[External] : Re: RFR: 8193904: Uninitialized final field access and qualified this

[Alex Buckley]

DU/DA analysis is about whether names have bindings. `x.foo` and `new 
C().foo` and `m().foo` are expressions, not names, so we don't attempt 
the analysis on them. As Jan points out [1], access via expressions is 
hard to track. `this.foo` is an expression, but a very easy one, so we 
treat it like the name `foo` and do the analysis. `A.B.C.this.foo` is an 
expression with a qualified-this subexpression and now you need a bunch 
of analysis to figure out whether it means the same as the name `foo`.

Alex

[1] 
https://bugs.openjdk.org/browse/JDK-8289777?focusedCommentId=14516785&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14516785


On 11/2/2022 1:18 PM, Archie Cobbs wrote:
> On Wed, Nov 2, 2022 at 2:47 PM Alex Buckley <alex.buckley at oracle.com 
> <mailto:alex.buckley at oracle.com>> wrote:
> 
>     JLS ch.16 is specific that only `foo` and `this.foo` cause an error.
>     See
>     the definition of "access" in the opening paragraphs of the chapter.
> 
> 
> Thanks for pointing that out, which I forgot to do. The JLS language is:
> 
> An access to its value consists of the simple name of the variable (or, 
> for a field, the simple name of the field qualified by |this|) occurring 
> anywhere in an expression except as the left-hand operand of the simple 
> assignment operator |=| ||
> 
> In theory one could argue that MyClass.this.foo is also an example of 
> "the simple name of the field qualified by |this" - just look at the 
> latter part, no?
> |
> |
> |
> Regardless, it looks like there needs to be a spec change... right? I'm 
> assuming we'd rather do that than continue to allow the current behavior.
> 
> Thanks,
> -Archie
> 
> -- 
> Archie L. Cobbs