Pageble methods with custom query fail creating the count query and does not warn about the missing alias

[alienisty]

This problem happens using springboot 2.4.5. Using Page as return type for a query method with a custom query, even a simple and plain query, causes an error creating the count query.
I've created a simple reproducing project demo.zip and the query method:

@RepositoryRestResource(path = "people", collectionResourceRel = "people")
public interface PersonRepository extends JpaRepository<Person, Long> {
	
	@Query("from Person where age > 18")
	public Page<Person> findAdults(Pageable pageable);
}

causes the following exception:

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'repositories' defined in class path resource [org/springframework/data/rest/webmvc/config/RepositoryRestMvcConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.data.repository.support.Repositories]: Factory method 'repositories' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'personRepository' defined in com.example.demo.repository.PersonRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Count query validation failed for method public abstract org.springframework.data.domain.Page com.example.demo.repository.PersonRepository.findAdults(org.springframework.data.domain.Pageable)!
	at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:658) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:486) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1334) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:564) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:524) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1380) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1300) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:887) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:791) ~[spring-beans-5.3.6.jar:5.3.6]
	... 152 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.data.repository.support.Repositories]: Factory method 'repositories' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'personRepository' defined in com.example.demo.repository.PersonRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Count query validation failed for method public abstract org.springframework.data.domain.Page com.example.demo.repository.PersonRepository.findAdults(org.springframework.data.domain.Pageable)!
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:653) ~[spring-beans-5.3.6.jar:5.3.6]
	... 166 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'personRepository' defined in com.example.demo.repository.PersonRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Count query validation failed for method public abstract org.springframework.data.domain.Page com.example.demo.repository.PersonRepository.findAdults(org.springframework.data.domain.Pageable)!
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1786) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:602) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:524) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:213) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1160) ~[spring-context-5.3.6.jar:5.3.6]
	at org.springframework.data.repository.support.Repositories.cacheRepositoryFactory(Repositories.java:100) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.repository.support.Repositories.populateRepositoryFactoryInformation(Repositories.java:93) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.repository.support.Repositories.<init>(Repositories.java:86) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration.repositories(RepositoryRestMvcConfiguration.java:284) ~[spring-data-rest-webmvc-3.4.8.jar:3.4.8]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.3.6.jar:5.3.6]
	... 167 common frames omitted
Caused by: java.lang.IllegalArgumentException: Count query validation failed for method public abstract org.springframework.data.domain.Page com.example.demo.repository.PersonRepository.findAdults(org.springframework.data.domain.Pageable)!
	at org.springframework.data.jpa.repository.query.SimpleJpaQuery.validateQuery(SimpleJpaQuery.java:93) ~[spring-data-jpa-2.4.8.jar:2.4.8]
	at org.springframework.data.jpa.repository.query.SimpleJpaQuery.<init>(SimpleJpaQuery.java:66) ~[spring-data-jpa-2.4.8.jar:2.4.8]
	at org.springframework.data.jpa.repository.query.JpaQueryFactory.fromMethodWithQueryString(JpaQueryFactory.java:76) ~[spring-data-jpa-2.4.8.jar:2.4.8]
	at org.springframework.data.jpa.repository.query.JpaQueryFactory.fromQueryAnnotation(JpaQueryFactory.java:56) ~[spring-data-jpa-2.4.8.jar:2.4.8]
	at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$DeclaredQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:146) ~[spring-data-jpa-2.4.8.jar:2.4.8]
	at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateIfNotFoundQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:216) ~[spring-data-jpa-2.4.8.jar:2.4.8]
	at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$AbstractQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:81) ~[spring-data-jpa-2.4.8.jar:2.4.8]
	at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.lookupQuery(QueryExecutorMethodInterceptor.java:100) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.lambda$mapMethodsToQuery$1(QueryExecutorMethodInterceptor.java:93) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195) ~[na:na]
	at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133) ~[na:na]
	at java.base/java.util.Collections$UnmodifiableCollection$1.forEachRemaining(Collections.java:1054) ~[na:na]
	at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[na:na]
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578) ~[na:na]
	at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.mapMethodsToQuery(QueryExecutorMethodInterceptor.java:95) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.lambda$new$0(QueryExecutorMethodInterceptor.java:85) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at java.base/java.util.Optional.map(Optional.java:265) ~[na:na]
	at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.<init>(QueryExecutorMethodInterceptor.java:85) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:303) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.lambda$afterPropertiesSet$5(RepositoryFactoryBeanSupport.java:323) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.util.Lazy.getNullable(Lazy.java:230) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.util.Lazy.get(Lazy.java:114) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:329) ~[spring-data-commons-2.4.8.jar:2.4.8]
	at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:144) ~[spring-data-jpa-2.4.8.jar:2.4.8]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1845) ~[spring-beans-5.3.6.jar:5.3.6]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1782) ~[spring-beans-5.3.6.jar:5.3.6]
	... 183 common frames omitted
Caused by: java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected token: where near line 1, column 14 [**select _count(where)_ from com.example.demo.model.Person where age > 18**]
	at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:138) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:734) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:114) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
	at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:362) ~[spring-orm-5.3.6.jar:5.3.6]
	at com.sun.proxy.$Proxy96.createQuery(Unknown Source) ~[na:na]
	at org.springframework.data.jpa.repository.query.SimpleJpaQuery.validateQuery(SimpleJpaQuery.java:87) ~[spring-data-jpa-2.4.8.jar:2.4.8]
	... 212 common frames omitted
Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected token: where near line 1, column 14 [select count(where) from com.example.demo.model.Person where age > 18]
	at org.hibernate.hql.internal.ast.QuerySyntaxException.convert(QuerySyntaxException.java:74) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.ErrorTracker.throwQueryException(ErrorTracker.java:93) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:301) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:189) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:144) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:113) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:73) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:162) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:613) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:725) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	... 220 common frames omitted

You can work around this problem by definining the count query explicitly in the annotation.

[schauder]

Could you please try @Query("from Person p where p.age > 18")?

[alienisty]

No exception in such case

[schauder]

Ok, that's what I expected. Spring Data JPA does require an alias for correctly constructing the count query.

For some reason it does not realise it doesn't have an alias, which would lead to a proper error message, but considers the where to be the alias, which is obviously not working.

I suspect that the use of the Hibernate syntax without select is causing this. Could you try one more thing?
Please try: "Select Person from Person where age > 18". You should get an error complaining about the missing alias.

In any case: To make your query work add the alias.
I'll keep this issue open for fixing the missing error informing the user about the missing alias.

[alienisty]

As far as I can tell requirement for an alias is not documented, at least not for the pagintion queries.
In any case if I use "select Person from Person where age > 18" I get the following NPE:

Caused by: java.lang.NullPointerException: null
	at java.base/java.lang.String$CaseInsensitiveComparator.compare(String.java:1224) ~[na:na]
	at java.base/java.lang.String$CaseInsensitiveComparator.compare(String.java:1218) ~[na:na]
	at java.base/java.util.TreeMap.getEntryUsingComparator(TreeMap.java:374) ~[na:na]
	at java.base/java.util.TreeMap.getEntry(TreeMap.java:343) ~[na:na]
	at java.base/java.util.TreeMap.get(TreeMap.java:277) ~[na:na]
	at org.hibernate.dialect.function.SQLFunctionRegistry.findSQLFunction(SQLFunctionRegistry.java:45) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.util.SessionFactoryHelper.findSQLFunction(SessionFactoryHelper.java:385) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.tree.IdentNode.getDataType(IdentNode.java:367) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.tree.SelectClause.initializeExplicitSelectClause(SelectClause.java:157) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.HqlSqlWalker.useSelectClause(HqlSqlWalker.java:1028) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.HqlSqlWalker.processQuery(HqlSqlWalker.java:796) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:694) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:330) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:278) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:276) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:192) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:144) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:113) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:73) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:162) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:613) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:725) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:114) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
	at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:362) ~[spring-orm-5.3.6.jar:5.3.6]
	at com.sun.proxy.$Proxy96.createQuery(Unknown Source) ~[na:na]
	at org.springframework.data.jpa.repository.query.SimpleJpaQuery.validateQuery(SimpleJpaQuery.java:87) ~[spring-data-jpa-2.4.8.jar:2.4.8]
	... 212 common frames omitted

[schauder]

Thanks for trying that. I'll review the documentation as well when working on this.

[gregturn]

Duplicates #2032.