[Records] Why components are not readOnly

[Alex Buckley]

On 1/21/2020 4:04 PM, Valentin Kovalenko wrote:
>> Brian
>> remember that modifying final fields is wholly outside of either the
> language or VM specification
> 
> Not that I am advocating for "tacking weird corner-case behavior in a dozen
> different places", but JLS does have a whole paragraph talking about
> modification of final fields via reflection and other
> implementstion-dependent mechanisms.
> 
> JLS 15.5.3 says: "final fields can be changed via reflection and other
> implementstion-dependent means".

Not 15.5.3. You mean 17.5.3, deep inside the chapter on the Java Memory 
Model. While that chapter underpins field access in Java programs, the 
material in 17.5.3 is plainly meant for advanced behavior by "the 
system". I recommend a less literal, more charitable reading of Brian's 
mail: "modifying final fields is wholly outside of the programming model 
available to ordinary Java programs or ordinary JVM bytecode."

Alex