Function createReverseMappedType

test/fixtures/snapshot/typescript.js:68217–68242

(source, target, constraint)

                isTupleType(type) && ts.some(getTypeArguments(type), isPartiallyInferableType);
        }
        function createReverseMappedType(source, target, constraint) {
            // We consider a source type reverse mappable if it has a string index signature or if
            // it has one or more properties and is of a partially inferable type.
            if (!(getIndexInfoOfType(source, stringType) || getPropertiesOfType(source).length !== 0 && isPartiallyInferableType(source))) {
                return undefined;
            }
            // For arrays and tuples we infer new arrays and tuples where the reverse mapping has been
            // applied to the element type(s).
            if (isArrayType(source)) {
                return createArrayType(inferReverseMappedType(getTypeArguments(source)[0], target, constraint), isReadonlyArrayType(source));
            }
            if (isTupleType(source)) {
                var elementTypes = ts.map(getTypeArguments(source), function (t) { return inferReverseMappedType(t, target, constraint); });
                var elementFlags = getMappedTypeModifiers(target) & 4 /* MappedTypeModifiers.IncludeOptional */ ?
                    ts.sameMap(source.target.elementFlags, function (f) { return f & 2 /* ElementFlags.Optional */ ? 1 /* ElementFlags.Required */ : f; }) :
                    source.target.elementFlags;
                return createTupleType(elementTypes, elementFlags, source.target.readonly, source.target.labeledElementDeclarations);
            }
            // For all other object types we infer a new object type where the reverse mapping has been
            // applied to the type of each property.
            var reversed = createObjectType(1024 /* ObjectFlags.ReverseMapped */ | 16 /* ObjectFlags.Anonymous */, /*symbol*/ undefined);
            reversed.source = source;
            reversed.mappedType = target;
            reversed.constraintType = constraint;
            return reversed;
        }
        function getTypeOfReverseMappedSymbol(symbol) {
            var links = getSymbolLinks(symbol);
            if (!links.type) {