refactor!: remove --hot in favor of directly using the HMR plugin (#3290)

BRAKING CHANGE:  the `--hot` option was removed for `webpack build` and `webpack watch` commands in favor directly usage `HotModuleReplacement` plugin

Author: snitin315

packages/serve/src/index.ts

@@ -98,11 +98,10 @@ class ServeCommand {
 
         for (const optionName in options) {
           const kebabedOption = cli.toKebabCase(optionName);
-          // `webpack-dev-server` has own logic for the `--hot` option
-          const isBuiltInOption =
-            kebabedOption !== "hot" &&
+          const isBuiltInOption = builtInOptions.find(
             // eslint-disable-next-line @typescript-eslint/no-explicit-any
-            builtInOptions.find((builtInOption: any) => builtInOption.name === kebabedOption);
+            (builtInOption: any) => builtInOption.name === kebabedOption,
+          );
 
           if (isBuiltInOption) {
             webpackCLIOptions[optionName] = options[optionName];

packages/webpack-cli/src/plugins/CLIPlugin.ts

@@ -9,17 +9,6 @@ export class CLIPlugin {
     this.options = options;
   }
 
-  setupHotPlugin(compiler: Compiler) {
-    const { HotModuleReplacementPlugin } = compiler.webpack || require("webpack");
-    const hotModuleReplacementPlugin = Boolean(
-      compiler.options.plugins.find((plugin) => plugin instanceof HotModuleReplacementPlugin),
-    );
-
-    if (!hotModuleReplacementPlugin) {
-      new HotModuleReplacementPlugin().apply(compiler);
-    }
-  }
-
   setupPrefetchPlugin(compiler: Compiler) {
     const { PrefetchPlugin } = compiler.webpack || require("webpack");
 
@@ -122,10 +111,6 @@ export class CLIPlugin {
       this.setupProgressPlugin(compiler);
     }
 
-    if (this.options.hot) {
-      this.setupHotPlugin(compiler);
-    }
-
     if (this.options.prefetch) {
       this.setupPrefetchPlugin(compiler);
     }

packages/webpack-cli/src/webpack-cli.ts

@@ -808,21 +808,6 @@ class WebpackCLI implements IWebpackCLI {
       },
 
       // Adding more plugins
-      {
-        name: "hot",
-        alias: "h",
-        configs: [
-          {
-            type: "string",
-          },
-          {
-            type: "boolean",
-          },
-        ],
-        negative: true,
-        description: "Enables Hot Module Replacement",
-        negatedDescription: "Disables Hot Module Replacement.",
-      },
       {
         name: "analyze",
         configs: [
@@ -2079,13 +2064,6 @@ class WebpackCLI implements IWebpackCLI {
       process.exit(2);
     }
 
-    if (typeof options.hot === "string" && options.hot !== "only") {
-      this.logger.error(
-        `'${options.hot}' is an invalid value for the --hot option. Use 'only' instead.`,
-      );
-      process.exit(2);
-    }
-
     const CLIPlugin = await this.tryRequireThenImport<
       Instantiable<CLIPluginClass, [CLIPluginOptions]>
     >("./plugins/CLIPlugin");
@@ -2322,7 +2300,6 @@ class WebpackCLI implements IWebpackCLI {
         new CLIPlugin({
           configPath: config.path.get(item),
           helpfulOutput: !options.json,
-          hot: options.hot,
           progress: options.progress,
           prefetch: options.prefetch,
           analyze: options.analyze,

test/build/hot/__snapshots__/hot-flag.test.js.snap.webpack4

@@ -47,30 +47,20 @@ exports[`basic serve usage should work and log warning on the \`watch option in
 
 exports[`basic serve usage should work in multi compiler mode: stderr 1`] = `""`;
 
-exports[`basic serve usage should work with "--hot" and "--port" options: stderr 1`] = `""`;
-
 exports[`basic serve usage should work with entries syntax: stderr 1`] = `""`;
 
 exports[`basic serve usage should work with the "--client-log-level" option: stderr 1`] = `""`;
 
-exports[`basic serve usage should work with the "--config" and "--env" options and expose dev server options: stderr 1`] = `""`;
-
 exports[`basic serve usage should work with the "--config" and "--env" options: stderr 1`] = `""`;
 
 exports[`basic serve usage should work with the "--config" option: stderr 1`] = `""`;
 
-exports[`basic serve usage should work with the "--hot" option using the "only" value: stderr 1`] = `""`;
-
-exports[`basic serve usage should work with the "--hot" option: stderr 1`] = `""`;
-
 exports[`basic serve usage should work with the "--mode" option #2: stderr 1`] = `""`;
 
 exports[`basic serve usage should work with the "--mode" option #3: stderr 1`] = `""`;
 
 exports[`basic serve usage should work with the "--mode" option: stderr 1`] = `""`;
 
-exports[`basic serve usage should work with the "--no-hot" option: stderr 1`] = `""`;
-
 exports[`basic serve usage should work with the "--open" option: stderr 1`] = `""`;
 
 exports[`basic serve usage should work with the "--output-public-path" option: stderr 1`] = `

test/build/hot/__snapshots__/hot-flag.test.js.snap.webpack5

@@ -47,30 +47,20 @@ exports[`basic serve usage should work and log warning on the \`watch option in
 
 exports[`basic serve usage should work in multi compiler mode: stderr 1`] = `""`;
 
-exports[`basic serve usage should work with "--hot" and "--port" options: stderr 1`] = `""`;
-
 exports[`basic serve usage should work with entries syntax: stderr 1`] = `""`;
 
 exports[`basic serve usage should work with the "--client-log-level" option: stderr 1`] = `""`;
 
-exports[`basic serve usage should work with the "--config" and "--env" options and expose dev server options: stderr 1`] = `""`;
-
 exports[`basic serve usage should work with the "--config" and "--env" options: stderr 1`] = `""`;
 
 exports[`basic serve usage should work with the "--config" option: stderr 1`] = `""`;
 
-exports[`basic serve usage should work with the "--hot" option using the "only" value: stderr 1`] = `""`;
-
-exports[`basic serve usage should work with the "--hot" option: stderr 1`] = `""`;
-
 exports[`basic serve usage should work with the "--mode" option #2: stderr 1`] = `""`;
 
 exports[`basic serve usage should work with the "--mode" option #3: stderr 1`] = `""`;
 
 exports[`basic serve usage should work with the "--mode" option: stderr 1`] = `""`;
 
-exports[`basic serve usage should work with the "--no-hot" option: stderr 1`] = `""`;
-
 exports[`basic serve usage should work with the "--open" option: stderr 1`] = `""`;
 
 exports[`basic serve usage should work with the "--output-public-path" option: stderr 1`] = `""`;