Avoid cycles when merging chunks

src/utils/chunkAssignment.ts

@@ -192,10 +192,12 @@ function assignEntryToStaticDependencies(
 }
 
 interface ChunkDescription {
+	dependencies: Set<Module>;
 	modules: Module[];
 	pure: boolean;
 	signature: string;
 	size: number;
+	transitiveDependencies: Set<Module>;
 }
 
 type ChunkPartition = {
@@ -333,9 +335,24 @@ function getPartitionedChunks(
 	for (const [signature, modules] of Object.entries(chunkModulesBySignature)) {
 		let size = 0;
 		let pure = true;
+		const dependencies = new Set<Module>();
+		const transitiveDependencies = new Set<Module>();
 		for (const module of modules) {
 			pure &&= !module.hasEffects();
 			size += module.magicString.toString().length;
+			for (const dependency of module.getDependenciesToBeIncluded()) {
+				if (!(dependency instanceof ExternalModule)) {
+					dependencies.add(dependency);
+					transitiveDependencies.add(dependency);
+				}
+			}
+		}
+		for (const module of transitiveDependencies) {
+			for (const dependency of module.getDependenciesToBeIncluded()) {
+				if (!(dependency instanceof ExternalModule)) {
+					transitiveDependencies.add(dependency);
+				}
+			}
 		}
 		(size < minChunkSize
 			? pure
@@ -344,7 +361,7 @@ function getPartitionedChunks(
 			: pure
 			? bigPureChunks
 			: bigSideEffectChunks
-		).push({ modules, pure, signature, size });
+		).push({ dependencies, modules, pure, signature, size, transitiveDependencies });
 	}
 	for (const chunks of [
 		bigPureChunks,
@@ -399,14 +416,31 @@ function mergeChunks(
 			closestChunk.size += size;
 			closestChunk.pure &&= pure;
 			closestChunk.signature = mergeSignatures(signature, closestChunk.signature);
+			const { dependencies, transitiveDependencies } = closestChunk;
+			for (const dependency of mergedChunk.dependencies) {
+				dependencies.add(dependency);
+			}
+			for (const dependency of mergedChunk.transitiveDependencies) {
+				transitiveDependencies.add(dependency);
+			}
 			getChunksInPartition(closestChunk, minChunkSize, chunkPartition).add(closestChunk);
 		}
 	}
 }
 
-// function isValidMerge(mergedChunk: ChunkDescription, targetChunk: ChunkDescription) {
-// 	return false;
-// }
+// If a module is a transitive but not a direct dependency of the other chunk,
+// merging is prohibited as that would create a new cyclic dependency.
+function isValidMerge(mergedChunk: ChunkDescription, targetChunk: ChunkDescription) {
+	for (const module of mergedChunk.modules) {
+		if (targetChunk.transitiveDependencies.has(module) && !targetChunk.dependencies.has(module))
+			return false;
+	}
+	for (const module of targetChunk.modules) {
+		if (mergedChunk.transitiveDependencies.has(module) && !mergedChunk.dependencies.has(module))
+			return false;
+	}
+	return true;
+}
 
 function getChunksInPartition(
 	chunk: ChunkDescription,

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_config.js

@@ -1,5 +1,4 @@
 module.exports = {
-	solo: true,
 	description: 'avoids circular dependencies when merging chunks',
 	options: {
 		input: ['main1.js', 'main2.js', 'main3.js'],

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/amd/generated-main1.js

@@ -0,0 +1,11 @@
+define(['exports', './generated-small'], (function (exports, small) { 'use strict';
+
+	const result = small.small + '0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789';
+	console.log(result);
+
+	const generated = 'generated' + result;
+
+	exports.generated = generated;
+	exports.result = result;
+
+}));

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/amd/generated-small.js

@@ -0,0 +1,7 @@
+define(['exports'], (function (exports) { 'use strict';
+
+	const small = '1';
+
+	exports.small = small;
+
+}));

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/amd/main1.js

@@ -1,5 +1,7 @@
-define(['./generated-small2'], (function (small2) { 'use strict';
+define(['exports', './generated-main1', './generated-small'], (function (exports, main1, small) { 'use strict';
 
-	console.log(small2.small1, small2.small2);
+
+
+	exports.generated = main1.generated;
 
 }));

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/amd/main2.js

@@ -1,5 +1,5 @@
-define(['./generated-small2'], (function (small2) { 'use strict';
+define(['./generated-main1', './generated-small'], (function (main1, small) { 'use strict';
 
-	console.log(small2.small1);
+	console.log(main1.result);
 
 }));

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/amd/main3.js

@@ -1,5 +1,5 @@
-define(['./generated-small2'], (function (small2) { 'use strict';
+define(['./generated-small'], (function (small) { 'use strict';
 
-	console.log(small2.small2);
+	console.log(small.small);
 
 }));

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/cjs/generated-main1.js

@@ -0,0 +1,11 @@
+'use strict';
+
+var small = require('./generated-small.js');
+
+const result = small.small + '0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789';
+console.log(result);
+
+const generated = 'generated' + result;
+
+exports.generated = generated;
+exports.result = result;

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/cjs/generated-small.js

@@ -0,0 +1,5 @@
+'use strict';
+
+const small = '1';
+
+exports.small = small;

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/cjs/main1.js

@@ -1,5 +1,8 @@
 'use strict';
 
-var small2 = require('./generated-small2.js');
+var main1 = require('./generated-main1.js');
+require('./generated-small.js');
 
-console.log(small2.small1, small2.small2);
+
+
+exports.generated = main1.generated;

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/cjs/main2.js

@@ -1,5 +1,6 @@
 'use strict';
 
-var small2 = require('./generated-small2.js');
+var main1 = require('./generated-main1.js');
+require('./generated-small.js');
 
-console.log(small2.small1);
+console.log(main1.result);

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/cjs/main3.js

@@ -1,5 +1,5 @@
 'use strict';
 
-var small2 = require('./generated-small2.js');
+var small = require('./generated-small.js');
 
-console.log(small2.small2);
+console.log(small.small);

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/es/generated-main1.js

@@ -0,0 +1,8 @@
+import { s as small } from './generated-small.js';
+
+const result = small + '0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789';
+console.log(result);
+
+const generated = 'generated' + result;
+
+export { generated as g, result as r };

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/es/generated-small.js

@@ -0,0 +1,3 @@
+const small = '1';
+
+export { small as s };

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/es/main1.js

@@ -1,3 +1,2 @@
-import { s as small1, a as small2 } from './generated-small2.js';
-
-console.log(small1, small2);
+export { g as generated } from './generated-main1.js';
+import './generated-small.js';

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/es/main2.js

@@ -1,3 +1,4 @@
-import { s as small1 } from './generated-small2.js';
+import { r as result } from './generated-main1.js';
+import './generated-small.js';
 
-console.log(small1);
+console.log(result);

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/es/main3.js

@@ -1,3 +1,3 @@
-import { a as small2 } from './generated-small2.js';
+import { s as small } from './generated-small.js';
 
-console.log(small2);
+console.log(small);

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/system/generated-main1.js

@@ -0,0 +1,17 @@
+System.register(['./generated-small.js'], (function (exports) {
+	'use strict';
+	var small;
+	return {
+		setters: [function (module) {
+			small = module.s;
+		}],
+		execute: (function () {
+
+			const result = exports('r', small + '0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789');
+			console.log(result);
+
+			const generated = exports('g', 'generated' + result);
+
+		})
+	};
+}));

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/system/generated-small2.js → test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/system/generated-small.js

@@ -3,9 +3,7 @@ System.register([], (function (exports) {
 	return {
 		execute: (function () {
 
-			const small1 = exports('s', '1');
-
-			const small2 = exports('a', '1');
+			const small = exports('s', '1');
 
 		})
 	};

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/system/main1.js

@@ -1,14 +1,12 @@
-System.register(['./generated-small2.js'], (function () {
+System.register(['./generated-main1.js', './generated-small.js'], (function (exports) {
 	'use strict';
-	var small1, small2;
 	return {
 		setters: [function (module) {
-			small1 = module.s;
-			small2 = module.a;
-		}],
+			exports('generated', module.g);
+		}, null],
 		execute: (function () {
 
-			console.log(small1, small2);
+
 
 		})
 	};

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/system/main2.js

@@ -1,13 +1,13 @@
-System.register(['./generated-small2.js'], (function () {
+System.register(['./generated-main1.js', './generated-small.js'], (function () {
 	'use strict';
-	var small1;
+	var result;
 	return {
 		setters: [function (module) {
-			small1 = module.s;
-		}],
+			result = module.r;
+		}, null],
 		execute: (function () {
 
-			console.log(small1);
+			console.log(result);
 
 		})
 	};

test/chunking-form/samples/minChunkSize/avoid-circular-dependencies/_expected/system/main3.js

@@ -1,13 +1,13 @@
-System.register(['./generated-small2.js'], (function () {
+System.register(['./generated-small.js'], (function () {
 	'use strict';
-	var small2;
+	var small;
 	return {
 		setters: [function (module) {
-			small2 = module.a;
+			small = module.s;
 		}],
 		execute: (function () {
 
-			console.log(small2);
+			console.log(small);
 
 		})
 	};