Function instantiateMappedTypeTemplate

test/fixtures/snapshot/typescript.js:63575–63582

(type, key, isOptional, mapper)

                createTupleType(elementTypes, newTupleModifiers, newReadonly, tupleType.target.labeledElementDeclarations);
        }
        function instantiateMappedTypeTemplate(type, key, isOptional, mapper) {
            var templateMapper = appendTypeMapping(mapper, getTypeParameterFromMappedType(type), key);
            var propType = instantiateType(getTemplateTypeFromMappedType(type.target || type), templateMapper);
            var modifiers = getMappedTypeModifiers(type);
            return strictNullChecks && modifiers & 4 /* MappedTypeModifiers.IncludeOptional */ && !maybeTypeOfKind(propType, 32768 /* TypeFlags.Undefined */ | 16384 /* TypeFlags.Void */) ? getOptionalType(propType, /*isProperty*/ true) :
                strictNullChecks && modifiers & 8 /* MappedTypeModifiers.ExcludeOptional */ && isOptional ? getTypeWithFacts(propType, 524288 /* TypeFacts.NEUndefined */) :
                    propType;
        }
        function instantiateAnonymousType(type, mapper, aliasSymbol, aliasTypeArguments) {
            var result = createObjectType(type.objectFlags | 64 /* ObjectFlags.Instantiated */, type.symbol);
            if (type.objectFlags & 32 /* ObjectFlags.Mapped */) {