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https://issues.apache.org/jira/browse/MCOMPILER-589?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17838936#comment-17838936
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Eric Hubert commented on MCOMPILER-589:
---------------------------------------
It looks like we can close the issue as invalid. It all seems to be caused by a
wrong/unintended configuration of the compiler plugin in the Maven project
which I think was a result of a non-optimal naming of the compiler plugin's
configuration parameter "generatedSourcesDirectory".
Other than the name may make suggest, it is only meant to be used for sources
generated by annotation processors (also properly documented via JavaDoc). With
this in mind, the above code (specifically the comments and the error message
make totally sense).
The project was configured like this:
{code}
<generatedSourcesDirectory>${project.basedir}/generated-sources</generatedSourcesDirectory>
{code}
placing annotation generated sources (if there were any) right next to other
generated sources instead of as by default in a subdirectory annotations. All
the years this configuration never caused issues, but with the added cleaning
of this directory before the compilation not only annotation processor
generated sources, but all sources were removed resulting in compilation errors.
> Compilation fails due to removed generated-sources after upgrade from 3.11.0
> to 3.12.0+
> ---------------------------------------------------------------------------------------
>
> Key: MCOMPILER-589
> URL: https://issues.apache.org/jira/browse/MCOMPILER-589
> Project: Maven Compiler Plugin
> Issue Type: Bug
> Affects Versions: 3.12.0, 3.12.1, 3.13.0
> Reporter: Eric Hubert
> Priority: Major
>
> After upgrading the used maven-compiler-plugin from 3.11.0 to 3.13.0 the
> class compilation fails, because generated resources are no longer present in
> the generated-sources folder.
> The project is setup in a way that during the generate-sources phase a plugin
> generates java sources which are stored in the configured generated-sources
> folder. Within the same phase these are added to the source using the
> build-helper-maven-plugin's add-source goal.
> When debugging the maven execution one can verify how the files are generated
> and placed in the correct folder. Once the maven-compiler-plugin > 3.11.0 is
> executed, the generated sources are deleted before the actual source code is
> compiled finally resulting in a compilation error. The issue can be
> reproduced with 3.12.1 and 3.12.0 and does not happen with 3.11.0.
> I did not yet find the time to debug the plugin, but briefly checked the
> release notes and found the ticket MCOMPILER-333 which might be the cause.
> Update: I now disabled incremental compilation by adding
> {code}
> -Dmaven.compiler.useIncrementalCompilation=false
> {code}
> on the command line to the Maven execution and all compiles fine and the
> generated-sources are used as expected. I think this way I put more evidence
> towards the changeset of MCOMPILER-333 to be the cause (therefore linking the
> ticket).
> I now also had a glance at the source code and have to admit that I do not
> really understand the reasoning of this change introducing an unconditional
> deletion of ALL files under generated-sources for incremental compilation
> (which is active by default). The generated sources are usually generated for
> a reason and must be processed during compilation. I'd expect this to break
> many use cases. What do I overlook here? I cannot see any direct relation to
> annotation processing as specified in the error message.
> {code}
> // MCOMPILER-333: Cleanup the generated source files created by
> annotation processing
> // to avoid issues with `javac` compiler when the source code is
> rebuild.
> if (getGeneratedSourcesDirectory() != null) {
> try (Stream<Path> walk =
> Files.walk(getGeneratedSourcesDirectory().toPath())) {
>
> walk.sorted(Comparator.reverseOrder()).map(Path::toFile).forEach(File::delete);
> // MCOMPILER-567: The directory must already exist
> because javac does not create it.
>
> Files.createDirectories(getGeneratedSourcesDirectory().toPath());
> } catch (IOException ex) {
> getLog().warn("I/O error deleting the annotation
> processing generated files: " + ex.getMessage());
> }
> }
> {code}
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