RFR: 8015831: Add lint check for calling overridable methods from a constructor [v7]

[Maurizio Cimadamore]

On Fri, 13 Jan 2023 11:05:51 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> So, to clarify, in this case:
>> 
>> 
>> import java.util.*;
>> 
>> class B {
>>     final Object ref;
>> 
>>      private B(Object ref) {
>>           Foo.consume(this);
>>           this.ref = ref;
>>       }
>>  }
>> 
>> 
>> Even though `this` leaks to a method clearly before it is fully initialized, we do not care because there can be no subclass involved observing this. I guess I was confused because, while subclasses are a particularly sneaky case where uninitialized values can show up, the above leak seems potentially dangerous as well - we're effectively leaking a class whose final field has not been initialized!
>> 
>> That said, if that was discussed, and it was decided for the warning not to deal with this case, that's ok.
>
> Perhaps my confusion might come from the name `this-escape` of the lint warning - which seems overpromising in this respect. But I looked at the description of the lint warning using `javac --help-lint` and I got this:
> 
> 
>     this-escape          Warn when a constructor invokes a method that could be overriden in a subclass;
> 
> 
> Which indeed aligns well with what this PR is doing. So that's ok.

Something seems to be up with the lint description for this-escape - compare this:


  serial               Warn about Serializable classes that do not have a serialVersionUID field. 
                         Also warn about other suspect declarations in Serializable and Externalizable classes and interfaces.

with this:


  this-escape          Warn when a constructor invokes a method that could be overriden in a subclass;
such a method would execute before the subclass constructor completes its initialization.


Indentation seems to be missing, which causes readability issues in the `--help-lint` output.

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PR: https://git.openjdk.org/jdk/pull/11874