From 59e86b3805edd8100409664790840907d022c621 Mon Sep 17 00:00:00 2001
From: Brummel <mould@mycelium.de>
Date: Sat, 9 May 2026 22:41:18 +0200
Subject: [PATCH] test: red for monomorphise_workspace unknown type on user ADT

---
 crates/ail/tests/typeclass_22c.rs         | 58 +++++++++++++++
 examples/test_22c_user_class_e2e.ail.json | 90 +++++++++++++++++++++++
 2 files changed, 148 insertions(+)
 create mode 100644 crates/ail/tests/typeclass_22c.rs
 create mode 100644 examples/test_22c_user_class_e2e.ail.json

diff --git a/crates/ail/tests/typeclass_22c.rs b/crates/ail/tests/typeclass_22c.rs
new file mode 100644
index 0000000..63b0d74
--- /dev/null
+++ b/crates/ail/tests/typeclass_22c.rs
@@ -0,0 +1,58 @@
+//! Iter 22c: milestone-22 acceptance — user-defined classes with
+//! instances over user-defined ADTs end-to-end (typecheck → mono →
+//! codegen → binary). The 22b.3 mono pass was tested only against
+//! instances over primitive types; this file pins the user-ADT path.
+//!
+//! Co-located with `typeclass_22b3.rs` so the typeclass-feature
+//! coverage is browsable in one directory.
+
+use std::path::Path;
+use std::process::Command;
+
+fn ail_bin() -> &'static str {
+    env!("CARGO_BIN_EXE_ail")
+}
+
+fn build_and_run(example: &str) -> String {
+    let manifest_dir = env!("CARGO_MANIFEST_DIR");
+    let workspace = Path::new(manifest_dir).parent().unwrap().parent().unwrap();
+    let src = workspace.join("examples").join(example);
+    let tmp = std::env::temp_dir().join(format!(
+        "ailang_22c_{}_{}",
+        example.replace('.', "_"),
+        std::process::id()
+    ));
+    std::fs::create_dir_all(&tmp).unwrap();
+    let out = tmp.join("bin");
+    let status = Command::new(ail_bin())
+        .args(["build", src.to_str().unwrap(), "-o"])
+        .arg(&out)
+        .status()
+        .expect("ail build failed to run");
+    assert!(status.success(), "ail build failed for {example}");
+    let output = Command::new(&out).output().expect("execute binary");
+    assert!(
+        output.status.success(),
+        "binary {} exited non-zero",
+        out.display()
+    );
+    String::from_utf8(output.stdout).expect("stdout utf8")
+}
+
+/// Property: a workspace declaring a user class with an instance over
+/// a user-defined ADT must build and run end-to-end. The instance
+/// body uses the ADT's constructor and pattern-matches against it,
+/// which exercises the mono pass's `synth` replay against ctor terms
+/// and ctor patterns whose owning type is locally defined.
+///
+/// Pre-22c: `ail build` fails with
+/// `monomorphise_workspace: unknown type: \`IntBox\``
+/// because `mono::build_workspace_env` does not seed the synth env's
+/// per-module local-type and ctor-index tables; `synth`'s bare-name
+/// lookup at `lib.rs:1855` (and the parallel ctor-index lookup at
+/// `lib.rs:2316`) fall through.
+#[test]
+fn user_class_instance_over_user_adt_builds_and_runs() {
+    let stdout = build_and_run("test_22c_user_class_e2e.ail.json");
+    assert_eq!(stdout.trim(), "42");
+}
diff --git a/examples/test_22c_user_class_e2e.ail.json b/examples/test_22c_user_class_e2e.ail.json
new file mode 100644
index 0000000..81a0a62
--- /dev/null
+++ b/examples/test_22c_user_class_e2e.ail.json
@@ -0,0 +1,90 @@
+{
+  "schema": "ailang/v0",
+  "name": "test_22c_user_class_e2e",
+  "imports": [],
+  "defs": [
+    {
+      "kind": "type",
+      "name": "IntBox",
+      "ctors": [
+        { "name": "MkIntBox", "fields": [{ "k": "con", "name": "Int" }] }
+      ]
+    },
+    {
+      "kind": "class",
+      "name": "Foo",
+      "param": "a",
+      "methods": [
+        {
+          "name": "foo",
+          "type": {
+            "k": "fn",
+            "params": [{ "k": "var", "name": "a" }],
+            "param_modes": ["borrow"],
+            "ret": { "k": "con", "name": "Int" },
+            "effects": []
+          }
+        }
+      ]
+    },
+    {
+      "kind": "instance",
+      "class": "Foo",
+      "type": { "k": "con", "name": "IntBox" },
+      "methods": [
+        {
+          "name": "foo",
+          "body": {
+            "t": "lam",
+            "params": ["b"],
+            "paramTypes": [{ "k": "var", "name": "a" }],
+            "retType": { "k": "con", "name": "Int" },
+            "body": {
+              "t": "match",
+              "scrutinee": { "t": "var", "name": "b" },
+              "arms": [
+                {
+                  "pat": {
+                    "p": "ctor",
+                    "ctor": "MkIntBox",
+                    "fields": [{ "p": "var", "name": "v" }]
+                  },
+                  "body": { "t": "var", "name": "v" }
+                }
+              ]
+            }
+          }
+        }
+      ]
+    },
+    {
+      "kind": "fn",
+      "name": "main",
+      "type": {
+        "k": "fn",
+        "params": [],
+        "ret": { "k": "con", "name": "Unit" },
+        "effects": ["IO"]
+      },
+      "params": [],
+      "body": {
+        "t": "do",
+        "op": "io/print_int",
+        "args": [
+          {
+            "t": "app",
+            "fn": { "t": "var", "name": "foo" },
+            "args": [
+              {
+                "t": "ctor",
+                "type": "IntBox",
+                "ctor": "MkIntBox",
+                "args": [{ "t": "lit", "lit": { "kind": "int", "value": 42 } }]
+              }
+            ]
+          }
+        ]
+      }
+    }
+  ]
+}