From 3ba755672c0b8d6a6b705b746893fb1ea24306e7 Mon Sep 17 00:00:00 2001
From: David Robertson <davidr@element.io>
Date: Thu, 6 Apr 2023 19:40:19 +0100
Subject: [PATCH 1/2] Inline backend-meta linting config

This has caused us too much pain---it makes things especially hard to
debug. I don't think the indirection is worth it, since we haven't used
it in anger across all of our projects.

Additionally: I think I'm coming round to the view that

- all CI config is a mess,
- efforts to reduce duplication are a Sisephean struggle that aren't
  worth it, so
- just copy and paste it and move on with your life.

Or perhaps this is just a crisis of faith?
---
 .github/workflows/tests.yml | 57 +++++++++++++++++++++++++++++++++++--
 1 file changed, 54 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index f01342c8b776..4333f55a533d 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -65,9 +65,59 @@ jobs:
       - run: .ci/scripts/check_lockfile.py
 
   lint:
-    uses: "matrix-org/backend-meta/.github/workflows/python-poetry-ci.yml@v2"
-    with:
-      typechecking-extras: "all"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Setup Poetry
+        uses: matrix-org/setup-python-poetry@v1
+        with:
+          install-project: "false"
+
+      - name: Import order (isort)
+        run: poetry run isort --check --diff .
+
+      - name: Code style (black)
+        run: poetry run black --check --diff .
+
+      - name: Semantic checks (ruff)
+        # --quiet suppresses the update check.
+        run: poetry run ruff --quiet .
+
+  lint-mypy:
+    runs-on: ubuntu-latest
+    name: Typechecking
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Setup Poetry
+        uses: matrix-org/setup-python-poetry@v1
+        with:
+          # We want to make use of type hints in optional dependencies too.
+          extras: all
+          # We have seen odd mypy failures that were resolved when we started
+          # installing the project again:
+          # https://github.com/matrix-org/synapse/pull/15376#issuecomment-1498983775
+          # To make CI green, err towards caution and install the project.
+          install-project: "true"
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@1.58.1
+      - uses: Swatinem/rust-cache@v2
+
+      # NB: I have two concerns with this action:
+      # 1. We occasionally see odd mypy problems that aren't reproducible
+      #    locally with clean caches. I suspect some dodgy caching behaviour.
+      # 2. The action uses GHA machinery that's deprecated
+      #    (https://github.com/AustinScola/mypy-cache-github-action/issues/277)
+      # It may be simpler to use actions/cache ourselves to restore .mypy_cache.
+      - name: Restore/persist mypy's cache
+        uses: AustinScola/mypy-cache-github-action@df56268388422ee282636ee2c7a9cc55ec644a41
+
+      - name: Run mypy
+        run: poetry run mypy
 
   lint-crlf:
     runs-on: ubuntu-latest
@@ -165,6 +215,7 @@ jobs:
     if: ${{ !cancelled() }} # Run this even if prior jobs were skipped
     needs:
       - lint
+      - lint-mypy
       - lint-crlf
       - lint-newsfile
       - lint-pydantic

From 3b56d7d3bf1b7ce973b14db9ee87c74469cbfe91 Mon Sep 17 00:00:00 2001
From: David Robertson <davidr@element.io>
Date: Thu, 6 Apr 2023 20:01:32 +0100
Subject: [PATCH 2/2] Changelog

---
 changelog.d/15409.misc | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/15409.misc

diff --git a/changelog.d/15409.misc b/changelog.d/15409.misc
new file mode 100644
index 000000000000..007111da34f2
--- /dev/null
+++ b/changelog.d/15409.misc
@@ -0,0 +1 @@
+Explicitly install Synapse during typechecking in CI.