Add knip unused code & dependency analyser (matrix-org#4013)

.github/workflows/static_analysis.yml

@@ -90,3 +90,19 @@ jobs:
                   path: _docs
                   # We'll only use this in a workflow_run, then we're done with it
                   retention-days: 1
+
+    analyse_dead_code:
+        name: "Analyse Dead Code"
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v4
+
+            - uses: actions/setup-node@v4
+              with:
+                  cache: "yarn"
+
+            - name: Install Deps
+              run: "yarn install --frozen-lockfile"
+
+            - name: Run linter
+              run: "yarn run lint:knip"

knip.ts

@@ -0,0 +1,36 @@
+import { KnipConfig } from "knip";
+
+export default {
+    entry: [
+        "src/index.ts",
+        "src/types.ts",
+        "src/browser-index.ts",
+        "src/indexeddb-worker.ts",
+        "scripts/**",
+        "spec/**",
+        "release.sh",
+        // For now, we include all source files as entrypoints as we have been bad about gutwrenched imports
+        "src/**",
+    ],
+    project: ["**/*.{js,ts}"],
+    ignore: ["examples/**"],
+    ignoreDependencies: [
+        // Required for `action-validator`
+        "@action-validator/*",
+        // Used for git pre-commit hooks
+        "husky",
+        // Used in script which only runs in environment with `@octokit/rest` installed
+        "@octokit/rest",
+        // Used by jest
+        "jest-environment-jsdom",
+        "babel-jest",
+        "ts-node",
+        // Used by `@babel/plugin-transform-runtime`
+        "@babel/runtime",
+    ],
+    ignoreBinaries: [
+        // Used when available by reusable workflow `.github/workflows/release-make.yml`
+        "dist",
+    ],
+    ignoreExportsUsedInFile: true,
+} satisfies KnipConfig;

package.json

@@ -19,6 +19,7 @@
         "lint:js-fix": "prettier --log-level=warn --write . && eslint --fix src spec",
         "lint:types": "tsc --noEmit",
         "lint:workflows": "find .github/workflows -type f \\( -iname '*.yaml' -o -iname '*.yml' \\) | xargs -I {} sh -c 'echo \"Linting {}\"; action-validator \"{}\"'",
+        "lint:knip": "knip",
         "test": "jest",
         "test:watch": "jest --watch",
         "coverage": "yarn test --coverage"
@@ -80,10 +81,8 @@
         "@babel/plugin-transform-runtime": "^7.12.10",
         "@babel/preset-env": "^7.12.11",
         "@babel/preset-typescript": "^7.12.7",
-        "@babel/register": "^7.12.10",
         "@casualbot/jest-sonar-reporter": "2.2.7",
         "@matrix-org/olm": "3.2.15",
-        "@peculiar/webcrypto": "^1.4.5",
         "@types/bs58": "^4.0.1",
         "@types/content-type": "^1.1.5",
         "@types/debug": "^4.1.7",
@@ -117,15 +116,17 @@
         "jest-mock": "^29.0.0",
         "lint-staged": "^15.0.2",
         "matrix-mock-request": "^2.5.0",
-        "node-fetch": "^2.7.0",
         "prettier": "3.2.5",
         "rimraf": "^5.0.0",
-        "ts-node": "^10.9.1",
+        "ts-node": "^10.9.2",
         "typedoc": "^0.25.10",
         "typedoc-plugin-coverage": "^3.0.0",
         "typedoc-plugin-mdn-links": "^3.0.3",
         "typedoc-plugin-missing-exports": "^2.0.0",
-        "typescript": "^5.3.3"
+        "typescript": "^5.3.3",
+        "node-fetch": "^2.7.0",
+        "knip": "^4.0.1",
+        "@peculiar/webcrypto": "^1.4.5"
     },
     "@casualbot/jest-sonar-reporter": {
         "outputDirectory": "coverage",

src/crypto/backup.ts

@@ -871,6 +871,9 @@ export const algorithmsByName: Record<string, BackupAlgorithmClass> = {
     [Aes256.algorithmName]: Aes256,
 };
 
+// the linter doesn't like this but knip does
+// eslint-disable-next-line tsdoc/syntax
+/** @alias */
 export const DefaultAlgorithm: BackupAlgorithmClass = Curve25519;
 
 /**