Function computeBaseConstraint

test/fixtures/snapshot/typescript.js:58997–59059

(t)

                return c !== noConstraintType && c !== circularConstraintType ? c : undefined;
            }
            function computeBaseConstraint(t) {
                if (t.flags & 262144 /* TypeFlags.TypeParameter */) {
                    var constraint = getConstraintFromTypeParameter(t);
                    return t.isThisType || !constraint ?
                        constraint :
                        getBaseConstraint(constraint);
                }
                if (t.flags & 3145728 /* TypeFlags.UnionOrIntersection */) {
                    var types = t.types;
                    var baseTypes = [];
                    var different = false;
                    for (var _i = 0, types_7 = types; _i < types_7.length; _i++) {
                        var type_4 = types_7[_i];
                        var baseType = getBaseConstraint(type_4);
                        if (baseType) {
                            if (baseType !== type_4) {
                                different = true;
                            }
                            baseTypes.push(baseType);
                        }
                        else {
                            different = true;
                        }
                    }
                    if (!different) {
                        return t;
                    }
                    return t.flags & 1048576 /* TypeFlags.Union */ && baseTypes.length === types.length ? getUnionType(baseTypes) :
                        t.flags & 2097152 /* TypeFlags.Intersection */ && baseTypes.length ? getIntersectionType(baseTypes) :
                            undefined;
                }
                if (t.flags & 4194304 /* TypeFlags.Index */) {
                    return keyofConstraintType;
                }
                if (t.flags & 134217728 /* TypeFlags.TemplateLiteral */) {
                    var types = t.types;
                    var constraints = ts.mapDefined(types, getBaseConstraint);
                    return constraints.length === types.length ? getTemplateLiteralType(t.texts, constraints) : stringType;
                }
                if (t.flags & 268435456 /* TypeFlags.StringMapping */) {
                    var constraint = getBaseConstraint(t.type);
                    return constraint ? getStringMappingType(t.symbol, constraint) : stringType;
                }
                if (t.flags & 8388608 /* TypeFlags.IndexedAccess */) {
                    if (isMappedTypeGenericIndexedAccess(t)) {
                        // For indexed access types of the form { [P in K]: E }[X], where K is non-generic and X is generic,
                        // we substitute an instantiation of E where P is replaced with X.
                        return getBaseConstraint(substituteIndexedMappedType(t.objectType, t.indexType));
                    }
                    var baseObjectType = getBaseConstraint(t.objectType);
                    var baseIndexType = getBaseConstraint(t.indexType);
                    var baseIndexedAccess = baseObjectType && baseIndexType && getIndexedAccessTypeOrUndefined(baseObjectType, baseIndexType, t.accessFlags);
                    return baseIndexedAccess && getBaseConstraint(baseIndexedAccess);
                }
                if (t.flags & 16777216 /* TypeFlags.Conditional */) {
                    var constraint = getConstraintFromConditionalType(t);
                    return constraint && getBaseConstraint(constraint);
                }