From 8ca2b5555d47e211c04136637477c5227172d885 Mon Sep 17 00:00:00 2001
From: Alex Waygood <Alex.Waygood@Gmail.com>
Date: Fri, 17 Oct 2025 20:30:17 +0100
Subject: [PATCH] Dogfood ty on py-fuzzer in CI (#20946)

---
 .github/workflows/ci.yaml       | 9 ++++++++-
 python/py-fuzzer/fuzz.py        | 2 +-
 python/py-fuzzer/pyproject.toml | 4 ++++
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 0a52349001..f4f0b9b607 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -277,7 +277,8 @@ jobs:
         run: cargo test -p ty_python_semantic --test mdtest || true
       - name: "Run tests"
         run: cargo insta test --all-features --unreferenced reject --test-runner nextest
-
+      # Dogfood ty on py-fuzzer
+      - run: uv run --project=./python/py-fuzzer cargo run -p ty check --project=./python/py-fuzzer
       # Check for broken links in the documentation.
       - run: cargo doc --all --no-deps
         env:
@@ -519,6 +520,7 @@ jobs:
         with:
           persist-credentials: false
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
+      - uses: astral-sh/setup-uv@d0cc045d04ccac9d8b7881df0226f9e82c39688e # v6.8.0
       - name: "Install Rust toolchain"
         run: rustup component add rustfmt
       # Run all code generation scripts, and verify that the current output is
@@ -533,6 +535,11 @@ jobs:
           ./scripts/add_plugin.py test --url https://pypi.org/project/-test/0.1.0/ --prefix TST
           ./scripts/add_rule.py --name FirstRule --prefix TST --code 001 --linter test
       - run: cargo check
+      # Lint/format/type-check py-fuzzer
+      # (dogfooding with ty is done in a separate job)
+      - run: uv run --directory=./python/py-fuzzer mypy
+      - run: uv run --directory=./python/py-fuzzer ruff format --check
+      - run: uv run --directory=./python/py-fuzzer ruff check
 
   ecosystem:
     name: "ecosystem"
diff --git a/python/py-fuzzer/fuzz.py b/python/py-fuzzer/fuzz.py
index 22f6965244..eacd7587b2 100644
--- a/python/py-fuzzer/fuzz.py
+++ b/python/py-fuzzer/fuzz.py
@@ -139,7 +139,7 @@ class FuzzResult:
                 case Executable.TY:
                     panic_message = f"The following code triggers a {new}ty panic:"
                 case _ as unreachable:
-                    assert_never(unreachable)
+                    assert_never(unreachable)  # ty: ignore[type-assertion-failure]
 
             print(colored(panic_message, "red"))
             print()
diff --git a/python/py-fuzzer/pyproject.toml b/python/py-fuzzer/pyproject.toml
index 020f91b899..52bc17f25a 100644
--- a/python/py-fuzzer/pyproject.toml
+++ b/python/py-fuzzer/pyproject.toml
@@ -32,6 +32,10 @@ warn_unreachable = true
 local_partial_types = true
 enable_error_code = "ignore-without-code,redundant-expr,truthy-bool"
 
+[tool.ty.rules]
+possibly-unresolved-reference = "error"
+unused-ignore-comment = "error"
+
 [tool.ruff]
 fix = true
 preview = true