feat: support #__NO_SIDE_EFFECTS__ annotation for function declaration

src/Graph.ts

@@ -17,14 +17,14 @@ import type {
 import { PluginDriver } from './utils/PluginDriver';
 import Queue from './utils/Queue';
 import { BuildPhase } from './utils/buildPhase';
+import { addAnnotations } from './utils/commentAnnotations';
 import {
  error,
  errorCircularDependency,
  errorImplicitDependantIsNotIncluded,
  errorMissingExport
 } from './utils/error';
 import { analyseModuleExecution } from './utils/executionOrder';
-import { addAnnotations } from './utils/pureComments';
 import { getPureFunctions } from './utils/pureFunctions';
 import type { PureFunctions } from './utils/pureFunctions';
 import { timeEnd, timeStart } from './utils/timers';

src/ast/nodes/ArrowFunctionExpression.ts

@@ -1,3 +1,4 @@
+import type { NormalizedTreeshakingOptions } from '../../rollup/types';
 import type { HasEffectsContext, InclusionContext } from '../ExecutionContext';
 import type { NodeInteraction } from '../NodeInteractions';
 import { INTERACTION_CALLED } from '../NodeInteractions';
@@ -38,6 +39,13 @@ export default class ArrowFunctionExpression extends FunctionBase {
  ): boolean {
  if (super.hasEffectsOnInteractionAtPath(path, interaction, context)) return true;
  if (interaction.type === INTERACTION_CALLED) {
+ if (
+ (this.context.options.treeshake as NormalizedTreeshakingOptions).annotations &&
+ this.annotationNoSideEffects
+ ) {
+ return false;
+ }
+
  const { ignore, brokenFlow } = context;
  context.ignore = {
  breaks: false,

src/ast/nodes/CallExpression.ts

@@ -59,7 +59,7 @@ export default class CallExpression
  }
  if (
  (this.context.options.treeshake as NormalizedTreeshakingOptions).annotations &&
- this.annotations
+ this.annotationPure
  )
  return false;
  return (

src/ast/nodes/NewExpression.ts

@@ -23,7 +23,7 @@ export default class NewExpression extends NodeBase {
  }
  if (
  (this.context.options.treeshake as NormalizedTreeshakingOptions).annotations &&
- this.annotations
+ this.annotationPure
  ) {
  return false;
  }

src/ast/nodes/shared/FunctionNode.ts

@@ -1,3 +1,4 @@
+import type { NormalizedTreeshakingOptions } from '../../../rollup/types';
 import { type HasEffectsContext, type InclusionContext } from '../../ExecutionContext';
 import type { NodeInteraction } from '../../NodeInteractions';
 import { INTERACTION_CALLED } from '../../NodeInteractions';
@@ -45,6 +46,14 @@ export default class FunctionNode extends FunctionBase {
 
  hasEffects(context: HasEffectsContext): boolean {
  if (!this.deoptimized) this.applyDeoptimizations();
+
+ if (
+ (this.context.options.treeshake as NormalizedTreeshakingOptions).annotations &&
+ this.annotationNoSideEffects
+ ) {
+ return false;
+ }
+
  return !!this.id?.hasEffects(context);
  }
 
@@ -54,6 +63,14 @@ export default class FunctionNode extends FunctionBase {
  context: HasEffectsContext
  ): boolean {
  if (super.hasEffectsOnInteractionAtPath(path, interaction, context)) return true;
+
+ if (
+ (this.context.options.treeshake as NormalizedTreeshakingOptions).annotations &&
+ this.annotationNoSideEffects
+ ) {
+ return false;
+ }
+
  if (interaction.type === INTERACTION_CALLED) {
  const thisInit = context.replacedVariableInits.get(this.scope.thisVariable);
  context.replacedVariableInits.set(

src/ast/nodes/shared/Node.ts

@@ -2,7 +2,8 @@ import type * as acorn from 'acorn';
 import { locate, type Location } from 'locate-character';
 import type MagicString from 'magic-string';
 import type { AstContext } from '../../../Module';
-import { ANNOTATION_KEY, INVALID_COMMENT_KEY } from '../../../utils/pureComments';
+import type { RollupAnnotation } from '../../../utils/commentAnnotations';
+import { ANNOTATION_KEY, INVALID_COMMENT_KEY } from '../../../utils/commentAnnotations';
 import type { NodeRenderOptions, RenderOptions } from '../../../utils/renderHelpers';
 import type { DeoptimizableEntity } from '../../DeoptimizableEntity';
 import type { Entity } from '../../Entity';
@@ -124,7 +125,12 @@ export interface ChainElement extends ExpressionNode {
 }
 
 export class NodeBase extends ExpressionEntity implements ExpressionNode {
- declare annotations?: acorn.Comment[];
+ /** Marked with #__NO_SIDE_EFFECTS__ annotation */
+ declare annotationNoSideEffects?: boolean;
+ /** Marked with #__PURE__ annotation */
+ declare annotationPure?: boolean;
+ declare annotations?: RollupAnnotation[];
+
  context: AstContext;
  declare end: number;
  esTreeNode: acorn.Node | null;
@@ -263,6 +269,12 @@ export class NodeBase extends ExpressionEntity implements ExpressionNode {
  if (key.charCodeAt(0) === 95 /* _ */) {
  if (key === ANNOTATION_KEY) {
  this.annotations = value;
+ this.annotationNoSideEffects = this.annotations!.some(
+ comment => comment.annotationType === 'noSideEffects'
+ );
+ this.annotationPure = this.annotations!.some(
+ comment => comment.annotationType === 'pure'
+ );
  } else if (key === INVALID_COMMENT_KEY) {
  for (const { start, end } of value as acorn.Comment[])
  this.context.magicString.remove(start, end);

src/utils/pureComments.ts → src/utils/commentAnnotations.ts

@@ -1,20 +1,32 @@
 import type * as acorn from 'acorn';
 import { base as basicWalker } from 'acorn-walk';
 import {
+ ArrowFunctionExpression,
  BinaryExpression,
  CallExpression,
  ChainExpression,
  ConditionalExpression,
+ ExportDefaultDeclaration,
+ ExportNamedDeclaration,
  ExpressionStatement,
+ FunctionDeclaration,
  LogicalExpression,
  NewExpression,
- SequenceExpression
+ SequenceExpression,
+ VariableDeclaration,
+ VariableDeclarator
 } from '../ast/nodes/NodeType';
 import { SOURCEMAPPING_URL_RE } from './sourceMappingURL';
 
+export type AnnotationType = 'noSideEffects' | 'pure';
+
+export interface RollupAnnotation extends acorn.Comment {
+ annotationType: AnnotationType;
+}
+
 interface CommentState {
  annotationIndex: number;
- annotations: acorn.Comment[];
+ annotations: RollupAnnotation[];
  code: string;
 }
 
@@ -93,11 +105,34 @@
  invalidAnnotation = true;
  break;
  }
+ case ExportNamedDeclaration:
+ case ExportDefaultDeclaration: {
+ node = (node as any).declaration;
+ continue;
+ }
+ case VariableDeclaration: {
+ // case: /*#__PURE__*/ const foo = () => {}
+ const declaration = node as any;
+ if (declaration.kind === 'const') {
+ // jsdoc only applies to the first declaration
+ node = declaration.declarations[0].init;
+ continue;
+ }
+ invalidAnnotation = true;
+ break;
+ }
+ case VariableDeclarator: {
+ node = (node as any).init;
+ continue;
+ }
+ case FunctionDeclaration:
+ case ArrowFunctionExpression:
  case CallExpression:
  case NewExpression: {
  break;
  }
  default: {
+ console.log({ node });
  invalidAnnotation = true;
  }
  }
@@ -134,25 +169,32 @@
  return true;
 }
 
-const pureCommentRegex = /[#@]__PURE__/;
+const annotationsRegexes: [AnnotationType, RegExp][] = [
+ ['pure', /[#@]__PURE__/],
+ ['noSideEffects', /[#@]__NO_SIDE_EFFECTS__/]
+];
 
 export function addAnnotations(
  comments: readonly acorn.Comment[],
  esTreeAst: acorn.Node,
  code: string
 ): void {
- const annotations: acorn.Comment[] = [];
+ const annotations: RollupAnnotation[] = [];
  const sourceMappingComments: acorn.Comment[] = [];
  for (const comment of comments) {
- if (pureCommentRegex.test(comment.value)) {
- annotations.push(comment);
- } else if (SOURCEMAPPING_URL_RE.test(comment.value)) {
+ for (const [annotationType, regex] of annotationsRegexes) {
+ if (regex.test(comment.value)) {
+ annotations.push({ ...comment, annotationType });
+ }
+ }
+ if (SOURCEMAPPING_URL_RE.test(comment.value)) {
  sourceMappingComments.push(comment);
  }
  }
  for (const comment of sourceMappingComments) {
  annotateNode(esTreeAst, comment, false);
  }
+
  handlePureAnnotationsOfNode(esTreeAst, {
  annotationIndex: 0,
  annotations,

test/form/samples/no-side-effects-function-declaration-preserve/_config.js

@@ -0,0 +1,5 @@
+// tests compiled from https://github.com/mishoo/UglifyJS2/blob/88c8f4e363e0d585b33ea29df560243d3dc74ce1/test/compress/pure_funcs.js
+
+module.exports = defineTest({
+ description: 'preserve __NO_SIDE_EFFECTS__ annotations for function declarations'
+});

test/form/samples/no-side-effects-function-declaration-preserve/_expected.js

@@ -0,0 +1,70 @@
+/*#__NO_SIDE_EFFECTS__*/
+function fnFromSub (args) {
+ console.log(args);
+ return args
+}
+
+function fnPure(args) {
+ return args
+}
+
+function fnEffects(args) {
+ console.log(args);
+ return args
+}
+
+/*#__NO_SIDE_EFFECTS__*/
+function fnA (args) {
+ console.log(args);
+ return args
+}
+
+/*#__NO_SIDE_EFFECTS__*/
+function fnB (args) {
+ console.log(args);
+ return args
+}
+
+const fnC = /*#__NO_SIDE_EFFECTS__*/ (args) => {
+ console.log(args);
+ return args
+};
+
+
+/*#__NO_SIDE_EFFECTS__*/ 
+const fnD = (args) => {
+ console.log(args);
+ return args
+};
+
+/*#__NO_SIDE_EFFECTS__*/ 
+const fnE = (args) => {
+ console.log(args);
+ return args
+};
+
+/**
+ * This is a jsdoc comment, with no side effects annotation
+ * 
+ * @param {any} args
+ * @__NO_SIDE_EFFECTS__
+ */ 
+const fnF = (args) => {
+ console.log(args);
+ return args
+};
+
+const fnAlias = fnA;
+
+/**
+ * Have both annotations
+ * 
+ * @__PURE__
+ * @__NO_SIDE_EFFECTS__
+ */
+const fnBothAnnotations = (args) => {
+ console.log(args);
+ return args
+};
+
+export { fnA, fnAlias, fnB, fnBothAnnotations, fnC, fnD, fnE, fnEffects, fnF, fnFromSub, fnPure };

test/form/samples/no-side-effects-function-declaration-preserve/functions.js

@@ -0,0 +1,73 @@
+export function fnPure(args) {
+ return args
+}
+
+export function fnEffects(args) {
+ console.log(args)
+ return args
+}
+
+/*#__NO_SIDE_EFFECTS__*/
+function fnA (args) {
+ console.log(args)
+ return args
+}
+export { fnA }
+
+/*#__NO_SIDE_EFFECTS__*/
+export function fnB (args) {
+ console.log(args)
+ return args
+}
+
+export const fnC = /*#__NO_SIDE_EFFECTS__*/ (args) => {
+ console.log(args)
+ return args
+}
+
+
+/*#__NO_SIDE_EFFECTS__*/ 
+const fnD = (args) => {
+ console.log(args)
+ return args
+}
+
+export { fnD }
+
+/*#__NO_SIDE_EFFECTS__*/ 
+export const fnE = (args) => {
+ console.log(args)
+ return args
+}
+
+/**
+ * This is a jsdoc comment, with no side effects annotation
+ * 
+ * @param {any} args
+ * @__NO_SIDE_EFFECTS__
+ */ 
+export const fnF = (args) => {
+ console.log(args)
+ return args
+}
+
+/*#__NO_SIDE_EFFECTS__*/ 
+export default function fnDefault(args) {
+ console.log(args)
+ return args
+}
+
+export * from './sub-functions'
+
+export const fnAlias = fnA
+
+/**
+ * Have both annotations
+ * 
+ * @__PURE__
+ * @__NO_SIDE_EFFECTS__
+ */
+export const fnBothAnnotations = (args) => {
+ console.log(args)
+ return args
+}

test/form/samples/no-side-effects-function-declaration-preserve/main.js

@@ -0,0 +1 @@
+export * from './functions'

test/form/samples/no-side-effects-function-declaration-preserve/sub-functions.js

@@ -0,0 +1,5 @@
+/*#__NO_SIDE_EFFECTS__*/
+export function fnFromSub (args) {
+ console.log(args)
+ return args
+}

test/form/samples/no-side-effects-function-declaration/_config.js

@@ -0,0 +1,5 @@
+// tests compiled from https://github.com/mishoo/UglifyJS2/blob/88c8f4e363e0d585b33ea29df560243d3dc74ce1/test/compress/pure_funcs.js
+
+module.exports = defineTest({
+ description: '__NO_SIDE_EFFECTS__ annotations for function declarations'
+});