[MBUILDCACHE-106] Missing compile source roots matching 'generated-sources' and 'generated-test-sources' when compiler is skipped

[reda-alaoui]

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[AlexanderAshitkin]

Could you please explain why we need to attach the sources to the project? The cache should not affect the build; it should only restore dependencies. If the build doesn't require these source roots, it doesn't seem correct to attach them.

[reda-alaoui]

The bug fixed by this PR can emerge with #177 merged.
If reconciliation is done like proposed in #177, we can have the following situation.

A project uses an annotation processor to generate some java files. A cached entry exists and comes from a verify -DskipTests. The new build verify reuses this entry by skipping all plugin executions preceding maven-surefire-plugin. Among the skipped executions is compiler:compile. After the tests comes maven-javadoc-plugin. When maven-javadoc-plugin runs, the build fails because maven-javadoc-plugin is unable to find the source files of the compiled generated-sources.
This is because maven-javadoc-plugin expects maven-compiler-plugin to have enriched the maven context with the additional source roots. But since this later was skipped by the cache, additional source roots are missing.

[AlexanderAshitkin]

It's possible that there are multiple generated source roots attached at different levels. The best solution would be to add extra metadata to accurately track and restore all the source roots. Alternatively, it's possible to implement a convention-based restoration by matching the logic in CacheControllerImpl#attachGeneratedSources to restore all the sources associated with a GENERATED_SOURCE cache entry. Check this part too:

        for (String sourceRoot : sourceRoots) {
            final Path sourceRootPath = Paths.get(sourceRoot);
            if (Files.isDirectory(sourceRootPath)
                    && sourceRootPath.startsWith(targetDir)
                    && !(sourceRootPath.startsWith(generatedSourcesDir)
                            || sourceRootPath.startsWith(generatedTestSourcesDir))) { // dir within target
                attachDirIfNotEmpty(sourceRootPath, targetDir, project);
            }
        }

[AlexanderAshitkin]

The fix should work in a generic case

[AlexanderAshitkin]

It's possible that there are multiple generated source roots attached at different levels. The best solution would be to add extra metadata to accurately track and restore all the source roots. Alternatively, it's possible to implement a convention-based restoration by matching the logic in CacheControllerImpl#attachGeneratedSources to restore all the sources associated with a GENERATED_SOURCE cache entry. Check this part too:

        for (String sourceRoot : sourceRoots) {
            final Path sourceRootPath = Paths.get(sourceRoot);
            if (Files.isDirectory(sourceRootPath)
                    && sourceRootPath.startsWith(targetDir)
                    && !(sourceRootPath.startsWith(generatedSourcesDir)
                            || sourceRootPath.startsWith(generatedTestSourcesDir))) { // dir within target
                attachDirIfNotEmpty(sourceRootPath, targetDir, project);
            }
        }