feat: drop support for webpack 1 and 3

We drop support for webpack < 4.0 to simplify our codebase and prepare for further refactoring. BREAKING CHANGE: 🧨 Dropped support for webpack 2.0 and webpack 3.0

Author: piotr-oles

.github/workflows/main.yml

@@ -50,8 +50,6 @@ jobs:
  packages:
  - webpack@5.0.0-alpha.5 ts-loader@^5.0.0 vue-loader@^15.2.4
  - webpack@^4.0.0 ts-loader@^5.0.0 vue-loader@^15.2.4
- - webpack@^3.10.0 ts-loader@^3.4.0 vue-loader@^13.5.0
- - webpack@^2.7.0 ts-loader@^3.4.0 vue-loader@^13.5.0
 
  steps:
  - uses: actions/checkout@v1
@@ -117,11 +115,14 @@ jobs:
  
  - name: Install dependencies
  run: yarn install --frozen-lockfile
+
+ - name: Install semantic-release
+ run: yarn global add semantic-release@16.0.0-beta.18
 
  - name: Download build artifact
  uses: actions/download-artifact@v1
  with:
  name: lib
 
  - name: Release
- run: yarn exec semantic-release
+ run: semantic-release

README.md

@@ -15,7 +15,9 @@
 
 ## Installation
 
-This plugin requires minimum **webpack 2.3**, **TypeScript 2.1** and optionally **ESLint 6.0.0** or **TSLint 4.0**
+This plugin requires minimum **webpack 4.0**, **TypeScript 2.1** and optionally **ESLint 6.0.0** or **TSLint 4.0**
+
+If you depend on **webpack 2.0** or **webpack 3.0**, please use [older version](https://github.com/TypeStrong/fork-ts-checker-webpack-plugin/tree/v3.1.1) of the plugin. 
 
 ```sh
 # with npm
@@ -273,26 +275,21 @@ We hope this will be resolved in future; the issue can be tracked [here](https:/
 
 This plugin provides some custom webpack hooks (all are sync):
 
-| Event name | Hook Access Key | Description | Params |
-| --------------------------------------- | -------------------- | ------------------------------------------------------------------------------ | ------------------------------------------- |
-| `fork-ts-checker-cancel` | `cancel` | Cancellation has been requested | `cancellationToken` |
-| `fork-ts-checker-waiting` | `waiting` | Waiting for results | `hasTsLint` |
-| `fork-ts-checker-service-before-start` | `serviceBeforeStart` | Async plugin that can be used for delaying `fork-ts-checker-service-start` | - |
-| `fork-ts-checker-service-start` | `serviceStart` | Service will be started | `tsconfigPath`, `tslintPath`, `memoryLimit` |
-| `fork-ts-checker-service-start-error` | `serviceStartError` | Cannot start service | `error` |
-| `fork-ts-checker-service-out-of-memory` | `serviceOutOfMemory` | Service is out of memory | - |
-| `fork-ts-checker-receive` | `receive` | Plugin receives diagnostics and lints from service | `diagnostics`, `lints` |
-| `fork-ts-checker-emit` | `emit` | Service will add errors and warnings to webpack compilation ('build' mode) | `diagnostics`, `lints`, `elapsed` |
-| `fork-ts-checker-done` | `done` | Service finished type checking and webpack finished compilation ('watch' mode) | `diagnostics`, `lints`, `elapsed` |
-
-The **Event name** is there for backward compatibility with webpack 2/3. Regardless
-of the version of webpack (2, 3 or 4) you are using, we will always access plugin hooks with **Hook Access Keys** as
-described below.
+| Hook Access Key | Description | Params |
+| -------------------- | ------------------------------------------------------------------------------ | ------------------------------------------- |
+| `cancel` | Cancellation has been requested | `cancellationToken` |
+| `waiting` | Waiting for results | `hasTsLint` |
+| `serviceBeforeStart` | Async plugin that can be used for delaying `fork-ts-checker-service-start` | - |
+| `serviceStart` | Service will be started | `tsconfigPath`, `tslintPath`, `memoryLimit` |
+| `serviceStartError` | Cannot start service | `error` |
+| `serviceOutOfMemory` | Service is out of memory | - |
+| `receive` | Plugin receives diagnostics and lints from service | `diagnostics`, `lints` |
+| `emit` | Service will add errors and warnings to webpack compilation ('build' mode) | `diagnostics`, `lints`, `elapsed` |
+| `done` | Service finished type checking and webpack finished compilation ('watch' mode) | `diagnostics`, `lints`, `elapsed` |
 
 ### Accessing plugin hooks
 
-All plugin hooks are compatible with both [webpack](https://webpack.js.org) version
-4 and version 2. To access plugin hooks and tap into the event, we need to use
+To access plugin hooks and tap into the event, we need to use
 the `getCompilerHooks` static method. When we call this method with a [webpack compiler instance](https://webpack.js.org/api/node/),
 it returns the series of [tapable](https://github.com/webpack/tapable)
 hooks where you can pass in your callbacks.

package.json

@@ -134,7 +134,6 @@
  "nativescript-vue-template-compiler": "^2.4.0",
  "prettier": "^1.14.3",
  "rimraf": "^3.0.0",
- "semantic-release": "^16.0.0-beta.18",
  "ts-loader": "^5.0.0",
  "tslint": "^5.11.0",
  "tslint-config-prettier": "^1.16.0",

src/hooks.ts

@@ -16,22 +16,9 @@ type ForkTsCheckerHookMap = Record<
  ForkTsCheckerHooks,
  SyncHook | AsyncSeriesHook
 >;
-type ForkTsCheckerLegacyHookMap = Record<ForkTsCheckerHooks, string>;
 
 const compilerHookMap = new WeakMap<webpack.Compiler, ForkTsCheckerHookMap>();
 
-export const legacyHookMap: ForkTsCheckerLegacyHookMap = {
- serviceBeforeStart: 'fork-ts-checker-service-before-start',
- cancel: 'fork-ts-checker-cancel',
- serviceStartError: 'fork-ts-checker-service-start-error',
- waiting: 'fork-ts-checker-waiting',
- serviceStart: 'fork-ts-checker-service-start',
- receive: 'fork-ts-checker-receive',
- serviceOutOfMemory: 'fork-ts-checker-service-out-of-memory',
- emit: 'fork-ts-checker-emit',
- done: 'fork-ts-checker-done'
-};
-
 function createForkTsCheckerWebpackPluginHooks(): ForkTsCheckerHookMap {
  return {
  serviceBeforeStart: new AsyncSeriesHook([]),