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Array literals contextually typed by tuple types with rest elements

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This commit is contained in:
Anders Hejlsberg 2018-06-16 13:30:17 -07:00
parent 3f03a37806
commit 43bac20b83
1 changed files with 5 additions and 4 deletions
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9
src/compiler/checker.ts
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@ -15993,7 +15993,7 @@ namespace ts {
function checkArrayLiteral(node: ArrayLiteralExpression, checkMode: CheckMode | undefined): Type {
const elements = node.elements;
let hasSpreadElement = false;
let hasNonEndingSpreadElement = false;
const elementTypes: Type[] = [];
const inDestructuringPattern = isAssignmentTarget(node);
const contextualType = getApparentTypeOfContextualType(node);
@ -16024,9 +16024,9 @@ namespace ts {
const type = checkExpressionForMutableLocation(e, checkMode, elementContextualType);
elementTypes.push(type);
}
hasSpreadElement = hasSpreadElement || e.kind === SyntaxKind.SpreadElement;
hasNonEndingSpreadElement = hasNonEndingSpreadElement || (index < elements.length - 1 && e.kind === SyntaxKind.SpreadElement);
}
if (!hasSpreadElement) {
if (!hasNonEndingSpreadElement) {
// If array literal is actually a destructuring pattern, mark it as an implied type. We do this such
// that we get the same behavior for "var [x, y] = []" and "[x, y] = []".
if (inDestructuringPattern && elementTypes.length) {
@ -16053,7 +16053,8 @@ namespace ts {
}
}
}
return createTupleType(elementTypes);
const hasSpreadElement = elements.length > 0 && elements[elements.length - 1].kind === SyntaxKind.SpreadElement;
return createTupleType(elementTypes, elementTypes.length - (hasSpreadElement ? 1 : 0), hasSpreadElement);
}
}
return createArrayType(elementTypes.length ?