Cascade does not propose fixes for purity errors

[reprogrammer]

Cascade doesn't propose fixes for some of the purity error messages that the nullness checker reports. Below is one such error message.

warning: [purity.invalid.overriding] String toString(BiGraph this) in em3d.BiGraph cannot override String toString(Object this) in java.lang.Object; attempting to use an incompatible purity declaration
   public String toString() {
                 ^
   found   : []
   required: [SIDE_EFFECT_FREE]

In this case, the fix would be to simply annotate the toString method as @SideEffectFree.

[reprogrammer]

One possible workaround is to use the flag -AsuppressWarnings=purity.invalid.overriding to suppress this warning in the first place because the checker framework manual suggests that the framework is going to support the inheritance of annotations from superclasses, which avoids the warning above.

[reprogrammer]

Another workaround is to rename the method toString in the applications under study to some other name.

[reprogrammer]

Overriding method clone (e.g., in jolden-bh) causes a similar error.