iter ct.1.4-followup: type-con rewrite test + doc clarity

2026-05-11 01:21:18 +02:00
parent d45977f9bb
commit a73f7d3213
2 changed files with 76 additions and 4 deletions
@@ -81,3 +81,64 @@ fn migrate_canonical_types_rewrites_bare_xmod_term_ctor() {
    let bytes_after = fs::read(&main_path).unwrap();
    assert_eq!(bytes_before, bytes_after, "migration must be idempotent");
 }
+
+/// Symmetric to `migrate_canonical_types_rewrites_bare_xmod_term_ctor`,
+/// but the only bare cross-module reference in the consumer is a
+/// `Type::Con` in a fn return type — the body carries no `Term::Ctor`
+/// at all. This pins the Type::Con rewrite branch of `rewrite_def` as
+/// a property: a regression that broke that branch (e.g. accidentally
+/// scoping `rewrite_type` to only fn params) would leave the Term::Ctor
+/// test green and ship the bug.
+#[test]
+fn migrate_canonical_types_rewrites_bare_xmod_type_con() {
+    let dir = tmp_dir("rewrites_bare_type_con");
+    // Defining module: `other` declares `type Foo`.
+    let other_path = dir.join("other.ail.json");
+    fs::write(&other_path, serde_json::to_vec_pretty(&serde_json::json!({
+        "schema": "ailang/v0",
+        "name": "other",
+        "imports": [],
+        "defs": [{ "kind": "type", "name": "Foo", "ctors": [{ "name": "MkFoo", "fields": [] }] }],
+    })).unwrap()).unwrap();
+    // Consumer module: imports `other`, body is a unit literal (no
+    // Term::Ctor) — the only bare cross-module reference is the
+    // Type::Con `Foo` in the fn return type.
+    let main_path = dir.join("main.ail.json");
+    let bare_module = serde_json::json!({
+        "schema": "ailang/v0",
+        "name": "main",
+        "imports": [{ "module": "other" }],
+        "defs": [{
+            "kind": "fn", "name": "f",
+            "type": { "k": "fn", "params": [], "ret": { "k": "con", "name": "Foo" }, "effects": [] },
+            "params": [],
+            "body": { "t": "lit", "lit": { "kind": "unit" } }
+        }],
+    });
+    fs::write(&main_path, serde_json::to_vec_pretty(&bare_module).unwrap()).unwrap();
+
+    // Run migration.
+    let status = Command::new(ail_bin())
+        .args(["migrate-canonical-types", dir.to_str().unwrap()])
+        .status()
+        .expect("ail binary must launch");
+    assert!(status.success(), "migration exited non-zero");
+
+    // Inspect rewritten consumer.
+    let after: serde_json::Value = serde_json::from_slice(
+        &fs::read(&main_path).unwrap()
+    ).unwrap();
+    let ret_name = after["defs"][0]["type"]["ret"]["name"].as_str().unwrap();
+    assert_eq!(ret_name, "other.Foo",
+        "fn-return Type::Con.name must be qualified after migration");
+
+    // Idempotence: run migration again, capture bytes, compare.
+    let bytes_before = fs::read(&main_path).unwrap();
+    let status2 = Command::new(ail_bin())
+        .args(["migrate-canonical-types", dir.to_str().unwrap()])
+        .status()
+        .expect("ail binary must launch");
+    assert!(status2.success(), "second migration exited non-zero");
+    let bytes_after = fs::read(&main_path).unwrap();
+    assert_eq!(bytes_before, bytes_after, "migration must be idempotent");
+}