[JENKINS-67960] Work around MCOMPILER-346 #511
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Background
See JENKINS-67960 and MCOMPILER-346. I have run into this bug repeatedly while working on Jenkins, most recently in jenkinsci/acceptance-test-harness#733.
Problem
When compiling Jenkins code with compilation errors with Java 11, MCOMPILER-346 is frequently encountered. If you encounter it with
-source 8, you get aNullPointerException. If you encounter it with-source 11, you get anAssertionError. Either way, you do not get a readable message with the compilation error. Therefore, you have no idea what you need to fix in order to get the code to compile.Solution
TBD. MCOMPILER-346 has remained open since June 28, 2018. I submitted a Minimal Reproducible Example (MRE) hoping that this will help the Maven developers resolve the issue.
Workaround
In the past, I have worked around this issue by switching back to Java 8. This works with
-source 8, but it does not work with-source 11for obvious reasons. Therefore, a new workaround is needed. I have just discovered a new workaround: running Maven with-Dmaven.compiler.forceJavacCompilerUse=true. Until MCOMPILER-346 is fixed, we should enable this workaround by default for all Jenkins builds. Otherwise, people compiling with Java 11 will get strangeNullPointerExceptions orAssertionErrors when their code does not compile rather than a comprehensible error message explaining the source of the compilation error.Testing done
See jenkinsci/pom#235.