Classpath scanning on inner classes fails against JDK 11 bytecode level [SPR-17096]

[spring-projects-issues]

Kedar Joshi opened SPR-17096 and commented

After upgrading to Spring 5.1 RC1 my application started failing with following exception - 

Caused by: java.lang.UnsupportedOperationException
 at org.springframework.asm.ClassVisitor.visitNestHostExperimental(ClassVisitor.java:156) ~[spring-core-5.1.0.RC1.jar:5.1.0.RC1]
 at org.springframework.asm.ClassReader.accept(ClassReader.java:541) ~[spring-core-5.1.0.RC1.jar:5.1.0.RC1]
 at org.springframework.asm.ClassReader.accept(ClassReader.java:391) ~[spring-core-5.1.0.RC1.jar:5.1.0.RC1]
 at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:65) ~[spring-core-5.1.0.RC1.jar:5.1.0.RC1]
 at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:103) ~[spring-core-5.1.0.RC1.jar:5.1.0.RC1]
 at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:123) ~[spring-core-5.1.0.RC1.jar:5.1.0.RC1]
  

Turned out, this is happening when spring tries to process classes which have inner class themselves. e.g.  in.workingtheory.Application class has an inner class FailureGeneration. Application will not start unless I remove this inner class altogether or remove class in.workingtheory.Application from class path scanning.

This is only reproducible on JDK 11 and Spring 5.1 RC1 but works fine on JDK 10.

Sample project for reproducing this issue is attached.

+Environment+

Oracle JDK 11 Build 23 (64 Bit)
Spring framework 5.1 RC1

---

Affects: 5.1 RC1

Attachments:

• Spring-5.1.zip (5.59 kB)

Issue Links:

• Upgrade to ASM 6.2 [SPR-16398] #20944 Upgrade to ASM 6.2
• LocalVariableTableParameterNameDiscoverer runs into UnsupportedOperationException in ClassVisitor.visitNestMemberExperimental() [SPR-17103] #21640 LocalVariableTableParameterNameDiscoverer runs into UnsupportedOperationException in ClassVisitor.visitNestMemberExperimental()
• Compatibility with JDK 11 [SPR-16391] #20937 Compatibility with JDK 11

Referenced from: commits e82efbc

[spring-projects-issues]

Juergen Hoeller commented

I assume this only happens when compiling with the default target (i.e. JDK 11 bytecode)? Does it work when compiling with -target 1.8 or even -target 10 and deploying to JDK 11?

[spring-projects-issues]

Juergen Hoeller commented

This seems to be a consequence of our ASM 6.2 upgrade which only has experimental support for the JDK 11 bytecode level and doesn't activate it by default. We can get around it by declaring our visitors as ASM7_EXPERIMENTAL (which we'll probably do for Spring Framework 5.1 RC2) but ideally we'd get a proper ASM 7 upgrade in time for 5.1's general availability.

[spring-projects-issues]

Kedar Joshi commented

Yes, you are right. This happens with JDK 11 bytecode only. Work fine on JDK 11 with bytecode level 1.8, 9 and 10.

[spring-projects-issues]

Juergen Hoeller commented

I've switched our SpringAsmInfo.ASM_VERSION to ASM7_EXPERIMENTAL for the time being. This should hopefully allow for parsing all currently known JDK 11 bytecode variants.