fix: handle conditional breaks in nested switch statement cases

src/ast/ExecutionContext.ts

@@ -11,12 +11,10 @@ interface ExecutionContextIgnore {
 	this: boolean;
 }
 
-export const BROKEN_FLOW_NONE = 0;
-export const BROKEN_FLOW_BREAK_CONTINUE = 1;
-export const BROKEN_FLOW_ERROR_RETURN_LABEL = 2;
-
 interface ControlFlowContext {
-	brokenFlow: number;
+	brokenFlow: boolean;
+	hasBreak: boolean;
+	hasContinue: boolean;
 	includedLabels: Set<string>;
 }
 
@@ -27,7 +25,7 @@ export interface InclusionContext extends ControlFlowContext {
 export interface HasEffectsContext extends ControlFlowContext {
 	accessed: PathTracker;
 	assigned: PathTracker;
-	brokenFlow: number;
+	brokenFlow: boolean;
 	called: DiscriminatedPathTracker;
 	ignore: ExecutionContextIgnore;
 	instantiated: DiscriminatedPathTracker;
@@ -36,7 +34,9 @@ export interface HasEffectsContext extends ControlFlowContext {
 
 export function createInclusionContext(): InclusionContext {
 	return {
-		brokenFlow: BROKEN_FLOW_NONE,
+		brokenFlow: false,
+		hasBreak: false,
+		hasContinue: false,
 		includedCallArguments: new Set(),
 		includedLabels: new Set()
 	};
@@ -46,8 +46,10 @@ export function createHasEffectsContext(): HasEffectsContext {
 	return {
 		accessed: new PathTracker(),
 		assigned: new PathTracker(),
-		brokenFlow: BROKEN_FLOW_NONE,
+		brokenFlow: false,
 		called: new DiscriminatedPathTracker(),
+		hasBreak: false,
+		hasContinue: false,
 		ignore: {
 			breaks: false,
 			continues: false,

src/ast/nodes/BreakStatement.ts

@@ -1,9 +1,4 @@
-import {
-	BROKEN_FLOW_BREAK_CONTINUE,
-	BROKEN_FLOW_ERROR_RETURN_LABEL,
-	type HasEffectsContext,
-	type InclusionContext
-} from '../ExecutionContext';
+import { type HasEffectsContext, type InclusionContext } from '../ExecutionContext';
 import type Identifier from './Identifier';
 import type * as NodeType from './NodeType';
 import { StatementBase } from './shared/Node';
@@ -16,11 +11,11 @@ export default class BreakStatement extends StatementBase {
 		if (this.label) {
 			if (!context.ignore.labels.has(this.label.name)) return true;
 			context.includedLabels.add(this.label.name);
-			context.brokenFlow = BROKEN_FLOW_ERROR_RETURN_LABEL;
 		} else {
 			if (!context.ignore.breaks) return true;
-			context.brokenFlow = BROKEN_FLOW_BREAK_CONTINUE;
+			context.hasBreak = true;
 		}
+		context.brokenFlow = true;
 		return false;
 	}
 
@@ -29,7 +24,9 @@ export default class BreakStatement extends StatementBase {
 		if (this.label) {
 			this.label.include();
 			context.includedLabels.add(this.label.name);
+		} else {
+			context.hasBreak = true;
 		}
-		context.brokenFlow = this.label ? BROKEN_FLOW_ERROR_RETURN_LABEL : BROKEN_FLOW_BREAK_CONTINUE;
+		context.brokenFlow = true;
 	}
 }

src/ast/nodes/ContinueStatement.ts

@@ -1,9 +1,4 @@
-import {
-	BROKEN_FLOW_BREAK_CONTINUE,
-	BROKEN_FLOW_ERROR_RETURN_LABEL,
-	type HasEffectsContext,
-	type InclusionContext
-} from '../ExecutionContext';
+import { type HasEffectsContext, type InclusionContext } from '../ExecutionContext';
 import type Identifier from './Identifier';
 import type * as NodeType from './NodeType';
 import { StatementBase } from './shared/Node';
@@ -16,11 +11,11 @@ export default class ContinueStatement extends StatementBase {
 		if (this.label) {
 			if (!context.ignore.labels.has(this.label.name)) return true;
 			context.includedLabels.add(this.label.name);
-			context.brokenFlow = BROKEN_FLOW_ERROR_RETURN_LABEL;
 		} else {
 			if (!context.ignore.continues) return true;
-			context.brokenFlow = BROKEN_FLOW_BREAK_CONTINUE;
+			context.hasContinue = true;
 		}
+		context.brokenFlow = true;
 		return false;
 	}
 
@@ -29,7 +24,9 @@ export default class ContinueStatement extends StatementBase {
 		if (this.label) {
 			this.label.include();
 			context.includedLabels.add(this.label.name);
+		} else {
+			context.hasContinue = true;
 		}
-		context.brokenFlow = this.label ? BROKEN_FLOW_ERROR_RETURN_LABEL : BROKEN_FLOW_BREAK_CONTINUE;
+		context.brokenFlow = true;
 	}
 }

src/ast/nodes/DoWhileStatement.ts

@@ -6,6 +6,7 @@ import {
 	StatementBase,
 	type StatementNode
 } from './shared/Node';
+import { hasLoopBodyEffects, includeLoopBody } from './shared/loops';
 
 export default class DoWhileStatement extends StatementBase {
 	declare body: StatementNode;
@@ -14,22 +15,12 @@ export default class DoWhileStatement extends StatementBase {
 
 	hasEffects(context: HasEffectsContext): boolean {
 		if (this.test.hasEffects(context)) return true;
-		const { brokenFlow, ignore } = context;
-		const { breaks, continues } = ignore;
-		ignore.breaks = true;
-		ignore.continues = true;
-		if (this.body.hasEffects(context)) return true;
-		ignore.breaks = breaks;
-		ignore.continues = continues;
-		context.brokenFlow = brokenFlow;
-		return false;
+		return hasLoopBodyEffects(context, this.body);
 	}
 
 	include(context: InclusionContext, includeChildrenRecursively: IncludeChildren): void {
 		this.included = true;
 		this.test.include(context, includeChildrenRecursively);
-		const { brokenFlow } = context;
-		this.body.include(context, includeChildrenRecursively, { asSingleStatement: true });
-		context.brokenFlow = brokenFlow;
+		includeLoopBody(context, this.body, includeChildrenRecursively);
 	}
 }

src/ast/nodes/ForInStatement.ts

@@ -15,6 +15,7 @@ import {
 	type StatementNode
 } from './shared/Node';
 import type { PatternNode } from './shared/Pattern';
+import { hasLoopBodyEffects, includeLoopBody } from './shared/loops';
 
 export default class ForInStatement extends StatementBase {
 	declare body: StatementNode;
@@ -30,15 +31,7 @@ export default class ForInStatement extends StatementBase {
 		const { body, deoptimized, left, right } = this;
 		if (!deoptimized) this.applyDeoptimizations();
 		if (left.hasEffectsAsAssignmentTarget(context, false) || right.hasEffects(context)) return true;
-		const { brokenFlow, ignore } = context;
-		const { breaks, continues } = ignore;
-		ignore.breaks = true;
-		ignore.continues = true;
-		if (body.hasEffects(context)) return true;
-		ignore.breaks = breaks;
-		ignore.continues = continues;
-		context.brokenFlow = brokenFlow;
-		return false;
+		return hasLoopBodyEffects(context, body);
 	}
 
 	include(context: InclusionContext, includeChildrenRecursively: IncludeChildren): void {
@@ -47,9 +40,7 @@ export default class ForInStatement extends StatementBase {
 		this.included = true;
 		left.includeAsAssignmentTarget(context, includeChildrenRecursively || true, false);
 		right.include(context, includeChildrenRecursively);
-		const { brokenFlow } = context;
-		body.include(context, includeChildrenRecursively, { asSingleStatement: true });
-		context.brokenFlow = brokenFlow;
+		includeLoopBody(context, body, includeChildrenRecursively);
 	}
 
 	initialise() {

src/ast/nodes/ForOfStatement.ts

@@ -15,6 +15,7 @@ import {
 	type StatementNode
 } from './shared/Node';
 import type { PatternNode } from './shared/Pattern';
+import { includeLoopBody } from './shared/loops';
 
 export default class ForOfStatement extends StatementBase {
 	declare await: boolean;
@@ -39,9 +40,7 @@ export default class ForOfStatement extends StatementBase {
 		this.included = true;
 		left.includeAsAssignmentTarget(context, includeChildrenRecursively || true, false);
 		right.include(context, includeChildrenRecursively);
-		const { brokenFlow } = context;
-		body.include(context, includeChildrenRecursively, { asSingleStatement: true });
-		context.brokenFlow = brokenFlow;
+		includeLoopBody(context, body, includeChildrenRecursively);
 	}
 
 	initialise() {

src/ast/nodes/ForStatement.ts

@@ -11,6 +11,7 @@ import {
 	StatementBase,
 	type StatementNode
 } from './shared/Node';
+import { hasLoopBodyEffects, includeLoopBody } from './shared/loops';
 
 export default class ForStatement extends StatementBase {
 	declare body: StatementNode;
@@ -28,27 +29,18 @@ export default class ForStatement extends StatementBase {
 			this.init?.hasEffects(context) ||
 			this.test?.hasEffects(context) ||
 			this.update?.hasEffects(context)
-		)
+		) {
 			return true;
-		const { brokenFlow, ignore } = context;
-		const { breaks, continues } = ignore;
-		ignore.breaks = true;
-		ignore.continues = true;
-		if (this.body.hasEffects(context)) return true;
-		ignore.breaks = breaks;
-		ignore.continues = continues;
-		context.brokenFlow = brokenFlow;
-		return false;
+		}
+		return hasLoopBodyEffects(context, this.body);
 	}
 
 	include(context: InclusionContext, includeChildrenRecursively: IncludeChildren): void {
 		this.included = true;
 		this.init?.include(context, includeChildrenRecursively, { asSingleStatement: true });
 		this.test?.include(context, includeChildrenRecursively);
-		const { brokenFlow } = context;
 		this.update?.include(context, includeChildrenRecursively);
-		this.body.include(context, includeChildrenRecursively, { asSingleStatement: true });
-		context.brokenFlow = brokenFlow;
+		includeLoopBody(context, this.body, includeChildrenRecursively);
 	}
 
 	render(code: MagicString, options: RenderOptions): void {

src/ast/nodes/IfStatement.ts

@@ -1,11 +1,7 @@
 import type MagicString from 'magic-string';
 import type { RenderOptions } from '../../utils/renderHelpers';
 import type { DeoptimizableEntity } from '../DeoptimizableEntity';
-import {
-	BROKEN_FLOW_NONE,
-	type HasEffectsContext,
-	type InclusionContext
-} from '../ExecutionContext';
+import { type HasEffectsContext, type InclusionContext } from '../ExecutionContext';
 import TrackingScope from '../scopes/TrackingScope';
 import { EMPTY_PATH, SHARED_RECURSION_TRACKER } from '../utils/PathTracker';
 import BlockStatement from './BlockStatement';
@@ -49,9 +45,8 @@ export default class IfStatement extends StatementBase implements DeoptimizableE
 			context.brokenFlow = brokenFlow;
 			if (this.alternate === null) return false;
 			if (this.alternate.hasEffects(context)) return true;
-			context.brokenFlow =
-				// eslint-disable-next-line unicorn/consistent-destructuring
-				context.brokenFlow < consequentBrokenFlow ? context.brokenFlow : consequentBrokenFlow;
+			// eslint-disable-next-line unicorn/consistent-destructuring
+			context.brokenFlow = context.brokenFlow && consequentBrokenFlow;
 			return false;
 		}
 		return testValue ? this.consequent.hasEffects(context) : !!this.alternate?.hasEffects(context);
@@ -168,7 +163,7 @@ export default class IfStatement extends StatementBase implements DeoptimizableE
 	private includeUnknownTest(context: InclusionContext) {
 		this.test.include(context, false);
 		const { brokenFlow } = context;
-		let consequentBrokenFlow = BROKEN_FLOW_NONE;
+		let consequentBrokenFlow = false;
 		if (this.consequent.shouldBeIncluded(context)) {
 			this.consequent.include(context, false, { asSingleStatement: true });
 			// eslint-disable-next-line unicorn/consistent-destructuring
@@ -177,9 +172,8 @@ export default class IfStatement extends StatementBase implements DeoptimizableE
 		}
 		if (this.alternate?.shouldBeIncluded(context)) {
 			this.alternate.include(context, false, { asSingleStatement: true });
-			context.brokenFlow =
-				// eslint-disable-next-line unicorn/consistent-destructuring
-				context.brokenFlow < consequentBrokenFlow ? context.brokenFlow : consequentBrokenFlow;
+			// eslint-disable-next-line unicorn/consistent-destructuring
+			context.brokenFlow = context.brokenFlow && consequentBrokenFlow;
 		}
 	}
 

src/ast/nodes/ReturnStatement.ts

@@ -1,10 +1,6 @@
 import type MagicString from 'magic-string';
 import type { RenderOptions } from '../../utils/renderHelpers';
-import {
-	BROKEN_FLOW_ERROR_RETURN_LABEL,
-	type HasEffectsContext,
-	type InclusionContext
-} from '../ExecutionContext';
+import { type HasEffectsContext, type InclusionContext } from '../ExecutionContext';
 import type * as NodeType from './NodeType';
 import { UNKNOWN_EXPRESSION } from './shared/Expression';
 import { type ExpressionNode, type IncludeChildren, StatementBase } from './shared/Node';
@@ -15,14 +11,14 @@ export default class ReturnStatement extends StatementBase {
 
 	hasEffects(context: HasEffectsContext): boolean {
 		if (!context.ignore.returnYield || this.argument?.hasEffects(context)) return true;
-		context.brokenFlow = BROKEN_FLOW_ERROR_RETURN_LABEL;
+		context.brokenFlow = true;
 		return false;
 	}
 
 	include(context: InclusionContext, includeChildrenRecursively: IncludeChildren): void {
 		this.included = true;
 		this.argument?.include(context, includeChildrenRecursively);
-		context.brokenFlow = BROKEN_FLOW_ERROR_RETURN_LABEL;
+		context.brokenFlow = true;
 	}
 
 	initialise(): void {

src/ast/nodes/SwitchStatement.ts

@@ -1,7 +1,6 @@
 import type MagicString from 'magic-string';
 import { type RenderOptions, renderStatementList } from '../../utils/renderHelpers';
 import {
-	BROKEN_FLOW_BREAK_CONTINUE,
 	createHasEffectsContext,
 	type HasEffectsContext,
 	type InclusionContext
@@ -25,28 +24,32 @@ export default class SwitchStatement extends StatementBase {
 
 	hasEffects(context: HasEffectsContext): boolean {
 		if (this.discriminant.hasEffects(context)) return true;
-		const { brokenFlow, ignore } = context;
+		const { brokenFlow, hasBreak, ignore } = context;
 		const { breaks } = ignore;
-		let minBrokenFlow = Infinity;
 		ignore.breaks = true;
+		context.hasBreak = false;
+		let onlyHasBrokenFlow = true;
 		for (const switchCase of this.cases) {
 			if (switchCase.hasEffects(context)) return true;
 			// eslint-disable-next-line unicorn/consistent-destructuring
-			minBrokenFlow = context.brokenFlow < minBrokenFlow ? context.brokenFlow : minBrokenFlow;
+			onlyHasBrokenFlow &&= context.brokenFlow && !context.hasBreak;
+			context.hasBreak = false;
 			context.brokenFlow = brokenFlow;
 		}
-		if (this.defaultCase !== null && !(minBrokenFlow === BROKEN_FLOW_BREAK_CONTINUE)) {
-			context.brokenFlow = minBrokenFlow;
+		if (this.defaultCase !== null) {
+			context.brokenFlow = onlyHasBrokenFlow;
 		}
 		ignore.breaks = breaks;
+		context.hasBreak = hasBreak;
 		return false;
 	}
 
 	include(context: InclusionContext, includeChildrenRecursively: IncludeChildren): void {
 		this.included = true;
 		this.discriminant.include(context, includeChildrenRecursively);
-		const { brokenFlow } = context;
-		let minBrokenFlow = Infinity;
+		const { brokenFlow, hasBreak } = context;
+		context.hasBreak = false;
+		let onlyHasBrokenFlow = true;
 		let isCaseIncluded =
 			includeChildrenRecursively ||
 			(this.defaultCase !== null && this.defaultCase < this.cases.length - 1);
@@ -63,19 +66,17 @@ export default class SwitchStatement extends StatementBase {
 			if (isCaseIncluded) {
 				switchCase.include(context, includeChildrenRecursively);
 				// eslint-disable-next-line unicorn/consistent-destructuring
-				minBrokenFlow = minBrokenFlow < context.brokenFlow ? minBrokenFlow : context.brokenFlow;
+				onlyHasBrokenFlow &&= context.brokenFlow && !context.hasBreak;
+				context.hasBreak = false;
 				context.brokenFlow = brokenFlow;
 			} else {
-				minBrokenFlow = brokenFlow;
+				onlyHasBrokenFlow = brokenFlow;
 			}
 		}
-		if (
-			isCaseIncluded &&
-			this.defaultCase !== null &&
-			!(minBrokenFlow === BROKEN_FLOW_BREAK_CONTINUE)
-		) {
-			context.brokenFlow = minBrokenFlow;
+		if (isCaseIncluded && this.defaultCase !== null) {
+			context.brokenFlow = onlyHasBrokenFlow;
 		}
+		context.hasBreak = hasBreak;
 	}
 
 	initialise(): void {