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NPE on missing service class #1189

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astubbs opened this issue Nov 1, 2021 · 2 comments · Fixed by #1191
Closed

NPE on missing service class #1189

astubbs opened this issue Nov 1, 2021 · 2 comments · Fixed by #1191
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@eamonnmcmanus
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Component: service P3 Status: accepted type=defect Bug, not working as expected

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@astubbs
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astubbs commented Nov 1, 2021 •
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I think this is happening to me after changing moving my implementations around

java: FATAL ERROR: java.lang.NullPointerException: Cannot invoke 
"com.google.common.collect.ImmutableSet.stream()" 
because the return value of 
"javax.lang.model.element.AnnotationValue.accept(javax.lang.model.element.AnnotationValueVisitor, Object)"
 is null
  	at com.google.auto.service.processor.AutoServiceProcessor$1.lambda$visitArray$0(AutoServiceProcessor.java:306)
  	at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:273)
  	at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
  	at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
  	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
  	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
  	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
  	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
  	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
  	at com.google.auto.service.processor.AutoServiceProcessor$1.visitArray(AutoServiceProcessor.java:307)
  	at com.google.auto.service.processor.AutoServiceProcessor$1.visitArray(AutoServiceProcessor.java:294)
  	at jdk.compiler/com.sun.tools.javac.code.Attribute$Array.accept(Attribute.java:349)
  	at com.google.auto.service.processor.AutoServiceProcessor.getValueFieldOfClasses(AutoServiceProcessor.java:293)
  	at com.google.auto.service.processor.AutoServiceProcessor.processAnnotations(AutoServiceProcessor.java:137)
  	at com.google.auto.service.processor.AutoServiceProcessor.processImpl(AutoServiceProcessor.java:121)
  	at com.google.auto.service.processor.AutoServiceProcessor.process(AutoServiceProcessor.java:109)
  	at org.jetbrains.jps.javac.APIWrappers$ProcessorWrapper.process(APIWrappers.java:152)
  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
  	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  	at java.base/java.lang.reflect.Method.invoke(Method.java:567)

Haven't quite been able to narrow it down exactly yet though.. Reproduced in this PR - see failing tests.

version: 1.0
@astubbs astubbs mentioned this issue Nov 1, 2021
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@astubbs
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astubbs commented Nov 1, 2021

I think it's something to do with the class originally being present, the service meta-inf file getting generated, the service class source file later being removed from the module, and it being compiled again without being cleaned first.

@astubbs astubbs changed the title NPE on missing class NPE on missing service class Nov 2, 2021
@eamonnmcmanus eamonnmcmanus self-assigned this Nov 2, 2021
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Looks like a simple one-line fix. If an @AutoService annotation references a missing class, the value on this line...

                    .flatMap(value -> value.accept(this, null).stream())

is the string "<error>", due to quirky javac behaviour. The visitor is expecting an array of class literals, or, in its recursive call, a single class literal, but not a string. Since the visitor has no override for visitString, a null default value is returned. We can simply provide an empty ImmutableSet as the default value to fix the problem. There is no need to handle this error case specially, since the compiler will be outputting its own errors about the missing class anyway.

copybara-service bot pushed a commit that referenced this issue Nov 2, 2021
@eamonnmcmanus
Handle missing classes better in AutoService.
74f0575 
Fixes #1189.
Closes https://github.com/google/auto/pull/1190/files.
Many thanks to @astubbs for the bug report and repro.

If an `@AutoService` annotation references a missing class, the `value` on [this line](https://github.com/google/auto/blob/15c76191f79a2a26a9f914541a5c9ac4965dd0c7/service/processor/src/main/java/com/google/auto/service/processor/AutoServiceProcessor.java#L306)...
```java
                    .flatMap(value -> value.accept(this, null).stream())
```
is the string `"<error>"`, due to quirky javac behaviour. Currently, the visitor expects an array of class literals, or, in its recursive call, a single class literal, but not a string. Since the visitor has no override for [`visitString`](https://docs.oracle.com/en/java/javase/11/docs/api/java.compiler/javax/lang/model/element/AnnotationValueVisitor.html#visitString(java.lang.String,P)), a null default value is returned. We can simply provide an empty `ImmutableSet` as the default value to fix the problem. There is no need to handle this error case specially, since the compiler will be outputting its own errors about the missing class anyway.

RELNOTES=AutoService no longer throws an exception for a missing service class.
PiperOrigin-RevId: 407146682
@copybara-service copybara-service bot mentioned this issue Nov 2, 2021
Merged
copybara-service bot pushed a commit that referenced this issue Nov 3, 2021
@eamonnmcmanus
Handle missing classes better in AutoService.
e247e2a 
Fixes #1189.
Closes https://github.com/google/auto/pull/1190/files.
Many thanks to @astubbs for the bug report and repro, which was the basis for the new test here.

If an `@AutoService` annotation references a missing class, the `value` on [this line](https://github.com/google/auto/blob/15c76191f79a2a26a9f914541a5c9ac4965dd0c7/service/processor/src/main/java/com/google/auto/service/processor/AutoServiceProcessor.java#L306)...
```java
                    .flatMap(value -> value.accept(this, null).stream())
```
is the string `"<error>"`, due to quirky javac behaviour. Currently, the visitor expects an array of class literals, or, in its recursive call, a single class literal, but not a string. Since the visitor has no override for [`visitString`](https://docs.oracle.com/en/java/javase/11/docs/api/java.compiler/javax/lang/model/element/AnnotationValueVisitor.html#visitString(java.lang.String,P)), a null default value is returned. We can simply provide an empty `ImmutableSet` as the default value to fix the problem. There is no need to handle this error case specially, since the compiler will be outputting its own errors about the missing class anyway.

RELNOTES=AutoService no longer throws an exception for a missing service class.
PiperOrigin-RevId: 407146682
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Handle missing classes better in AutoService. google/auto
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