Incremental compilation after failure issues when all classes are not removed

[asodja]

We got some reports from GE and also internally that after added incremental compilation after failure feature there are issues with Groovy incremental compilation. It would be good if we add an option to opt-out of this feature just in case. Or maybe even to opt-in for Groovy.

The report was, that when a super class is changed, then sometimes exception like is thrown:

Standard error from JVM:
    Terminating due to fatal error
    java.lang.NoClassDefFoundError: org/gradle/.../AppTest$__spock_feature_5_0_closure3

Note: original class name is censored since this is not public repo. Check a build scan https://e.grdev.net/s/omiun4on2i5jy to see the actual class name.

After some investigation we figured, that output directory contains wrong classes. It should contain these:

AppTest$__spock_feature_4_0_closure2.class
AppTest$__spock_feature_4_0_closure3$_closure15.class
AppTest$__spock_feature_4_0_closure3.class
AppTest$__spock_feature_4_1_closure4$_closure16.class
AppTest$__spock_feature_4_1_closure4.class
AppTest$__spock_feature_4_2_closure5.class
AppTest$__spock_feature_4_3_closure6.class
AppTest$__spock_feature_4_3_closure7.class
AppTest$__spock_feature_4_4_closure8.class
AppTest$__spock_feature_4_4_closure9$_closure17$_closure18.class
AppTest$__spock_feature_4_4_closure9$_closure17$_closure19.class
AppTest$__spock_feature_4_4_closure9$_closure17.class
AppTest$__spock_feature_4_4_closure9.class
AppTest$__spock_feature_4_5_closure10.class
AppTest$__spock_feature_4_5_closure11$_closure20$_closure21.class
AppTest$__spock_feature_4_5_closure11$_closure20$_closure22.class
AppTest$__spock_feature_4_5_closure11$_closure20.class
AppTest$__spock_feature_4_5_closure11.class
AppTest$__spock_feature_4_6_closure12.class
AppTest$__spock_feature_4_7_closure13.class
AppTest$__spock_feature_4_7_closure14.class
AppTest$_setup_closure1.class
AppTest.class

But it contained these:

AppTest$__spock_feature_4_1_closure4$_closure16.class
AppTest$__spock_feature_4_1_closure4.class
AppTest$__spock_feature_4_2_closure5.class
AppTest$__spock_feature_4_3_closure6.class
AppTest$__spock_feature_4_3_closure7.class
AppTest$__spock_feature_4_4_closure8.class
AppTest$__spock_feature_4_4_closure9$_closure17$_closure18.class
AppTest$__spock_feature_4_4_closure9$_closure17$_closure19.class
AppTest$__spock_feature_4_4_closure9$_closure17.class
AppTest$__spock_feature_4_4_closure9.class
AppTest$__spock_feature_4_5_closure10.class
AppTest$__spock_feature_4_5_closure11$_closure20$_closure21.class
AppTest$__spock_feature_4_5_closure11$_closure20$_closure22.class
AppTest$__spock_feature_4_5_closure11$_closure20.class
AppTest$__spock_feature_4_5_closure11.class
AppTest$__spock_feature_4_6_closure12.class
AppTest$__spock_feature_4_7_closure13.class
AppTest$__spock_feature_4_7_closure14.class
AppTest$__spock_feature_5_0_closure3$_closure15.class
AppTest$__spock_feature_5_1_closure4$_closure16.class
AppTest$__spock_feature_5_4_closure9$_closure17$_closure18.class
AppTest$__spock_feature_5_4_closure9$_closure17$_closure19.class
AppTest$__spock_feature_5_4_closure9$_closure17.class
AppTest$__spock_feature_5_5_closure11$_closure20$_closure21.class
AppTest$__spock_feature_5_5_closure11$_closure20$_closure22.class
AppTest$__spock_feature_5_5_closure11$_closure20.class
AppTest$_setup_closure1.class
AppTest.class

We suspect, that we don't clean all .class files that will be produced by the AppTest.groovy file before compilation. And since we don't delete some classes Groovy has them at compile time on the classpath, and that is why it creates new extra spock_feature_5_5 classes.

While I wasn't able to reproduce the original issue, I was able to reproduce that we don't clean all the classes for AppTest.groovy.

A simpler test case that shows that we don't clean all classes is:

file: A.java
class A {}

file: B.java
class B extends A {}
class C {} // this class is in the same file

If/when we change A, classes B and C will be recompiled since we will pass B.java to a compiler (B.class is a dependency of A.class, so we pass B.java to the compiler). But we won't delete origin C.class. So C.class will be on the classpath at the compile time.