RFR: 8291359: Specification of method j.l.foreign.VaList::skip still deserves clarification [v4]

[Maurizio Cimadamore]

On Fri, 2 Dec 2022 16:59:25 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   rewrite doc
>
> src/java.base/share/classes/java/lang/foreign/VaList.java line 55:
> 
>> 53:  * and any other type that fits into a {@code long}.
>> 54:  * <h2 id="safety">Safety considerations</h2>
>> 55:  * Accessing a value through a variable argument list using the wrong memory layout will result in undefined behavior.
> 
> Note that I went with "through" here, instead of "in", since we describe a va list as a "stateful cursor used to iterate over a set of arguments" in the section before this.

I think we can condense this:


 For instance, if a variable argument list currently points at a C {@code int} value, then accessing it using
 * {@link #nextVarg(ValueLayout.OfLong)} is illegal. Similarly, accessing the variable argument list with  {@link #skip(MemoryLayout...)}, and providing a layout other than {@link ValueLayout.OfInt} is illegal. Any such illegal accesses might not be detected by the implementation, and can corrupt the variable argument list, so that the behavior of subsequent accesses is also undefined.
 ```

-------------

PR: https://git.openjdk.org/jdk/pull/11440