Function removeSubtypes

test/fixtures/snapshot/typescript.js:61160–61222

(types, hasObjectTypes)

            return includes;
        }
        function removeSubtypes(types, hasObjectTypes) {
            // [] and [T] immediately reduce to [] and [T] respectively
            if (types.length < 2) {
                return types;
            }
            var id = getTypeListId(types);
            var match = subtypeReductionCache.get(id);
            if (match) {
                return match;
            }
            // We assume that redundant primitive types have already been removed from the types array and that there
            // are no any and unknown types in the array. Thus, the only possible supertypes for primitive types are empty
            // object types, and if none of those are present we can exclude primitive types from the subtype check.
            var hasEmptyObject = hasObjectTypes && ts.some(types, function (t) { return !!(t.flags & 524288 /* TypeFlags.Object */) && !isGenericMappedType(t) && isEmptyResolvedType(resolveStructuredTypeMembers(t)); });
            var len = types.length;
            var i = len;
            var count = 0;
            while (i > 0) {
                i--;
                var source = types[i];
                if (hasEmptyObject || source.flags & 469499904 /* TypeFlags.StructuredOrInstantiable */) {
                    // Find the first property with a unit type, if any. When constituents have a property by the same name
                    // but of a different unit type, we can quickly disqualify them from subtype checks. This helps subtype
                    // reduction of large discriminated union types.
                    var keyProperty = source.flags & (524288 /* TypeFlags.Object */ | 2097152 /* TypeFlags.Intersection */ | 58982400 /* TypeFlags.InstantiableNonPrimitive */) ?
                        ts.find(getPropertiesOfType(source), function (p) { return isUnitType(getTypeOfSymbol(p)); }) :
                        undefined;
                    var keyPropertyType = keyProperty && getRegularTypeOfLiteralType(getTypeOfSymbol(keyProperty));
                    for (var _i = 0, types_10 = types; _i < types_10.length; _i++) {
                        var target = types_10[_i];
                        if (source !== target) {
                            if (count === 100000) {
                                // After 100000 subtype checks we estimate the remaining amount of work by assuming the
                                // same ratio of checks per element. If the estimated number of remaining type checks is
                                // greater than 1M we deem the union type too complex to represent. This for example
                                // caps union types at 1000 unique object types.
                                var estimatedCount = (count / (len - i)) * len;
                                if (estimatedCount > 1000000) {
                                    ts.tracing === null || ts.tracing === void 0 ? void 0 : ts.tracing.instant("checkTypes" /* tracing.Phase.CheckTypes */, "removeSubtypes_DepthLimit", { typeIds: types.map(function (t) { return t.id; }) });
                                    error(currentNode, ts.Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent);
                                    return undefined;
                                }
                            }
                            count++;
                            if (keyProperty && target.flags & (524288 /* TypeFlags.Object */ | 2097152 /* TypeFlags.Intersection */ | 58982400 /* TypeFlags.InstantiableNonPrimitive */)) {
                                var t = getTypeOfPropertyOfType(target, keyProperty.escapedName);
                                if (t && isUnitType(t) && getRegularTypeOfLiteralType(t) !== keyPropertyType) {
                                    continue;
                                }
                            }
                            if (isTypeRelatedTo(source, target, strictSubtypeRelation) && (!(ts.getObjectFlags(getTargetType(source)) & 1 /* ObjectFlags.Class */) ||
                                !(ts.getObjectFlags(getTargetType(target)) & 1 /* ObjectFlags.Class */) ||
                                isTypeDerivedFrom(source, target))) {
                                ts.orderedRemoveItemAt(types, i);
                                break;
                            }
                        }
                    }