Set up eslint and remove tslint (AssemblyScript#1293)

.eslintignore

@@ -0,0 +1,6 @@
+dist/
+docs/
+lib/parse/index.js
+out/
+raw/
+tests/parser/

.eslintrc.js

@@ -0,0 +1,252 @@
+module.exports = {
+  root: true,
+  parser: "@typescript-eslint/parser",
+  plugins: [
+    "@typescript-eslint",
+  ],
+  extends: [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/eslint-recommended",
+    "plugin:@typescript-eslint/recommended",
+  ],
+  parserOptions: {
+    ecmaVersion: 2020,
+    sourceType: "module",
+    ecmaFeatures: {}
+  },
+  globals: {
+    "BigInt64Array": "readonly",
+    "BigUint64Array": "readonly"
+  },
+
+  // === General rules =========================================================
+
+  rules: {
+    // Omitted semicolons are hugely popular, yet within the compiler it makes
+    // sense to be better safe than sorry.
+    "semi": "error",
+
+    // Our code bases uses 2 spaces for indentation, and we enforce it here so
+    // files don't mix spaces, tabs or different indentation levels.
+    "indent": ["error", 2, {
+      "SwitchCase": 1,
+      "VariableDeclarator": "first",
+      "offsetTernaryExpressions": true,
+      "ignoredNodes": [ // FIXME: something's odd here
+        "ConditionalExpression > *",
+        "ConditionalExpression > * > *",
+        "ConditionalExpression > * > * > *"
+      ]
+    }],
+
+    // This is mostly visual style, making comments look uniform.
+    "spaced-comment": ["error", "always", {
+      "markers": ["/"],   // triple-slash
+      "exceptions": ["/"] // all slashes
+    }],
+
+    // This tends to be annoying as it encourages developers to make everything
+    // that is never reassigned a 'const', sometimes semantically incorrect so,
+    // typically leading to huge diffs in follow-up PRs modifying affected code.
+    "prefer-const": "off",
+
+    // It is perfectly fine to declare top-level variables with `var`, yet this
+    // rule doesn't provide configuration options that would help.
+    "no-var": "off",
+
+    // Quite often, dealing with multiple related cases at once or otherwise
+    // falling through is exactly the point of using a switch.
+    "no-fallthrough": "off",
+
+    // Typical false-positives here are `do { ... } while (true)` statements or
+    // similar, but the only option provided here is not checking any loops.
+    "no-constant-condition": ["error", { checkLoops: false }],
+
+    // Functions are nested in blocks occasionally, and there haven't been any
+    // problems with this so far, so turning the check off.
+    "no-inner-declarations": "off",
+
+    // Quite common in scenarios where an iteration starts at `current = this`.
+    "@typescript-eslint/no-this-alias": "off",
+
+    // Disabled here, but enabled again for JavaScript files
+    "no-unused-vars": "off",
+
+    // Disabled here, but enabled again for TypeScript files
+    "@typescript-eslint/no-unused-vars": "off"
+  },
+  overrides: [
+
+    // === JavaScript rules ====================================================
+
+    {
+      env: {
+        "browser": true,
+        "amd": true,
+        "node": true,
+        "es6": true
+      },
+      files: [
+        "**/*.js"
+      ],
+      rules: {
+        // Node's support for ESM is still not great, but this rule is likely
+        // to become activated once compatibility doesn't suck anymore.
+        "@typescript-eslint/no-var-requires": "off",
+
+        // Enforcing to remove function parameters on stubs makes code less
+        // maintainable, so we instead allow unused function parameters.
+        "no-unused-vars": [
+          "warn", {
+            "vars": "local",
+            "args": "none",
+            "ignoreRestSiblings": false
+          }
+        ]
+      }
+    },
+
+    // === TypeScript rules ====================================================
+
+    {
+      files: [
+        "**/*.ts"
+      ],
+      rules: {
+        // Enforcing to remove function parameters on stubs makes code less
+        // maintainable, so we instead allow unused function parameters.
+        "@typescript-eslint/no-unused-vars": [
+          "warn", {
+            "vars": "local",
+            "args": "none",
+            "ignoreRestSiblings": false
+          }
+        ]
+      }
+    },
+
+    // === AssemblyScript rules (extends TypeScript rules) =====================
+
+    {
+      files: [
+        "**/assembly/**/*.ts",
+        "src/**/*.ts",
+        "lib/parse/src/**/*.ts"
+      ],
+      rules: {
+        // Namespaces are quite useful in AssemblyScript
+        "@typescript-eslint/no-namespace": "off",
+
+        // There is actually codegen difference here
+        "@typescript-eslint/no-array-constructor": "off",
+
+        // Sometimes it can't be avoided to add a @ts-ignore
+        "@typescript-eslint/ban-ts-comment": "off",
+
+        // Utilized to achieve portability in some cases
+        "@typescript-eslint/no-non-null-assertion": "off",
+      }
+    },
+
+    // === Compiler rules (extends AssemblyScript rules) =======================
+
+    {
+      files: [
+        "src/**/*.ts",
+        "std/assembly/**/*.ts"
+      ],
+      rules: {
+        // There is an actual codegen difference here - TODO: revisit
+        "no-cond-assign": "off",
+
+        // Not all types can be omitted in AS yet - TODO: revisit
+        "@typescript-eslint/no-inferrable-types": "off",
+
+        // Used rarely to reference internals that are not user-visible
+        "@typescript-eslint/triple-slash-reference": "off",
+
+        // The compiler has its own `Function` class for example
+        "no-shadow-restricted-names": "off",
+        "@typescript-eslint/ban-types": "off"
+      }
+    },
+
+    // === Standard Library rules (extends AssemblyScript rules) ===============
+
+    {
+      files: [
+        "std/assembly/**/*.ts"
+      ],
+      rules: {
+        // We are implementing with --noLib, so we shadow all the time
+        "no-shadow-restricted-names": "off",
+
+        // Similarly, sometimes we need the return type to be String, not string
+        "@typescript-eslint/ban-types": "off"
+      }
+    },
+
+    // === Standard Definition rules (extends TypeScript rules) ================
+
+    {
+      files: [
+        "std/**/*.d.ts"
+      ],
+      rules: {
+        // Often required to achieve compatibility with TypeScript
+        "@typescript-eslint/no-explicit-any": "off",
+
+        // Interfaces can be stubs here, i.e. not yet fully implemented
+        "@typescript-eslint/no-empty-interface": "off",
+
+        // Definitions make use of `object` to model rather unusual constraints
+        "@typescript-eslint/ban-types": "off"
+      }
+    },
+
+    // === Compiler Definition rules (extends TypeScript rules) ================
+
+    {
+      files: [
+        "./index.d.ts",
+        "./index.release.d.ts",
+      ],
+      rules: {
+        // Our definitions are complicated, and all attempts to describe them
+        // as modules have failed so far. As such, we re-export namespaces.
+        "@typescript-eslint/no-namespace": "off",
+        "@typescript-eslint/triple-slash-reference": "off"
+      }
+    },
+
+    // === Test rules (extends TypeScript rules) ===============================
+
+    {
+      files: [
+        "./tests/compiler/**/*.ts",
+        "./lib/loader/tests/assembly/**/*.ts"
+      ],
+      rules: {
+        // Tests typically include unusual code patterns on purpose. This is
+        // very likely not an extensive list, but covers what's there so far.
+        "no-empty": "off",
+        "no-cond-assign": "off",
+        "no-compare-neg-zero": "off",
+        "no-inner-declarations": "off",
+        "no-constant-condition": "off",
+        "use-isnan": "off",
+        "@typescript-eslint/no-namespace": "off",
+        "@typescript-eslint/no-unused-vars": "off",
+        "@typescript-eslint/no-empty-function": "off",
+        "@typescript-eslint/no-non-null-assertion": "off",
+        "@typescript-eslint/no-extra-semi": "off",
+        "@typescript-eslint/no-inferrable-types": "off",
+        "@typescript-eslint/ban-types": "off",
+        "@typescript-eslint/triple-slash-reference": "off",
+        "@typescript-eslint/ban-ts-comment": "off",
+        "@typescript-eslint/no-extra-non-null-assertion": "off",
+        "@typescript-eslint/no-empty-interface": "off"
+      }
+    },
+  ]
+};

cli/asc.d.ts

@@ -176,7 +176,7 @@ export function main(argv: string[], options: APIOptions, callback?: (err: Error
 export function main(argv: string[], callback?: (err: Error | null) => number): number;
 
 /** Checks diagnostics emitted so far for errors. */
-export function checkDiagnostics(emitter: any, stderr?: OutputStream): boolean;
+export function checkDiagnostics(emitter: Record<string,unknown>, stderr?: OutputStream): boolean;
 
 /** An object of stats for the current task. */
 export interface Stats {
@@ -200,7 +200,7 @@ export interface Stats {
 export function createStats(): Stats;
 
 /** Measures the execution time of the specified function.  */
-export function measure(fn: Function): number;
+export function measure(fn: () => void): number;
 
 /** Formats a high resolution time to a human readable string. */
 export function formatTime(time: number): string;
@@ -212,4 +212,4 @@ export function printStats(stats: Stats, output: OutputStream): void;
 export function createMemoryStream(fn?: (chunk: Uint8Array | string) => void): MemoryStream;
 
 /** Compatible TypeScript compiler options for syntax highlighting etc. */
-export const tscOptions: { [key: string]: any };
+export const tscOptions: Record<string,unknown>;