Function getSingleBaseForNonAugmentingSubtype

test/fixtures/snapshot/typescript.js:67422–67452

(type)

            return isArrayType(type) || !(type.flags & 98304 /* TypeFlags.Nullable */) && isTypeAssignableTo(type, anyReadonlyArrayType);
        }
        function getSingleBaseForNonAugmentingSubtype(type) {
            if (!(ts.getObjectFlags(type) & 4 /* ObjectFlags.Reference */) || !(ts.getObjectFlags(type.target) & 3 /* ObjectFlags.ClassOrInterface */)) {
                return undefined;
            }
            if (ts.getObjectFlags(type) & 33554432 /* ObjectFlags.IdenticalBaseTypeCalculated */) {
                return ts.getObjectFlags(type) & 67108864 /* ObjectFlags.IdenticalBaseTypeExists */ ? type.cachedEquivalentBaseType : undefined;
            }
            type.objectFlags |= 33554432 /* ObjectFlags.IdenticalBaseTypeCalculated */;
            var target = type.target;
            if (ts.getObjectFlags(target) & 1 /* ObjectFlags.Class */) {
                var baseTypeNode = getBaseTypeNodeOfClass(target);
                // A base type expression may circularly reference the class itself (e.g. as an argument to function call), so we only
                // check for base types specified as simple qualified names.
                if (baseTypeNode && baseTypeNode.expression.kind !== 79 /* SyntaxKind.Identifier */ && baseTypeNode.expression.kind !== 206 /* SyntaxKind.PropertyAccessExpression */) {
                    return undefined;
                }
            }
            var bases = getBaseTypes(target);
            if (bases.length !== 1) {
                return undefined;
            }
            if (getMembersOfSymbol(type.symbol).size) {
                return undefined; // If the interface has any members, they may subtype members in the base, so we should do a full structural comparison
            }
            var instantiatedBase = !ts.length(target.typeParameters) ? bases[0] : instantiateType(bases[0], createTypeMapper(target.typeParameters, getTypeArguments(type).slice(0, target.typeParameters.length)));
            if (ts.length(getTypeArguments(type)) > ts.length(target.typeParameters)) {
                instantiatedBase = getTypeWithThisArgument(instantiatedBase, ts.last(getTypeArguments(type)));
            }
            type.objectFlags |= 67108864 /* ObjectFlags.IdenticalBaseTypeExists */;
            return type.cachedEquivalentBaseType = instantiatedBase;
        }
        function isEmptyLiteralType(type) {
            return strictNullChecks ? type === implicitNeverType : type === undefinedWideningType;
        }