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Infer tuples for jsx children if contextually typed by a tuple (#27409)

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This commit is contained in:
Wesley Wigham
2018-10-04 17:56:38 -07:00
committed by GitHub
parent deeb40129d
commit e1d346ea53
6 changed files with 260 additions and 21 deletions
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52
src/compiler/checker.ts
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@@ -17189,31 +17189,14 @@ namespace ts {
const minLength = elementCount - (hasRestElement ? 1 : 0);
// 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] = []".
let tupleResult: Type | undefined;
if (inDestructuringPattern && minLength > 0) {
const type = cloneTypeReference(<TypeReference>createTupleType(elementTypes, minLength, hasRestElement));
type.pattern = node;
return type;
}
if (contextualType && contextualTypeIsTupleLikeType(contextualType)) {
const pattern = contextualType.pattern;
// If array literal is contextually typed by a binding pattern or an assignment pattern, pad the resulting
// tuple type with the corresponding binding or assignment element types to make the lengths equal.
if (!hasRestElement && pattern && (pattern.kind === SyntaxKind.ArrayBindingPattern || pattern.kind === SyntaxKind.ArrayLiteralExpression)) {
const patternElements = (<BindingPattern | ArrayLiteralExpression>pattern).elements;
for (let i = elementCount; i < patternElements.length; i++) {
const e = patternElements[i];
if (hasDefaultValue(e)) {
elementTypes.push((<TypeReference>contextualType).typeArguments![i]);
}
else if (i < patternElements.length - 1 || !(e.kind === SyntaxKind.BindingElement && (<BindingElement>e).dotDotDotToken || e.kind === SyntaxKind.SpreadElement)) {
if (e.kind !== SyntaxKind.OmittedExpression) {
error(e, Diagnostics.Initializer_provides_no_value_for_this_binding_element_and_the_binding_element_has_no_default_value);
}
elementTypes.push(strictNullChecks ? implicitNeverType : undefinedWideningType);
}
}
}
return createTupleType(elementTypes, minLength, hasRestElement);
else if (tupleResult = getArrayLiteralTupleTypeIfApplicable(elementTypes, contextualType, hasRestElement, elementCount)) {
return tupleResult;
}
else if (forceTuple) {
return createTupleType(elementTypes, minLength, hasRestElement);
@@ -17222,6 +17205,31 @@ namespace ts {
return getArrayLiteralType(elementTypes, UnionReduction.Subtype);
}
function getArrayLiteralTupleTypeIfApplicable(elementTypes: Type[], contextualType: Type | undefined, hasRestElement: boolean, elementCount = elementTypes.length) {
if (contextualType && contextualTypeIsTupleLikeType(contextualType)) {
const minLength = elementCount - (hasRestElement ? 1 : 0);
const pattern = contextualType.pattern;
// If array literal is contextually typed by a binding pattern or an assignment pattern, pad the resulting
// tuple type with the corresponding binding or assignment element types to make the lengths equal.
if (!hasRestElement && pattern && (pattern.kind === SyntaxKind.ArrayBindingPattern || pattern.kind === SyntaxKind.ArrayLiteralExpression)) {
const patternElements = (<BindingPattern | ArrayLiteralExpression>pattern).elements;
for (let i = elementCount; i < patternElements.length; i++) {
const e = patternElements[i];
if (hasDefaultValue(e)) {
elementTypes.push((<TypeReference>contextualType).typeArguments![i]);
}
else if (i < patternElements.length - 1 || !(e.kind === SyntaxKind.BindingElement && (<BindingElement>e).dotDotDotToken || e.kind === SyntaxKind.SpreadElement)) {
if (e.kind !== SyntaxKind.OmittedExpression) {
error(e, Diagnostics.Initializer_provides_no_value_for_this_binding_element_and_the_binding_element_has_no_default_value);
}
elementTypes.push(strictNullChecks ? implicitNeverType : undefinedWideningType);
}
}
}
return createTupleType(elementTypes, minLength, hasRestElement);
}
}
function getArrayLiteralType(elementTypes: Type[], unionReduction = UnionReduction.Literal) {
return createArrayType(elementTypes.length ?
getUnionType(elementTypes, unionReduction) :
@@ -17637,11 +17645,13 @@ namespace ts {
error(attributes, Diagnostics._0_are_specified_twice_The_attribute_named_0_will_be_overwritten, unescapeLeadingUnderscores(jsxChildrenPropertyName));
}
const contextualType = getApparentTypeOfContextualType(openingLikeElement.attributes);
const childrenContextualType = contextualType && getTypeOfPropertyOfContextualType(contextualType, jsxChildrenPropertyName);
// If there are children in the body of JSX element, create dummy attribute "children" with the union of children types so that it will pass the attribute checking process
const childrenPropSymbol = createSymbol(SymbolFlags.Property | SymbolFlags.Transient, jsxChildrenPropertyName);
childrenPropSymbol.type = childrenTypes.length === 1 ?
childrenTypes[0] :
createArrayType(getUnionType(childrenTypes));
(getArrayLiteralTupleTypeIfApplicable(childrenTypes, childrenContextualType, /*hasRestElement*/ false) || createArrayType(getUnionType(childrenTypes)));
const childPropMap = createSymbolTable();
childPropMap.set(jsxChildrenPropertyName, childrenPropSymbol);
spread = getSpreadType(spread, createAnonymousType(attributes.symbol, childPropMap, emptyArray, emptyArray, /*stringIndexInfo*/ undefined, /*numberIndexInfo*/ undefined),