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🤖 Pick PR #47927 (Don't error if binding pattern type...) into release-4.6 (#48005)
* Cherry-pick PR #47927 into release-4.6 Component commits: c4aa31b early return if pattern type is never * Update LKG Co-authored-by: Gabriela Araujo Britto <[email protected]> Co-authored-by: typescript-bot <[email protected]>
1 parent f4fe064 commit 78ee4ca

16 files changed

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‎lib/tsc.js

+3
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@@ -58514,6 +58514,9 @@ var ts;
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if (parentType && parentType.flags & 1048576 && !(parent.kind === 163 && isSymbolAssigned(symbol))) {
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var pattern = declaration.parent;
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var narrowedType = getFlowTypeOfReference(pattern, parentType, parentType, undefined, location.flowNode);
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if (narrowedType.flags & 131072) {
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return neverType;
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}
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return getBindingElementTypeFromParentType(declaration, narrowedType);
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}
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}

‎lib/tsserver.js

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@@ -70031,6 +70031,9 @@ var ts;
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if (parentType && parentType.flags & 1048576 /* Union */ && !(parent.kind === 163 /* Parameter */ && isSymbolAssigned(symbol))) {
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var pattern = declaration.parent;
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var narrowedType = getFlowTypeOfReference(pattern, parentType, parentType, /*flowContainer*/ undefined, location.flowNode);
70034+
if (narrowedType.flags & 131072 /* Never */) {
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return neverType;
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}
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return getBindingElementTypeFromParentType(declaration, narrowedType);
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}
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}

‎lib/tsserverlibrary.js

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@@ -70225,6 +70225,9 @@ var ts;
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if (parentType && parentType.flags & 1048576 /* Union */ && !(parent.kind === 163 /* Parameter */ && isSymbolAssigned(symbol))) {
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var pattern = declaration.parent;
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var narrowedType = getFlowTypeOfReference(pattern, parentType, parentType, /*flowContainer*/ undefined, location.flowNode);
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if (narrowedType.flags & 131072 /* Never */) {
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return neverType;
70230+
}
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return getBindingElementTypeFromParentType(declaration, narrowedType);
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}
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}

‎lib/typescript.js

+3
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‎lib/typescriptServices.js

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‎lib/typingsInstaller.js

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‎src/compiler/checker.ts

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@@ -25127,6 +25127,9 @@ namespace ts {
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if (parentType && parentType.flags & TypeFlags.Union && !(parent.kind === SyntaxKind.Parameter && isSymbolAssigned(symbol))) {
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const pattern = declaration.parent;
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const narrowedType = getFlowTypeOfReference(pattern, parentType, parentType, /*flowContainer*/ undefined, location.flowNode);
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if (narrowedType.flags & TypeFlags.Never) {
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return neverType;
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}
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return getBindingElementTypeFromParentType(declaration, narrowedType);
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}
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}

‎tests/baselines/reference/arrayDestructuringInSwitch1.js

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//// [arrayDestructuringInSwitch1.ts]
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export type Expression = BooleanLogicExpression | 'true' | 'false';
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export type BooleanLogicExpression = ['and', ...Expression[]] | ['not', Expression];
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export function evaluate(expression: Expression): boolean {
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if (Array.isArray(expression)) {
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const [operator, ...operands] = expression;
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switch (operator) {
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case 'and': {
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return operands.every((child) => evaluate(child));
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}
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case 'not': {
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return !evaluate(operands[0]);
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}
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default: {
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throw new Error(`${operator} is not a supported operator`);
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}
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}
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} else {
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return expression === 'true';
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}
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}
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//// [arrayDestructuringInSwitch1.js]
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"use strict";
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exports.__esModule = true;
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exports.evaluate = void 0;
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function evaluate(expression) {
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if (Array.isArray(expression)) {
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var operator = expression[0], operands = expression.slice(1);
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switch (operator) {
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case 'and': {
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return operands.every(function (child) { return evaluate(child); });
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}
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case 'not': {
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return !evaluate(operands[0]);
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}
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default: {
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throw new Error("".concat(operator, " is not a supported operator"));
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}
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}
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}
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else {
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return expression === 'true';
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}
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}
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exports.evaluate = evaluate;

‎tests/baselines/reference/arrayDestructuringInSwitch1.symbols

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=== tests/cases/compiler/arrayDestructuringInSwitch1.ts ===
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export type Expression = BooleanLogicExpression | 'true' | 'false';
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>Expression : Symbol(Expression, Decl(arrayDestructuringInSwitch1.ts, 0, 0))
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>BooleanLogicExpression : Symbol(BooleanLogicExpression, Decl(arrayDestructuringInSwitch1.ts, 0, 67))
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export type BooleanLogicExpression = ['and', ...Expression[]] | ['not', Expression];
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>BooleanLogicExpression : Symbol(BooleanLogicExpression, Decl(arrayDestructuringInSwitch1.ts, 0, 67))
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>Expression : Symbol(Expression, Decl(arrayDestructuringInSwitch1.ts, 0, 0))
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>Expression : Symbol(Expression, Decl(arrayDestructuringInSwitch1.ts, 0, 0))
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export function evaluate(expression: Expression): boolean {
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>evaluate : Symbol(evaluate, Decl(arrayDestructuringInSwitch1.ts, 1, 84))
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>expression : Symbol(expression, Decl(arrayDestructuringInSwitch1.ts, 3, 25))
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>Expression : Symbol(Expression, Decl(arrayDestructuringInSwitch1.ts, 0, 0))
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if (Array.isArray(expression)) {
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>Array.isArray : Symbol(ArrayConstructor.isArray, Decl(lib.es5.d.ts, --, --))
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>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
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>isArray : Symbol(ArrayConstructor.isArray, Decl(lib.es5.d.ts, --, --))
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>expression : Symbol(expression, Decl(arrayDestructuringInSwitch1.ts, 3, 25))
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const [operator, ...operands] = expression;
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>operator : Symbol(operator, Decl(arrayDestructuringInSwitch1.ts, 5, 11))
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>operands : Symbol(operands, Decl(arrayDestructuringInSwitch1.ts, 5, 20))
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>expression : Symbol(expression, Decl(arrayDestructuringInSwitch1.ts, 3, 25))
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switch (operator) {
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>operator : Symbol(operator, Decl(arrayDestructuringInSwitch1.ts, 5, 11))
29+
30+
case 'and': {
31+
return operands.every((child) => evaluate(child));
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>operands.every : Symbol(Array.every, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
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>operands : Symbol(operands, Decl(arrayDestructuringInSwitch1.ts, 5, 20))
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>every : Symbol(Array.every, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
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>child : Symbol(child, Decl(arrayDestructuringInSwitch1.ts, 8, 31))
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>evaluate : Symbol(evaluate, Decl(arrayDestructuringInSwitch1.ts, 1, 84))
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>child : Symbol(child, Decl(arrayDestructuringInSwitch1.ts, 8, 31))
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}
39+
case 'not': {
40+
return !evaluate(operands[0]);
41+
>evaluate : Symbol(evaluate, Decl(arrayDestructuringInSwitch1.ts, 1, 84))
42+
>operands : Symbol(operands, Decl(arrayDestructuringInSwitch1.ts, 5, 20))
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>0 : Symbol(0)
44+
}
45+
default: {
46+
throw new Error(`${operator} is not a supported operator`);
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>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
48+
>operator : Symbol(operator, Decl(arrayDestructuringInSwitch1.ts, 5, 11))
49+
}
50+
}
51+
} else {
52+
return expression === 'true';
53+
>expression : Symbol(expression, Decl(arrayDestructuringInSwitch1.ts, 3, 25))
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}
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}

‎tests/baselines/reference/arrayDestructuringInSwitch1.types

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=== tests/cases/compiler/arrayDestructuringInSwitch1.ts ===
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export type Expression = BooleanLogicExpression | 'true' | 'false';
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>Expression : Expression
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export type BooleanLogicExpression = ['and', ...Expression[]] | ['not', Expression];
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>BooleanLogicExpression : BooleanLogicExpression
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export function evaluate(expression: Expression): boolean {
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>evaluate : (expression: Expression) => boolean
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>expression : Expression
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if (Array.isArray(expression)) {
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>Array.isArray(expression) : boolean
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>Array.isArray : (arg: any) => arg is any[]
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>Array : ArrayConstructor
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>isArray : (arg: any) => arg is any[]
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>expression : Expression
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const [operator, ...operands] = expression;
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>operator : "and" | "not"
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>operands : Expression[] | [Expression]
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>expression : BooleanLogicExpression
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switch (operator) {
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>operator : "and" | "not"
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case 'and': {
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>'and' : "and"
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30+
return operands.every((child) => evaluate(child));
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>operands.every((child) => evaluate(child)) : boolean
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>operands.every : { <S extends Expression>(predicate: (value: Expression, index: number, array: Expression[]) => value is S, thisArg?: any): this is S[]; (predicate: (value: Expression, index: number, array: Expression[]) => unknown, thisArg?: any): boolean; } | { <S extends Expression>(predicate: (value: Expression, index: number, array: Expression[]) => value is S, thisArg?: any): this is S[]; (predicate: (value: Expression, index: number, array: Expression[]) => unknown, thisArg?: any): boolean; }
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>operands : Expression[] | [Expression]
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>every : { <S extends Expression>(predicate: (value: Expression, index: number, array: Expression[]) => value is S, thisArg?: any): this is S[]; (predicate: (value: Expression, index: number, array: Expression[]) => unknown, thisArg?: any): boolean; } | { <S extends Expression>(predicate: (value: Expression, index: number, array: Expression[]) => value is S, thisArg?: any): this is S[]; (predicate: (value: Expression, index: number, array: Expression[]) => unknown, thisArg?: any): boolean; }
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>(child) => evaluate(child) : (child: Expression) => boolean
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>child : Expression
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>evaluate(child) : boolean
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>evaluate : (expression: Expression) => boolean
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>child : Expression
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}
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case 'not': {
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>'not' : "not"
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return !evaluate(operands[0]);
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>!evaluate(operands[0]) : boolean
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>evaluate(operands[0]) : boolean
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>evaluate : (expression: Expression) => boolean
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>operands[0] : Expression
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>operands : Expression[] | [Expression]
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>0 : 0
51+
}
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default: {
53+
throw new Error(`${operator} is not a supported operator`);
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>new Error(`${operator} is not a supported operator`) : Error
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>Error : ErrorConstructor
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>`${operator} is not a supported operator` : string
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>operator : never
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}
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}
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} else {
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return expression === 'true';
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>expression === 'true' : boolean
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>expression : "true" | "false"
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>'true' : "true"
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}
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}

‎tests/baselines/reference/arrayDestructuringInSwitch2.errors.txt

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tests/cases/compiler/arrayDestructuringInSwitch2.ts(11,13): error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.
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==== tests/cases/compiler/arrayDestructuringInSwitch2.ts (1 errors) ====
5+
type X = { kind: "a", a: [1] } | { kind: "b", a: [] }
6+
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function foo(x: X): 1 {
8+
const { kind, a } = x;
9+
switch (kind) {
10+
case "a":
11+
return a[0];
12+
case "b":
13+
return 1;
14+
default:
15+
const [n] = a;
16+
~~~
17+
!!! error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.
18+
return a;
19+
}
20+
}

‎tests/baselines/reference/arrayDestructuringInSwitch2.js

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1+
//// [arrayDestructuringInSwitch2.ts]
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type X = { kind: "a", a: [1] } | { kind: "b", a: [] }
3+
4+
function foo(x: X): 1 {
5+
const { kind, a } = x;
6+
switch (kind) {
7+
case "a":
8+
return a[0];
9+
case "b":
10+
return 1;
11+
default:
12+
const [n] = a;
13+
return a;
14+
}
15+
}
16+
17+
//// [arrayDestructuringInSwitch2.js]
18+
function foo(x) {
19+
var kind = x.kind, a = x.a;
20+
switch (kind) {
21+
case "a":
22+
return a[0];
23+
case "b":
24+
return 1;
25+
default:
26+
var n = a[0];
27+
return a;
28+
}
29+
}

‎tests/baselines/reference/arrayDestructuringInSwitch2.symbols

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=== tests/cases/compiler/arrayDestructuringInSwitch2.ts ===
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type X = { kind: "a", a: [1] } | { kind: "b", a: [] }
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>X : Symbol(X, Decl(arrayDestructuringInSwitch2.ts, 0, 0))
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>kind : Symbol(kind, Decl(arrayDestructuringInSwitch2.ts, 0, 10))
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>a : Symbol(a, Decl(arrayDestructuringInSwitch2.ts, 0, 21))
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>kind : Symbol(kind, Decl(arrayDestructuringInSwitch2.ts, 0, 34))
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>a : Symbol(a, Decl(arrayDestructuringInSwitch2.ts, 0, 45))
8+
9+
function foo(x: X): 1 {
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>foo : Symbol(foo, Decl(arrayDestructuringInSwitch2.ts, 0, 53))
11+
>x : Symbol(x, Decl(arrayDestructuringInSwitch2.ts, 2, 13))
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>X : Symbol(X, Decl(arrayDestructuringInSwitch2.ts, 0, 0))
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const { kind, a } = x;
15+
>kind : Symbol(kind, Decl(arrayDestructuringInSwitch2.ts, 3, 9))
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>a : Symbol(a, Decl(arrayDestructuringInSwitch2.ts, 3, 15))
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>x : Symbol(x, Decl(arrayDestructuringInSwitch2.ts, 2, 13))
18+
19+
switch (kind) {
20+
>kind : Symbol(kind, Decl(arrayDestructuringInSwitch2.ts, 3, 9))
21+
22+
case "a":
23+
return a[0];
24+
>a : Symbol(a, Decl(arrayDestructuringInSwitch2.ts, 3, 15))
25+
>0 : Symbol(0)
26+
27+
case "b":
28+
return 1;
29+
default:
30+
const [n] = a;
31+
>n : Symbol(n, Decl(arrayDestructuringInSwitch2.ts, 10, 13))
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>a : Symbol(a, Decl(arrayDestructuringInSwitch2.ts, 3, 15))
33+
34+
return a;
35+
>a : Symbol(a, Decl(arrayDestructuringInSwitch2.ts, 3, 15))
36+
}
37+
}

‎tests/baselines/reference/arrayDestructuringInSwitch2.types

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1+
=== tests/cases/compiler/arrayDestructuringInSwitch2.ts ===
2+
type X = { kind: "a", a: [1] } | { kind: "b", a: [] }
3+
>X : X
4+
>kind : "a"
5+
>a : [1]
6+
>kind : "b"
7+
>a : []
8+
9+
function foo(x: X): 1 {
10+
>foo : (x: X) => 1
11+
>x : X
12+
13+
const { kind, a } = x;
14+
>kind : "a" | "b"
15+
>a : [1] | []
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>x : X
17+
18+
switch (kind) {
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>kind : "a" | "b"
20+
21+
case "a":
22+
>"a" : "a"
23+
24+
return a[0];
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>a[0] : 1
26+
>a : [1]
27+
>0 : 0
28+
29+
case "b":
30+
>"b" : "b"
31+
32+
return 1;
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>1 : 1
34+
35+
default:
36+
const [n] = a;
37+
>n : never
38+
>a : never
39+
40+
return a;
41+
>a : never
42+
}
43+
}

‎tests/cases/compiler/arrayDestructuringInSwitch1.ts

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export type Expression = BooleanLogicExpression | 'true' | 'false';
2+
export type BooleanLogicExpression = ['and', ...Expression[]] | ['not', Expression];
3+
4+
export function evaluate(expression: Expression): boolean {
5+
if (Array.isArray(expression)) {
6+
const [operator, ...operands] = expression;
7+
switch (operator) {
8+
case 'and': {
9+
return operands.every((child) => evaluate(child));
10+
}
11+
case 'not': {
12+
return !evaluate(operands[0]);
13+
}
14+
default: {
15+
throw new Error(`${operator} is not a supported operator`);
16+
}
17+
}
18+
} else {
19+
return expression === 'true';
20+
}
21+
}

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