": [{ "k": "var", "name": "a" }],
"retType": { "k": "con", "name": "Str" },
"body": { "t": "lit", "lit": { "kind": "str", "value": "s" } }
}
}]
},
{
"kind": "instance",
"class": "Foo",
"type": { "k": "con", "name": "Int" },
"methods": [{
"name": "foo",
"body": {
"t": "lam",
"params": ["x"],
"paramTypes": [{ "k": "var", "name": "a" }],
"retType": { "k": "con", "name": "Str" },
"body": { "t": "lit", "lit": { "kind": "str", "value": "f" } }
}
}]
},
{
"kind": "fn",
"name": "main",
"type": {
"k": "fn", "params": [], "ret": { "k": "con", "name": "Str" },
"effects": []
},
"params": [],
"body": {
"t": "let",
"name": "_t",
"value": {
"t": "app",
"fn": { "t": "var", "name": "show" },
"args": [{ "t": "lit", "lit": { "kind": "int", "value": 5 } }]
},
"body": {
"t": "let",
"name": "show",
"value": { "t": "lit", "lit": { "kind": "str", "value": "shadow" } },
"body": {
"t": "let",
"name": "_u",
"value": { "t": "var", "name": "show" },
"body": {
"t": "app",
"fn": { "t": "var", "name": "foo" },
"args": [{ "t": "lit", "lit": { "kind": "int", "value": 7 } }]
}
}
}
}
}
]
}