[GROOVY-8833] @Canonical creates invalid hashCode

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 2.5.2
• Fix Version/s: 3.0.0-alpha-4, 2.5.3
• Component/s: Compiler
• Assignee: Paul King
• Reporter: Octavia Togami
• Created: 07/Oct/18 07:36
• Updated: 13/Dec/18 10:05
• Resolved: 08/Oct/18 10:28

Description

Applying @Canonical to a class will generate an invalid hashCode method that throws a runtime cast exception. This does not happen if you apply the individual annotations by themselves.

These tests can be injected into a Groovy test class to see the problem: https://gist.github.com/kenzierocks/fb0932756c3955a7ddbc0b710791af11

I suspect the underlying cause is that @EqualsAndHashCode does not set accessedVariable on its _result variable, which causes the verifier to overwrite it with toString's _result variable (see FinalVariableAnalyzer#fixVar). This results in an invalid cast. I observed this behavior while debugging the compiler. I'm not sure why this doesn't also happen if the two annotations are applied by themselves, rather than via @Canonical.

 

I was able to fix this problem by setting _result to reference itself in the AST, but perhaps that's not the right fix here.