WIP

lib/DevSupportPlugin.js

@@ -0,0 +1,59 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+"use strict";
+
+const NullFactory = require("./NullFactory");
+const NullDependency = require("./dependencies/NullDependency");
+
+class DevSupportPlugin {
+	constructor() {
+	}
+
+	apply(compiler) {
+		compiler.hooks.compilation.tap("DevSupportPlugin", (compilation, {
+			normalModuleFactory
+		}) => {
+			compilation.dependencyFactories.set(DevSupportDependency, new NullFactory());
+			compilation.dependencyTemplates.set(DevSupportDependency, new DevSupportDependency.Template());
+
+			const handler = (parser, parserOptions) => {
+				if(typeof parserOptions.devSupport !== "undefined" && !parserOptions.devSupport)
+					return;
+
+				parser.hooks.program.tap("DevSupportPlugin", () => {
+					const module = parser.state.module;
+					const dep = new DevSupportDependency(parser.state, module.buildInfo.strict);
+					module.buildInfo.strict = false;
+					module.addDependency(dep);
+				});
+			};
+			normalModuleFactory.hooks.parser.for("javascript/auto").tap("DevSupportPlugin", handler);
+			normalModuleFactory.hooks.parser.for("javascript/esm").tap("DevSupportPlugin", handler);
+		});
+	}
+}
+
+class DevSupportDependency extends NullDependency {
+	constructor(parserState, strict) {
+		super();
+		this.parserState = parserState;
+		this.strict = strict;
+	}
+
+	get type() {
+		return "dev support";
+	}
+}
+
+DevSupportDependency.Template = class DevSupportDependencyTemplate {
+	apply(dep, source, runtime, dependencyTemplates) {
+		source.insert(-1, `/* ${JSON.stringify(dep.parserState.harmonySpecifier && Array.from(dep.parserState.harmonySpecifier))} */`);
+		source.insert(-1, "(function() {");
+		if(dep.strict) source.insert(-1, "\"use strict\";");
+		source.insert(Infinity, "}());");
+	}
+};
+
+module.exports = DevSupportPlugin;

lib/WebpackOptionsApply.js

@@ -56,6 +56,7 @@ const NamedModulesPlugin = require("./NamedModulesPlugin");
 const NamedChunksPlugin = require("./NamedChunksPlugin");
 const DefinePlugin = require("./DefinePlugin");
 const SizeLimitsPlugin = require("./performance/SizeLimitsPlugin");
+const DevSupportPlugin = require("./DevSupportPlugin");
 
 class WebpackOptionsApply extends OptionsApply {
 	constructor() {
@@ -302,6 +303,7 @@ class WebpackOptionsApply extends OptionsApply {
 				minimizer.apply(compiler);
 			}
 		}
+		new DevSupportPlugin().apply(compiler);
 
 		if(options.performance) {
 			new SizeLimitsPlugin(options.performance).apply(compiler);